Leverage or crowd out: the National Independent Innovation Demonstration Zone policies and green innovation efficiency of enterprises

National independent innovation demonstration zone has been assigned the unique mission of demonstrating and leading national innovation and playing a key supportive role in enhancing green innovation. Based on the sample data of A-share listed companies in China from 2007–2021, we apply a multi-period difference-in-differences model to analyze whether the implementation of the national independent innovation demonstration zone policy plays a leveraging effect or a crowding out effect on the green innovation efficiency of enterprises and systematically test the regulatory mechanism of government subsidies and media attention in the process of this influence. The empirical results show that the implementation of the National Independent Innovation Demonstration Zones policy has a positive impact on the green innovation efficiency of enterprises and that the green innovation induced by this reform is not the leverage effect of additional R&D investment on the basis of the existing innovation activities of enterprises but rather the result of the reallocation of resources to crowd out existing non-green innovation. It is further found that government grants and media attention positively moderate the positive driving effect of national independent innovation demonstration zone policy on the green innovation efficiency of enterprises.