Robust Protection of III–V Nanowires in Water Splitting by a Thin Compact TiO₂ Layer

Narrow-band-gap III–V semiconductor nanowires (NWs) with a suitable band structure and strong light-trapping ability are ideal for high-efficiency low-cost solar water-splitting systems. However, due to their nanoscale dimension, they suffer more severe corrosion by the electrolyte solution than thin-film counterparts. Thus, short-term durability is major obstacle using these NWs practical applications. Here, we demonstrated first time that thin layer (∼7 nm thick) of compact TiO2 deposited atomic deposition can provide robust protection NWs. The protected GaAs maintain 91.4% its photoluminescence intensity after 14 months storage in ambient atmosphere, which suggests pinhole-free. Working as photocathode water splitting, exhibited 45% larger photocurrent density compared unprotected counterparts high Faraday efficiency 91% also record-long highly stable performance among narrow-band-gap NW photoelectrodes; 67 h photoelectrochemical stability test reaction acid (pH = 1), show no apparent indication corrosion, stark contrast fully failed 35 h. These findings an effective way enhance both NW-based photoelectrodes, important applications solar-energy-based