Synthesis Of Novel Porous Copper-based Nanomaterials For CO₂ Electrocatalytic Reduction

Electrocatalytic reduction technology reduces CO₂to liquid fuels or chemical products with high added value such as ethylene,methane and ethanol,which contributes to an effective solution for reducing carbon emissions and providing clean energy.Increasing the selectivity of the reduction product and the energy utilization efficiency during the reduction process are the basis for deepening the mechanism of electrocatalytic reduction of CO₂and promoting practical industrial application.In order to solve the key problems of low product selectivity and high overpotential in the process of electrocatalytic reduction of CO₂,two kinds of porous copper-based nanomaterial catalysts have been developed,which achieve high selectivity of reduction products and high stability of reduction process.The main research contents and results of the thesis are as follows:Study on the electrocatalytic reduction of CO₂by foamed copper supported spherical ordered macro-porous copper oxide(SOMa-CuO)nano-catalyst.First,Cu(NO₃)₂was supported on the SBA-15 hard template prepared by hydrothermal synthesis.Under high temperature conditions,Cu(NO₃)₂was decomposed and the template was removed with Na OH to obtain SOMa-CuO.Field emission scanning electron microscopy(SEM),field emission transmission electron microscopy(TEM)and Brunauer-Emmett-Teller(BET)confirmed that the SOMa-CuO catalyst with the spherical shape was formed by stacking twelve sides and corners of nanorods.X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and X-ray energy spectroscopy(EDS)showed that the composition was mainly copper oxide.The electrode system composed of copper foam supported by SOMa-CuO not only achieves a current density of 52 m A·cm^-1at 0.9 V,but also maintains its stability to180 min.SOMa-CuO has a rich exposed active site and macro-porous structure,which has a large roughness coefficient of 13.06 m F and a low Tafel slope of 143m V·dec^-1.Study on CO₂RR properties of three-dimensional ordered mesoporous copper sphere array(3D-OMCuSA)nano-catalysts.A polymethyl methacrylate(PMMA)inverse opal was used as a hard template,and a nonionic surfactant Brij 58 was used as a soft template.A 3D-OMCuSA with a regular internal pore structure was prepared by a two-step method.The morphological structure of SEM,TEM and BET showed that 3D-OMCuSA has a very regular three-dimensional ordered mesoporous structure,XRD and XPS confirmed that the components are mainly elemental copper and trace amounts of cuprous oxide.When CO₂RR of 3D-OMCuSA in 0.1 M KHCO₃solution,the starting point is not only at-0.4 V,but the Tafel slope can be as low as 109.6m V·dec^-1.3D-OMCuSA regular ordered three-dimensional interpenetrating mesopores not only provides abundant exposed active catalytic sites,but also has high mass transfer efficiency and electrical conductivity.The peak Faraday efficiency of ethylene and ethanol at-0.83 V is 29.79%and 10.78%,respectively.