Advanced oxide materials synthesis for photonic and energy applications

Advanced oxide materials synthesized using innovative plasma-based deposition techniques are investigated for applications in photonics and sustainable energy technologies. These materials show strong potential for next-generation photonic devices with enhanced functionality and performance, as well as for water purification and green hydrogen production. In this work, undoped and doped vanadium dioxide (VO2) thin films and titania-based photocatalysts are synthesized by pulsed laser deposition (PLD). VO2 is distinguished by its sharp and reversible metal–insulator transition (MIT) occurring near 68 °C, which can be triggered by thermal, optical, or other external stimuli, resulting in dramatic changes in electrical resistivity and infrared/THz optical properties. Our investigations address: (i) the influence of various dopants (W, B, N, S, Cr) and their concentrations on the MIT characteristics and phase stability of VO2; (ii) dopant-induced modifications of optical properties analyzed through density functional theory (DFT); (iii) the combined effects of tungsten doping and interfacial strain from (001) rutile TiO2 substrates; and (iv) the development of a novel low-temperature, large-area synthesis route for high-quality VO2 films compatible with flexible, heat-sensitive polymer substrates. In parallel, titania-based photocatalysts are fabricated by PLD. A six-layer nitrogen-gradient-doped TiO2 structure incorporating multiple homojunctions exhibits markedly enhanced photocatalytic activity for water purification and photocurrent generation compared to undoped or uniformly doped TiO2. Furthermore, TiO2/BiVO4 heterostructures are engineered to overcome unfavorable band alignment, demonstrating the versatility of PLD for fabricating high-performance photocatalysts. These results provide valuable insights for advanced photonic devices, environmental remediation, solar fuels, and energy conversion technologies.