Ag-V-O thin-film materials libraries, with both composition (Ag22-77V23-78Ox) and thickness (123-714 nm) gradients were fabricated using combinatorial reactive magnetron cosputtering aiming on establishing relations between composition, structure, and functional properties. As-deposited libraries were annealed in air at 300 degrees C for 10 h. High-throughput characterization methods of composition, structure and functional properties were used to identify photoelectrochemically active regions. The phases AgV6O15, Ag2V4O11, AgVO3, and Ag4V2O7 were observed throughout the composition gradient. The photoelectrochemical properties of Ag-V-O films are dependent on composition and morphology. An enhanced photocurrent density (similar to 300-554 mu A/cm(2)) was obtained at 30 to 45 at.% Ag along the thickness gradient. Thin films of these compositions show a nanowire morphology, which is an important factor for the enhancement of photoelectrochemical performance. The photoelectrochemically active regions were further investigated by high-throughput synchrotron-X-ray diffraction and transmission electron microscopy (Ag32V68Ox) which confirmed the presence of Ag2V4O33 as the dominating phase along with the minor phases AgV6O38 and AgVO3. This enhanced photoactive region shows bandgap values of similar to 2.30 eV for the direct and similar to 1.87 eV for the indirect bandgap energies. The porous nanostructured films improve charge transport and are hence of interest for photoelectrochemical water splitting. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.