Development of single crystalline Al-doped ZnS nanodiscs as efficient photocatalysts for H2 evolution reaction

Abstract

The rapid photoinduced charge carrier recombination hinders the photocatalytic efficiency of binary zinc sulfide (ZS) photocatalysts. Enhanced charge separation through electronic and band structure modification via metal cation doping has gained much attention. Herein, aluminum (Al) doping with Pt single atoms (SAs) into single crystalline ZnS nanodiscs (Pt-AZS) with shallow defect states is reported. Rietveld refinement of XRD confirms lattice expansion with modulated electronic distribution. The additional Al-electron traps improved the lifetime of charge carriers, enhancing their interfacial transport to the metal cocatalyst, as confirmed by in situ XPS and time-resolved photoluminescence spectroscopy. The 1.6 wt% Pt loading on the AZS (200) facet exhibited an enhanced H₂ evolution rate of 17.1 mmol g⁻¹ h⁻¹ under AM1.5G irradiation with an apparent quantum yield (AQY) of 34% at 345 nm using a WB40 filter. Under UV light irradiation, Pt-AZS showed a high H₂ generation rate of 38 mmol g⁻¹ h⁻¹, which is two times more than that of bare Pt-ZS. This work elucidates the efficacy of Al doping with Pt SAs in a single crystalline photocatalyst to facilitate electron transport via suppressed band-bending at the Mott–Schottky interface, thereby boosting photocatalytic H₂ production.