Core–Shell Silicon@Mesoporous TiO2 Heterostructure: Towards Solar-Powered Photoelectrochemical Conversion

Abstract

Core–shell heterostructured nanomaterials with mesopores have enormous potential applications in diverse fields. Herein, we report a facile extended Stöber method to synthesize core–shell heterostructured semiconducting nanomaterials with mesoporosity. Silver (Ag) metal-assisted chemically wet etched p-type silicon nanowires (Si NWs) were used as the core, and layer-controllable mesoporous n-type anatase TiO2 was grown as the shell to successfully fabricate the core–shell p-Si@mesoporous n-TiO2 hybrid materials. Detailed characterization reveals that the TiO2 shell was composed of aggregated crystalline TiO2 nanoparticles with diameters of ≈15 nm, where the TiO2 coating thickness was tuned ≈50 nm. The interstitial pores of these nanoparticles were observed with average pore sizes of 4–8 nm. The core–shell structured p-Si@mesoporous n-TiO2 hybrid materials were demonstrated as photocathodes for the solar-driven photoelectrochemical (PEC) production of H2 at the semiconductor/electrolyte interface.