Does digital economy improve city-level eco-efficiency in China?

Previous research focused on the impact of the digital economy on economic development, but did not consider its impact on eco-efficiency. We address this gap by taking China's national big data comprehensive pilot zone (NBD-CPZ) as a quasi-natural experiment, and evaluating its impact on city eco-efficiency using data for 284 Chinese cities from 2006 to 2020. The study found that the NBD-CPZ significantly improved city eco-efficiency, and this impact increased gradually over time. A mechanism analysis shows that the NBD-CPZ impacted city eco-efficiency by reducing mismatched resources and promoting green technology advances. A heterogeneity analysis indicates that the NBD-CPZ's effect on city eco-efficiency was more significant in old industrial cities, resource-based cities, and cities with high energy intensity. This study provides empirical evidence and highlights policy implications for narrowing the ecological civilization disparities between regions from the perspective of a digital economy.