Facile Passivation of Silicon Nanowires Array as Stable Photoanode in Aqueous Electrolytes

We herein report a facile approach to passivate Si(100) nanowires (SiNWs) array by methylation and poly(3,4-ethylenedioxythiophene) (PEDOT) coating as stable photoanode in aqueous electrolytes. The photoanode was stable in both acid and base electrolytes. This facile approach deals with both the dangling bond and the anti-corrosion protection of SiNWs array. A combination of microstructural characterization, photoelectrochemical (PEC) measurements and electrochemical impedance spectroscopy (EIS) analysis were employed to confirm the methyl-terminated SiNWs/PEDOT (CH₃-SiNWs/PEDOT) array structure and the role of methylation in enhancing the photocurrent of SiNWs array photoanode. It was found that the methylation increased the donor concentration and significantly decreased the charge transfer impedance (Rct), which means that the methylation facilitates majority transport and collection, and thus may account for the PEC enhancement.