Enhanced photoresponse and fast charge transfer: three-dimensional macroporous g-C3N4/GO-TiO2 nanostructure for hydrogen evolution

Abstract

Utilizing solar light to produce hydrogen is an advanced strategy to alleviate the energy crisis. Graphitic carbon nitride (g-C₃N₄) and graphene oxide (GO) have demonstrated significant potential in synthesizing highly efficient photocatalysts due to their favorable charge separation and transfer. However, the simple 2D structure generally leads to a weak adhesion to the surface cocatalyst, which negatively affects the photoresponse, interfacial charge transfer and durability of the resultant photocatalyst. Herein, we designed a 3D macroporous g-C₃N₄/GO (p-CNG) skeleton to enhance the adhesion stability of the cocatalyst (anatase TiO₂ NPs). The typical macroporous structure remarkably increased the BET surface area (65.81 m² g⁻¹) of the 3D p-CNG skeleton, which was 2.5-fold greater than that of the nonporous 3D CNG composite. The enhanced adhesion of the anatase TiO₂ NPs on the 3D p-CNG skeleton promoted the formation of a heterointerface, leading to the fast interfacial charge transfer and improved photoresponse. Hence, the optimal 3D p-CNG/TiO₂ (p-CNGT) catalyst represented excellent HER activity (33.1 μmol g⁻¹ h⁻¹) under the simulated solar light, which was 8.9-fold greater than that of the pristine anatase TiO₂ NPs and 4.7-fold greater than that of the 3D p-CNG skeleton. Therefore, the high apparent quantum yield (12.4%) was achieved under illumination of λ = 400 nm. Due to the stable interfacial adhesion, the resultant catalyst represented excellent regenerability and durability during five cycles and 20 h of illumination. This work proposed an effective strategy for improving the HER activity and enhancing the durability of the existing catalyst.