In-situ synthesis of Cu nanoparticles hybridized with carbon quantum dots as a broad spectrum photocatalyst for improvement of photocatalytic H2 evolution

•In-suit Cu nanoparticles hybridized with carbon quantum dots (CQDs) were obtained.•An evident enhancement of H2 evolution was achieved after modification with CQDs.•Cu/CQDs photocatalyst has a broad spectrum response for photocatalytic reaction.•A possible mechanism is illustrated for the photocatalytic activity improvement.

Exploration of broad spectrum photocatalyst for photocatalytic reaction is of great importance. Cu nanoparticles (NPs) were used for photocatalytic hydrogen evolution due to its surface plasmon resonance (SPR) effect and broad spectrum response. Here, Cu NPs were modified with carbon quantum dots (CQDs) for further improvement of photocatalytic ability. Cu/CQDs composites were prepared by facile in-situ photoreduction and a much higher H2 evolution rate was achieved than that of pure Cu NPs. The highest H2 evolution rate was 64 mmol g−1 h−1 for sample C which contains 15.6 wt% of CQDs. CQDs act as an electron reservoir to trap electrons generated from Cu NPs and hinder the recombination of electron-hole pair. Due to surface plasmon resonance (SPR) effect of Cu nanoparticles, broad spectrum photocatalytic activities of these samples were achieved under monochromatic light irradiation at 700, 800 and 900 nm, respectively. A possible mechanism is illustrated for the photocatalytic activity improvement of Cu nanoparticles modified with CQDs.

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