Efficient photocatalytic biomass-alcohol conversion with simultaneous hydrogen evolution over ultrathin 2D NiS/Ni-CdS photocatalyst

Abstract

The photocatalytic conversion of biomass into high-value chemicals, coupled with simultaneous hydrogen (H2) evolution, leveraging the electrons and holes generated by solar energy, holds great promise for addressing energy demands. In this study, we constructed a dual functional photocatalytic system formed by NiS loaded on Ni doped two-dimensional (2D) CdS nanosheet (NiS/Ni-CdSNS) heterostructure for visible-light-driven H2 evolution and ethanol oxidation to acetaldehyde. Remarkably, the 2D NiS/Ni-CdSNS exhibited significant activity and selectivity in both photocatalytic H2 evolution and ethanol oxidation, achieving yields of 7.98 mmol g−1 h−1 for H2 and 7.33 mmol g−1 h−1 for acetaldehyde. The heterogeneous interface of the composite facilitated efficient charge separation, while NiS provided abundant sites for proton reduction, thereby promoting the overall dual-functional photocatalytic activity. Density functional theory calculations further reveal that both Ni doping and NiS loading can reduce the reaction energy barrier of ethanol oxidation of free radicals, and NiS/Ni-CdSNS composite materials exhibit stronger ethanol C-H activation ability to generate key intermediate •CH(OH)CH3 on the surface. This work serves as a valuable guide for the rational design of efficient dual functional photocatalytic systems that combine H2 evolution with the selective conversion of organic compounds into high-value chemicals.