Nanoarchitectonics of S‐Scheme Heterojunction Photocatalysts: A Nanohouse Design Improves Photocatalytic Nitrate Reduction to Ammonia Performance

Abstract Photocatalytic nitrate reduction reaction (NitRR) is a promising route for environment remediation and sustainable ammonia synthesis. To design efficient photocatalysts, the recently emerged nanoarchitectonics approach holds great promise. Here, we report a nanohouse‐like S‐scheme heterjunction photocatalyst with high photocatalytic NitRR performance. The nano‐house has a floor of plate‐like metal organic framework‐based photocatalyst (NH2‐MIL‐125), on which another photocatalyst Co(OH)2 nanosheet is grown while ZIF‐8 hollow cages are also constructed as the surrounding wall/roof. Experimental and simulation results indicate that the positively charged, highly porous and hydrophobic ZIF‐8 wall can modulate the environment in the nanohouse by (i) NO3− enrichment/NH4+ discharge and (ii) suppression of the competitive hydrogen evolution reaction. In combination with the enhanced electron‐hole separation and strong redox capability in the NH2‐MIL‐125@Co(OH)2 S‐scheme heterjunction confined in the nano‐house, the designed photocatalyst delivers an ammonia yield of 2454.9 μmol g−1 h−1 and an apparent quantum yield of 8.02 % at 400 nm in pure water. Our work provides new insights into the design principles of advanced photocatalytic NitRR photocatalyst.