Can Big Data Policy Promote Urban Carbon Unlocking Efficiency?

National big data comprehensive pilot zones (BDCPZs) are key platforms for piloting and implementing big data policy. Additionally, the exploration of their impact on carbon unlocking efficiency and its mechanisms holds significant value. Here, using panel data of 281 prefecture-level cities from 2007 to 2023, we developed a staggered difference-in-differences (DID) model for the systematic investigation of the effects of big data policy on carbon unlocking efficiency and its mechanisms. Our findings demonstrate that BDCPZs significantly enhance carbon unlocking efficiency via four pathways: (1) the rationalization of industrial structure; (2) the optimization of energy structure; (3) the improvement of digital technological innovation; and (4) the application of artificial intelligence technology. On the other hand, heterogeneity testing revealed that the positive effect of the establishment of BDCPZs on carbon unlocking efficiency is more pronounced in cross-regional pilot zones and non-industrial tax-dominated areas. Finally, we also found that the establishment of BDCPZs has significant spatial spillover effects on the carbon unlocking efficiency of surrounding cities. It will be necessary to further strengthen the systematic planning of BDCPZs to enhance carbon unlocking efficiency.