Hydrogen evolution by catalyzing water splitting on two-dimensional g-C3N4-Ag/AgBr heterostructure

Due to the increasing pressure of social environment and the increasing demand of human for energy, it is urgent to seek a sustainable and pollution-free new energy. Hydrogen is considered as a new type of energy because of its high calorific value, no environmental pollution and low cost of raw materials. In this experiment, to improve the visible-light driven catalytic activity of two-dimensional g-C3N4, g-C3N4 and Ag/AgBr nanoparticles (NPs) were used as the carrier and cocatalyst, and the g-C3N4/Ag/AgBr (CNAA-alpha, alpha = 1, 2 and 3) heterojunction photocatalysts with different amounts of Ag/AgBr were synthesized via solvothermal technology. The morphology, composition, structure, photochemical and electrochemical characteristics of the samples were analyzed through XRD, FTIR, TEM, XPS and a series of photoelectrochemical characterizations, and the visible-light driven catalytic hydrogen evolution activities of the samples were studied by catalyzing water splitting. Research showed that the CNAA-2 exhibited the smallest overvoltage (86.5 mV vs RHE) and Tafel slope (61.0 mV.dec(-1)), so that the highest photocatalytic activity (47.84 mu mol.g(-1).h(-1)) for hydrogen evolution was obtained at the absence of Pt co-catalyst. Furthermore, this heterojunction photocatalyst exhibited good photostability and could be recycled several times with no significant decrease of its activity. This indicated that the addition of Ag/AgBr NPs to the two-dimensional g-C3N4 nanosheets to construct an effective p-n heterojunction system at their interfaces could promote the conduction of photo-induced carriers and inhibit their combination, so that it would significantly improve the photoresponse ability and catalytic activity of two-dimensional g-C3N4 nanosheets.