Photo-driven nitrogen fixation enabled by oxygen vacancies and Co doping in brown TiO2−x

Co-TiO 2-x  with abundant OVs made via one-step hydrothermal. • Optimal sample: high NH 3  yield, good stability & selectivity. • Co & OVs enhance N 2  adsorption/activation for sustainable NH 3 . Photocatalytic nitrogen fixation represents a promising green technology for ammonia synthesis, but its efficiency is largely limited by the adsorption and activation of N 2 molecules on catalyst surfaces. In this study, cobalt-doped brown TiO 2-x with abundant oxygen vacancies was successfully synthesized via a simple one-step hydrothermal method. The brown TiO 2-x exhibits excellent light absorption capacity and abundant oxygen vacancies. Cobalt doping further promotes the separation of photogenerated charge carriers and the photocatalytic reduction ability of brown TiO 2-x , while also inducing the generation of additional oxygen vacancies (OVs). These OVs serve as active sites, effectively improving the adsorption and activation of N 2 , and subsequently reducing it to ammonia. Experimental results demonstrate that the photocatalytic nitrogen fixation performance of the Co doped TiO 2-x is significantly improved. The as-fabricated 7%Co-doped TiO 2-x sample achieves an ammonia production rate of 257.58 μmol·g −1 ·h −1 . In addition, it also exhibits good stability and NH 3 selectivity. This work highlights the promise of coupled doping and defect engineering for creating high-efficiency photocatalysts for sustainable ammonia production. Download: Download high-res image (365KB) Download: Download full-size image