The g-ZnO/PtSe2 S-scheme heterojunction with controllable band structure for catalytic hydrogen production

The structural, photo-electronic catalytic properties, and the biaxial strain modulation of band structure for the g-ZnO/PtSe2 S-scheme heterojunction are studied by First-principles calculation. The stability for the heterojunction is verified by negative generation energy and ab-initio molecular dynamic simulation. The photo-generated carrier motion and band structure are in accordance with the S-scheme, and the electron mobility of up to 2023 cm2/Vs is obtained in the Zigzag direction. The absorption of visible light is improved, and an absorption peak of 2.893 × 105 cm−1 at 434.337 nm is observed. Due to a higher redox potential, photocatalytic water splitting can occur in the pH range of 0∼14, and a high solar to hydrogen (STH) efficiency of 30.7 % is obtained. The over-potential of hydrogen evolution reaction (HER) (3.719 V) is lower than oxygen evolution reaction (4.128 V), which tends to proceed at the g-ZnO interface. When the strain ≥4 %, the bandgap alignment of the g-ZnO/PtSe2 heterojunction changes from a staggered gap (Type-Ⅱ) to straddling gap (Type-Ⅰ). The g-ZnO/PtSe2 heterojunction exhibits high electron mobility, high STH efficiency, strong absorption of visible light, strong HER ability, and a tunable band structure, expecting as a promising candidate material for catalytic water splitting.