A highly active Z-scheme NiGa2O4/anthraquinone/MoO3 photocatalyst via charge transfer for sunlight photocatalytic simultaneous conversions of nitrite and sulfite

Abstract

A b s t r a c t The separation efficiency of photogenerated electron-hole pairs (e−–h+) is an important factor for a highly photocatalytic activity of Z-scheme photocatalytic system. In order to suppress the recombining of photogenerated e− and h+ and enhance the electron transfer rate, anthraquinone (AQ) as special electron transfer channel is combined with NiGa2O4 and MoO3, forming a Z-scheme NiGa2O4/AQ/MoO3 photocatalyst. Due to unique chemical and physical properties, AQ provides a novel electron transmission way. Compared with traditional conductive channels (for example, noble metals and graphene), in this way, the AQ may greatly enhance the electron transfer efficiency. In addition, the related morphology, optical properties and chemical composition were investigated by a sequence of characterization methods. The influences of photocatalyst species, irradiation time and used times in simultaneously converting nitrite and sulfite under simulated sunlight were also studied. The results indicate that the prepared Z-scheme NiGa2O4/AQ/MoO3 photocatalyst exhibits a much high activity. The conversion rates of nitrite and sulfite can reach 89.81% and 94.47%, respectively, under simulated sunlight irradiation for four hours. The enhanced photocatalytic activity is attributed to the fact that AQ can rapidly transfer electron by inner charge transfer. This charge transfer way can provide a new idea to design subsequent photocatalysts.