strong synergistic effect of the (110) and (100) facets of the SrTiO3 perovskite micro/nanocrystal: decreasing the binding energy of exciton and superb photooxidation capability for Co2+

Abstract

Crystal facet regulation is an effective method for preparing SrTiO₃ or other perovskite semiconductor materials with high photochemical catalysis performance. In general, the edge-truncated cube of SrTiO₃ micro-nano particles has been widely reported because of the multiple crystal facets exposed at the same time. However, the effect of the (110) facet and the interaction between the (100) and (110) facets on the properties of photo-induced carriers is still not very clear. In this article, we have designed and prepared two edge-truncated cube SrTiO₃—a small and large area proportion of the (110) facet, respectively. In addition to the morphological and structural characterization, high-resolution XPS and femtosecond multiphoton transient absorption (fs-TA) spectroscopy were used to detect the atomic vacancy and were applied to confirm the state of carrier transition. The results showed that the larger (110) facet led to two influences—more Sr vacancies and more self-trapping excitons (STEs) with an ultra-low binding energy (E_b = 2.13 meV), about 1.17 meV lower than that of the sample with the smaller (110) facet. In particular, the larger (110) facet also caused a much higher photooxidation performance for Co²⁺ to Co³⁺. This study not only enriches the arsenal of SrTiO₃ materials but also sheds new insights into the understanding of the synergistic effect essence of the (100) and (110) facets, which could promote the development of new perovskite photocatalytic materials, particularly in the recovery of heavy metals.