Preparation Of Cu-based Alloy/Carbon Nanofiber Hybrid Material And Its Application In Electrocatalytic Hydrogen Evolution

Energy depletion and environmental degradation are two major obstacles to the strategy of sustainable development,so the development of green new energy to replace fossil fuels is the future trend of energy development.Hydrogen energy is recognized as one of the most promising energy carriers due to its cleanliness,efficiency and sustainability.In lots of hydrogen production methods,the electrocatalytic water splitting attracts wide attention due to its simplicity,high product purity and rich reserves.The platinum-based material as the best hydrogen evolution catalyst can not be used for large commercial application because the price is expensive and the earth reserve is low.Therefore,how to reduce the production cost while improving the catalytic activity of hydrogen evolution and stability has become an urgent problem to be solved.With the rapid development of nanotechnology,zero-dimensional nanoparticles and one-dimensional nanofibers are widely used in many fields due to their special nano-effects and large specific surface area.At the same time,resource-rich and cheap Cu-based nano-materials because of its unique physical and chemical properties have gradually entered the people's attention.Based on the above reasons,a series of ultrafine carbon nanofibers were prepared by using electrospinning and high temperature carbonation.The nanofibers were used as supporting materials to support Cu-based nanoparticles?NPs?and then they act as an electrode material for electrocatalytic water splitting.In addition,we systematically studied the relationship among the morphology,size of Cu-based nanoparticles and the catalytic activity.The main contents are as follows:?1?A PVA aqueous solution containing Cu salts was prepared by sol-gel process.And then the solution was electrospun into nanofibers and followed by carbonization to obtain CuNPS/CNFs hybrid materials.The surface morphology and internal structure of the materials were characterized by scanning electron microscopy?SEM?and transmission electron microscopy?TEM?.CuNPs have a high dispersion and the size of them is 5-20 nm.The diameter of carbon nanofibers is 100-400 nm.In addition,the crystal structure and surface valence state were analyzed by X-ray diffraction?XRD?and X-ray energy dispersive spectroscopy?XPS?,which proved the successful preparation of CuNPs/CNFs hybrid materials.The electrocatalytic water splitting tests under acidic conditions showed that when the current density was 10 mA cm^-2,the overpotential was only 200 mV and the Tafel slope was as low as 152 mV dec^-1.?2?In order to further improve the catalytic activity of the material,Pt element was introduced into CuNPs,and a series of Pt-Cu/CNFs hybrid materials were obtained by changing the mass ratio of Pt salt and Cu salt.And the temperature during carbonation was adjusted to precisely control the size and morphology of Pt-Cu nanoparticles.The relationship between the size and morphology of Pt-CuNPs and mass ratio of metal salts,the carbonization temperature and the electrocatalytic activity of Pt-Cu nanoparticles were investigated.?3?In order to investigate the effect of the structure and composition of Cu-based materials on the catalytic activity,a series of Au-Cu/CNFs hybrid materials were obtained by adjusting the mass ratio of Au salt and Cu salt in the precursor solution.The Au-Cu/CNFs hybrid material gradually changes from AuCu₃ alloy to Au₃Cu alloy phase.At the same time,more and more Cu atoms accumulate and grow into Cu shell to form Au₃Cu-Cu core-shell nanoparticles.