Reliable bi-functional nickel-phosphate /TiO2 integration enables stable n-GaAs photoanode for water oxidation under alkaline condition

• DOI: 10.1038/s41467-023-41120-0
• Publication Date: 2023-09-05T15:03:30Z
• Authors: Maheswari Arunach...; Rohini Subhash Ka...; Kai Zhu; Soon Hyung Kang
• Keywords: Science; Q; 02 engineering and technology; 0210 nano-technology; Article

Hydrogen is one of the most widely used essential chemicals worldwide, and it also employed in production many other chemicals, especially carbon-free energy fuels produced via photoelectrochemical (PEC) water splitting. At present, gallium arsenide represents efficient photoanode material for PEC oxidation, but known to either be anodically photocorroded or photopassivated by native metal oxides competitive reaction, limiting efficiency stability. Here, we report chemically etched GaAs that decorated with thin titanium dioxide (~30 nm-thick, crystalline) surface passivation layer along nickel-phosphate (Ni-Pi) cocatalyst as a hole-sink layer. The integration Ni-Pi bifunctional co-catalyst results highly electrode ~ 100 mV cathodic shift onset potential. In this work, has enhanced photostability under 110 h testing oxidation at steady current density Jph > 25 mA·cm-2. Et-GaAs/TiO2/Ni-Pi║Ni-Pi tandem configuration best unassisted bias-free splitting device highest (~7.6 mA·cm-2) stable solar-to-hydrogen conversion 9.5%.