Novel Two-Dimensional Metal-Based π-d Conjugated Nanosheets as Photocatalyst for Nitrogen Reduction Reaction: The First-Principle Investigation

Photocatalytic nitrogen reduction reaction (NRR) is becoming a promising route for producing green and sustainable ammonia under ambient conditions. However, the development of highly efficient photocatalysts for NRR still remains a grand challenge as a result of the sluggish activation of inert N2, the competitive hydrogen evolution reaction (HER), and inadequate photogenerated external potential, which usually cause extremely poor NRR performance and low light utilization efficiency. Herein, on the basis of density functional theory (DFT) computations, we rationally designed a series of two-dimensional (2D) π-d conjugated metal-B3N3 (M3B6N6S12) semiconductors. Using the electron "σ acceptance-π* backdonation" process, Mo3B6N6S12 and Nb3B6N6S12 can efficiently activate and reduce N2 to ammonia with a rather low overpotential of 0.07 and 0.21 V, respectively. Importantly, a high photogenerated external potential enables spontaneous NRR on Mo3B6N6S12 and Nb3B6N6S12 under visible/infrared light irradiation, contributing to the extraordinary photoactivity of Mo3B6N6S12 and Nb3B6N6S12 as promising solar light-driven N2 fixation catalysts. Meanwhile, the competing HER is effectively restrained. For the first time, we rationally propose a series of M3B6N6S12 semiconductors as promising metal-based photocatalysts for N2 reduction with extraordinary photoactivity and a high photogenerated external potential. This work paves a new path for the rational designing of 2D metal-based NRR photocatalysts with high activity, good selectivity, and high stability.