Photocatalytic reduction of CO2 Ag-BiVO4 composites modified with lignin carbon quantum dots
摘要
Photocatalytic CO2 reduction technology can use sunlight to convert CO2 into fuel or chemical raw materials, slowdown the greenhouse effect and achieve sustainable development. Therefore, we have developed a series of high-quality carbon quantum dots using alkaline lignin (AL) as the core raw material and using high efficiency hydrothermal method. Ag-BiVO4 composite was prepared by hydrothermal method. Then, the Ag-BiVO4-CQDs photocatalytic composite was prepared by constant temperature water bath method. The structure and morphology of the composites were characterized by X-ray diffraction, transmission electron microscope and X-ray photoelectron spectroscopy. Through optical and electrochemical tests, it can be seen that the composite has better interfacial charge transfer and electron transport ability. In the visible light catalytic CO2 reduction reaction, Ag-BiVO4 can selectively reduce CO2 to CH4, and the CH4 yield is greatly improved after Ag-BiVO4 combines with CQDs. The 3 h CH4 yield increased from 17.64 μmol/g to 97.82 μmol/g after reduction by adding 40 mL CQDs to Ag-BiVO4 composite, which is 5.54 times that of Ag-BiVO4. The results showed that the introduced CQDs were uniformly attached to Ag-BiVO4. As an electron transport medium, CQDs can efficiently facilitate the transfer of photogenerated carriers, suppress the recombination of electron–hole pairs, and enhance the photocatalytic performance of Ag-BiVO4-CQDs for CO2 reduction.