Synthesis of SrTiO 3 submicron cubes with simultaneous and competitive photocatalytic activity for H 2 O splitting and CO 2 reduction.

Single crystalline strontium titanate (SrTiO 3 ) 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 4 ) and hydrogen (H 2 ) were simultaneously produced. The average production rate of methane up to 8 h is 4.39 μmol g -1 h -1 but drops to 0.46 μmol g -1 h -1 . However, the average production rate of hydrogen is 14.52 before 8 h but then increases to 120.23 μmol g -1 h -1 after 8 h. The rate change of the two processes confirms the competition between the H 2 O splitting and CO 2 reduction reactions. Band structure and surface characteristics of the SrTiO 3 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 3 . This work demonstrates that SrTiO 3 photocatalysts are efficient in producing sustainable fuels via water splitting and carbon dioxide reduction reactions.