Photoelectrochemical Hydrogen Production of TiO₂ Passivated Pt/Si-Nanowire Composite Photocathode

Si nanowire (SiNW) arrays decorated with Pt nanoparticles are passivated with TiO₂ surface layer using atomic layer deposition (ALD). The sandwich structure TiO₂/Pt/SiNW shows superior photoelectrochemical performance to the control planar silicon electrodes, especially under the concentrated solar radiation. Pt nanoparticles separated from aqueous electrolyte by TiO₂ layer of more than 15 nm still well catalyze surface photoelectrochemical hydrogen production without direct contact to the electrolyte. This structural configuration shows remarkable chemical stability and anodically shifted onset potential, suggesting great promise for applications in solar hydrogen production. The maximum photon-to-energy conversion efficiency of the TiO₂/Pt/SiNW reaches 15.6%