Combinatorial Approach to Improve Photoelectrodes Based on BiVO4

The photoelectrochemical behavior of materials based on binary Bi–V oxides was investigated by preparing libraries of ternary metal oxides using high-throughput combinatorial inkjet printing of oxide precursors onto conductive glass substrates. Subsequent pyrolysis of the printed films, with addition of various levels of a third metal oxide precursor, produced libraries of metal oxides that were immersed under potential control into an electrolyte solution and evaluated for water photooxidation or photoreduction activity using a laser scanning technique to produce photocurrent images. It was found that the photoelectrolysis activity of the Bi–V oxides of various stoichiometries was best at a Bi/V ratio of 1 to 1 or the BiVO4 phase. The photocurrent generation of this phase was improved by the addition of various amounts of W, Cu, Fe, Mg, and Mn. Addition of W led to the largest increase in photocurrent of up to 18 times; however the electronic band gap was increased compared to that of unsubstituted BiVO4.