Construction of Z-scheme and p-n heterostructure: Three-dimensional porous g-C3N4/graphene oxide-Ag/AgBr composite for high-efficient hydrogen evolution

Abstract Hydrogen is known as an alternative new energy for its advantages of non-pollution and high calorific value, and photocatalysis technology is regarded as one of the most effective means to produce hydrogen in recent years. In this topic, aiming at the poor photoresponse, fast combination of photo-induced carriers and unstable structure of traditional photocatalysts, the three-dimensional porous g-C3N4/graphene oxide framework was constructed by compounding two-dimensional graphene oxide and two-dimensional g-C3N4 via hard template (SiO2 nanoparticles) method and selective chemical etching. Then, silver bromide nanoparticles, a superior photosensitizer, were immobilized on the three-dimensional porous framework to construct the three-dimensional porous g-C3N4/graphene oxide-AgBr photocatalyst with Ag plasmas by solvothermal method. Research showed that this novel photocatalyst based on Z-scheme heterostructure (GO-AgBr), p-n heterostructure (g-C3N4-AgBr) and Ag plasmas presented high-efficient visible-light driven hydrogen evolution (3.69 mmol/g/h) at the absence of Pt co-catalyst, which is higher than the majority of existing catalysts, and it also possessed strong stability on its activity and structure. Accordingly, the enhanced hydrogen evolution and photostability were attributed to the highly ordered structure and fast interfacial electron conduction of three-dimensional porous framework, superior photosensitivity of AgBr and synergistic effect of Ag plasmas. Therefore, this study provided a potential method for exploitation of hydrogen energy.