Photocatalytic activity of non-oxides materials TiB2, TiC, and TiN

This study aims to explore, for the first time, the effect of the anion species on the photocatalytic activity of the compounds TiB2, TiC, and TiN for H2 production. Therefore, non-oxide titanium compounds have been investigated as alternative semiconductor materials to replace TiO2. In this case, these non-oxide materials were evaluated as photocatalysts for the production of hydrogen due to their negative conduction band energies, which facilitate the accumulation of electrons on the surface and promote the water-splitting reaction. Specifically, TiN exhibits the lowest electron-hole recombination, favoring the generation of hydrogen because more electrons are transferred in this material compared to TiB2 and TiC (2- and 3-fold higher amounts of H2, respectively). Photoluminescence (PL) analysis revealed that TiN spectra showed the lowest emission, indicating a lower concentration of recombination sites, attributed to the presence of Ti-3d orbitals, resulting in improved electrical conductivity and enhanced charge transfer during the reaction. However, in the case of TiC, some of the Ti-3d orbitals are not occupied by free electrons, resulting in partial oxidation, this leads to a higher resistance to charge transfer, promoting electron-hole recombination, which in turn affects the activity of hydrogen generation. Therefore, commercial TiN can be considered a viable candidate for use in photocatalytic systems.