Sustainable Logistics for E-Commerce: A Literature Review and Bibliometric Analysis

: This study aims to present a bibliometric analysis and literature review and to identify publications, main topics, and trends in recent years about the sustainability of logistics operations in e-commerce environments. For this, we considered 99 documents from Scopus published in 2021 and 2022 that address logistics, e-commerce, and sustainability. The bibliometric analysis shows that authors from Italy and India stand out for generating the largest number of publications, and correspondingly, institutional afﬁliations from these countries present the largest scientiﬁc production. It is established that journals such as Sustainability , International Journal of Logistics Research and Applications , and Sustainable Cities and Society lead both in the number of published articles and the number of articles with the highest citations. Within the main topics are the sustainability of e-commerce logistics, last-mile logistics and delivery logistics, urban and city logistics, environmental impact, urban transport, packing and packaging, trafﬁc and congestion, supply chains, the effects of the COVID-19 pandemic, China and cross-border e-commerce, vehicle routing, optimization methods, and decision-making techniques in operations for cost and energy efﬁciency. Similarly, this study identiﬁes the main research trends related to multiple dimensions of sustainability; technological developments including electric vehicles and specialized software; crowdshipping; operation modes such as collection and delivery points, parcel lockers, and micro-depots


Introduction
Before the COVID-19 pandemic, the world had shown an increase in the transport of goods in urban areas.During the social issolation and lockdown measures, urban mobility transport and the distribution of products presented a substantial change representing an unsustainable development of the urban environment [1,2].Consequently, some market development dynamics have changed permanently over recent years, with online shopping becoming more popular among city dwellers [3], including the purchase of fresh food and other perishable products through e-commerce platforms [4][5][6].It has been promoted, in part, by the increase in urbanization and the need for supplies and provisions in cities, the increase in e-commerce, and the appearance of new forms of purchase and consumption habits that increase the purchases of products online, making goods travel and be delivered in cities around the world [7,8].E-commerce can be understood as the online purchase and sale of goods or services through the Internet [9], either business to business (B2B), consumer to consumer (C2C), or business to consumer (B2C) [10].Compared to purchases in physical stores, e-commerce and home deliveries tend to generate positive consumer perceptions regarding environmental impact by reducing consumer transportation and reducing flows of non-sold items between warehouses and physical stores [11].
However, the constant growth of e-commerce transactions and the parcel distribution in cities increases the entry of trucks and cargo vehicles in cities, generating negative externalities related to the increase in congestion, emissions, and pollution [12,13].One of the most representative areas of urban merchandise transport is last-mile deliveries, which this reason, an international group that included experienced authors and methodologists developed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews) guideline, which consists of four phases: identification, screening, eligibility, and inclusion [40].Since the PRISMA statement recommends that authors report their search strategies for all databases, registries, or websites [41], this systematic literature review embraces such criteria, which are described below.
The identification phase sets the number of records identified through database searching and other sources.Documents were searched in the Scopus and Web of Science databases that included the concept of logistics, e-commerce, and sustainability (or similar terms) in their title, abstract, or keywords.The objective was to identify the existing literature on this topic published in the last two years, including all types of documents such as articles, reviews, conference papers, and book chapters, among others, in any language and from any country of origin.For this, a document search was performed in the Scopus database using the following search equation: TITLE-ABS-KEY (logistics AND e-commerce AND sustainab*), obtaining 253 documents from the year 2000.Then, the search equation was limited to the years 2021 and 2022, adding the following restriction to the search equation AND (LIMIT-TO (PUBYEAR, 2022) OR LIMIT-TO (PUBYEAR, 2021)) to present a literature analysis on the sustainability of logistics operations in e-commerce environments in recent years, evidencing the effects of the COVID-19 pandemic.A total of 99 documents were obtained, representing 40.7% of the initial search, as shown in Figure 1, demonstrating that the documents obtained represent a relevant contribution to the scientific output around the research topic and reflect the main research in sustainable e-commerce logistics under the COVID-19 pandemic.
Sustainability 2022, 14, x FOR PEER REVIEW logistics in e-commerce published in the year 2021 and 2022 (the search was perform the beginning of June 2022).In a systematic literature review, the eligibility criteria documents must be specified, which must be consistent with the purpose of the res so the document search methods must be made explicit in order to present transp and reliable results to draw conclusions and support decision making [39].For this re an international group that included experienced authors and methodologists deve the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analys Scoping Reviews) guideline, which consists of four phases: identification, screenin gibility, and inclusion [40].Since the PRISMA statement recommends that authors r their search strategies for all databases, registries, or websites [41], this systematic ture review embraces such criteria, which are described below.
The identification phase sets the number of records identified through dat searching and other sources.Documents were searched in the Scopus and Web of Sc databases that included the concept of logistics, e-commerce, and sustainability (or si terms) in their title, abstract, or keywords.The objective was to identify the existing ature on this topic published in the last two years, including all types of documents as articles, reviews, conference papers, and book chapters, among others, in any lang and from any country of origin.For this, a document search was performed in the S database using the following search equation: TITLE-ABS-KEY (logistics AND e merce AND sustainab*), obtaining 253 documents from the year 2000.Then, the s equation was limited to the years 2021 and 2022, adding the following restriction search equation AND (LIMIT-TO (PUBYEAR, 2022) OR LIMIT-TO (PUBYEAR, 202 present a literature analysis on the sustainability of logistics operations in e-comm environments in recent years, evidencing the effects of the COVID-19 pandemic.A of 99 documents were obtained, representing 40.7% of the initial search, as shown i ure 1, demonstrating that the documents obtained represent a relevant contribution scientific output around the research topic and reflect the main research in sustaina commerce logistics under the COVID-19 pandemic.The screening phase sets the number of records after duplicates are removed, of which, when comparing the 99 Scopus documents with the 94 WOS documents, we found 85 replicated documents; WOS contributed nine documents to those found in Scopus, obtaining a base of 108 documents.The eligibility phase sets the number of full-text articles assessed for eligibility and the number of full-text articles excluded, with reasons.Consequently, the 108 documents from Scopus and WOS were applied as eligibility criteria to address issues related to logistics, urban delivery, supply chain-related topics, urban distribution, last-mile delivery, transportation, packaging, or vehicle routing.After applying these criteria, three articles that dealt with users' sentiment toward text review, omnichannel approaches, and tourism were eliminated and moved away from the scope of this study.The inclusion phase of the PRISMA method sets the number of studies included in qualitative and quantitative synthesis, which in this case was 105 documents.Then, these documents received an analysis based on leading authors, institutional affiliation, documents by country/territory, subject areas, leading journals, most-cited documents, main research topics addressed, and the co-occurrence of concepts.The screening phase sets the number of records after duplicates are remove which, when comparing the 99 Scopus documents with the 94 WOS documents, we f 85 replicated documents; WOS contributed nine documents to those found in Scopu taining a base of 108 documents.The eligibility phase sets the number of full-text ar assessed for eligibility and the number of full-text articles excluded, with reasons.C quently, the 108 documents from Scopus and WOS were applied as eligibility crite address issues related to logistics, urban delivery, supply chain-related topics, urban tribution, last-mile delivery, transportation, packaging, or vehicle routing.After app these criteria, three articles that dealt with users' sentiment toward text review, omni nel approaches, and tourism were eliminated and moved away from the scope o study.The inclusion phase of the PRISMA method sets the number of studies includ qualitative and quantitative synthesis, which in this case was 105 documents.Then, documents received an analysis based on leading authors, institutional affiliation, d ments by country/territory, subject areas, leading journals, most-cited documents, research topics addressed, and the co-occurrence of concepts.
The analysis of authors, institutional affiliation, and countries/territories indicate geographic location and institutions concentrating on the scientific production of th search topic.The subject areas establish the approach received by the publications on tainable e-commerce logistics and clarify how this topic is addressed in the literature journals and authors with the greatest number of published documents make it po to point out the recommended sources for the publication of works and the docum with the most impact.The main topics and research concepts are identified throug keywords of the collected documents, and the co-occurrence of these concepts is e lished through clusters generated with the VOSviewer software, identifying res nodes in each cluster through the size of its corresponding spheres.

Results
The results of the bibliometric analysis indicate that the authors with the gre contributions to the sustainability of logistics operations in e-commerce are Bulde (France/Belgium), Prajapati (Jabalpur, India), Pratap (Varanasi, India), Chelladurai (J The analysis of authors, institutional affiliation, and countries/territories indicates the geographic location and institutions concentrating on the scientific production of the research topic.The subject areas establish the approach received by the publications on sustainable e-commerce logistics and clarify how this topic is addressed in the literature.The journals and authors with the greatest number of published documents make it possible to point out the recommended sources for the publication of works and the documents with the most impact.The main topics and research concepts are identified through the keywords of the collected documents, and the co-occurrence of these concepts is established through clusters generated with the VOSviewer software, identifying research nodes in each cluster through the size of its corresponding spheres.

Results
The results of the bibliometric analysis indicate that the authors with the greatest contributions to the sustainability of logistics operations in e-commerce are Buldeo Rai (France/Belgium), Prajapati (Jabalpur, India), Pratap (Varanasi, India), Chelladurai (Jabalpur, India), Mangiaracina (Milan, Italy), Seghezzi (Milan, Italy), Tumino (Milan, Italy), and Macharis (Brussels, Belgium), each providing three or more documents in the last two years, as shown in Table A1.
Collaborative work is also identified between Gatta and Marcucci [33,51], affiliated to the Università degli Studi Roma Tre.In Austria, Brandtner, Herman, Pfoser, and Schauer are co-authors at the University of Applied Sciences Upper Austria [52,53].Settey and Gnap, from the University of Žilina in Slovakia, co-author two studies [1,54], and Villa and Monzón are co-authors in Spain affiliated with the Polytechnic University of Madrid and the Camilo José Cela University [7,55].In Asia, Dang, Nguyen, and Wang work together [56,57], generating relationships between VNUHCM and the National Kaohsiung University of Science and Technology.
Table 1 corroborates this information and shows the main institutional affiliations and the institutions producing the most scientific output on the research topic.In this sense, Politecnico di Milano (Milan, Italy) heads the list, participating in 5.7% of the publications [20,[48][49][50]58,59], in which the majority of leading authors such as Mangiaracina, Seghezzi, Tumino, and Siragusa participate.In second place is the IIITDM Jabalpur (Jabalpur, India) and the Indian Institute of Technology (BHU), contributing four documents [44][45][46][47], where leading authors such as Prajapati, Chan, Chelladurai, and Pratap participate.Likewise, among the institutions that provide three documents are the Università degli Studi di Padova (Padua, Italy) [34,60,61], and Vrije Universiteit Brussel (Belgium) [19,42,43].In this way, the significant contribution by universities in Italy and India in the field of research is remarkable.Likewise, Table 2 corroborates this information, showing that Italy ranks second, participating in 12.4% of documents, while China leads with institutions from that country in 31.4% of published documents.Therefore, China presents the largest number of document production; however, said production is not concentrated in a few institutions or authors because the institutions of that country that contribute the most documents are Shanxi University and Tongji University, each with two documents, respectively.Likewise, China leads the scientific output due to the rapid expansion of the express delivery industry in that country and the environmental pollution problem triggered by the express packaging wastes that severely impact human health and sustainable social development [62].Moreover, Table 3 shows that the dominant subject area of sustainable e-commerce logistics is social sciences due to the sustainability approach and its social dimension.Environmental sciences and energy are related to the environmental dimension of sustainability, while the business, administration, and accounting area oversees the economic dimension and e-commerce business models.Areas such as engineering support the technical, operational, and logistical components of e-commerce.Areas such as computer science, decision making, and mathematics address optimization models to improve the three sustainability dimensions.Regarding publication sources, the leading journal in the number of published documents is Sustainability (MDPI), contributing 24.8% of the published articles on the research topic, followed by the International Journal of Logistics Research and Applications, which contributes 4.8% of the articles.It is noteworthy that of the nine leading journals that have contributed two or more documents in the last two years, three correspond to conferences and proceedings containing documents related to preliminary findings and the rapid dissemination of research results.This research can probably be published in a complete and refined version in journals that also make up the ranking in Table 4.In fact, of the 105 documents obtained in this analysis, 72.4% of the documents correspond to articles, 20.0% to conference papers, 5.7% to literature reviews, and 1.9% to book chapters.
It should be noted from Table A2 that four of the most-cited articles belong to the journal Sustainability (MDPI), while three of these articles belong to the journal Sustainable Cities and Society (Elsevier).Similarly, the International Journal of Logistics Research and Applications (Taylor and Francis) provides two of the most-cited articles on the research topic.Likewise, these journals stand out for the impact of the articles published by obtaining significant citations.Table A2 also shows that nine articles belong to journals of the publisher MDPI, while nine articles belong to journals published by Elsevier.On the other hand, it is identified that authors such as Mangiaracina and Seghezzi are co-authors of two of the most-cited articles in the last two years [20,48].Likewise, Villa and Monzón [7,55], Wang, Dang, and Nguyen [56,57], and Buldeo Rai and Macharis [19,43] are co-authors of two of the most-cited articles.Most of the articles in Table A2 are open access, except for [8,15,19,63,64]; thus, it is relevant to consider open access journals and publication sources that increase the visibility and impact of publications on the research topic.It is also highlighted that three of the most-cited documents are literature reviews [15,33,36], which usually receive a high number of citations by becoming seminal articles that compile the main contributions of publications around a research topic.represent the central topic and the concepts used in the search equation.Figure 3 sh that the topics of last-mile logistics and delivery logistics stand out, being addressed i documents (24.8%), as well as urban and city logistics that are addressed in 21 docum (20.0%).In this sense, much of the discussion on sustainable e-commerce logistics foc on urban contexts and addresses the challenges related to environmental impact (po tion control, recycling, circular economy, green logistics, reverse logistics), ur transport, packaging, traffic, and congestion.Other relevant issues are related to supply chains and supply chain managem and the effects of the COVID-19 pandemic that increased the use of e-commerce and erated significant changes in consumer behavior.Likewise, topics such as China cross-border e-commerce are booming, as China represents the country with the lar participation in e-commerce worldwide and plays a significant role in the world econ regarding the manufacture of products and movement of goods [65-68].Cross-bord commerce also highlights the need to move products abroad using international logi [69][70][71][72], and it requires traceability systems to help overcome information uncertainty asymmetry among supply chain stakeholders from the supply side to end-customer prevent counterfeit goods [73].From a technical point of view, vehicle routing issues st out, supported by multi-objective optimization [74,75], and planning and decision-m ing techniques to increase cost and energy efficiency [76][77][78], and minimize the total associated with order processing [47] (economic dimension).Likewise, additional cepts related to freight transport solutions, such as electronic vehicles and drones and tribution solutions such as crowdsourcing and parcel lockers, are relevant in the literat For the social dimension, topics related to accident prevention, reduction of traffic gestion, circular economy, and improvement of the delivery service are identified in documents analyzed.
The association of these concepts is illustrated in Figure 4, which details the co currence analysis of concepts and keywords through four clusters focused on e-c merce, sustainability, sustainable development, and supply chain.The findings of The association of these concepts is illustrated in Figure 4, which details the cooccurrence analysis of concepts and keywords through four clusters focused on e-commerce, sustainability, sustainable development, and supply chain.The findings of co-occurrence analysis enabled the identification of the core concepts focusing on sustainable e-commerce logistics between 2021 and 2022.For this, the input database was previously prepared by gathering the keywords from the Scopus and WOS documents and unifying similar concepts such as "last-mile delivery" and "last mile delivery" (last-mile delivery); "electronic commerce", "e-commerce", "and e-commerces" (e-commerce); and "supply chain" and "supply chains" (supply chain).Then, keywords such as "literature review", "survey", and "China" were excluded, which are recurrent in the analyzed documents, but do not represent structural concepts of e-commerce, sustainability, and logistics.Consequently, the VOSviewer software was configured with the following parameters: type of analysisco-occurrence; counting method-full counting; unit of analysis-all keywords.Of the 105 documents analyzed, 818 keywords were obtained, of which 21 met the established threshold (minimum number of occurrences of a keyword: 5).Thus, using the data on the total link strength and occurrence between keywords (Table 5), four clusters of scientific areas and themes were identified.The clusters were named considering the core keyword with the highest total link strength and occurrence.
The first biggest cluster (red) was called e-commerce and involved the keywords with the highest level of links.The links characterize the numbers of keywords used with the analyzed words.Thus, Figure 5a shows that the keyword "e-commerce" is associated in the analyzed documents with concepts such as logistics, COVID-19, supply chain management, consumption behavior, innovation, and reverse logistics, highlighting the context in which logistics develops, directly affected by the post-pandemic effects on supply chain management, innovation challenges, reverse logistics efforts to reduce externalities, and the change in preferences of consumer purchasing modes.
The second cluster (green) shown in Figure 5b focuses on the sustainability concept, associating with concepts such as city logistics, last-mile delivery, traffic congestion, and urban logistics, which are directly associated with economic, social, and environmental dimensions of sustainability.The third cluster (blue) presented in Figure 5c has the sustainable development concept as its central node and is directly related to environmental impact, urban transportation, packaging, and planning, which are related to the impacts of logistics planning and operations.The fourth cluster (yellow) shown in Figure 5d corresponds to the concept of supply chain, meeting the concept of last mile, vehicle routing, and sales, which represent the main supply chain processes addressed in e-commerce.

Main Approaches to Sustainable Logistics in E-Commerce
The analysis of the documents obtained in the literature review established several approaches in which the discussion around the sustainability of e-commerce logistics is focused, highlighting the dimensions of sustainability, technological developments, crowdshipping, operation modes, and government policymaking.

Dimensions of Sustainability
It is increasingly necessary to address e-commerce logistics from the environmental, economic, and social dimensions of sustainability to guarantee the sustainability of a logistics network in the long term [79], and balancing economic, social, and environmental benefits related to resources, energy, and the environment [80].It can even consider a technological dimension related to innovative products, services, and processes such as automatic parcel lockers, drones, and autonomous vehicles [22], and collaborative innovation in delivery platforms to contribute to the enhancement of consumers' wellbeing and boost economic growth [81].In this sense, the methodologies to prioritize dimensions of sustainability are valuable to establish their importance according to a given context, considering the trade-offs for sustainability dimensions [82].In some circumstances, the environmental dimension is the most important, followed by the social and economic dimension [22], while in other cases, the economic dimension is the best ranked [57].Moreover, in the literature, few studies have simultaneously addressed the dimensions of sustainability.
The criteria addressed in the economic dimension are mainly related to financial stability and growth, financial benefits, and commercial opportunities for electronic businesses.The social dimension is usually evaluated through customer satisfaction [74], the improvement of the community environment, value generation to stakeholders [65], the constant growth of the territories, and dynamic areas in cities supported by smart loading zones [83,84].Likewise, the environmental dimension corresponds to the preservation of natural resources, the improvement of the CO 2 footprint in urban areas [85], the reduction of the pollution footprint through efficient last-mile delivery routes [63,86], and the strategies to encourage consumers to buy online by bundling products into orders for fewer deliveries and selecting less packaging waste options [87,88].

Technological Developments
Technologies represent one of the principal means to reduce the negative externalities on the environment and guarantee sustainable urban transport.These technologies include communication platforms, vehicle tracking systems, and route-planning support tools [30], and new developments should lead to achieving the maximum end-to-end integration of digital platforms [65].Since a shift towards more eco-sustainable alternative fuels and the optimization of the distances traveled by light goods vehicles appears necessary, electric vehicles represent another type of technology for the substitution of traditional diesel-and petrol-driven vehicles [59,89], producing zero tailpipe emissions [90], and compared to diesel vehicles can provide emissions savings of up to 30%, a significant reduction in noise, and future improvements in these technologies are expected to contribute even more to its sustainability [8].Other challenges of electric vehicles are related to the fleet sizes, schedule, and the required structural and infrastructural changes to support the efficient running of their operations [90].
Likewise, this requires the promotion systems to collect and disseminate information on urban freight transport and electric mobility so that logistics operators and government authorities understand the implications of technological developments in sustainable logistics [8].As logistics service providers have had a positive effect on satisfaction in e-commerce logistics [56,57,91], they now need to accelerate the decarbonization of last-mile delivery, while e-commerce retailers need to further develop the relationship with logistics service providers, and suppliers of hardware such as cargo bikes, stationary and mobile parcel lockers, and drones need to improve the convenience for logistics service providers with their products [92].
Moreover, the inclusion of crowdshipping logistics models and technologies such as autonomous vehicles (AGV) and drones, among others, improve the last-mile operation and accelerate the benefits of sustainable urban freight transport [93].However, it requires the development of technological platforms to control the urban freight and passenger transport system effectively and globally [33].In this sense, there are research opportunities in vehicle routing, vehicle routing problems with drones [94], scheduling, telematics systems to reduce CO 2 emissions and fuel consumption [95], data collection standardization, and data collection methodologies and sources to promote mobility in cities [35].

Crowdshipping
Crowdshipping or crowdsourcing logistics represents a social collaboration strategy that delegates delivery to third parties who act as last-mile couriers, thus reducing the number of delivery trucks in urban/suburban areas, lowering delivery costs, and maintaining the service level [9].In crowdshipping, deliveries are assigned to a network of ordinary people through an open call [20], where the capacity available in various modes of transport is expected to be used to make deliveries [96].Although it encourages using cleaner transport modes such as walking, cycling, or public transport, the mode most used by couriers remains passenger vehicles and trucks.Crowdshipping platforms offer a variety of trading systems, including exclusive/private platforms, on-demand delivery platforms, community-based platforms, ship and shopping platforms, and first/last-mile delivery to/from local carriers [9].
Crowdshipping business models for last-mile deliveries in the e-commerce market represent a relevant trend in scientific research [15], facing challenges related to minimizing total transportation costs, enhancing the formality of work for independent contractors or platform employees, guaranteeing the service level, and reducing the negative externalities of emissions and traffic congestion.Likewise, other research opportunities include the analysis of parking availability, optimization of existing trips, efficient schedule of deliveries, analysis of infrastructure and information systems, and pricing and payment strategies [9,97].Therefore, crowdshipping could reduce fixed costs and empty vehicle space, generating a more sustainable, environmentally friendly, and economically efficient community [9,15].

Operation Modes
Collection and delivery centers represent one of the operation modes that improve the sustainability of e-commerce logistics and emerge as a solution to failed home deliveries, facilitating the consolidation of merchandise in optimized trips.This operation mode reduces the number of trips and vehicles to be used by logistics operators (economic dimension), reducing logistics flows to citizens (social and environmental dimension) [22].These centers are conceived as a network of facilities located in accessible places, close enough to avoid using motorized transport for the customer collection trip, where carriers deliver orders and e-consumers pick up online purchases as an alternative to home delivery [98,99].However, important factors for the success of this operation mode include horizontal collaboration, building strong network partnerships with customers, and distribution channel actors [100].Therefore, the viability of these operation modes depends on local parameters such as regulations, droplet densities, and collection point networks, for which the results of previous studies cannot be generalized or transferred to other contexts [43].
Similarly, other operation modes such as micro-depots and parcel lockers represent logistics facilities located within or near an urban area, where a logistics operator can load or unload, sort, store, and deliver parcels from it to the final recipient.Its purpose is to facilitate the consolidation of deliveries and reduce the environmental impact by using last-mile vehicles such as cargo bikes, electric vehicles, drones, and autonomous vehicles, highlighting that, in some cases, citizens prefer the use of drone or bike distribution in city centers to reduce social and environmental issues [101].However, the choice of consumers to collect packages from lockers depends on the available infrastructure and the time needed to reach the collection point and requires ensuring accessibility on foot and by bicycle [102].
The most common micro depots usually belong to a single company, but they can operate in a shared mode, where they are used by multiple logistics operators, guaranteeing their financial viability [79].These operation modes will be accepted by companies as they do not represent additional costs and demonstrate better results when comparing door-todoor deliveries [13,103], and as they promote quick commerce (Q-commerce) to accelerate logistics and provide customers with small quantities of products almost instantly, both for B2C deliveries and B2B order fulfillment [104][105][106].Likewise, business models based on dark stores allow the gross price to be lower than the physical store due to low operating costs and market entry costs [51].Therefore, the establishment of urban logistics centers, from their design, must conceive the reduction of kilometers traveled to make deliveries [1] and consider in future research opportunities the inclusion of variables such as the size of the order, the transportation mode, the duration and frequency of trips, the mapping of consumer preferences, the dynamics of pricing policies, and the integration of urban express delivery service models [14,107,108].

Government Policymaking
The change in the planning and operation of e-commerce logistics in a sustainable way must be supported by government policies, regulations, restrictions, regional and national integrations, investments in infrastructure, and the application of strategies that satisfy the stakeholders and allow them to grow in the long term while maintaining harmony between the economic, social, and environmental aspects [15,30].Local governments and companies operating in cities must focus last-mile solutions on easily accessible collection points, discouraging home deliveries, while in non-urban zones, it is preferable to encourage home delivery through well-established logistics operators.Likewise, it seeks to support more sustainable last-mile initiatives that reduce operating costs through sustain-able transportation modes, such as electric vehicles or cargo bicycles [43].Likewise, the reduction of environmental impacts can be achieved by encouraging the use of innovative technologies and initiatives such as the IoT (Internet of Things), big data, route optimization algorithms, parcel lockers, the collaboration between couriers and logistics providers [109], blockchain technology to create efficient and transparent intelligent logistics [110], algorithms and mathematical models for the location of city hubs [111], location of urban logistics facilities [1,112], location of parcel lockers [113], and relocation of retail stores for changing the spatial structure to promote the conceptualization of a smart city [64].Other initiatives to encourage are related to the use of consolidation centers and urban distribution in flexible hours, regulations for loading and unloading parking zones [89], promoting territorial plans for the development of underground logistics systems [55,86], limits to the access of cargo vehicles to urban areas, the definition of specific hours for logistics operations, and economic incentives for individuals as a way to promote modernization of urban vehicle fleets, among others [7,22,106].
When the benefits of cooperation are greater, cooperation will occur, promoting winwin cooperation [114,115], so it is important to promote the coordination between the government, local authorities, logistics operators, transportation business, educational institutions, and private actors because conflicts with local authorities are a determining factor in the failure of projects, especially when logistics operators are the ones directly affected by them [22,106,116].For example, between the government, local authorities, and logistics operators, a system of rewards could be adopted for companies that share information on the environmental and social sustainability of their deliveries, thus encouraging more companies to be transparent with customers so that they make informed decisions [117].
Consequently, the design of government policies around e-commerce logistics can encompass the dimensions of sustainability by raising consumers' awareness of ecofriendly delivery [115], promoting working conditions that guarantee fair wages and job stability and protect the physical and mental health of the actors (social dimension).Likewise, these policies should encourage environmentally friendly vehicles such as bicycles, electric vehicles, drones, and public transport to mobilize packages, as well as laws and regulations related to the e-commerce logistics packaging (paper and plastic products), the reuse and recycling of waste delivered to the consumer, and reverse logistics providers [57,62,[118][119][120][121] (environmental dimension).Finally, policies and public projects should guarantee the required infrastructure to offer efficient logistics systems [92], allow the operation of package collection points in strategic and safe places, and promote economic benefits via subsidies and tax deductions (economic dimension).

Conclusions
E-commerce logistics has become a significant element for the sustainability of business models based on online sales due to the economic, environmental, and social impact related to the mobilization of merchandise and parcels in urban areas.This study identified the growth of publications on sustainable e-commerce logistics in recent years, highlighting the importance of this topic in the scientific and business community.The bibliometric analysis established that the authors with the highest number of publications, and correspondingly, the institutional affiliations with the most scientific output, belong to Italy and India.The results of this study suggest considering the submission of future documents on the research topic to the journals Sustainability, the International Journal of Logistics Research and Applications, and Sustainable Cities and Society, since they lead both in the number of articles published and in the number of articles with the highest citations.
Likewise, this study identifies the main management topics around sustainable ecommerce logistics, highlighting last-mile logistics and delivery logistics, urban and city logistics, environmental impact, urban transport, packaging, traffic and congestion, supply chains, China and cross-border e-commerce, and the effects of the COVID-19 pandemic.From a technical point of view, the main topics are related to vehicle routing supported by multi-objective optimization, optimization methods, and planning and decision-making techniques to increase cost and energy efficiency.Similarly, the literature review showed research trends around freight transport solutions related to electronic vehicles and drones and delivery solutions such as crowdshipping and collection and delivery centers.
From the literature review, it is established that sustainable e-commerce logistics is approached from the economic (stability, growth and financial benefit, commercial opportunities), social (environment improvements of the community, growth of territories), and environmental dimension (conservation of natural resources and improvement of the CO 2 footprint in urban areas).Likewise, the analyzed documents indicate research trends around considering multiple dimensions of sustainability and their prioritization, technological developments for transportation modes and electronic platforms, the delegation of deliveries to third parties (crowdshipping), operation modes through collection and delivery centers, parcel lockers, and micro-depots as a solution to cargo consolidation, fast home deliveries, reduction of polluting gases, and cost reduction.Likewise, government policy requirements must encourage the use of bicycles, electric vehicles, drones, and public transport and boost the creation of collection and delivery points.Moreover, policymakers should guarantee the good condition of the roads, adjust logistics operation schedules, and promote economic benefits through subsidies and tax deductions.
Unlike previous research, this study presents a literature review and bibliometric analysis on the sustainability of logistics operations in e-commerce environments analyzing the approaches to address the economic, social, and environmental dimensions through technological developments, social collaboration strategies, modes of operation, and government policies.Thus, this study does not focus solely on freight transport, green vehicles, logistics data, sustainable packaging, green deliveries on e-commerce, and environmental sustainability for the last-mile logistics services industry, as recent last-mile logistics and e-commerce literature reviews have done.
There are some limitations that should be considered for future research.Future studies can employ other relational methods such as co-citation analysis and co-authorship analysis and employ other common software programs for relational methods such as Gephi, CiteSpace, Tree of Science, and HistCite™.Although our dataset from Scopus and Web of Science is comprehensive, it is not exhaustive, since our analysis did not include all journals and conference proceedings available worldwide that can be found in other databases and sources such as ScienceDirect, Scielo, Proquest, Jstor, Ebsco, and Google Scholar.In addition, future research can focus on other publications different from peerreviewed articles, such as research notes, gray literature, blueprints, and technical reports to present a clearer overview of the main trends, directions, and performance of sustainable e-commerce logistics.Likewise, future work may focus on studying the perceptions and requirements of logistics operators and other stakeholders to identify the main difficulties and barriers to contributing to sustainable e-commerce logistics.

Document Cites OA * Source Topic
Sustainability in e-commerce packaging: A review [36] 39 Yes Journal of Cleaner Production (Elsevier) The authors review the evolution of packaging in the last century through a literature review on packaging in e-commerce, emphasizing the environmental aspect.The results show that since the 1990s, it has become difficult to reduce the costs and environmental impacts of packaging because some packaging products are made from non-renewable materials.Among the recommendations, the need to investigate new packaging derived from renewable sources, such as carton board, is highlighted.Another alternative may be the improvement of distribution processes to take better advantage of available packaging, as well as the use of additive manufacturing to optimize packaging volumes and shapes.
A compromised decision-making approach to third-party logistics selection in sustainable supply chain using fuzzy AHP and fuzzy VIKOR methods [56] 29 Yes Mathematics (MDPI) The authors propose a model to support decision making in the evaluation and selection of logistics operators (3PL) based on a multicriteria method such as the fuzzy AHP to weigh criteria and the fuzzy VIKOR method to prioritize alternatives.The model includes criteria such as reliability and delivery time, logistics cost, network management, service quality, and customer's voice.The use of linguistic variables makes it possible to mitigate the uncertainty in the weighting of criteria, and the model determines the logistics operator that best meets the criteria of sustainable development.
Outsourcing reverse logistics for e-commerce retailers: A two-stage fuzzy optimization approach [57] 22 Yes Axioms (MDPI) This study develops a method for the selection and evaluation of reverse logistics operators.The authors use the fuzzy AHP method to establish the importance weight of the criteria and use the fuzzy TOPSIS method to prioritize the alternatives.The proposed method is applied in a case in Vietnam, highlighting that the most important criteria for selecting reverse logistics operators are response time, customer's voice, cost, quality of service, and delivery.

Document Cites OA * Source Topic
The adoption of green vehicles in last mile logistics: A systematic review [33] 22 Yes Sustainability (MDPI) The authors present a literature review on the adoption of green vehicles for urban freight transport, with special emphasis on e-commerce.The study analyzes 159 documents that revolve around optimization and scheduling, policies, sustainability, and e-commerce.The findings indicate that green vehicles are competitive for urban deliveries characterized by frequent stop-and-go movements and low consolidation levels.The need for incentives to motivate the adoption of green vehicles is highlighted, and the use of autonomous vehicles is viewed as a promising and challenging issue.'Pony express' crowdsourcing logistics for last-mile delivery in B2C e-commerce: an economic analysis [20] 20 Yes

International Journal of Logistics Research and Applications (Taylor and
Francis) The authors investigate the economic profitability of an express courier crowdsourcing logistics initiative in an urban area.The study presents a model to estimate delivery costs using crowdsourced services and compares them to the cost of traditional express courier services.

Mobility restrictions and e-commerce:
Holistic balance in Madrid centre during COVID-19 lockdown [7] 18 Yes Economies (MDPI) The authors intend to measure and compare the traffic of Madrid Central in the periods before and after the COVID-19 pandemic, to quantify the e-commerce orders generated by residents and the light cargo vehicles required to deliver the packages of said orders, measuring their environmental impact.The results show that after the pandemic, the number of packages delivered doubled, increasing the number of light cargo vehicles and contamination.The challenge of combining new forms of mobility in large cities to meet the large volumes of e-commerce deliveries demanded by residents is highlighted.
Who is interested in a crowdsourced last mile?A segmentation of attitudinal profiles [19] 16 No Travel Behaviour and Society (Elsevier) The authors identify the type of consumers interested in a collaborative last-mile process and the collaborative logistics services that they consider interesting.The study conducts a survey with a thousand consumers representing the population of Belgium.The results recommend that retailers should focus on a crowdsourcing solution that combines the collection and delivery of products between the local network of their employees, to target consumers and accentuate the quality of collaborative logistics to improve information transparency.Sustainable last mile delivery on e-commerce market in cities from the perspective of various stakeholders.Literature review [15] 13 No Sustainable Cities and Society (Elsevier) This study focuses on identifying, through a literature review, trends in sustainable last-mile delivery in e-commerce, from the point of view of various stakeholders.
It is highlighted that recent articles address new technological and organizational solutions such as IoT, autonomous vehicles, crowdshipping, parcel lockers, and e-commerce customer behavior analysis.
On-demand food delivery: Investigating the economic performances [48] 10 Yes International Journal of Retail and Distribution Management (Emerald) The authors address economic performance about fresh food deliveries at home supported by online platforms, where multiple actors such as customers, riders, and platforms influence.They develop a cost model, apply it to a case in Milan, Italy, and apply a sensitivity analysis.They identify details about prices, demand levels, and types of wages that affect the system.Yes Sustainability (MDPI) This article presents the results of a survey in Shanghai (China) of consumer channel choice preferences for the grocery store market.Different purchasing attributes are analyzed, such as the price of the product and the delivery service, the range of products, the delivery time, the time window, and the travel time.
Sharing is caring: How non-financial incentives drive sustainable e-commerce delivery [42] 5 Yes Transportation Research Part D: Transport and Environment (Elsevier) This study investigates how to encourage sustainable consumer decision making at the web store checkout page using only non-financial incentives such as information, ordering options, social media engagement, and social norm.
It is shown that providing information on the ecological footprint of delivery options is the most decisive incentive and that the impact of sharing on social networks and social norms are positive.This article explores the changing dynamics of a city's spatial structure with a specific focus on e-commerce induced changes in the retail landscape and analyzes division and fragmentation, reconceptualization, and relocation of retail stores.Based on the requirement for a path-dependent analysis, this paper calls for an ideological shift in the conceptualization of a smart city definition from a concept to a process.
Efficiency of light electric vehicles in last mile deliveries-Szczecin case study [123] 4 Yes Sustainable Cities and Society (Elsevier) The authors study the energy efficiency of electric vehicles under real conditions of package delivery operation.The results of the research showed a high potential of electric vehicles and the usefulness of electromobility in last-mile deliveries, in such a way that it allowed the implementation of electric charging vehicles in vehicle fleets in a real company.
E-grocery: Comparing the environmental impacts of the online and offline purchasing processes [50] 4 Yes

International Journal of Logistics Research and Applications (Taylor and
Francis) The authors apply an activity-based approach to assess the environmental impacts (in terms of kgCO2e) of online and offline purchasing processes in the Italian grocery industry, covering all purchasing phases: replenishment, pre-sale and sale, collection and assembly, delivery, and after-sales.The results indicate that electronic shopping is potentially more sustainable than physical shopping, with emissions ranging from 10% to 30% less.
Delivery to homes or collection points?A sustainability analysis for urban, urbanised and rural areas in Belgium [43] 4

Yes
Transport Reviews (Elsevier) The authors compare deliveries to stores serving as collection points and homes for online-ordered non-food products in Belgium.The results are evaluated based on their generated external costs and differentiated according to three area types: urban, urbanized, and rural areas.Considering the case-specific density of the collection points, the results indicate that home deliveries are preferred in rural and urbanized areas when solely considering the sustainability impact.

Figure 1 .Figure 1 .
Figure 1.Documents published in Scopus on sustainable e-commerce logistics.Likewise, the search equation (logistics AND e-commerce AND sustainable* (T Timespan: 1 January 2000 to 1 June 2022 (Publication Date)) was used in the Web o ence (WOS) database, finding 182 papers available as of 2013 from the Web of Sc Core Collection.New parameters were applied to the search equation to delimit the uments published in 2021 and 2022 (Timespan: 1 January 2021 to 31 June 2022 (Public Date)), obtaining 94 records.Figure 2 shows that of the documents published since

Sustainability 2022 ,
14, x FOR PEER REVIEW (182 documents), 51.6% correspond to 2021 and 2022, representing more than half o documents published in WOS in the last ten years around the research topic.

Figure 2 .
Figure 2. Documents published in Web of Science on sustainable e-commerce logistics.

Figure 2 .
Figure 2. Documents published in Web of Science on sustainable e-commerce logistics.

Figure 3 .
Figure 3. Main topics addressed in the literature.

Figure 3 .
Figure 3. Main topics addressed in the literature.

Figure 4 .
Figure 4. Co-occurrence analysis of concepts and keywords.
* Documents in which one or several authors with corresponding institutional affiliation participate.

Table 2 .
Scientific output per country.

Table 3 .
Most recurrent subject areas in the research topic.

Table 4 .
Publication sources with the greatest number of published documents.

Table 5 .
Findings of the co-occurrence analysis.
* Based on article keywords.

Table A2 .
Most cited documents in sustainable e-commerce logistics.