Autonomous self-optimizing defects by refining energy levels through hydrogenation in CeO2–x polymorphism: a walking mobility of oxygen vacancy with enhanced adsorption capabilities and photocatalytic stability

Abstract

We approach a self-consistent technique to enhance solar absorption by a proper balance of trapping sites through hydrogenation. Understanding the impact of hydrogenation on oxygen vacancy sites in CeO₂ is crucial in improving the photocatalytic performance of a catalyst. This unique method paves the way to control surface defects, size, and core/shell thickness through the manipulation of surface defects. A large content of defects has a detrimental influence on partially reduced CeO_2−x and causes a deterioration in the performance of the catalyst. Therefore, rational optimization of defects on the surface is of paramount importance. The study was carried out using a multi-technique characterization tools such as XRD, HRTEM, UV-vis, XPS, Raman, PL and FTIR studies. Two important benefits can be gained from this work. First, band-gap reduction does not ensure substantial enhancement of photocatalytic activity as band-gap renormalization occurs after hydrogenation. Second, non-stoichiometric Ce³⁺ is optimized through mobility of oxygen vacancies. This work opens a new door to moving non-stoichiometric CeO_2−x close to ordered CeO₂ by refining energy levels through hydrogenation.