Enhanced photocatalytic N2 fixation via defective and fluoride modified TiO2 surface

Abstract Photocatalytic N2 fixation (PNF) provides a low-cost route to generate ammonia. The poor conversion efficiency from photon to ammonia seriously hinders the step forward because of the low concentration of N2 molecules. Herein, we demonstrate a photocatalyst with surface oxygen vacancies (Vo) and a F modified surface to facilitate N2 adsorption and activation on the surface of catalysts. The Vo site promotes the chemical adsorption of N2, electron transfer from catalyst to N2. F modification switches the TiO2 surface properties from hydrophilic to aerophilic, thus facilitating the adsorption of N2. Meanwhile, the hydrogen reduction reaction (HER) is suppressed, as protons hard to adsorb on F capped surfaces. The optimal NH3 production rate can reach 206 μmolh−1g−1, which is ∼ 9 times higher than that of pure TiO2 nanoparticles (∼23 μmolh−1g−1). This report provides a potential strategy to overcome mass transfer limitation and achieve a high conversion efficiency in PNF.