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

Core-shell heterostructured nanomaterials with mesopores have enormous potential applications in diverse fields. Herein, we report a facile extended Stober 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 approximate to 15 nm, where the TiO2 coating thickness was tuned approximate to 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 H-2 at the semiconductor/electrolyte interface.