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

Abstract

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-γ-TaON (CQDs/H-γ-TaON) hollow urchin heterojunctions that can enhance the UV–visible–NIR broad spectrum active photocatalytic property. Novel CQDs/H-γ-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 496.5µmolh−1 with an apparent quantum efficiency of 12.2% under 420nm (about 61 times higher than that of conventional TaON) was achieved over CQDs/H-γ-TaON heterojunction, corresponding the order of hydrogen production rate: CQDs/H-γ-TaON>H-γ-TaON>γ-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-γ-TaON. The CQDs/H-γ-TaON heterojunctions may open up more opportunities in the design of efficient broad spectrum active photocatalysts for environmental remediation and clean energy generation.