Dual‑Function Pt/Ir‑Doped CdS Catalysts: Defect Engineering for Visible-Light HMF Photo Oxidation and Hydrogen Evolution Reaction

Abstract

We systematically controlled the surface defect density of CdS nanoparticles by doping the surface with Li+, Ir4+, and Pt2+ ions and evaluated the resulting effects on the photocatalytic and electrocatalytic performances. Compared with pristine CdS and Li-doped CdS (Lidp-CdS), Ir- and Pt-doped CdS (Irdp-CdS and Ptdp-CdS, respectively) exhibited markedly enhanced photocatalytic activity for visible-light-driven selective oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid, as well as improved electrocatalytic hydrogen evolution reaction performance. In situ X-ray photoelectron spectroscopy and electrochemical measurements suggested that the incorporation of Ir and Pt onto the surface promoted sulfur depletion and the formation of interfacial defect states, thereby improving charge separation and carrier transport. In contrast, Li⁺ remained as Li2O species on the surface without substantial interaction with the CdS lattice, resulting in negligible changes in interfacial charge transfer and catalytic activity. The consistent improvements under photochemical and electrochemical conditions demonstrate that noble-metal doping and defect engineering provide an effective strategy for developing multipurpose sulfide-based catalysts.