Properties of nitrogen-doped indium oxide films prepared using chemical vapor deposition technique for photoelectrochemical application

This study reports on the morphological, structural, and optical properties as well as photocatalytic activity of N-In2O3 films. The carbothermal reduction process was used to synthesized In2O3 films on Ni/Si substrates under atmospheric pressure, followed by annealing under ammonia flow for various durations. The effect of N-doping on the materials' properties was investigated using FE-SEM, EDX, HR-XRD, and UV-Vis. The narrowing of the bandgap from 3.09 eV for the un-doped to 2.95 eV for the sample with the highest N-concentration was observed. Photoelectrochemical study of In2O3 based electrodes shows enhancement in their photoanodic activity with increasing N-doping. The most efficient electrode generates 1.33 mA/cm(2) photocurrent density at 0.46 V vs. Ag/ AgCl, about three times more than the intrinsic electrode, achieving an applied bias to photon conversation efficiency (ABPE) of 1.03% and an incident photon to current conversion efficiency (IPCE) of 33.80% at lambda = 420 nm. The enhanced PEC performance could be attributed to the increased donor concentration in the electrodes due to N-doping, as revealed by Mott-Schottky analysis. The result demonstrates that N-doping of CVD synthesized In2O3 films could be an excellent way of improving their PEC performance.