Synthesis of Bi2FexNbO7 films applied as a catalyst for hydrogen production using visible-light photo-electrolysis

Abstract

The seek for feasible sustainable mobility alternatives is a major concern of the society nowadays. By its turn, the production of hydrogen represents one of the main lines of study on clean energy, since hydrogen presents the possibility of storage and association with other renewable energy sources. In this regard, photo-electrolysis is a promising option for hydrogen generation. This process optimizes the electrolysis of water by using external energy to increase the potential of a photo-electrode, which must be a material that absorbs sunlight (usually a semiconductor activated by solar radiation), promoting the generation of H2 at the cathode. Titanium dioxide (TiO2) is the most applied semiconductor in photocatalytic applications. However, the band gap of this material limits its activity only under UV light, disregarding about 90% of incident solar radiation. Researchers explore catalysts that can be activated under visible light, such as bismuth-based mixed oxide semiconductors, which have attracted interest because of their excellent stability, visible light absorption, and photocatalytic properties. This research aims to develop and characterize photo-anodes based on bismuth, niobium and iron oxides (Bi2FexNbO7), for production of hydrogen via photo-electrolysis of water. The films were produced by the sol-gel process and deposited under a conductive glass slide by dip-coating. The effect of the iron concentration was evaluated by UV-Vis spectroscopy and SEM analysis, in order to estimate its hydrogen production potential.