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.