Efficient visible-light-driven alcohol oxidation coupled hydrogen production on 0D/0D “n-NiWO4/p-CdS” S-scheme heterojunction

Abstract

The theory of S-scheme transfer mechanism have significant implications for exploring the mechanism of photocatalytic carrier migration and its intrinsic dynamics. Modeled NiWO₄/CdS heterojunction photocatalyst (referred to as NWO/CS) was synthesized using a simple hydrothermal method and applied for alcohol oxidation coupled with H₂ production. Systematically investigates the factors contributing to its enhanced performance and the internal charge transfer mechanisms. The 28% NWO/CS composite exhibited the highest activity, with a H₂ production and the aldehyde generation rates of 16.08 mmol⋅g⁻¹⋅h⁻¹ and 16.88 mmol⋅g⁻¹⋅h⁻¹, which are about 320 times higher than those of NiWO₄ (0.05 mmol⋅g⁻¹⋅h⁻¹ and 0.06 mmol⋅g⁻¹⋅h⁻¹) and 16 times higher than that of CdS (1.09 mmol⋅g⁻¹⋅h⁻¹ and 1.12 mmol⋅g⁻¹⋅h⁻¹). Based on the in-situ XPS, transient surface photovoltage, theoretical calculations, and other physicochemical characterization results, we have confirmed that the built-in electric field formed at the interface and the transfer of photogenerated charges follows the S-scheme mechanism between relative “n-NiWO₄” and relative “p-CdS” are the key factors that promote efficient charge separation and significantly enhance the subsequent reaction activity. This work provides a theoretical basis for improving photocatalytic performance and understanding photocatalytic mechanisms.