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

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 CoSe 2 /CN NS composite is successfully fabricated by a successive high-temperature calcination method of g-C 3 N 4 followed by in-situ hot injection process of CoSe 2 for the first time. The optimal 7.5% CoSe 2 /CN NS 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 (H 2 O 2 , · OH and · O 2 − ) 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 H 2 O 2 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 H 2 O 2 production during photocatalytic hydrogen evolution process. • CoSe 2 /g-C 3 N 4 heterojunction photocatalyst is synthesized by interfacial engineering route. • The 0D/2D nanojunction expand visible light harvesting, improve carriers separation. • A fast and directional transfer of carriers is achieved by a type-I band alignment. • Long carrier lifetime, acceleration of H 2 O 2 decomposition enhance H 2 evolution.