Breaking the Urban Carbon Lock-in: The Effects of Heterogeneous Science and Technology Innovation Policies on Urban Carbon Unlocking Efficiency

Digital technologies such as big data are reshaping resource allocation, raising interest in whether and how Heterogeneous science and technology innovation (STI) policies can help unlock urban carbon lock-in. Using panel data for 286 prefecture-level cities in China from 2009 to 2023, this paper examines the effects of heterogeneous STI policy intensity—classified as supply-side, demand-side, complementary-factor, and institutional-reform policies—on urban carbon unlocking efficiency. We develop a mechanism-based framework and empirically assess (i) the moderating roles of digital infrastructure, science and technology finance, and government green attention, and (ii) spatial spillover effects using spatial econometric models. The results show that all four policy types significantly improve local carbon unlocking efficiency, with institutional-reform policies exhibiting the largest marginal effect. When the four types are included jointly, only supply-side and demand-side policies retain statistically significant direct effects. Heterogeneity analyses indicate that demand-side, complementary-factor, and institutional-reform policies are more effective in low-pollution cities, whereas supply-side and demand-side policies have stronger effects in high energy-consuming cities. Mechanism tests further reveal that digital infrastructure amplifies policy effectiveness by facilitating factor mobility, science and technology finance strengthens policy impacts by easing financial constraints, and government green attention enhances policy effectiveness by improving implementation. Finally, carbon unlocking efficiency displays significant spatial dependence: supply-side and institutional-reform policies generate positive spillovers, while complementary-factor policies exhibit negative spillovers. Overall, the findings provide empirical evidence to inform the design and coordination of heterogeneous STI policy portfolios aimed at improving urban carbon unlocking efficiency.