Ordered Ti-doped FeVO₄ nanoblock photoanode with improved charge properties for efficient solar water splitting

Highly photoactive FeVO₄ photoanodes with ordered nanoblock morphology and uniform Ti-doping were prepared by drop-casting mixed Ti and V precursors onto FeOOH nanorod films and following an annealing process. The results indicate that Ti⁴⁺ is uniformly doped into the FeVO₄ lattice by substituting V⁵⁺ and provides an increased number of O₂^- vacancies. The optimized film thickness and doping level are 620 nm and 0.3%, respectively. Compared to the undoped sample, the Ti-doped photoanode showed ~ 219% enhancement in photocurrent at 1.0 V vs Ag/AgCl under back illumination of AM 1.5, reaching a state-of-the-art value of ~ 1.47 mA cm^-2, and also achieved stable and efficient overall water splitting activity with evolution rates of 28.3 and 14.1 μmol cm^-2h^-1 for H₂ and O₂, respectively. The excellent PEC performance could be attributed to the remarkably enhanced charge carrier concentration and conductivity, and the facilitated charge transfer kinetics across the semiconductor/electrolyte interface, as a result of Ti-doping.