Tunable Nanostructure of TiO2/Reduced Graphene Oxide Composite for High Photocatalysis
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In this study TiO2/reduced graphene oxide (TiO2/rGO) bipyramid with tunable nano-structure was fabricated by two-step solvothermal process and subsequent heat-treatment in air. The as-synthesized anatase TiO2 nanocrystals possessed morphological bipyramid with exposed dominantly by (101) facets. Polyethylenimine was utilized during the com-bination of TiO2 and graphene oxide (GO) to tune the surface charge, hindering the re-stack of graphene during solvothermal process and resulting in 1 to 5 layers of rGO wrapped on TiO2 surface. After a further calcination, a portion of carbon quantum dots (CQDs) with a diameter about 2 nm were produced owing to the oxidizing and cutting of rGO on TiO2. The as-prepared TiO2/rGO hybrid showed a highly photocatalytic activity, which is about 3.2 and 7.7 times enhancement for photodegradation of methyl orange with compared to pure TiO2 and P25, respectively. We assume that the improvement of photocatalysis is attributed to the chemical bonding between rGO/CQDs and TiO2 that accelerates photogenerated electron-hole pair separation, as well as enhances light harvest.
Abstract
In this study TiO2/reduced graphene oxide (TiO2/rGO) bipyramid with tunable nano-structure was fabricated by two-step solvothermal process and subsequent heat-treatment in air. The as-synthesized anatase TiO2 nanocrystals possessed morphological bipyramid with exposed dominantly by (101) facets. Polyethylenimine was utilized during the com-bination of TiO2 and graphene oxide (GO) to tune the surface charge, hindering the re-stack of graphene during solvothermal process and resulting in 1 to 5 layers of rGO wrapped on TiO2 surface. After a further calcination, a portion of carbon quantum dots (CQDs) with a diameter about 2 nm were produced owing to the oxidizing and cutting of rGO on TiO2. The as-prepared TiO2/rGO hybrid showed a highly photocatalytic activity, which is about 3.2 and 7.7 times enhancement for photodegradation of methyl orange with compared to pure TiO2 and P25, respectively. We assume that the improvement of photocatalysis is attributed to the chemical bonding between rGO/CQDs and TiO2 that accelerates photogenerated electron-hole pair separation, as well as enhances light harvest.
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