The Impact of Integration of Innovation–Industry–Talent Chains on Urban Carbon Productivity: Mechanism and Heterogeneity

In the new development stage, promoting the integration of innovation–industry–talent chains (three chains) is an important measure to achieve low-carbon transformation and development. This study analyzes the internal logic of integration of three chains from the perspective of the triple helix theory. Based on panel data of 282 Chinese cities from 2003 to 2022, this paper adopts the composite system synergy model to measure the level of integration of three chains and further identifies its comprehensive impact and underlying mechanisms on urban carbon productivity. The results show that the integration of three chains can significantly improve urban carbon productivity, with this conclusion validated by multiple robustness and endogeneity tests. Heterogeneity analysis indicates that the positive effect of the integration of three chains on carbon productivity is more pronounced in low-carbon pilot cities, key environmental protection cities, non-resource-based cities, and innovative cities. Mechanism tests reveal that three-chain integration indirectly enhances urban carbon productivity by facilitating industry agglomeration, stimulating technology innovation, and accelerating energy transition. Compared with prior studies, this paper has extended the research boundaries of three-chain integration and provides policy recommendations for improving urban carbon productivity through multi-chain synergy.