Preparation of NaNbO 3 microcube with abundant oxygen vacancies and its high photocatalytic N 2 fixation activity in the help of Pt nanoparticles.

In this study, the photocatalytic N immobilization performance of NaNbO is enhanced via oxygen vacancy introduction and Pt loading. The designed Pt-loaded NaNbO with rich oxygen defects (Pt/O-NaNbO) is synthesized by combining ion-exchange and photodeposition methods. Characterization result indicates that the O-NaNbO has hollow microcube morphology and higher surface area than NaNbO. The introduced oxygen defects greatly affect the energy band structure. The band gap is slightly narrowed and the conduction band is raised, allowing O-NaNbO to generate electrons with strong reducibility. Moreover, the oxygen defects reduced the work function of NaNbO, leading to increased charge separation in the bulk phase. The loaded Pt nanoparticles can further increase the surface charge separation via the formed Schottky barriers between Pt and O-NaNbO, which was thought to be the primary cause of the increased photocatalytic activity. Additionally, the oxygen vacancies and metal Pt also contribute to the adsorption and activation of N. Under the combined effect of the above changes, Pt/O-NaNbO presents much higher photoactivity than NaNbO. The optimized NH production rate reaches 293.3 μmol/L gh under simulated solar light, which is approximately 2.2 and 20.2 times higher than that of O-NaNbO and NaNbO, respectively. This research offers a successful illustration of how to improve photocatalytic N fixation and may shed some light on how to design and construct efficient photocatalysts by combining several techniques.