Hydrogen production by photoelectrolysis of aqueous solutions of phenol using mixed oxide semiconductor films of Bi–Nb–M–O (M = Al, Fe, Ga, In) as photoanodes

• We evaluated the Bi–Nb–M–O/304 SS films in the hydrogen production.
• All the films exhibit good electrical transport properties.
• The Bi–Nb–Fe–O/304 SS film exhibited the highest photoelectrolytic activity.
• The activity of the films is a sum of structural and electron transport properties.

The simultaneous hydrogen production and oxidation of phenol by photoelectrolysis using mixed oxide semiconductor films of Bi–Nb–M–O (M = Al, Fe, Ga, In) was evaluated in a three-electrode cell. The experiments were carried out under visible light irradiation. The films were prepared on AISI/SAE 304 stainless steel plates by the sol–gel method and deposited using the dip-coating technique. The films have been previously characterized by SEM-EDS, XRD and XPS. XPS deconvolution spectra reveal that the Nb is present as a dopant in all the films. Linear sweep voltammetry and current–time measurements show that all the films exhibit higher electron transport properties under visible light in comparison with the analogous electrolytic process (in the dark). All the films have the ability to carry out simultaneously the hydrogen production and the oxidation of phenol in the reaction conditions evaluated. The Bi–Nb–Fe–O/304 SS film exhibits the highest photoelectrolytic activity related to its lower band-gap and the presence of BiFeO3 perovskite-type phase. The results indicate that these materials can be used in photoelectrolytic cell for simultaneously environmental remediation processes and hydrogen production.

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