Synthesis of SrTiO submicron cubes with simultaneous and competitive photocatalytic activity for HO splitting and CO reduction.

Single crystalline strontium titanate (SrTiO) submicron cubes have been synthesized based on a molten salt method. The submicron cubes showed superior photocatalytic activity towards both water splitting and carbon dioxide reduction, in which methane (CH) and hydrogen (H) were simultaneously produced. The average production rate of methane up to 8 h is 4.39 μmol g h but drops to 0.46 μmol g h. However, the average production rate of hydrogen is 14.52 before 8 h but then increases to 120.23 μmol g h after 8 h. The rate change of the two processes confirms the competition between the HO splitting and CO reduction reactions. Band structure and surface characteristics of the SrTiO submicron cubes were characterized by diffuse reflective UV-Vis spectroscopy, Mott-Schottky analysis, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The results reveal that the simultaneous and competitive production of methane and hydrogen is due to a thermodynamics factor, as well as the competition between the adsorption of carbon dioxide and water molecules on the surface of the faceted SrTiO. This work demonstrates that SrTiO photocatalysts are efficient in producing sustainable fuels water splitting and carbon dioxide reduction reactions.