Regulation of oxygen vacancies in SrTiO3 perovskite for efficient photocatalytic nitrogen fixation

Photocatalytic nitrogen (N-2) fixation provides a green avenue for the production of ammonia (NH3), which is extremely significant for global biogeochemical cycle. However, there is still lack of highly efficient catalyst to improve the N-2 photofixation efficiency. In this work, oxygen vacancy engineered perovskite SrTiO3 materials have been prepared by post reduction using lithium alkylamine solution and served as effective catalysts for visible-light-driven N-2-to-NH3 conversion. The formation and concentration of oxygen vacancies were confirmed by electron paramagnetic resonance, X-ray photoelectron spectroscopy and thermogravimetric analyses. The SrTiO3 catalyst with optimized oxygen vacancies concentration exhibited improved photocatalytic N-2 reduction rate of 306.87 mu mol.g(-1).h(-1), which is approach ten-fold higher than that of pristine SrTiO3. Electrochemical impedance spectroscopy and photoluminescence measurements reveal that optimum amount of oxygen vacancies can promote the effective adsorption of N-2 molecules and improve the photocatalytic performance by facilitating the fast separation of photo-generated charge carriers. Moreover, the as-fabricated defective SrTiO3 exhibited outstanding stability, which makes it emerge the promising potential for further practical applications. This work offers a feasible method for the design of high performance photocatalysts through defect engineering. (C) 2022 Elsevier B.V. All rights reserved.