Abstract
Developing a photocatalyst system for solar energy conversion to electric energy or chemical energy is a topic of great interest for fundamental and practical importance. In this study, hydrogen production by a new Z-scheme photocatalysis water-splitting system was examined over Rh-doped SrTiO3 (denoted as Rh:SrTiO3) with Ru nanoparticle as cocatalyst for H2 evolution and BiVO4 photocatalyst for O2 evolution under visible light irradiation, where Co(bpy)32+/3+ was used as electron mediator. The catalysts were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), and Ultraviolet–visible spectroscopy. We present a fast and efficient method to synthesize Rh-doped SrTiO3 photocatalyst via microwave-assisted hydrothermal method. Our results showed a significant effect of Ti precursor on morphology of Rh:SrTiO3 prepared by microwave-assisted hydrothermal synthesis. The Ru/Rh:SrTiO3 prepared by TiCl4 precursor showed a nanoporous structure and high photocatalytic activity. The combination of Ru/Rh:SrTiO3 with BiVO4 achieves a high H2 evolution rate (317 μmoL g−1 h−1) and O2 evolution rate (168 μmol g−1 h−1) in 0.5 mM Co(bpy)32+/3+ solution under visible light irradiation.
Highlights
Hydrogen is an environmentally clean chemical fuel with high energy density
These results show that the Rh-doped SrTiO3 photocatalyst prepared by microwave-assisted hydrothermal method exhibited a very high hydrogen evolution rate of water-splitting reaction under visible light irradiation
We demonstrated that microwave-assisted hydrothermal method has distinct advantages in synthesis Rh-doped SrTiO3 nanoparticles with high crystallinity
Summary
Hydrogen is an environmentally clean chemical fuel with high energy density. Developing a photocatalyst system to generate hydrogen from water gives us a chance to produce hydrogen from an inexhaustible renewable source, i.e., sunlight and water. Much effort has been devoted to studies of the splitting of water into hydrogen and oxygen in the years following the discovery of photocatalytic water splitting using a semiconductor photoelectrode, TiO2 , as was demonstrated by Fujishima and. For a semiconductor photocatalyst for photocatalytic water-splitting reaction, the conduction band edge of the photocatalyst should be more negative than the reduction potential of H2 O to form H2 , and band edge of valence band should be more positive than the oxidation potential of H2 O is required to form O2. The band gap of the semiconductor photocatalyst must be larger than the theoretical dissociation energy of the water molecule (1.23 eV). Several studies have reported that transition metal oxides with d0 and d10 electron configurations have showed photocatalytic activity of water splitting under UV light such as
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