Theoretical design of Z-scheme photocatalyst for water splitting with excellent catalytic performance: GeSe/PtS2 heterojunction

In the face of the urgent need for energy transition, Z-scheme heterojunctions are considered highly suitable candidates for future photocatalytic applications, owing to their exceptional optoelectronic characteristics and high catalytic efficiency. This paper systematically investigates the geometric structure, optoelectronic properties, and catalytic efficiency of the GeSe/PtS₂ heterojunction through detailed first-principles calculations. The findings indicate that the band structure of the GeSe/PtS₂ heterojunction presents a staggered Type-Ⅱ band alignment and exhibits an indirect band gap measuring 1.75 eV Charge transfer analysis reveals that under the interplay of an intrinsic electric field directed from GeSe to PtS₂ and the band bending occurring at the heterojunction interface, the GeSe/PtS₂ heterojunction conforms to the obvious Z-scheme electron transfer mechanism characteristics. This facilitates the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) to proceed smoothly on opposite sides of the heterojunction. Across the pH range of 0 to 14, the heterojunction's band edge positions successfully span the redox potentials of water, and can still meet the hydrolysis potential requirements under strain. In addition, the GeSe/PtS₂ heterojunction not only effectively compensates for the poor absorption of PtS₂ monolayer to visible light, but also achieves a wider visible light absorption range through the strain-induced redshift in the spectrum. At the same time, the solar to hydrogen (STH) efficiency of up to 15.56 % further underscores the substantial catalytic potential of the GeSe/PtS₂ heterojunction, offering promising design strategies for a technological revolution in the field of photocatalysis.