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Photoelectrochemical (PEC) water splitting is a viable route for green hydrogen generation. In PEC cells, the electrodes are coated with suitable semiconductor materials, which absorb the sunlight, generating charge carriers that are used to split water molecules into H2 and O2. CuFeO2 is one promising photocathode material for water splitting. However, its performance is limited by electron/hole pairs recombination within the film and at the film/substrate interface. Aerosol deposition (AD) can be employed to minimize charge recombination by spraying dense, thin films and by establishing a good back-contact interface. In this study, CuFeO2 powders were synthesized through a conventional solid-state technique and sprayed by AD under varied parameter sets. The effect of particle size distributions, carrier gas, gas pressure and substrate temperature was investigated. The best spraying parameter set was then tuned to obtain thin coatings (< 1 µm). Single-particle deformation and coatings microstructure were investigated by scanning electron microscopy. Optical properties of CuFeO2 films were analyzed by UV–Vis spectroscopy, while photoelectrochemical performances were estimated through amperometry tests under simulated sunlight. The results of this research show that CuFeO2 photocathodes can be successfully manufactured by AD. Their performance can be optimized by adjusting coating thickness and by annealing in air. [ABSTRACT FROM AUTHOR]

[Display omitted] • Strontium fluoride forms weakly-interacting interfaces with Ag(1 1 1). • Almost ideal and continuous dielectric layer is formed when growth is carried out at room temperature. • A valence band offset of 6.7 eV between Ag and SrF 2 is obtained for 5 nm of dielectric film. • High temperature growth causes the formation of 3D fluoride structures. Molecular beam epitaxy (MBE) is used to grow ultrathin SrF 2 layers at different temperatures on Ag(1 1 1) epitaxial films prepared on mica. The electronic properties, structure and morphology of the films are probed by ultraviolet and x-ray photoelectron spectroscopies (UPS and XPS) supported by ab-initio calculations, reflection high energy electron diffraction (RHEED) and atomic force microscopy (AFM). The SrF 2 films are composed of crystallites with their [1 1 1] direction parallel to the substrate normal, thereby reproducing the symmetry of the substrate. Twinned domains are also observed. At the Ag/SrF 2 interface, fluoride molecules do not dissociate and the interaction with the substrate is weak. At room temperature, fluoride crystallites merge together, resulting in a continuous film covering the entire substrate when it reaches a nominal thickness of 5 nm. Growth at higher temperature induces the formation of triangular 3D islands, leaving sizable portions of the Ag substrate uncovered. At 400 °C, also a small fraction of SrF 2 (0 0 1)-oriented crystallites are observed, with their [1 −1 0] axis rotated by about 30° with respect to the [1 −1 0] substrate direction. [ABSTRACT FROM AUTHOR]