1. Introduction
In recent years, the international situation has become increasingly tense. Resource shortages, environmental pollution, continuing financial crises and economic uncertainties created by the global pandemic have all posed serious obstacles to the sustainable development of all countries [
1]. In the context of the negative attitude of the United States toward these issues and the European Union struggling with its own debt crisis, China, as an emerging economy, has attracted increasing attention from the international community [
2]. As the most populous country in the world, China faces severe pressures on resources, the environment and poverty alleviation. Therefore, China has always adhered to innovation-driven green technology and an open and shared development strategy and has actively cooperated with other countries. It has gradually changed from a passive participant in maintaining the global economic order and environmental governance to a contributor and leader. Policies and initiatives that reflect China’s wisdom have become key tools to address global economic and environmental problems.
Among the many initiatives implemented, the Belt and Road Initiative, proposed in 2013, has had the greatest impact on the global economy and environment [
3]. This initiative hopes to build an open, efficient and win–win platform for regional cooperation through multilateral mechanisms and to jointly promote the sustainable development of participating countries. As of November 2021, the Initiative included 141 countries and 32 international organizations. The Belt and Road Initiative spans the continents of Asia, Europe and Africa with complex geological conditions. However, countries in the “Silk Road Economic Belt” region are mostly located in the inland hinterland where energy resources are abundant, but the ecological environment is quite fragile; here, water resources are limited and are often in a semiarid state, forest cover is lower than the world average, and the “21st Century Maritime Silk Road” region mostly passes through developing countries, which have ecological problems, especially marine ecological problems, caused by low productivity development [
4]. The implementation of the Belt and Road Initiative faces the risk of ecological and environmental damage. Therefore, China has incorporated the concept of green development into the implementation of the Belt and Road Initiative in the hope of delivering high-quality green technologies through a green innovation-driven strategy so that the regions along the routes can share the fruits of China’s development and learn from China’s past experience of pollution first and treatment later.
As a regional means of environmental governance, the Belt and Road Initiative can theoretically enhance the level of green technology innovation through policy effects, thus promoting local sustainable development. However, the development of reality is not as optimistic. According to the “Global Environmental Performance Index Report” released by Yale University and other institutions, although the average economic growth rate of regions along the Belt and Road is higher than the world average economic growth rate, their energy use is far beyond the world average for the same period. There are also numerous problems in local development, such as a low efficiency of resource utilization and a low technical level. Additionally, according to the Pollution Haven Hypothesis (PHH), in order to achieve their own sustainable development, developed regions often tend to transfer labor-intensive and heavily polluted industries to developing areas, which affects the latter’s technological progress and green development. Thus, the following questions are raised: has the implementation of the Belt and Road Initiative caused pollution transfer in the regions along the routes? Has the initiative truly helped elevate the level of green innovation in the Belt and Road regions? Is China fulfilling its commitment to building a green and sustainable Belt and Road strategy? This paper tries to answer these questions by exploring the promotion effects of the Belt and Road Initiative on the green innovation quality.
Most of the existing research on the Belt and Road Initiative focuses on outbound investment and trade relations. Han et al. [
5] found that the Belt and Road Initiative significantly promoted China’s outward foreign direct investment (OFDI), and the positive impact of investment on private enterprises was more significant. Chen and Qi [
6] measured the investment efficiency of 98 Belt and Road countries through the stochastic frontier gravity model, and the results show that China’s FDI potential was higher in noncarbon-intensive industries than in carbon-intensive industries, which indicates that the FDI investment strategy of the Belt and Road Initiative was more inclined to be green and low-carbon. Li et al. [
7] found that trade flows between China and 64 countries along the Belt and Road became more frequent after the Belt and Road Initiative was put forward. Baniya et al. [
8] analyzed the trade-related impact of the Belt and Road Initiative through a gravity model, and the results show that the initiative increased trade flows between participating countries by 4.1%.
In addition to its specific impact on foreign trade, the Belt and Road Initiative is essentially a new way of undertaking regional economic cooperation, and many scholars have also focused on its economic impact. Sun et al. [
9] evaluated the promotion effect of the Belt and Road Initiative on economic growth by combining propensity score matching and a difference-in-difference (PSM-DID) model. The results show that the initiative effectively promoted the rapid growth of GDP in the Belt and Road regions, but the improvement of per capita GDP was not obvious. Bird et al. [
10] explored the impact of the Belt and Road Initiative on economic growth in Central Asia by building a spatial gravity model, and the results show that the actual economic income brought about by the initiative accounted for approximately 2–3% of the total regional income. When the initiative creates clusters of economic activity in some regions, incomes can rise by as much as 12%.
As global environmental issues have become increasingly intense, scholars have begun to pay more attention to the resource and environmental impacts of the Belt and Road Initiative. Abbas et al. [
11] believed that using renewable and clean energy can help countries along the Belt and Road maintain environmental conditions without affecting technological progress and economic growth. Jiang et al. [
2] used the PSM-DID method to find that the Belt and Road Initiative can significantly improve the energy saving and emission reduction benefits of participating countries and revealed the influencing mechanism of the policy through an analysis of the mediation effect; that is, the Belt and Road Initiative improves the sustainable development level of participating countries through technology spillover and industrial structure optimization. He et al. [
12] analyzed the economic and environmental performance of 61 countries along the Belt and Road and found that the average annual growth rate of the green total factor productivity in the countries along the Belt and Road Initiative was 3.1%. Some countries show robust economic growth, while environmental performance slows green growth. In addition, technological innovation is not only the main driving force for economic development but also a key element in solving environmental problems [
13]; therefore, some scholars have also discussed the impact of the Belt and Road Initiative from an innovative perspective. Xu et al. [
14] believed that foreign trade and technological innovation are the main driving forces for the development of the participating countries of the Belt and Road Initiative, but technological innovation has an obvious threshold effect on the improvement of the green development level of the participating countries. Li et al. [
15] studied the impact of direct investment on enterprise innovation in countries along the Belt and Road from the perspective of host country characteristics. The results show that OFDI can promote Chinese enterprises’ innovation through multiple reverse innovation spillover channels, and the promotion effect is more significant after the Belt and Road Initiative was proposed. Li et al. [
16] used the differential difference model to test the impact of the Belt and Road Initiative on enterprise innovation efficiency and its dynamic evolution process. The results show that the implementation of the Belt and Road Initiative significantly improves the innovation investment of enterprises in the short term. In the long run, the innovation output and efficiency of enterprises are also significantly improved. Yang et al. [
17] constructed a PSM-DID model to empirically test the impact of the Belt and Road Initiative on enterprise innovation and upgrading and its mechanism. The results show that the Belt and Road Initiative significantly improves the quantity and quality of enterprise patent innovation, which promotes enterprise innovation and upgrading.
In summary, with the implementation of the Belt and Road Initiative and its increasing global influence, there are abundant studies on the Belt and Road Initiative, especially in terms of outbound investment, trade and economic impact. Regarding the environmental impact of the Belt and Road Initiative, most studies focus on the assessment of emission reduction benefits and the level of the green economy in the regions along the Belt and Road. As a key tool to solve environmental problems, green innovation refers to a series of technologies, processes or products that have been developed to avoid, eliminate or mitigate eco-environmental pollution and destruction, reduce energy consumption, and improve environmental quality. Currently, a few scholars have discussed the impact of the Belt and Road Initiative on innovation, but most of these discussions are based on the perspective of microenterprises. Few scholars have paid attention to whether the Belt and Road Initiative has truly promoted the level of green innovation and, as an open policy, few studies have explored whether the Belt and Road Initiative has policy spillover effects. To fill the above research gaps, this paper takes the Belt and Road Initiative as a quasi-natural experiment with 291 prefecture-level cities in China as samples and uses the DID method to explore the impact of the initiative on green innovation quality and its policy spillover effect at the city level. In addition, the differences between technologies are reflected not only in the environmental protection degree and production links, but also in the differences in innovation quality due to different technological levels [
18]. In reality, some enterprises prefer low-quality innovation and apply for a large number of invalid patents for strategic competition [
19]. Especially in the context of the Belt and Road Initiative, strongly encouraging innovation and the government’s enhancement of innovation subsidies, enterprises are more willing to pursue the quantity of innovation rather than the quality of innovation to obtain a policy tilt. To better reflect the original intention of this paper, adopting green innovation quality instead of quantity to represent the regional green innovation level can better reflect the policy effect of the Belt and Road Initiative.
The marginal contribution of this paper is as follows. (1) This paper establishes a theoretical analysis framework, discusses the internal mechanism of the Belt and Road Initiative’s effect on regional green innovation quality based on the five aspects of “policy communication”, “infrastructure connectivity”, “unimpeded trade”, “financial integration” and the “people-to-people bond”, and empirically tests the research hypothesis to thus enrich the research horizon. (2) This paper uses the DID method to test the exogenous impact brought about by the Belt and Road Initiative, accurately verifies the impact of the Belt and Road Initiative on the quality of green innovation in cities along the Belt and Road and performs a series of robustness tests to prove the robustness of the results. (3) Considering that the Belt and Road Initiative is a regional open policy, we identify and test the policy spillover effects of the initiative and provide a reference for the promotion and strengthening of further policies.
3. Theories and Hypotheses
Since the Belt and Road Initiative was proposed, its cooperation has focused on many areas, such as the economy, politics, transportation and culture. All participants build a new platform for international innovation cooperation around policy communication, infrastructure connectivity, unimpeded trade, financial integration and people-to-people bonds (hereinafter referred to as the “Five Links”) to improve regional innovation efficiency through high-quality resource complementarity and information and knowledge sharing, achieving high-quality economic growth and jointly addressing global issues such as economic downturns and environmental degradation. The Belt and Road Initiative will not only help to eliminate the uncertainty of overseas investment and encourage the exchange of innovative and environmentally friendly enterprises, but also stimulate their environmental protection and innovation motivation and optimize the green innovation capacity and layout of cities along the Belt and Road. Based on this context, we attempt to combine the contents of the “Five Links” and the top framework design of the Belt and Road Initiative to elaborate on how the initiative affects and promotes urban green innovation quality.
First, in the “Five Links”, policy communication is the foundation, and a good political environment can promote innovation cooperation between regional enterprises [
20,
21,
22]. At present, more than 100 countries and regions and some important international organizations have actively participated in the Belt and Road Initiative. The stable and reliable alliance formed by them has provided a guarantee for the effective implementation of innovation activities, and the consensus on environmental protection within the alliance has promoted the green processes of innovation activities. Second, infrastructure connectivity is the bridge of communication. Infrastructure connectivity should be a priority area for jointly building the Belt and Road Initiative, which specifically includes transportation infrastructure construction, information infrastructure construction, communication construction, etc. At present, China is building the China–Europe Freight Train and China–Laos Railway and has close ties with countries in Northeast Asia and Central Asia. Research shows that the improvement of infrastructure can enhance the level of technological innovation [
23]. Good infrastructure can attract a large number of enterprises to invest and set up factories locally to form a scale effect and effectively reduce costs. At the same time, it can also attract the inflow of innovative talent and promote the aggregation of knowledge and technology to improve innovation efficiency and quality [
24]. With the continuous development of transportation, electricity, the internet and communication facilities, cities along the Belt and Road have gradually expanded their coverage to neighboring areas, and the continuous aggregation of innovation factors contributes to the improvement of the green innovation ability of cities along the Belt and Road. Third, unimpeded trade and financial integration are also important parts of the Belt and Road Initiative. On the one hand, trade liberalization can effectively expand the market size, reduce trade costs, improve the return on R&D investment, and stimulate the innovation vitality of enterprises [
25]. As a national opening-up policy, the Belt and Road Initiative advocates for the liberalization of international trade, encourages innovative enterprises to participate in international competition and carries out transnational or transregional exchanges and cooperation. Learning and absorbing excellent experience is conducive to transferring the excess capacity of innovative enterprises in the regions along the Belt and Road and realizing the upgrading of the urban industrial structure. On the other hand, a good financial environment can promote enterprise innovation [
26]. The Asian Infrastructure Investment Bank (AIIB), established in December 2015 under the leadership of China, is an important platform for financing the Belt and Road Initiative. By 2020, the AIIB had more than 100 members and had approved 87 projects involving 24 economies with a total investment of more than USD 19.6 billion. The establishment of the AIIB has solved the financing difficulties of high-tech and environmental protection enterprises and stimulated enterprises to carry out high-quality innovation. Finally, people-to-people bonds are a nonnegligible part of the Belt and Road Initiative. Some studies believe that having similar cultures is conducive to exchange and cooperation between countries [
27]. When the exchanges and cultures between countries along the Belt and Road become smoother, the cooperation between enterprises on green innovation will also be further enhanced.
Accordingly, the Belt and Road Initiative has promoted green innovation in the cities along the routes through the “Five Links”. However, we hold that the top-level framework design of the Belt and Road initiative plays a decisive role in the construction process of the Belt and Road Initiative and the Five Links. When designing the top-level framework of the Belt and Road Initiative, China has set as its goal the building of a new platform for international cooperation and new drivers for common development. Apart from making the initiative a road of openness, green development and innovation, China has also adopted the strategic principle of “High-Quality Development”. The “High-Quality Development” strategy, proposed at the 19th National Congress of the Communist Party of China (CPC), places more emphasis on the quality of economic growth than its speed. Innovation is the primary driving force for development [
28]. The High-Quality Development strategy requires a focus on improving the transformational ability of scientific and technological achievements and on breaking through core technological difficulties by promoting a deep integration of industry, universities and research, by increasing the support of fiscal and tax policies, by creating a fair market environment, and by improving the intellectual property protection system. At the same time, the strategy indicates that green and sustainable innovation is an important part of high-quality innovation, which emphasizes the environmental quality of the innovation results. As the Belt and Road Initiative deepens, along with the concept of high-quality development, the notion of a high-quality innovation drive continues throughout the implementation of the initiative, which will necessarily lead to an improvement in the quality of green innovation in the cities along the routes. As an important external development strategy of China, the Belt and Road Initiative has always been committed to high-quality and sustainable development with high standards and has always striven to complement each city’s advantages through regional exchange and innovation cooperation to promote the common improvement of all parties. Based on the above theoretical review, we propose the following hypothesis:
Hypothesis 1 (H1). The Belt and Road Initiative will affect the quality of urban green innovation. Specifically, the quality of green innovation in the cities along the Belt and Road will be significantly improved after the initiative is proposed.
Some research has shown that policy implementation has uncertain policy space spillover effects on neighboring areas [
29]. As an open policy in China, the Belt and Road Initiative aims to maximize its reach through active exchanges and cooperation. Moreover, improving the quality of green innovation in the Belt and Road regions through initiatives is essentially an incentive environmental regulation, which has a strong spatial correlation that is similar to technological innovation [
30]. Therefore, ignoring the policy spillover effect of the Belt and Road Initiative may affect the effectiveness of the policy evaluation results; because of this, we also attempt to explain the policy spillover effect of the Belt and Road Initiative to improve the quality of green innovation from the aspects of policy communication, infrastructure connectivity, etc.
First, from the perspective of policy communication, the Belt and Road Initiative actively promotes innovation cooperation between the Belt and Road and surrounding regions, strengthens information interaction and knowledge sharing, and guides local governments to adopt similar policies [
30], which is conducive to promoting the implementation of green innovation strategies in surrounding areas. Second, in terms of infrastructure connectivity, the improvement of infrastructure along the Belt and Road benefits the surrounding areas, facilitates the interregional flow of information and talent, promotes the orderly flow of innovation elements and the effective diffusion of knowledge, and provides an impetus for high-quality innovation in the surrounding areas [
31]. Finally, in terms of unimpeded trade, there are obvious cost effects and technology spillover effects in the trade process among the cities in the Belt and Road region and surrounding area [
32]. On the one hand, the convenient transportation conditions in the Belt and Road area will effectively reduce the trade cost of enterprises in surrounding areas so that enterprises have sufficient funds for R&D investment and talent introduction, indirectly improving the innovation quality of enterprises. On the other hand, enterprises in the surrounding areas can absorb advanced technologies from the green and high-tech products that they purchase and implement imitation innovation. Through the interaction of the learning effect and complementary effect, the green innovation ability of enterprises can be improved, which is conducive to the overall improvement of the green innovation level in surrounding areas. Accordingly, regions along the Belt and Road have improved local economic and environmental conditions through high-quality green innovation, which has a good demonstration effect on the surrounding areas and has effectively promoted the coordinated development of green innovation quality in the surrounding areas through policy communication, infrastructure connectivity and unimpeded trade. Based on the above theoretical review, we propose the following hypothesis:
Hypothesis 2 (H2). The Belt and Road Initiative has a policy spillover effect. Specifically, the quality of green innovation in the vicinity of the cities along the Belt and Road will also be significantly improved after the initiative is proposed.
6. Conclusions and Policy Implications
The Belt and Road Initiative, as an open national policy dedicated to building an open, efficient and win–win regional cooperation platform through multilateral mechanisms, has attracted widespread attention worldwide, and there is no doubt that it can promote foreign trade and the economic growth of all parties involved; however, whether it can improve the technological level of the regions along the route and guide local green and sustainable development is still controversial. To solve this problem, this paper examines the impact of the Belt and Road Initiative on the quality of green innovation. Based on the sample data of 291 prefecture-level cities in China from 2018 to 2019, we group green innovation into green innovation quantity, low-quality green innovation, and high-quality green innovation according to the total amount and category of local patent applications and use the DID method to construct a quasi-natural experimental framework for the Belt and Road Initiative and regional green innovation quality. The conclusions are as follows. (1) Based on the results of the benchmark model analysis, the Belt and Road Initiative has a positive effect on both the quantity and quality of urban green innovation in the treatment group. Based on the impact degree, the impact coefficient of the initiative on the “invention model” green patent application is greater than that on the “utility model” green patent application, which signifies that the Belt and Road Initiative does contribute to the high-quality development of green innovation levels in the regions along the routes. (2) According to the robustness test results, the main conclusions of this paper are still valid in a series of robustness tests, such as a parallel trend test, a placebo test by the advance policy impact time on the treatment group and changing the samples in the control and treatment groups, and re-estimation that uses the PSM-DID method, which show that the main effect is highly robust. (3) Based on the results of the policy spillover test, the Belt and Road Initiative has not only a direct promotion effect on the quality of green innovation in the regions along the routes but also a policy spillover effect on neighboring regions to enhance their quality of green innovation, thereby further verifying the robustness of the conclusion that the implementation of the Belt and Road Initiative contributes to the improvement of green innovation quality in the spatial dimension. The regression coefficient of the long-term effect is larger than that of the short-term effect, which reveals that the incentive effect of green innovation under the Belt and Road Initiative exerts a certain periodicity, and its incentive effect gradually becomes significant in the long term.
Based on the results in this paper, the Belt and Road Initiative represents a successful step in improving the level of green technology and innovation quality, and the results have the following policy implications. First, the Belt and Road Initiative has enhanced connectivity among the regions along the routes and has promoted the optimization of the mode of free allocation among regions and the division of cooperation among different markets. The initiative has not only boosted the quantity of innovation in the Belt and Road regions but also further enhanced the depth and quality of green innovation. Therefore, decision-makers should continue to accelerate the development of the Belt and Road Initiative into a high-quality platform for regional cooperation, further improve the top-level design of the Belt and Road Initiative and the construction of the “Five Links”, give full play to China’s advantages in infrastructure and production capacity cooperation, and promote sustainable development shared by all parties. Second, although the technology levels in the regions along the Belt and Road have improved significantly after policy implementation, the overall situation is still behind the world average level. In the future, the policy environment of the Belt and Road Initiative should continue to be improved, this should involve formulating unified industry standards and regulations to reduce the cost of technological exchange and innovation between enterprises; persuading countries and regions along the Belt and Road to pay more attention to the relationship between economic development and environmental protection; and strengthening the business environment and optimizing legal, institutional, social and media safeguards. Additionally, according to the findings of this paper, the policy effects of the Belt and Road Initiative will diminish dramatically in the fifth year after the policy’s implementation; therefore, the sustainability of the policy effect should be ensured through continuous adjustment and improvement of policy programs. Finally, considering the spatial spillover of the green innovation incentive effect of the Belt and Road Initiative, the promotion of the initiative and the construction of the platforms should focus on balanced development and avoid vicious competition and the inefficiency of innovation resource utilization caused by the unbalanced development of inter-regional trading markets.
Although this paper empirically examines the promotion effect of the Belt and Road Initiative on the quality of green innovation and passes a series of robustness tests, the following content still needs further research. Limited by data acquisition ability, we only selected 291 cities in China as samples to construct the treatment group and the control group, and future research can further expand the sample size to examine the reliability of the results in this paper. In addition, we propose that the Belt and Road Initiative promotes the quality of green innovation through the five approaches of “policy communication”, “infrastructure connectivity”, “unimpeded trade”, “financial integration” and “people-to-people bonds”, but we do not examine its functional mechanism. Therefore, it will be interesting to develop more data and indicators to evaluate the action path of the Belt and Road Initiative on affecting green innovation.