S-Scheme Heterojunctions Formed by MnSe₂ Cubic Microparticles Supported on Red Phosphorus Nanosheets as Photocatalyst for H₂ Production

Efficient photocatalysts possess significant potential for the technology of green hydrogen (H 2 ) production and environmental sustainability. Photocatalytic water splitting represents a promising method for the generation of green H 2 . In this study, cubic MnSe 2 was combined with amorphous RP nanosheets through a simple solvent evaporation method. The results demonstrated that 5 wt % MnSe 2 /RP composite exhibited an optimal H 2 production rate of 940 μmol g –1 h –1, using Na 2 S/Na 2 SO 3 as a sacrificial agent, under 300 W Xe lamp irradiation, which is 3.5 and 22 times higher than that obtained by pure RP (210 μmol g –1 h –1 ) and MnSe 2 (40 μmol g –1 h –1 ), respectively. Furthermore, the migration paths of MnSe 2 /RP were examined through ·O 2 – radical trapping experiments, confirming that the charge transfer between MnSe 2 and RP follows the S-scheme route, which promotes charge separation and provides more active sites for the reduction of H + to H 2 . In addition, the surface composition and structure analysis were analyzed using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, etc. This study presents a promising approach to utilizing selenides as efficient photocatalysts by constructing S-scheme heterojunctions in the field of photocatalysis.