Relating the structure, properties, and activities of nanostructured SrTiO3 and SrO–(SrTiO3)n (n = 1 and 2) for photocatalytic hydrogen evolution

Abstract

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.