Intrinsic GaAs-engineered p-i-n GaAs/GaAs/AlGaAs nanowires for improved-performance solar water splitting

We demonstrate that the addition of an intrinsic GaAs shell to form a p-i-n junction with GaAs/GaAs/AlGaAs core/shells nanowire (NW) enhances the photocurrent density by fivefold compared to a conventional p-n junction with GaAs/AlGaAs NW. The GaAs/AlGaAs material system offers distinct advantages due to its strong visible-light absorption, tunable band structure, and compatibility with protective and catalytic overlayers, such as TiO2, which can enhance surface stability and charge separation. What we believe to be a novel photocathode structure demonstrates a one-sun photocurrent density of 0.542 mA/cm2 at an applied potential of 0.20 V with respect to the reversible hydrogen electrode (RHE). This work demonstrates the suitability of GaAs/GaAs/AlGaAs p-i-n core/shells NWs for PEC water splitting and their potential for green hydrogen production.