Morphology and Thermal Tuning of α-CuV2O6 Photoanodes for Optimized Photoelectrochemical Performance

Abstract Microstructural engineering provides an effective strategy to enhance semiconductor photoelectrodes without modifying the intrinsic electronic structure. Here, phase-pure α-CuV2O6 photoanodes were mechanically and thermally tuned to control particle size, film morphology, and interfacial charge-transfer kinetics for optimal photoelectrochemical (PEC) water oxidation. Mechanical grinding reduced the average particle size from micrometer to submicrometer dimensions while preserving the triclinic lattice, enabling uniform, high-coverage films with unchanged optical bandgaps (Eg ≈ 1.8–1.9 eV). Systematic optimization of the number of spray-coating cycles and anneal temperature afforded 60 spray cycles and 450 °C as the optimal conditions, where improved densification and maximized electrochemically active surface area enhanced carrier utilization and suppressed interfacial recombination simultaneously. The optimized photoanodes delivered a photocurrent density of 1.70 mA cm–2 at 1.80 V vs RHE, which is the record maximum photocurrent reported thus far for α-CuV2O6 photoelectrodes experimentally. Transient photocurrent analysis confirmed that performance gains originated primarily from reduced surface recombination rather than changes in optical absorption or interfacial energetics. These new findings demonstrate that morphology-driven kinetic control offers a simple, scalable route to unlock the latent PEC activity of copper vanadate photoanodes and elevate their performance levels closer to theoretical expectations.