Photocatalytic hydrogen evolution reaction with high solar-to-hydrogen efficiency driven by the Sb2S3 monolayer and RuI2/Sb2S3 heterostructure with solar light

The feasibility and solar-to-hydrogen efficiency (riSTH) of the photocatalytic hydrogen evolution reaction (HER) with the Sb2S3-P21/m monolayer and RuI2/Sb2S3-P3m1 heterostructure are investigated by employing the firstprinciples calculations. The Sb2S3 monolayers with P21/m and P3m1 space groups are identified and the stabilities are confirmed. The band edges of the Sb2S3-P21/m monolayer can but those of the P3m1 one cannot straddle the oxidation and reduction potentials for the HER of the water-splitting to produce hydrogen. Therefore, we construct a RuI2/Sb2S3-P3m1 heterostructure that can drive the HER for hydrogen generation with the Z-scheme. The maximum riSTH of the Sb2S3-P21/m monolayer can reach 17.51% under +5% biaxial strains, while that of the RuI2/Sb2S3-P3m1 heterostructure can reach 9.45% under +9% biaxial strains. The Gibbs free energy change (dGH) is used to assess the feasibility of HER. The preferable H-adsorbed sites are identified, and the corresponding dGHs are 1.037-1.425 eV for the Sb2S3-P21/m monolayer and 1.233-2.132 eV for the RuI2/ Sb2S3-P3m1 heterostructure. Therefore, the present Sb2S3 monolayers can be achieved to drive HER for hydrogen generation from overall water splitting, especially the Sb2S3-P21/m one demonstrating high solar-tohydrogen conversion efficiency.