Synthesis Of Transition Metal/Heteroatom Doped Carbon Nano Material Electrocatalyst

Hydrogen isthought as potential candidate with clean fuel with high energy density,eco-friendlyto replace non renewable fossil energy fuels,andelectrohemicle water splitting to produce hydrogen is considered as apotential method.A hydrogen evolution reaction occurs at the cathode and an oxygen evolution reaction occurs at the anode.However,due to various shortcomings such as high energy consumption and low conversion efficiency in the process of water splitting,the use of efficient electrocatalyst materials to accelerate the kinetics of HER and OER is very important for the large-scale development of water splitting technology.To date,the optimal catalysts for HER and OER are based on precious metal catalysts.Therefore,it is very important to develop new catalysts with good catalytic activity,high stability and low price.In this paper,three kinds of transition metal / heteroatom doped nanomaterials with high catalytic activity were prepared derived from Cu-MOF,Zn-MOF and carbon nanospheres by using host-guest strategy and pyrolysis technology.The electrocatalytic performance is optimized by tuning the composition,morphology and porosity structure.The specific research content is as follows:1.Cu-MOF loaded with phosphomolybdic acid was prepared by in-situ synthesis using copper nitrate hydrate as the metal source,1,3,5-pyrimellitic acid as the ligand,and phosphomolybdic acid as the guest molecule.The final catalyst is obtained by pyrolysis method.SEM and TEM tests revealed that Mo/Cu-MOF-800 was porous carbon materials supporting nanoparticles.XRD results showed that the material consists of three crystals: Mo₂ C,Mo₂N and metallic Cu.Nitrogen adsorption and desorption tests show that Mo/Cu-MOF-800 has the highest surface area and hierarchically pore structure.It was found that Mo/Cu-MOF-800 showed the largest electrochemical specific surface area and low charge transport resistance in alkaline electrolyte.It required overpotential of 28 m V to deliver 10 m A cm^-2 is only 28 m V,which has excellent long-term stability.Also,it has excellent long-term stability.2.Zn-MOF andphosphomolybdic acid hybrid was preparedzinc nitrate hydrate as metal source,1,3,5-pyromellitic acid as ligand and phosphomolybdic acid as guest molecule.The catalysts synthesized byheating at different temperature.The results of SEM and TEM indicated that Mo/Zn-MOF-900 displayed a tubular structure with a diameter of 10-15 nm.The material is composed of Zn O and Mo₂ N by XRD result.Nitrogen adsorption desorption test showed that Mo/Zn-MOF-900 had high surface area andhierarchically pore structure,which was conducive to the exposure of active sites and rapid mass transport Mo/Zn-MOF-900 needed 390 m V to reach 10 m A.cm^-2 in alkaline solution attributed to the higher electrochemical specific surface area and low charge transport resistance.3.The carbon nanospheres includingmolybdophosphoric acid and copperion were constructedin-situhydrothermalsynthesis Then the precursor was pyrolyzed at different temperature.The SEM and TEM result showed that Cu,Mo/CMSs-800 exhibitedregular spherical shape and uniform size,its diameterwas about 200 nm.The material is was composed of Cu and Mo C,andmicro,-/meso-/macro-pores,which is conducive to the rapid transport of materials.It was found that Cu,Mo/CMSs-800 showed thelectrochemical specific surface area and lower charge transfer resistance in alkaline electrolyte.When 10 m A cm^-2 is obtained,it required the overpotentialof only 127 m V,which is lower than that of other synthesized reference samples and has excellent long-term stability.