Photocatalytic Activity of Thin Layers Obtained via Electrodeposition and Annealing of Nanostructured WFeZn and WFeCu Alloys

Improvement of the efficiency of the water-splitting process is one of the crucial issues to be dealt with in the coming years. In this study, a new method for the preparation of photocatalysts is presented. Two novel light-activated oxygen evolution catalysts were developed, consisting of oxidized forms of tungsten, iron, and zinc or copper. In the two-step synthesis, thin layers of nanostructured tungsten–iron–third metal alloys are electrodeposited from an aqueous bath initially, and then they are annealed in an oxidizing atmosphere. The electroplating technique was used in the designed process to combine high precision in deposition and control of composition with relatively low economic and environmental costs. In addition, the easier formation of highly active tungstate forms in the catalysts may be favored by the structure of the alloy precursors. Conditions for obtaining the layers were optimized based on recorded photocurrents. The analysis of electrode surfaces was performed using spectroscopic and microscopic techniques. The oxygen released during the photooxidation of water with ternary metal oxide semiconductors was monitored using an O₂ membrane sensor (Clark electrode), and the conversion efficiency was found to be approximately 30%.