Optimization of Triton-X 100 surfactant in the development of Bismuth Oxide thin film semiconductor for improved photoelectrochemical water oxidation behavior

• TX-100 surfactant modified bismuth oxide semiconductor film developed via drop-cast method.
• H2O → O2 photocurrent improves twice over 2% TX-100-bismuth oxide film compared to pure matrix.
• Uniformity & better crystallinity of Bismuth Oxide film achieved by addition of 2% TX-100.
• Surfactant modified bismuth oxide shows lower bandgap energy & improved visible absorptivity.
• Smaller Rct & increased ND leads the modified Bismuth Oxide film to better PEC performance

Photocatalytically active bismuth oxide thin films have been developed through direct drop-casting method on In-doped tin oxide (ITO) coated glass substrates using 5 mM Bi(NO3)3 dissolved in ethylene glycol containing 0–4% Triton-X 100 (TX-100) surfactant and annealed in air at 600 °C to obtain the desired metal oxide. The diffuse reflectance spectra of the surfactant modified bismuth oxide reveals the band gap energy as 2.95 eV indicating near visible absorptivity of the material which have been confirmed through linear sweep voltammetry under periodic UV–Vis and visible irradiation for oxidation of water and sacrificial reagent, SO32−. Electrochemical impedance spectroscopic Mott–Schottky analysis confirms n-type semiconductivity for these materials. Addition of an optimized level of 2% TX-100 surfactant to the precursor solution improves the photoelectrochemical performance of the film up to two times. The electrochemical action spectra indicates a maximum value of the incident photon to current conversion efficiency (IPCE) for the 2% surfactant modified bismuth oxide as 28% and the corresponding absorbed photon to current conversion efficiency (APCE) as 44%. Addition of surfactant to Bi3+ precursor solution leads to growth of uniformly distributed particles over the surface with better crystallinity.

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