Abstract
SrTiO3-graphene nanocomposites were prepared via photocatalytic reduction of graphene oxide by UV light-irradiated SrTiO3 nanoparticles. Fourier transformed infrared spectroscopy analysis indicates that graphene oxide is reduced into graphene. Transmission electron microscope observation shows that SrTiO3 nanoparticles are well assembled onto graphene sheets. The photocatalytic activity of as-prepared SrTiO3-graphene composites was evaluated by the degradation of acid orange 7 (AO7) under a 254-nm UV irradiation, revealing that the composites exhibit significantly enhanced photocatalytic activity compared to the bare SrTiO3 nanoparticles. This can be explained by the fact that photogenerated electrons are captured by graphene, leading to an increased separation and availability of electrons and holes for the photocatalytic reaction. Hydroxyl (·OH) radicals were detected by the photoluminescence technique using terephthalic acid as a probe molecule and were found to be produced over the irradiated SrTiO3 nanoparticles and SrTiO3-graphene composites; especially, an enhanced yield is observed for the latter. The influence of ethanol, KI, and N2 on the photocatalytic efficiency was also investigated. Based on the experimental results, ·OH, h+, and H2O2 are suggested to be the main active species in the photocatalytic degradation of AO7 by SrTiO3-graphene composites.PACS61.46. + w; 78.67.Bf; 78.66.Sq
Highlights
Semiconductor photocatalysts have attracted considerable attention over the past decades due to their potential applications in solar energy conversion and environmental purification [1,2]
The oxygen-containing functional groups of graphene oxide are deprotonated when it immersed in water, which leads to negative charges created on graphene oxide [27]
The SrTiO3 particles are expected to be adsorbed onto the graphene oxide sheets through electrostatic interactions
Summary
Semiconductor photocatalysts have attracted considerable attention over the past decades due to their potential applications in solar energy conversion and environmental purification [1,2]. The combination of graphene with photocatalysts is demonstrated to be an efficient way to promote the separation of photogenerated electron–hole pairs and enhance their photocatalytic activity [14,15,16,17,18,19,20,21]. In these photocatalyst-graphene composites, photogenerated electrons can be readily captured by graphene which acts as an electron acceptor, leading to an increasing availability of photogenerated electrons and holes participating in the photocatalytic reactions. The investigation concerning the photocatalytic performance of SrTiO3-graphene nanocomposites has been rarely reported
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