Hierarchical carbon quantum dots/hydrogenated-γ-TaON heterojunctions for broad spectrum photocatalytic performance

There remains a pressing challenge in the efficient utilization of broad spectrum solar energy in the photocatalytic applications. Here we design and fabricate carbon quantum dots/hydrogenated-gamma-TaON (CQDs/H-gamma-TaON) hollow urchin heterojunctions that can enhance the UV-visible-NIR broad spectrum active photocatalytic property. Novel CQDs/H-gamma-TaON photocatalysts have harnessed UV, visible, and near -infrared light to decompose organic contaminants in aqueous solution. Moreover, efficient photocatalytic hydrogen production as high as 496.5 mot h(-1) with an apparent quantum efficiency of 12.2% under 420 nm (about 61 times higher than that of conventional TaON) was achieved over CQDs/H-gamma-TaON heterojunction, corresponding the order of hydrogen production rate: CQDs/H-gamma-TaON > H-gamma-TaON >gamma-TaON. The improved UV and visible photocatalytic property can be attributed to high surface area from hollow nanostructures and efficient charge transfer based photoluminescence, electrochemical impedance and Mott -Schottky analysis. Especially, the NIR photocatalytic activity from the synergistic effects of the hydrogenation and the decoration of CQDs is ascribed to the efficient charge separation and transfer and up-converted photoluminescence property of CQDs that absorb NIR light and convert into visible light and transfer to visible light photocatalytic H-gamma-TaON. The CC)Ds/H-gamma-TaON heterojunctions may open up more opportunities in the design of efficient broad spectrum active photocatalysts for environmental remediation and clean energy generation. (C) 2015 Elsevier Ltd. All rights reserved.