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 hetero-structure 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 mmol center dot g-1 center dot h-1 and exhibits good mineralization efficiency for tetracycline hydrochloride (40.6%) within 120 min under light irradiation, respectively. The photogenerated charge migration be-haviors, the generation process and function of various radical species (H2O2, middotOH and middotO2-) 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.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Regulating charge carrier transfer kinetics in multi-component hetero-structures through surface-interface design is crucial for efficient photocatalytic hydrogen evolution reaction. In this work, a novel CoSe2/CNNS composite is synthesized for the first time via a high-temperature calcination method followed by an in-situ hot injection process. The optimized 7.5% CoSe2/CNNS heterostructure exhibits a moderate hydrogen production rate of 1386.8 mmol center dot g-1 center dot h-1 and efficient mineralization of tetracycline hydrochloride (40.6%) within 120 min under light irradiation. The study also analyzes the charge migration behaviors, generation process, and function of various radical species. Moreover, the photocatalytic hydrogen evolution reaction process and the intermediates and active species for tetracycline hydrochloride degradation are discussed. The enhanced photocatalytic activity is attributed to the material's light trapping ability, rapid photocarriers transfer efficiency, and accelerated H2O2 decomposition ability via a continuous reduction route.