Cobaltous selenide/g-C3N4 heterojunction photocatalyst based on double-electron migration mechanism promotes hydrogen production and tetracycline hydrochloride degradation

Abstract

Regulating photogenerated charge carrier transfer kinetics in multi-component heterostructure by surface-interface design is of great significance for accelerating efficiently photocatalytic hydrogen evolution reaction. Herein, a novel binary CoSe2/CNNS composite is successfully fabricated by a successive high-temperature calcination method of g-C3N4 followed by in-situ hot injection process of CoSe2 for the first time. The optimal 7.5% CoSe2/CNNS heterostructure reaches moderate hydrogen production rate of 1386.8 μmol·g−1·h−1 and exhibits good mineralization efficiency for tetracycline hydrochloride (40.6%) within 120 min under light irradiation, respectively. The photogenerated charge migration behaviors, the generation process and function of various radical species (H2O2, ·OH and ·O2−) are detailedly analyzed. Moreover, photocatalytic hydrogen evolution reaction process and the intermediates and active species for tetracycline hydrochloride degradation can also be discussed. Such significantly enhanced photocatalytic activity can be resulting from good light trapping ability, rapid photocarriers transfer efficiency and accelerated H2O2 decomposition ability via a continuous two-electron/two-step reduction route. This work provides an effective strategy to control and understand the charge migration kinetics as well as to suppress H2O2 production during photocatalytic hydrogen evolution process.