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Cd<sub>0.5</sub>Zn<sub>0.5</sub>S Quantum Dots onto Onion-Like Carbon
Nanoparticles to Boost Photocatalytic Hydrogen Generation
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Abstract
Carbon
dots (C dots, size < 10 nm) have been conventionally decorated
onto semiconductor matrixes for photocatalytic H<sub>2</sub> evolution,
but the efficiency is largely limited by the low loading ratio of
the C dots on the photocatalyst. Here, we propose an inverse structure
of Cd<sub>0.5</sub>Zn<sub>0.5</sub>S quantum dots (QDs) loaded onto
the onionlike carbon (OLC) matrix for noble metal-free photocatalytic
H<sub>2</sub> evolution. Cd<sub>0.5</sub>Zn<sub>0.5</sub>S QDs (6.9
nm) were uniformly distributed on an OLC (30 nm) matrix with both
upconverted and downconverted photoluminescence property. Such an
inverse structure allows the full optimization of the QD/OLC interfaces
for effective energy transfer and charge separation, both of which
contribute to efficient H<sub>2</sub> generation. An optimized H<sub>2</sub> generation rate of 2018 μmol/h/g (under the irradiation
of visible light) and 58.6 μmol/h/g (under the irradiation of
550–900 nm light) was achieved in the Cd<sub>0.5</sub>Zn<sub>0.5</sub>S/OLC composite samples. The present work shows that using
the OLC matrix in such a reverse construction is a promising strategy
for noble metal-free solar hydrogen production
