Atomic‐Scale Mott–Schottky Heterojunctions of Boron Nitride Monolayer and Graphene as Metal‐Free Photocatalysts for Artificial Photosynthesis

Heterojunction photocatalysts at present are still suffering from the low charge separation/transfer efficiency due to the poor charge mobility of semiconductor‐based photocatalysts. Atomic‐scale heterojunction‐type photocatalysts are regarded as a promising and effective strategy to overcome the drawbacks of traditional photocatalysts for higher photoenergy conversion efficiencies. Herein, an atomic‐scale heterojunction composed of a boron nitride monolayer and graphene (h‐BN‐C/G) is constructed to significantly shorten the charge transfer path to promote the activation of molecular oxygen for artificial photosynthesis (exemplified with oxidative coupling of amines to imines). As the thinnest heterojunction, h‐BN‐C/G gives the highest conversion, which is eightfold higher than that of the mechanical mixture of graphene and boron nitride monolayers. h‐BN‐C/G exhibits a high turnover frequency value (4.0 mmol benzylamine g−1 h−1), which is 2.5‐fold higher than that of the benchmark metal‐free photocatalyst in the literature under even critical conditions.