Improvement of photocatalytic activity of surfactant modified In2O3 towards environmental remediation

Abstract

The present paper describes photocatalytically active In₂O₃ thin films developed using a direct drop-cast method on F-doped tin oxide (FTO) coated glass substrates using 10 mM In(NO₃)₃ dissolved in ethylene glycol containing 0–0.0125 M Triton-X 100 (TX-100) surfactant and annealed in air at 600 °C to obtain the desired metal oxide. The absorption spectrum measured the direct band gap of the surfactant modified In₂O₃ as 3.48 eV along with an indirect gap of 2.69 eV indicating near visible absorptivity of the materials, which was established through linear sweep voltammetry under periodic UV-Vis and visible irradiation for oxidation of water and a sacrificial reagent, SO₃²⁻. The electrochemical impedance spectroscopic (Mott–Schottky) analysis confirms n-type semiconductivity for these materials. Addition of an optimized level of 0.01 M TX-100 surfactant to the precursor solution improves the photoelectrochemical performance of the film to 2.3 fold. The electrochemical action spectra indicate a maximum value of the incident photon to current conversion efficiency (IPCE) for the 0.01 M surfactant modified In₂O₃ of 28% and the corresponding absorbed photon to current conversion efficiency (APCE) of 40%. Addition of surfactant to the In³⁺ precursor solution results in uniformly distributed particle growth on the surface with better crystallinity.