Accelerated hydrogen production on atomically thin silicon nanosheets photocatalyst with unique surface adsorption chemistry

Compared with widely explored layered materials, the atomically thin layer based on nonlayered materials and their thickness dependent properties are less reported. Recently, silicon nanosheet as a novel non-layered 2D material is getting burgeoning attentions. Herein, based on density functional theory calculations, we reveal that freestanding atomically thin silicon nanosheets display favorable hydrogen evolution kinetics including small hydrogen adsorption energy and low hydrogen evolution barrier, which is distinct from multilayer silicon nanosheets and bulk silicon surface. This unique surface adsorption chemistry greatly contributes to the photocatalytic hydrogen production process. Atomically thin silicon nanosheets were further prepared by a liquid phase exfoliation approach and its cocatalyst-free photocatalytic hydrogen production performance is evaluated. The results confirmed that the photocatalytic activity of atomically thin silicon nanosheets vigorously outperforms that of bulk silicon and multilayer silicon flakes. The average hydrogen production rates of A-SiNS can reach158.8 μmol h⁻¹ g⁻¹, which is about 3.2 times higher than that of M-SiNS (49.5 μmol h⁻¹ g⁻¹). This work not only supports atomically thin silicon nanosheets as a potential candidate for photocatalytic reactions but also brings new insights into its unique physiochemical properties and applications.