In-depth investigation on the self-catalyzed growth of W₂N/In₂O₃ composite nanowires synthesized via nitrogen plasma assisted in-situ thermal annealing for boosting photoelectrochemical performance

Enhancing the charge separation efficiency through interface engineering of In₂O₃-based photoanodes represents a critical and complex research endeavor in the field of water splitting. Herein, we report a self-catalyzed growth of intrinsic Indium oxide (In₂O₃) Nanowires (NWs) and Tungsten nitride/Indium oxide (W₂N/In₂O₃) composite nanowires (CNWs) on c-Si substrates by plasma assisted reactive thermal evaporation (PARTE) and nitrogen plasma assisted in-situ thermal annealing, respectively. The nitrogen plasma assisted in-situ thermal annealing effectively transforms the intrinsic In₂O₃ NWs to W₂N/In₂O₃ CNWs. The optical energy gap, E_g gradually decreases from 2.49 to 2.40 eV when combine with W₂N nanostructures. Decrease in the E_g simultaneously increases the photocurrent density of W₂N/In₂O₃ CNWs at V = 0.4 V from 1.9 to 3.8 mA/cm². This could attribute to the effective electron−hole separations at the interfaces of the heterojunction CNWs. The correlation between the substantially prolonged lifetime of charge carriers and narrowing the bandgap of the composite NWs could be feasible as a good electrochemical electrode. Moreover, the self-catalyzed and secondary growth mechanisms of hierarchically branched In₂O₃ NWs and W₂N/In₂O₃ CNWs are discussed.