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

Abstract

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/cm2 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 λ = 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.