Surface Reconstructed Ni0.95Pt0.05/Si Photoelectrodes for Bias-free Hydrogen Evolution Coupled with 5-hydroxymethylfurfural Oxidation

Coupling hydrogen evolution reaction (HER) with biomass valorization using a photoelectrochemical (PEC) system presents a promising approach for effectively converting solar energy to chemical energy. A crucial biomass valorization reaction is the production of value-added 2,5-furandicarboxylic acid (FDCA) via 5-Hydroxymethylfurfural (HMF) oxidation reaction (HMFOR). To achieve efficient FDCA production, we demonstrate an effective photoanode strategy that combines metal silicidation, dopant segregation, and surface reconstruction to create a bimetallic silicide Ni_0.95Pt_0.05Si/n-Si photoanode. The oxide-free Ni_0.95Pt_0.05Si/n-Si interface prepared by the metal-silicidation process ensures efficient interfacial charge transport, while dopant segregation enhances the Schottky barrier height and photovoltage, and surface reconstruction dramatically improves the catalytic activity of the photoanode surface. The as-prepared Ni_0.95Pt_0.05Si/n-Si photoanode exhibited excellent PEC performance for HMFOR with high conversion of HMF (97.2 %) and yield of FDCA (80.3 %) under illumination. Furthermore, by integrating a surface reconstructed Ni_0.95Pt_0.05Si/n-Si photoanode with a Ni_0.95Pt_0.05Si/p-Si photocathode, a dual-photoelectrode system was constructed capable of simultaneous production of FDCA and H₂, which achieves high photocurrent density of 5 mA cm⁻² at zero bias under illumination. This study offers an auspicious prospect for high cost-effectiveness conversion from solar energy to industrial monomers.