Dissolution‐Induced Surface Reconstruction of Ni_0.95Pt_0.05Si/p‐Si Photocathode for Efficient Photoelectrochemical H₂ Production

Abstract Metal silicide/Si photoelectrodes have demonstrated significant potential for application in photoelectrochemical (PEC) water splitting to produce H₂. To achieve an efficient and economical hydrogen evolution reaction (HER), a paramount consideration lies in attaining exceptional catalytic activity on the metal silicide surface with minimal use of noble metals. Here, this study presents the design and construction of a novel Ni_0.95Pt_0.05Si/p‐Si photocathode. Dopant segregation is used to achieve a Schottky barrier height as high as 1.0 eV and a high photovoltage of 420 mV. To achieve superior electrocatalytic activity for HER, a dissolution‐induced surface reconstruction (SR) strategy is proposed to in situ convert surface Ni_0.95Pt_0.05Si to highly active Pt₂Si. The resulting SR Ni_0.95Pt_0.05Si/p‐Si photocathode exhibits excellent HER performance with an onset potential of 0.45 V (vs RHE) and a high maximum photocurrent density of 40.5 mA cm⁻² and a remarkable applied bias photon‐to‐current efficiency (ABPE) of 5.3% under simulated AM 1.5 (100 mW cm⁻²) illumination. The anti‐corrosion silicide layer effectively protects Si, ensuring excellent stability of the SR Ni_0.95Pt_0.05Si/p‐Si photoelectrode. This study highlights the potential for achieving efficient PEC HER using bimetallic silicide/Si photocathodes with reduced Pt consumption, offering an auspicious perspective for the cost‐effective conversion of solar energy to chemical energy.