Can outward foreign direct investment improve China's green economic efficiency?

Under the constraints of energy and environment, improving green economic efficiency (GEE) has become the key path to promote the sustainable economic development. Among the driving factors of GEE, the role of outward foreign direct investment (OFDI) is worth exploring. In this paper, we adopt the inter-provincial panel data of China from 2011 to 2019 and System Generalized Method of Moments (SYS-GMM) to explore the influence of OFDI on GEE. We find that OFDI significantly improves China's GEE, and reverse technology spillover through direct investment in developed countries is an important way for OFDI to promote GEE. Regional heterogeneity test shows that OFDI significantly promotes GEE in eastern China; however, the promotion effect is not significant in midwestern China. Besides, the promoting effect of OFDI on GEE has been further improved after 2016. We further adopt panel threshold model and find that when the financial development (FD) and human capital (HUM) exceeds 2.0954 and 0.0290, respectively, the promoting effects of OFDI on GEE are greatly enhanced. We suppose that the above conclusions can provide guidance for policymakers to optimize OFDI and improve GEE.