Preparation And Enzyme-like Catalytic Properties Of Carbon Dots And Copper Oxide

Fluorescent carbon dots?CDs?are a new type of zero-dimensional carbon materials that are environmentally friendly and have a wide range of raw materials.Due to their good light absorption properties and efficient photogenerated charge transfer and storage capabilities,they have attracted much attention in the field of photocatalysis,but they are also facing the problem of insufficient catalytic activity.Generally,the catalytic performance is improved by forming a two-component heterostructure of CDs and other semiconductors.Copper oxide semiconductors have a narrow optical band gap and good catalytic performance,but face serious optical corrosion,poor stability,and insufficient photogenerated carrier separation capabilities.Therefore,in this paper,the self-oxidation ability of copper oxide is combined with electron-rich CDs to form a heterostructure to enhance the light absorption properties of the composite,improve the separation ability of photogenerated charges,and at the same time improve the stability of copper oxide and achieve The purpose of doubling the catalytic performance.The research content of this article has the following two aspects:?1?Cu₂O-CDs-Cu ternary composite material was successfully prepared by one-step hydrothermal method with CDs,copper acetylacetonate and water,which fully proved the reducibility of CDs.The morphology of Cu₂O-CDs-Cu was characterized by SEM,TEM and HRTEM.The results showed that Cu and Cu₂O wrapped on the surface of CDs to form a core-shell structure.By comparing the solid absorption of Cu₂O and Cu₂O-CDs-Cu,it was found that the solid absorption of Cu₂O-CDs-Cu was significantly enhanced.In the photocatalysis experiment with o-phenylenediamine?OPD?as the substrate,the catalytic reaction rates of Cu₂O and Cu₂O-CDs-Cu were found to be 2.07?M min^-1 and 9.47?M min^-1,respectively,the reaction rate increased more than fourfold,and Cu₂O-CDs-Cu catalysis shows a positive correlation with the absorption of photons.By analyzing the results of electrochemical impedance and different light intensity,different wavelength,catalytic testing at different temperatures and other characterization methods,it is found that this is due to light accelerating the generation,separation and migration of photo-generated carriers,and at the same time,it also promotes Cu₂O-CDs-Cu produces high-energy"hot"electrons,which plays an important role in increasing the catalytic rate.?2?The scarcity of Cu₄O₃ and the complexity of preparation limit its research.In this paper,CuO was prepared hydrothermally by cuprous chloride and ammonia,and the hydrothermal reaction was carried out in ammonia-modified CDs solution to successfully prepare the conical copperite nanocomposite with stable carbon point?CDs@Cu₄O₃?.By comparing the performance difference between CuO and CDs@Cu₄O₃ in catalyzing o-phenylenediamine?OPD?,the catalytic rates under light were found to be 21.59?M min^-1 and 78.19?M min^-1respectively.After compounding,the reaction rate increased by 3.62 times.When dopamine?DA?is used as the catalytic substrate,the catalytic rate of CDs@Cu₄O₃ is also more than twice that of CuO.Moreover,CDs@Cu₄O₃ not only has a variety of enzyme catalytic activities,but also has the responsiveness to a variety of external stimuli such as light,temperature,pH,and oxidants.At the same time,CDs@Cu₄O₃ shows high stability in the catalytic system.Through the comparative analysis of the FTIR,XPS,EIS,band gap and other characterization results of CuO and CDs@Cu₄O₃,it is found that the reason for the high activity and high stability is the coordination of multivalent copper ions(Cu⁺/Cu²⁺)with the amino groups on the surface of CDs.The delocalized electrons of CDs change the oxidation-reduction potential of Cu⁺,which accelerates the exposure of active sites required for enzyme-like catalytic reaction,and the impedance after recombination is significantly reduced,which is more conducive to the separation and migration of photo-generated carriers.