Two-Dimensional Layered Co(OH)₂/g-C₃N₄/Ni(OH)₂ Ternary Nanocomposites for Enhanced Visible-Light Photocatalytic H₂-Production Activity

Two-dimensional (2D) layered nanocomposite provides a surface-to-surface heterojunction, which is an effective way to improve the photocatalytic performance because larger contact areas can promote the separation rate of interfacial charge carriers. In this study, Co(OH)2/g-C3N4/Ni(OH)2 2D layered photocatalysts have been successfully synthesized through a simple precipitation–hydrothermal method. The composite achieves a high H2-production rate of 899 μmol·h–1·g–1, which exceeds the rate of samples only coupled with Co(OH)2 and Ni(OH)2 by 4.0 and 1.9 times, respectively. In addition, the activity is even higher than that of the optimized Pt-g-C3N4 sample (1 wt. % Pt–C). The characterization results reveal the close contact of g-C3N4 and Ni/Co hydroxides, and such a face-to-face contact can greatly improve the interfacial charge-transfer rate, resulting in a high photocatalytic performance. This work demonstrates a simple way to enhance the photocatalytic H2 production of g-C3N4 under the cooperative effect of Co(OH)2 and Ni(OH)2 and provides novel insights into constructing other 2D ternary heterostructure nanocomposites.