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.