Photoelectrolytic hydrogen production using Bi2MNbO7 (M = Al, Ga) semiconductor film electrodes prepared by dip-coating

The performance of Bi2MNbO7 (M = Al, Ga) films on AISI/SAE 304 stainless steel was evaluated in the photoelectrochemical hydrogen production as a function of the annealing temperature of the films (400, 500 and 600 °C) and the composition of the electrolyte solution (containing KOH, KCN and KCl). The films were prepared by sol–gel dip-coating on AISI/SAE 304 stainless steel followed by a thermal annealing. The photoelectrochemical evaluation (UV–Vis, 2.5 V) was carried out in a conventional two-compartment electrochemical cell by using the prepared films as photoanode and a silver plate as cathode. During the process, circulating current was recorded and hydrogen production and cyanide degradation were measured. In both cases, it was found that the higher activity was obtained with the films annealed at 500 °C and using an electrolyte solution 0.3 M of KOH and 120 ppm of CN−. Further works on the subject should involve a cathode evaluation to avoid the electrode polarization in presence of KCl and an experimental design to optimize the evaluated variables.