This study uses global patent cooperation data from 1999 to 2020, employs social network analysis, and explores the changes in and driving forces of global innovation networks (GINs) in the past 20 years as well as the change in China's position in the global innovation system. The results show that on the whole, the network accessibility of GINs has continuously improved, showing scale‐free network characteristics. The important nodes in the network are mainly developed countries such as Europe and the United States, and the node polarization effect has weakened; the network has four agglomeration subgroups. The phenomenon of subgroups and factions is not obvious. Further factor identification shows that economic factors and technological information factors have the strongest correlation with the innovation network and that demographic factors have a weaker correlation with the innovation network. In addition, China's position in the innovation network has been increasing year by year, and the role of ‘transit stations’ has become increasingly prominent.

Air pollution significantly impacts sustainable development and public health. Taking the implementation of China's Environmental Protection Tax Law in China as a quasi-natural experiment, this paper employs the difference-in-differences (DID) and spatial DID models to evaluate the effects of environmental tax reform on urban air pollution. The findings are as follows. (1) Environmental tax reform can significantly reduce urban air pollution, and a series of robustness tests have also been conducted to provide further evidence. (2) Green technology innovation and industrial structure upgrading from a vital transmission mechanism for environmental tax reform to improve air quality. (3) Environmental tax reform significantly inhibits urban air pollution in cities located north of the Qinling-Huaihe line and big cities. (4) Moreover, environmental tax reform not only promotes the improvement of local air quality but also has a significant negative spatial spillover effect, reducing air pollution in neighboring cities. The research conclusions provide theoretical support and policy suggestions for promoting sustainable economic development, rationally optimizing environmental protection tax policies and improving urban air quality.

This paper examines the spatial and temporal evolution of the global industrial robot trade network (GIRTN) from 2000 to 2023 using complex network analysis, and it systematically evaluates China’s position in the GIRTN and its evolutionary trend by combining node reciprocity, the industry concentration index, the Herfindahl–Hirschman index, and betweenness centrality. The study shows that the GIRTN is characterized by significant imbalance, a “small world”, and weak reciprocity. Traditional industrial countries such as Japan, Germany, and France have dominated the global market for a long time, accounting for more than 80% of the market share. However, market imbalances have been mitigated with the rise of emerging economies such as China, South Korea, and Singapore. Despite increasing global trade linkages, there are significant differences in trade intensity. China’s position and competitiveness in the GIRTN have significantly improved, as demonstrated by its continued rise in the ranking of total exports, the improvement in the attractiveness and quality of its products, the diversification of its trading partners, and the optimization of its export structure. These changes indicate that China has gained significant competitive advantages and has great potential for development.