Environmental Taxes, Technological Innovation, and Carbon Productivity: A Spatial Mediation Analysis of Regional Spillover Effects

Against the backdrop of China’s dual carbon goals, investigating the impact of environmental taxes on carbon productivity is crucial for formulating effective regional environmental policies and achieving carbon peaking and carbon neutrality targets. This study employs panel data from 31 Chinese provinces spanning the period 2013–2023 and applies a spatial mediation model to empirically examine whether environmental taxes influence regional and neighboring carbon productivity through technological innovation. Furthermore, the study explores the underlying transmission mechanisms and regional heterogeneity of this effect. The analysis reveals that environmental taxation significantly enhances carbon productivity, accompanied by notable spatial spillover effects. Technological innovation serves as a partial mediator, indicating that such taxes indirectly foster productivity gains by stimulating the development of green technologies. From a regional perspective, the positive influence of environmental taxation is strongest in eastern China, produces moderate spillover effects in the central provinces, and demonstrates comparatively limited policy efficacy in the western regions.