Fabrication and photoelectrochemical study of vertically oriented TiO₂/Ag/SiNWs arrays

Ordered channeled and porous TiO₂ and Ag modified silicon nanowires (TiO₂/Ag/SiNWs) heterostructured nanocrystals arrays are synthesized by a two-step method based on an electrochemical etching procedure and a sol-gel process. The morphology and photoelectrochemical properties of the TiO₂/Ag/SiNWs are studied. The TiO₂/Ag/SiNWs photocatalysts possess ordered channels and a porous structure with large specific surface area. UV-visible diffuse reflectance spectroscopy and ultraviolet Raman scattering demonstrate that the incorporated Ag significantly enhances light absorption by the TiO₂/SiNWs in the visible spectral range and improves the separation of photo-induced charge carriers in the TiO₂/SiNWs. The photoelectrochemical properties of the TiO₂/Ag/SiNWs are investigated by monitoring the degradation of pnitrophenol (PNP) and Ag enhances PNP photodegradation under UV-vis irradiation due to the Ag-TiO₂ heterojunctions and surface texture. The photoelectrochemical properties of TiO₂/Ag/SiNWs have promising applications in photoelectrochemical solar cells and other light-harvesting devices.