Construction of 2D/2D Z-scheme MnO2-x/g-C3N4 photocatalyst for efficient nitrogen fixation to ammonia

Abstract

Reducing nitrogen to ammonia with solar energy has become a wide concern when it comes to photocatalysis research. It is considered to be one of the more promising alternate options for the conventional Haber–Bosch cycle. Herein, 2D g-C3N4 composites with modifying ultrathin sheet MnO2-x were prepared and used as nitrogen fixation photocatalyst. With the assistance of the nature of MnO2-x, the generation rate of NH3 reached 225 μmol g−1 h−1, which is more than twice over the rate of pristine 2D g-C3N4 (107 μmol g−1 h−1). The presence of ultrathin sheet MnO2-x shortens the gap of the carriers to the surface of photocatalyst. Thus the speed of electron transfer gets increased. Besides, the construction of Z-scheme heterojunction boosts the separation and migration of photogenerated carriers. As a result, the nitrogen reduction reaction (NRR) performance gets enhanced. The work may provide an example of promoting the NRR performance of non-metallic compound.