Enhancement of photoelectrochemical responses via annealing of air-based sputtered TiN films in controlled atmospheres

This study demonstrates the significant enhancement of the photoelectrochemical performance of air-based sputter-deposited TiN films via annealing in an N₂/H₂ atmosphere. For comparison, the films were also annealed in air and N₂, with all three atmospheres subjected to varying nitrogen/oxygen partial pressures. X-ray diffraction results showed that the relative intensities of rutile TiO₂ increased with decreasing the nitrogen/oxygen partial pressures. The preferred orientation of TiO₂ shifted from (101) in air and N₂ to a stable (110) in N₂/H₂, facilitating the formation of faceted TiO₂. An optimal photocurrent density of 3650 ± 160 µA/cm² was achieved at 1000 °C for 5 h in N₂/H₂, surpassing values reported in the literature. The enhanced performance is attributed to large-faceted TiO₂ grains, oxygen vacancies in TiO₂, and synergistic effects of low resistivity and plasmonic properties of TiN. This facile approach offers a promising strategy for advancing photoelectrochemical applications.