Fabrication of P-doped Co9S8/g-C3N4 heterojunction for excellent photocatalytic hydrogen evolution

Developing lower-cost and higher-efficient photocatalysts is still a major challenge for the solar to hydrogen energy conversion by photocatalytic water splitting. Herein, P-doped Co9S8 (P-Co9S8) was synthesized by a hydrothermal process using low-cost RP as raw material, and then P-Co9S8 was employed to construct heterojunction with g-C3N4 via a mechanical-mixing method. Investigation shows that P-Co9S8 can not only improve the electrical conductivity and surface area of the composite, but also can lower the over potential of H-2 evolution, leading to an enhanced H-2 evolution kinetics. The H-2 evolution rate of resultant 25% P-Co9S8/g-C3N4 reached 4362 mmol g(-1) h(-1) under UV and visible light, being nearly 121.2 times higher than that of g-C3N4. The charge transfer between P-Co9S8 and g-C3N4 follows the Type-I route based on the photoelectrochemical analysis, leading to more electrons on the conduction band of P-Co9S8 to participate the H-2 evolution processes. This work provides a new way for preparation of P-doped sulfides with potential applications in the field of photocatalysis. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study synthesized P-Co9S8 through a hydrothermal process and constructed a heterojunction with g-C3N4, demonstrating that P-Co9S8 not only improves the electrical conductivity and surface area of the composite, but also lowers the over potential of H-2 evolution, leading to enhanced H-2 evolution kinetics. The H-2 evolution rate of the resultant 25% P-Co9S8/g-C3N4 reached 4362 mmol g(-1) h(-1) under UV and visible light, which is nearly 121.2 times higher than that of g-C3N4.