Understanding targeted modulation mechanism in SrTiO3 using K+ for solar water splitting

Abstract

Co-applying facet and defect engineering on SrTiO3 is critical to enhance the photocatalytic activity, and the Sr2+ vacancies contribute to the greater modulation capacity in A-site for designing defect engineering. Here, we use advanced characterizations combined with density functional theory to elucidate the origin of K-modulated facet and defect in SrTiO3 nanoparticles, thereby affecting the photocatalytic activities in overall water splitting. We found that the differences in binding strength between K2CO3 and different facets led to the exposure of non-equivalent facets. Based on the facet engineering, we demonstrated that the K-doping process consisted of filling and substitution process, and the lowest defect concentration existed at their intersection and with a maximum bending degree of surface energy band between {100} and {110} facets. The optimized 3%K-doped SrTiO3 composites have an intrinsic activity comparable to state-of-the-art catalysts. This work provides a significant theoretical guidance for rationally designing the high-performance SrTiO3-based photocatalysts.