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Search Results (225)

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Keywords = metal scarcity

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78 pages, 2585 KiB  
Review
Engineered Metal Nanoparticles: A Possible Small Solution to Big Problems Associated with Toxigenic Fungi and Mycotoxins
by Eva María Mateo, Fernando Mateo, Andrea Tarazona and Misericordia Jiménez
Toxins 2025, 17(8), 378; https://doi.org/10.3390/toxins17080378 - 30 Jul 2025
Viewed by 545
Abstract
Mycotoxins are secondary metabolites produced primarily by certain species of the genera Aspergillus, Fusarium, Penicillium, Alternaria, and Claviceps. Toxigenic fungi and mycotoxins are prevalent in staple foods, resulting in significant economic losses and detrimental impacts on public health [...] Read more.
Mycotoxins are secondary metabolites produced primarily by certain species of the genera Aspergillus, Fusarium, Penicillium, Alternaria, and Claviceps. Toxigenic fungi and mycotoxins are prevalent in staple foods, resulting in significant economic losses and detrimental impacts on public health and food safety. These fungi demonstrate remarkable adaptation to water and heat stress conditions associated with climate change, and the use of synthetic antifungals can lead to the selection of resistant strains. In this context, the development of novel strategies for their prevention and control of food is a priority objective. This review synthesizes the extant knowledge concerning the antifungal and anti-mycotoxin potential of the primary metal nanoparticles (silver, copper) and metal oxide nanoparticles (copper oxide and zinc oxide) studied in the literature. It also considers synthesis methods and the lack of consensus on technical definitions and regulations. Despite methodological gaps and the scarcity of publications analyzing the effect of these NPs on fungal growth and mycotoxin production simultaneously, it can be concluded that these NPs present high reactivity, stability, and the ability to combat these food risks. However, aspects related to their biosafety and consumer acceptance remain major challenges that must be addressed for their implementation in the food industry. Full article
(This article belongs to the Special Issue Occurrence, Toxicity, Metabolism, Analysis and Control of Mycotoxins)
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16 pages, 3298 KiB  
Article
High-Performance Catalytic Oxygen Evolution with Nanocellulose-Derived Biocarbon and Fe/Zeolite/Carbon Nanotubes
by Javier Hernandez-Ortega, Chamak Ahmed, Andre Molina, Ronald C. Sabo, Lorena E. Sánchez Cadena, Bonifacio Alvarado Tenorio, Carlos R. Cabrera and Juan C. Noveron
Catalysts 2025, 15(8), 719; https://doi.org/10.3390/catal15080719 - 28 Jul 2025
Viewed by 399
Abstract
The oxygen evolution reaction (OER) plays a central role as an anode in electrocatalytic processes such as energy conversion and storage and the generation of molecular oxygen from the electrolysis of water. Currently, precious metal oxides such as IrO2 and RuO2 [...] Read more.
The oxygen evolution reaction (OER) plays a central role as an anode in electrocatalytic processes such as energy conversion and storage and the generation of molecular oxygen from the electrolysis of water. Currently, precious metal oxides such as IrO2 and RuO2 are recognized as reference OER electrocatalysts with reasonably high activity; however, their widespread use in practical devices has been severely hindered by their high cost and scarcity. It is essential to design alternative OER electrocatalysts made of low-cost and abundant earth elements with significant activity and robustness. We report four new nanocellulose-derived Fe–zeolite nanocomposites, namely Fe/Zeolite@CCNC (1), Fe/Zeolite@CCNF (2), Fe/Zeolite/CNT@CCNC (3), and Fe/Zeolite/CNT@CCNF (4). Two different types of nanocellulose were investigated: nanocellulose nanofibrils and nanocellulose nanocrystals. Characterization with TEM, SEM-EDS, PXRD, and XPS is reported. The nanocomposites exhibited electrocatalytic activity for OER that varies based on the origin of biocarbon and the composition content. The effect of adding carbon nanotubes to the nanocomposites was studied, and an improvement in OER catalysis was observed. The electrochemical double-layer capacitance and electrochemical impedance spectroscopy of the nanocomposites are reported. The nanocomposite 3 exhibited the highest performance, with an onset potential value of 1.654 V and an overpotential of 551 mV, which exceeds the activity of RuO2 for OER catalysis at 10 mA/cm2 in the glassy carbon electrode. A 24 h chronoamperometry study revealed that the catalyst is active for ~2 h under continuous operating conditions. BET surface analysis showed that the crystalline nanocellulose-derived composite exhibited 301.47 m2/g, and the fibril nanocellulose-derived composite exhibited 120.39 m2/g, indicating that the increased nanoporosity of the former contributes to the increase in OER catalysis. Full article
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14 pages, 3187 KiB  
Article
Characterizations of Electrospun PVDF-Based Mixed Matrix Membranes with Nanomaterial Additives
by Haya Taleb, Venkatesh Gopal, Sofian Kanan, Raed Hashaikeh, Nidal Hilal and Naif Darwish
Nanomaterials 2025, 15(15), 1151; https://doi.org/10.3390/nano15151151 - 25 Jul 2025
Viewed by 359
Abstract
Water scarcity poses a formidable challenge around the world, especially in arid regions where limited availability of freshwater resources threatens both human well-being and ecosystem sustainability. Membrane-based desalination technologies offer a viable solution to address this issue by providing access to clean water. [...] Read more.
Water scarcity poses a formidable challenge around the world, especially in arid regions where limited availability of freshwater resources threatens both human well-being and ecosystem sustainability. Membrane-based desalination technologies offer a viable solution to address this issue by providing access to clean water. This work ultimately aims to develop a novel permselective polymeric membrane material to be employed in an electrochemical desalination system. This part of the study addresses the optimization, preparation, and characterization of a polyvinylidene difluoride (PVDF) polymeric membrane using the electrospinning technique. The membranes produced in this work were fabricated under specific operational, environmental, and material parameters. Five different additives and nano-additives, i.e., graphene oxide (GO), carbon nanotubes (CNTs), zinc oxide (ZnO), activated carbon (AC), and a zeolitic imidazolate metal–organic framework (ZIF-8), were used to modify the functionality and selectivity of the prepared PVDF membranes. Each membrane was synthesized at two different levels of additive composition, i.e., 0.18 wt.% and 0.45 wt.% of the entire PVDF polymeric solution. The physiochemical properties of the prepared membranes were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), zeta potential, contact angle, conductivity, porosity, and pore size distribution. Based on findings of this study, PVDF/GO membrane exhibited superior results, with an electrical conductivity of 5.611 mS/cm, an average pore size of 2.086 µm, and a surface charge of −38.33 mV. Full article
(This article belongs to the Section Synthesis, Interfaces and Nanostructures)
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17 pages, 6360 KiB  
Article
Integrating Lanthanide-Reclaimed Wastewater and Lanthanide Phosphate in Corn Cultivation: A Novel Approach for Sustainable Agriculture
by George William Kajjumba, Savanna Vacek and Erica J. Marti
Sustainability 2025, 17(15), 6734; https://doi.org/10.3390/su17156734 - 24 Jul 2025
Viewed by 343
Abstract
With increasing global challenges related to water scarcity and phosphorus depletion, the recovery and reuse of wastewater-derived nutrients offer a sustainable path forward. This study evaluates the dual role of lanthanides (Ce3+ and La3+) in recovering phosphorus from municipal wastewater [...] Read more.
With increasing global challenges related to water scarcity and phosphorus depletion, the recovery and reuse of wastewater-derived nutrients offer a sustainable path forward. This study evaluates the dual role of lanthanides (Ce3+ and La3+) in recovering phosphorus from municipal wastewater and supporting corn (Zea mays) cultivation through lanthanide phosphate (Ln-P) and lanthanide-reclaimed wastewater (LRWW, wastewater spiked with lanthanide). High-purity precipitates of CePO4 (98%) and LaPO4 (92%) were successfully obtained without pH adjustment, as confirmed by X-ray photoelectron spectroscopy (XPS) and energy-dispersive spectroscopy (EDS). Germination assays revealed that lanthanides, even at concentrations up to 2000 mg/L, did not significantly alter germination rates compared to traditional coagulants, though root and shoot development declined above this threshold—likely due to reduced hydrogen peroxide (H2O2) production and elevated total dissolved solids (TDSs), which induced physiological drought. Greenhouse experiments using desert-like soil amended with Ln-P and irrigated with LRWW showed no statistically significant differences in corn growth parameters—including plant height, stem diameter, leaf number, leaf area, and biomass—when compared to control treatments. Photosynthetic performance, including stomatal conductance, quantum efficiency, and chlorophyll content, remained unaffected by lanthanide application. Metal uptake analysis indicated that lanthanides did not inhibit phosphorus absorption and even enhanced the uptake of calcium and magnesium. Minimal lanthanide accumulation was detected in plant tissues, with most retained in the root zone, highlighting their limited mobility. These findings suggest that lanthanides can be safely and effectively used for phosphorus recovery and agricultural reuse, contributing to sustainable nutrient cycling and aligning with the United Nations’ Sustainable Development Goals of zero hunger and sustainable cities. Full article
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35 pages, 10932 KiB  
Review
Recent Advances in Non-Noble Metal Electrocatalysts for Hydrogen Evolution Reaction in Water Splitting
by Aiyi Dong, Zifeng Li, Yinhua Ma, Weimin Liao, Fengjiao Zhao, Xun Zhang and Honglin Gao
Nanomaterials 2025, 15(14), 1106; https://doi.org/10.3390/nano15141106 - 16 Jul 2025
Viewed by 490
Abstract
Electrochemical water splitting is an efficient and eco-friendly method for hydrogen production, offering a sustainable energy solution. Currently, the noble metal platinum is considered to be the most efficient catalyst for electrochemical hydrogen evolution reactions (HERs). Due to the scarcity and high cost [...] Read more.
Electrochemical water splitting is an efficient and eco-friendly method for hydrogen production, offering a sustainable energy solution. Currently, the noble metal platinum is considered to be the most efficient catalyst for electrochemical hydrogen evolution reactions (HERs). Due to the scarcity and high cost of noble metal materials, there is an urgent need to find abundant and cost-effective non-noble metal catalysts to reduce the overpotential of HERs. In recent years, significant scientific advancements have been reported in non-noble metal HER catalysts. This review categorizes and reviews the recent non-noble metal HER catalysts and their reaction mechanisms. An exhaustive overview of proven effective catalyst categories is provided, offering early-career researchers a panoramic understanding of this dynamic research field. Finally, we address current challenges and future directions in this field to encourage further research efforts and the development of non-noble metal catalysts. Full article
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28 pages, 4234 KiB  
Review
A Review on Laser-Induced Graphene-Based Electrocatalysts for the Oxygen Reduction Reaction in Electrochemical Energy Storage and Conversion
by Giulia Massaglia and Marzia Quaglio
Nanomaterials 2025, 15(14), 1070; https://doi.org/10.3390/nano15141070 - 10 Jul 2025
Viewed by 480
Abstract
The increasing demand for efficient and sustainable energy conversion technologies has driven extensive research into alternative electrocatalysts for the oxygen reduction reaction (ORR). Platinum-based catalysts, while highly efficient, suffer from high costs, scarcity, and long-term instability Laser-Induced Graphene (LIG) has recently attracted considerable [...] Read more.
The increasing demand for efficient and sustainable energy conversion technologies has driven extensive research into alternative electrocatalysts for the oxygen reduction reaction (ORR). Platinum-based catalysts, while highly efficient, suffer from high costs, scarcity, and long-term instability Laser-Induced Graphene (LIG) has recently attracted considerable interest as an effective metal-free electrocatalyst for oxygen reduction reaction (ORR), owing to its remarkable electrical conductivity, customizable surface functionalities, and multi-scale porous architecture. This review explores the synthesis strategies, physicochemical properties, and ORR catalytic performance of LIG. Additionally, this review offered a detailed overview regarding the effective pole of heteroatom doping (N, S, P, B) and functionalization techniques to enhance catalytic activity. Finally, we highlight the current challenges and future perspectives of LIG-based ORR catalysts for fuel cells and other electrochemical energy applications. Furthermore, laser-induced-graphene (LIG) has emerged as a highly attractive candidate for electrochemical energy conversion systems, due to its large specific surface area, tunable porosity, excellent electrical conductivity, and cost-effective fabrication process. This review discusses recent advancements in LIG synthesis, its structural and electrochemical properties, and its applications in supercapacitors, batteries, fuel cells, and electrocatalysis. Despite its advantages, challenges such as mechanical stability, electrochemical degradation, and large-scale production remain key areas for improvement. Additionally, this review explores future perspectives on optimizing LIG for next-generation energy storage and conversion technologies. Full article
(This article belongs to the Special Issue Nanomaterials Based (Bio) Electrochemical Energy and Storage Sytems)
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22 pages, 8995 KiB  
Article
Evaluation of the Adsorption Capacity of the BiOX (X = Cl, I) and BiOX-GO Nanomaterials (NMs) for Water Treatment
by Jorge H. Martinez-Montelongo, Martha L. Jiménez-González, Abner González-Pérez, Monika Mortimer, F. J. Avelar-González, Jorge E. Macias-Díaz and Iliana E. Medina-Ramírez
Processes 2025, 13(7), 2179; https://doi.org/10.3390/pr13072179 - 8 Jul 2025
Viewed by 390
Abstract
Water pollution is a global problem that severely impacts human and environmental health, water recycling, and the economy. In Mexico, due to water scarcity, potable water contains significant amounts of heavy metals (i.e., arsenic (As)); thus, there is a need for efficient and [...] Read more.
Water pollution is a global problem that severely impacts human and environmental health, water recycling, and the economy. In Mexico, due to water scarcity, potable water contains significant amounts of heavy metals (i.e., arsenic (As)); thus, there is a need for efficient and sustainable water treatment strategies. Bismuth oxyhalides, BiOX (X = Cl, Br, I), exhibit three-dimensional (3D) porous structures suitable for efficient adsorption activity. In addition, bismuth is an abundant and biocompatible element appropriate for fabricating sustainable environmental remediation technologies, such as adsorptive BiOX nanomaterials (NMs). In this study, we examine the adsorption capacity of BiOX (X = Cl, I), BiOX-GO (GO: graphene oxide) and GO NMs to remove methylene blue (MB), methyl orange (MO) and arsenite (AsO33−) from aqueous solution. BiOCl-GO 10%, BiOI, BiOI-GO 1%, BiOI-GO 10% and GO have an enhanced adsorption capacity, removing MB (20 ppm) within one hour using a low dose of NMs (1 mg/mL). In addition, BiOX-GO NMs can be easily separated from the solution and regenerated upon visible light activation due to the photocatalytic activity of the materials. The efficiency of the NMs under study for MO removal decreases, with the GO material having the highest efficiency (96%), followed by BiOX-GO 10% (78%). BiOCl-GO 1% removes arsenic from aqueous solution at low doses and short treatment times; 5 mg As/g adsorbent takes five hours; however, at longer adsorption times (24 h), BiOI-GO 1% excels in its arsenic removal capacity. Perlite-supported BiOCl NMs exhibit a weak capacity for water treatment due to the poor mechanical strength of perlite and the amount of surface-exposed BiOCl material. For the photocatalytic removal of arsenic (oxidation–adsorption), BiOI-GO 1% excels in arsenic removal with efficiencies > 70%. Full article
(This article belongs to the Special Issue Sustainable Adsorbent Materials for Wastewater Treatment)
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21 pages, 4094 KiB  
Article
Strategies for Nickel and Cobalt Mobilisation from Ni-Based Superalloy Residue Powders Using a Sustainable and Cost-Effective Bioleaching Method
by Andra D. Constantin, Stephen Hall, Fatemeh Pourhossein and Sebastien Farnaud
Processes 2025, 13(7), 2157; https://doi.org/10.3390/pr13072157 - 7 Jul 2025
Viewed by 365
Abstract
The demand for strategic elements, including nickel and cobalt, increases each year due to rapid technological advancements. However, due to their scarcity and environmental concerns, the development of sustainable recycling processes supported by green-energy technologies is becoming essential. In this study, a process [...] Read more.
The demand for strategic elements, including nickel and cobalt, increases each year due to rapid technological advancements. However, due to their scarcity and environmental concerns, the development of sustainable recycling processes supported by green-energy technologies is becoming essential. In this study, a process relying on indirect bioleaching was used to recover nickel and cobalt from three different superalloy residue powders as a second source of metals, as part of a wider study to recycle superalloys within a waste process. A comparison between the three methods was carried out to analyse the bioleaching mechanisms of the target metals. Acidolysis was selected for further study due to its set-up simplicity and superior recovery rates. Variations in agitation speed of the lixiviant processing the Ni 30167 superalloy revealed that 270 rpm achieved the optimal active metal surface–oxidising agent interaction, with 60% and 70% dissolution rates after 24 h for nickel and cobalt, respectively. For the Re 30168 superalloy, extraction rates of 60% and 50% were obtained in 48 h for nickel and cobalt, respectively. The effect of hydrogen peroxide as an additive to improve metal solubilisation and overcome passivation, are discussed together with the challenges posed by the presence of iron, the materials’ elemental complexity, and its interaction with different oxidising agents. Full article
(This article belongs to the Special Issue Advances in Wastewater and Solid Waste Treatment Processes)
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16 pages, 7221 KiB  
Article
Transfer Learning-Based Interpretable Soil Lead Prediction in the Gejiu Mining Area, Yunnan
by Ping He, Xianfeng Cheng, Xingping Wen, Yan Yi, Zailin Chen and Yu Chen
Sensors 2025, 25(13), 4209; https://doi.org/10.3390/s25134209 - 5 Jul 2025
Viewed by 292
Abstract
Accurate prediction of soil lead (Pb) content in small sample scenarios is often limited by data scarcity and variability in soil properties, with traditional spectral modeling methods yielding suboptimal precision. To address this, we propose a transfer learning-based framework integrated with SHAP analysis [...] Read more.
Accurate prediction of soil lead (Pb) content in small sample scenarios is often limited by data scarcity and variability in soil properties, with traditional spectral modeling methods yielding suboptimal precision. To address this, we propose a transfer learning-based framework integrated with SHAP analysis for predicting soil Pb content in the Gejiu mining area, Yunnan. Using pH data from the European LUCAS soil database as the source domain, spectral features were extracted via a 1D-ResNet model and transferred to the target domain (130 soil samples from Gejiu) for Pb prediction. SHAP analysis was applied to clarify the role of spectral characteristics in cross-component transfer learning, uncovering shared and adaptive features between pH and Pb predictions. The transfer learning model (ResNet-pH-Pb) significantly outperformed direct modeling methods (PLS-Pb, SVM-Pb, and ResNet-Pb), with an R2 of 0.77, demonstrating superior accuracy. SHAP analysis showed that the model retained key pH-related wavelengths (550–750 nm and 1600–1700 nm) while optimizing Pb-related wavelengths (e.g., 919 nm and 959 nm). This study offers a novel approach for soil heavy metal prediction under small sample constraints and provides a theoretical basis for understanding spectral prediction mechanisms through interpretability analysis. Full article
(This article belongs to the Section Smart Agriculture)
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29 pages, 2767 KiB  
Article
Closed-Loop Valorization of Annatto Seed Waste into Biochar: A Sustainable Platform for Phosphorus Adsorption and Safe Nutrient Recycling in Agro-Industries
by Diana Guaya, Camilo Piedra and Inmaculada Carmona
Molecules 2025, 30(13), 2842; https://doi.org/10.3390/molecules30132842 - 2 Jul 2025
Viewed by 462
Abstract
Valorizing agro-industrial waste into functional materials for environmental remediation and resource recovery is essential for advancing circular economy models. This study presents a novel closed-loop strategy to convert annatto (Bixa orellana) seed residues into biochar for phosphate recovery from aqueous solutions [...] Read more.
Valorizing agro-industrial waste into functional materials for environmental remediation and resource recovery is essential for advancing circular economy models. This study presents a novel closed-loop strategy to convert annatto (Bixa orellana) seed residues into biochar for phosphate recovery from aqueous solutions and real agro-industrial wastewater. A novel ternary modification with Fe, Zn, and Mn metals was applied to enhance the phosphate adsorption performance of the biochar. Materials were synthesized via pyrolysis at 600 °C and 700 °C, with ABC-M700 exhibiting the highest performance. Comprehensive characterization (FTIR, SEM–EDS, and XRF) confirmed the successful incorporation of metal (oxy)hydroxide functional groups, which facilitated phosphate binding. Adsorption studies revealed that ABC-M700 achieved a maximum phosphate removal capacity of 6.19 mg·g−1, representing a 955% increase compared to unmodified ABC-N700 (0.59 mg·g−1), and a 31% increase relative to ABC-M600 (4.73 mg·g−1). Physicochemical characterization indicated increased surface area, well-developed mesoporosity, and the formation of metal (oxy)hydroxide functionalities. ABC-M700 achieved a maximum adsorption capacity of 73.22 mg·g−1 and rapid kinetics, removing 95% of phosphate within 10 min and reaching equilibrium at 30 min. The material exhibited notable pH flexibility, with optimal performance in the range of pH 6–7. Performance evaluations using real wastewater from the same agro-industry confirmed its high selectivity, achieving 80% phosphate removal efficiency despite the presence of competing ions and organic matter. Phosphate fractionation revealed that 78% of adsorbed phosphate was retained in stable, metal-associated fractions. Although the material showed limited reusability, it holds potential for integration into nutrient recycling strategies as a slow-release fertilizer. These findings demonstrate a low-cost, waste-derived adsorbent with strong implications for circular economy applications and sustainable agro-industrial wastewater treatment. This study establishes a scalable model for agro-industries that not only reduces environmental impact but also addresses phosphorus scarcity and promotes resource-efficient waste management. Full article
(This article belongs to the Special Issue Porous Carbon Materials: Preparation and Application)
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31 pages, 1734 KiB  
Review
Progress, Challenges and Opportunities in Recycling Electric Vehicle Batteries: A Systematic Review Article
by Hamid Safarzadeh and Francesco Di Maria
Batteries 2025, 11(6), 230; https://doi.org/10.3390/batteries11060230 - 13 Jun 2025
Cited by 1 | Viewed by 1812
Abstract
Objective: The rapid growth of electric vehicle (EV) adoption has led to an unprecedented increase in lithium-ion battery (LIB) demand and end-of-life waste, underscoring the urgent need for effective recycling strategies. This review evaluates current progress in EV battery recycling and explores future [...] Read more.
Objective: The rapid growth of electric vehicle (EV) adoption has led to an unprecedented increase in lithium-ion battery (LIB) demand and end-of-life waste, underscoring the urgent need for effective recycling strategies. This review evaluates current progress in EV battery recycling and explores future prospects. Design: Review based on PRISMA 2020. Data sources: Scientific publications indexed in major databases such as Scopus, Web of Science, and ScienceDirect were searched for relevant studies published between 2020 and 15 April 2025. Inclusion criteria: Studies were included if they were published in English between 2020 and 15 April 2025, and focused on the recycling of electric vehicle batteries. Eligible studies specifically addressed (i) recycling methods, technologies, and material recovery processes for EV batteries; (ii) the impact of recycled battery systems on power generation processes and grid stability; and (iii) assessments of materials used in battery manufacturing, including efficiency and recyclability. Review articles and meta-analyses were excluded to ensure the inclusion of only original research data. Data extraction: Data were independently screened and extracted by two researchers and analyzed for recovery rates, environmental impact, and system-level energy contributions. One researcher independently screened all articles and extracted relevant data. A second researcher validated the accuracy of extracted data. The data were then organized and analyzed based on reported quantitative and qualitative indicators related to recycling methods, material recovery rates, environmental impact, and system-level energy benefits. Results: A total of 23 studies were included. Significant progress has been made in hydrometallurgical and direct recycling processes, with recovery rates of critical metals (Li, Co, Ni) improving. Second-life battery applications also show promise for grid stabilization and renewable energy storage. Furthermore, recycled batteries show potential in stabilizing power grids through second-life applications in BESS. Conclusion: EV battery recycling is a vital strategy for addressing raw material scarcity, minimizing environmental harm, and supporting energy resilience. However, challenges persist in policy harmonization, technology scaling, and economic viability. Future progress will depend on integrated efforts across sectors and regions to build a circular battery economy. Full article
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22 pages, 2567 KiB  
Review
Non-Platinum Group Metal Oxygen Reduction Catalysts for a Hydrogen Fuel Cell Cathode: A Mini-Review
by Naomi Helsel and Pabitra Choudhury
Catalysts 2025, 15(6), 588; https://doi.org/10.3390/catal15060588 - 13 Jun 2025
Viewed by 988
Abstract
Although platinum-based catalysts are highly effective for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs), their high cost and scarcity limit large-scale commercialization. As a result, platinum group metal-free catalysts—particularly Fe-N-C materials—have received increasing attention as promising alternatives. Despite [...] Read more.
Although platinum-based catalysts are highly effective for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs), their high cost and scarcity limit large-scale commercialization. As a result, platinum group metal-free catalysts—particularly Fe-N-C materials—have received increasing attention as promising alternatives. Despite significant progress, no platinum-group metal-free (PGM-free) catalyst has yet matched the performance and durability of commercial Pt/C in acidic media. Recent advances in synthesis strategies, however, have led to notable improvements in the activity, stability, and active site density of Fe-N-C catalysts. This review highlights key synthesis approaches, including pyrolysis, MOF-derived templates, and cascade anchoring, and discusses how these methods contribute to improved nitrogen coordination, electronic structure modulation, and active site engineering. The continued refinement of these strategies, alongside improved catalyst screening techniques, is essential for closing the performance gap and enabling the practical deployment of non-PGM catalysts in PEMFC technologies. Full article
(This article belongs to the Special Issue Feature Review Papers in Electrocatalysis)
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9 pages, 2327 KiB  
Article
First-Principles Calculations for the H Adsorption of Monolayer MoTe2 for Hydrogen Evolution Reaction
by Xujing Gao and Jianling Meng
Inorganics 2025, 13(6), 197; https://doi.org/10.3390/inorganics13060197 - 13 Jun 2025
Viewed by 367
Abstract
Hydrogen from water splitting is seen as a promising future energy source. Pt electrochemical catalysts with an ideal hydrogen evolution reaction (HER) performance face problems relating to their cost and scarcity. Research into transition metal dichalcogenides (TMDs) as alternative catalysts is in demand. [...] Read more.
Hydrogen from water splitting is seen as a promising future energy source. Pt electrochemical catalysts with an ideal hydrogen evolution reaction (HER) performance face problems relating to their cost and scarcity. Research into transition metal dichalcogenides (TMDs) as alternative catalysts is in demand. In our work, H adsorption on monolayer MoTe2 is investigated at different sites and rates. Through structure and charge distribution analysis, it is found that uniform charge distribution facilitates H adsorption. In addition, the enhanced electronic density of states and reduced band gap calculated by the electronic energy band structure are advantageous for H adsorption. And the Mo edge of MoTe2 is sensitive to the H adsorption rate. Finally, the H adsorbed on the sites is stable at 600 K, as shown in molecular dynamics (MD) calculations. Our work provides a further mechanism for H adsorption on MoTe2. Full article
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24 pages, 1387 KiB  
Review
Sustainable Recovery of Critical Minerals from Wastes by Green Biosurfactants: A Review
by Bita Deravian and Catherine N. Mulligan
Molecules 2025, 30(11), 2461; https://doi.org/10.3390/molecules30112461 - 4 Jun 2025
Viewed by 853
Abstract
Biosurfactants have emerged as promising agents for environmental remediation due to their ability to complex, chelate, and remove heavy metals from contaminated environments. This review evaluates their potential for recovering critical minerals from waste materials to support renewable energy production, emphasizing the role [...] Read more.
Biosurfactants have emerged as promising agents for environmental remediation due to their ability to complex, chelate, and remove heavy metals from contaminated environments. This review evaluates their potential for recovering critical minerals from waste materials to support renewable energy production, emphasizing the role of biosurfactant–metal interactions in advancing green recovery technologies and enhancing resource circularity. Among biosurfactants, rhamnolipids demonstrate a high affinity for metals such as lead, cadmium, and copper due to their strong stability constants and functional groups like carboxylates, with recovery efficiencies exceeding 75% under optimized conditions. Analytical techniques, including Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Fourier-Transform Infrared spectroscopy (FTIR), and Scanning Electron Microscopy (SEM), are instrumental in assessing recovery efficiency and interaction mechanisms. The review introduces a Green Chemistry Metrics Framework for evaluating biosurfactant-based recovery processes, revealing 70–85% lower Environmental Factors compared to conventional methods. Significant research gaps exist in applying biosurfactants for extraction of metals like lithium and cobalt from batteries and other waste materials. Advancing biosurfactant-based technologies hold promise for efficient, sustainable metal recovery and resource circularity, addressing both resource scarcity and environmental protection challenges simultaneously. Full article
(This article belongs to the Special Issue Green Chemistry Approaches to Analysis and Environmental Remediation)
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19 pages, 3090 KiB  
Article
Effect of Forest Species Canopy on the Accumulation of Toxic Metals in the Soil Within and Around Macedonia Airport, Northern Greece
by Ioannis Mousios, Marianthi Tsakaldimi, Evangelia Gkini, Theocharis Chatzistathis and Petros Ganatsas
Urban Sci. 2025, 9(6), 191; https://doi.org/10.3390/urbansci9060191 - 27 May 2025
Viewed by 619
Abstract
Soil pollution at airports is a critical environmental issue that affects not only the local ecology but also the health of people living near these infrastructures. The main causes of pollution include the use of chemical products such as de-icing agents, fuels, and [...] Read more.
Soil pollution at airports is a critical environmental issue that affects not only the local ecology but also the health of people living near these infrastructures. The main causes of pollution include the use of chemical products such as de-icing agents, fuels, and lubricants, as well as waste from aircraft and ground vehicles. These substances often seep into the soil, leading to the accumulation of toxic elements. However, due to security reasons, there is a great scarcity of real data on the impact of airport operations on ecosystems and the role trees could play in pollutant limitation. Thus, the aim of this study was to determine whether airport operations have toxic effects on soils within and around Macedonia Airport, Thessaloniki, Northern Greece, by determining the concentrations of potentially toxic elements (Cu, Ni, Pb, Mn, Fe, Co, Cr, Cd, and Zn) in soil samples taken within the airport and near the airport. Furthermore, this study aimed to investigate the effect of the canopies of forest species on the accumulation of toxic metals in the soil inside the airport and in the peripheral zone. The results show that, overall, no important pollution was detected in the soil of the Thessaloniki Airport, Northern Greece, both inside and outside the airport area. Some differences were observed in the content of toxic metals studied between the samples taken inside and outside the airport, and some effects of tree canopy were noted. However, all values were lower than the defined permissible limits according to international standards (except for iron). It is important, however, to perform regular re-checking of soil quality with new samples in order to prevent soil contamination and mitigate any contamination found. Full article
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