Coupling and Coordinated Development Between Informal Environmental Regulation and the Efficiency of Government Environmental Protection Expenditure in China: Spatial–Temporal Difference and Driving Factors

ABSTRACT The coordinated development of informal environmental regulation (IER) and the efficiency of government environmental protection expenditure (EGEPE) is key to enhancing the effectiveness of environmental governance. This study focuses on 30 provinces in China over the period from 2008 to 2020, developing a multi‐indicator assessment framework that encompasses both IER and EGEPE. We employ a suite of analytical methods, including the SBM (slack‐based measure) model with undesirable outputs, the entropy technique, a coupling coordination model and a two‐way fixed‐effects model, to dissect the regional disparities, spatiotemporal dynamics and determinant factors influencing the coupling coordination between IER and EGEPE. The results show: ① The coupling coordination degree of IER and EGEPE in the three major regions of China has been on an upward trend, but presents pronounced regional disparities, characterised by East > West > Central regions; ② The number of areas with high‐level coordination has gradually increased, mainly concentrated in the eastern region, while the central and western regions show a trend of ‘low‐level equilibrium trap’ and the trend surface analysis presents a spatial pattern of ‘low in north and high in south—high in east and low in central and western’; ③ Technological innovation plays an important role in promoting the coupling coordination of IER and EGEPE, reflecting the key position of technological development and efficiency improvement in environmental governance.