Synthesis of Atomically Thin g-C<sub>3</sub>N<sub>4</sub> Nanosheets via Supercritical CO<sub>2</sub> Doping with Single-Atom Cobalt for Photocatalytic Hydrogen Evolution
Wenxiu Li, Wenxiu Li, Wei Li, Wei Li, Zanwu Guo, Yi Song, Shaoru Tang, Yanan Ma, Xueqing Xing, Qian Wang
Abstract
The atomically thin nanosheets of graphitic carbon nitride (g-C3N4) with mesopores have been successfully exfoliated with supercritical CO2 (scCO2). The thickness of the as-synthesized samples could be directly tailored by simply regulating the scCO2 pressure. The obtained bilayer mesoporous g-C3N4 nanosheets doped with monatomic Co through a microwave-assisted approach havve been employed as single-atom catalysts to enhance the photocatalytic hydrogen evolution performance. The as-prepared Co/P/CN-sc sample exhibited a boosted H2 production performance due to its unique structural advantages by exposing more active sites and facilitating the separation of charge carriers. Based on X-ray photoelectron spectroscopy, steady-state and time-resolved photoluminescence spectroscopy, X-ray absorption fine structure measurement, and density functional theory (DFT) calculations, a possible mechanism has been proposed. The work shows a new perspective for designing an inexpensive photocatalyst with a unique structure through a facile and green approach for photocatalytic hydrogen evolution.