Relating the structure, properties, and activities of nanostructured SrTiO3 and SrO–(SrTiO3)n (n = 1 and 2) for photocatalytic hydrogen evolution†
This study focuses on relating the structure of perovskite oxides with their properties and activities and provides a comparative study of the three members of the Sr–Ti–O system for photocatalytic hydrogen evolution. The three oxides focused on in this study are based on perovskite structure viz. SrTiO3 and SrO–(SrTiO3)n (n = 1 and 2). We have successfully synthesized these three oxides through a methodology that combined the polymeric citrate precursor method with the hydrothermal method. Their crystal structure, morphology, and optical properties (absorption and photoluminescence) were systematically explored. SrTiO3 belonged to a class of cubic perovskite while Sr2TiO4 (n = 1) and Sr3Ti2O7 (n = 2) belonged to layered Ruddlesden–Popper based perovskite oxides. We observed the cube-shaped morphology for nanostructured SrTiO3 and layered morphology for Ruddlesden–Popper based oxides, Sr2TiO4 and Sr3Ti2O7. The photocatalytic hydrogen evolution performance of these nanostructured oxides was investigated. Amongst the three nanostructured oxides, the maximum amount of hydrogen was evolved with Sr3Ti2O7 as the photocatalyst. These results were supported by photoluminescence, time-resolved photoluminescence, and photoelectrochemical studies.