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

Abstract

Photocatalytic nitrogen (N2) 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 N2 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 N2-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 N2 reduction rate of 306.87 μmol·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 N2 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.