Fabrication of S-scheme FeCoS2/Red phosphorus heterojunction for efficient photocatalytic H2 evolution

Abstract

Establishing efficient charge transfer channels remains a great challenge to improve the photocatalytic activity of red phosphorus (RP). Herein, the flower-like spherical FeCoS2 was employed to improve the activity of RP nanosheets, S-scheme FeCoS2/RP heterojunction was obtained through a facile solvent evaporation strategy. The optimized 5 wt% FeCoS2/RP exhibited an excellent H2 evolution rate of 2254.2 μmol g−1 h−1, which is 17.5 and 71.1-fold than that of pristine RP (129.1 μmol g−1 h−1) and FeCoS2 (31.7 μmol g−1 h−1), respectively. The analysis shows that bimetallic sulfides FeCoS2 can not only increase the electrochemically active surface area, decrease the H2 evolution overpotential and water contact angle of the composite, but also provide more photoinduced charges and reduce their transfer resistance, more importantly, the charge transfer between FeCoS2 and RP follows the S-scheme route, which can reserve the electrons and holes with higher the thermodynamic driving force. Further investigation shows that the activity of FeCoS2 is superior to monometallic sulfides FeS and CoS due to its synergistic effect between Fe and Co. This work provides new insights for constructing S-scheme RP-based heterojunction with high photocatalytic efficiency and stability.