Digital–Intelligent Technology Innovation, Urban Pollution–Carbon Synergy, and Sustainable Urban Transition in China: Mechanisms, Boundary Conditions, and Spatial Spillovers

This study examines whether digital–intelligent technology innovation supports sustainable urban transition by improving urban pollution–carbon synergy in China. Using panel data for 278 prefecture-level cities from 2012 to 2023, we measure digital–intelligent technology innovation by the per capita intensity of patent applications in key digital–intelligent technology fields and construct an urban pollution–carbon synergy index based on a global non-radial directional distance function combined with data envelopment analysis. The results show that digital–intelligent technology innovation is positively associated with urban pollution–carbon synergy, and this finding remains robust to alternative variable definitions, sample adjustments, alternative frontier settings, and supplementary identification strategies. Further analyses suggest that the relationship is stage-dependent rather than purely linear, with stronger sustainability gains emerging after critical development thresholds are crossed. Channel analyses indicate that green technological innovation, digital inclusive finance, and AI firm agglomeration are important routes through which digital–intelligent innovation is translated into environmental governance capacity. Additional analyses show that the effect is stronger on the carbon mitigation dimension than on the pollution reduction dimension, is more pronounced in cities with higher human capital and more developed financial technology, and exhibits both temporal persistence and spatial spillover effects. In addition, digital–intelligent technology innovation is associated with higher energy efficiency, lower total energy consumption, and lower PM2.5, SO 2 , total CO 2 emissions, and CO 2 intensity. Overall, these findings contribute to the sustainability literature by showing that digital–intelligent innovation can facilitate sustainable urban transition when it is effectively transformed through green innovation, financial support, and local application scenarios.