Tailoring defects in SrTiO₃ by one step nanoarchitectonics for realizing photocatalytic nitrogen fixation in pure water

Abstract

Surface contamination of materials by nitrogenous impurities is a major problem that can bias the quantification of ammonia in photocatalytic N₂ fixation reactions. In this work, SrTiO₃ nanocubes were prepared by using a nitrogenous precursor and engineered with Ti³⁺ sites and oxygen vacancy defects in a one-step solvothermal approach. It was observed that the synthesized materials were containing surface nitrogenous impurities and therefore a rigorous cleaning procedure was adopted to eliminate them to the best extent. The contribution of unavoidable surface impurities was deduced in the form of adventitious NH₃ by employing control experiments and a realistic photocatalytic NH₃ generation was achieved. It was found that pristine SrTiO₃ showed no photocatalytic activity, whereas one of the defected SrTiO₃ materials showed the highest NH₃ formation under natural sunlight in pure water, which was ascribed to the tuned defect sites, enhanced surface area and efficient separation of photogenerated charges. Based on the experimental results, a stringent protocol has been suggested for materials synthesis while working with nitrogenous precursors and for subsequent photocatalytic N₂ fixation experiments. Thus, the present study provides a simple and affordable procedure for catalyst synthesis for the studied application and expands the scope of perovskite oxide materials to fabricate efficient photocatalysts for sustainable NH₃ production.