Supporting carbon quantum dots on NH2-MIL-125 for enhanced photocatalytic degradation of organic pollutants under a broad spectrum irradiation

The rapid recombination of photoinduced electron-holes and the low utilization of solar energy have become two disadvantages limiting the performance of current photocatalysts. In this work, a novel composite photocatalyst, in which the carbon quantum dots (CQDs) were supported on the NH2-MIL-125 (a kind of metal-organic frameworks (MOFs)), was designed and constructed. The CQDs could not only serve as electron-acceptors for promoting the photoinduced charge separation in NH2-MIL-125, but also act as the spectrum converter (convert near-infrared light into visible light) to realize the enhanced light absorption by NH2-MIL-125. The NH2-MIL-125 supported CQDs (CQDs/NH2-MIL-125) displayed significantly enhanced photocatalytic activity compared with NH2-MIL-125 for Rhodamine B (RhB) degradation, regardless of the light source varied from the full-spectrum, visible light or even near-infrared light. Moreover, the photocatalytic efficiency of CQDs/NH2-MIL-125 was influenced by the CQDs content, and the composite with 1% CQDs loading exhibited the best performance. The excellent photocatalytic performance of CQDs/NH2-MIL-125 is attributed to the enhanced photoinduced charge separation and improved utilization efficiency of light energy. This work is expected to provide an attractive strategy for constructing high-efficiency photocatalyts towards environmental remediation.