Preparation of highly dispersed Ni single-atom doped ultrathin g-CN nanosheets by metal vapor exfoliation for efficient photocatalytic CO reduction.

Single-atom photocatalysts can modulate the utilization of photons and facilitate the migration of photogenerated carriers. However, the preparation of single-atom uniformly doped photocatalysts is still a challenging topic. Herein, we propose the preparation of Ni single-atom doped g-CN photocatalysts by metal vapor exfoliation. The Ni vapor produced by calcining nickel foam at high temperature accumulates in between g-CN layers and poses a certain vapor pressure to destroy the interlayer van der Waals forces of g-CN. Individual metal atoms are doped into the structure while exfoliating g-CN into nanosheets by metal vapor. Upon optimization of Ni content, the Ni single atom doped g-CN nanosheets with 2.81 wt% Ni exhibits the highest CO reduction performance in the absence of sacrificial agents. The generation rates of CO and CH are 19.85 and 1.73 μmol gh, respectively. The improved photocatalytic performance is attributed to the anchoring Ni of single atoms on g-CN nanosheets, which increases both carrier separation efficiency and reaction sites. This work provides insight into the design of photocatalysts with highly dispersed single-atom.