The Preparation Of Nickel And Cobalt-based Nanoarray Materials And Their Electrocatalytic Performance

The development of novel sustainable energy is becoming the focus of national research due to the increasingly serious environmental pollution and the increasing energy crisis.Hydrogen,due to their high energy density and recyclable characteristics,is considered to be an ideal energy carrier and fuel,and electrochemical water cracking,for the mass of high purity hydrogen production provides a feasible method.This literary grace water hot method,the annealing method,electrodeposition method and electrical activation method,and other materials preparation methods,the combination of success could be prepared with different morphology structure of Ni,Co catalyst,through XRD,SEM,TEM and EDX,XPS etc.Various characterization methods,the structure of the samples,the morphology,element distribution and the change of valence state have been characterized,and by using linear sweep and cyclic voltammograms test means such as the electrochemical properties of different materials was studied,and probes into the microscopic mechanism of the composite catalytic decomposition of water.The main research contents are as follows:（1）Based on the Ti mesh,the NiO@Ni-P/Ti composite was prepared by electrodepositing Ni-P alloy on NiO nanosheets alloy.The structure of NiO nanoarray was completely maintained by the preparation of composite materials obtained by SEM image analysis.Its electrochemical performance shows that oxygen evolution reaction（OER）activity of NiO@Ni-P/Ti composite material performance is obviously better than that of Ni-P/Ti and NiO/Ti,only needs 292 mV level to reach 10 mA?cm^-2,with lone-time electrochemical stability and Faraday efficiency of 98.1%.The reason for the excellent OER performance of NiO@Ni-P/Ti composites are explained by computational chemistry,because the heterogeneity of Ni-P and NiO significantly reduces the reaction free energy of the four-electron transfer process.（2）The development of high-performance non-precious metal catalysts for neutral conditions is still a huge challenge.We have reported two kinds of nanowire array catalysts based on Mn and Co,respectively for the cathode and anode of the electrolytic system.First by hydrothermal MnCo₂O₄ nanoarrays catalyst was prepared with annealing process,then make MnCo₂O₄/CC as precursor,by anodic polarization in the potassium tetraborate electrolyte,the method of successful preparation of a new type of Mn-Co-Bi/CC electrode.Electrochemical data show that MnCo₂O₄/CC is an excellent catalyst for hydrogen evolution reaction（HER）,only needs-293 mV to achieve 10mA?cm^-2,while Mn-Co-Bi/CC behave better in OER performance,needing 366 mV to achieve 10 mA?cm^-2,compared to the most reported neutral OER catalyst.The two-electrode electrolyser using Mn-Co-Bi/CC as anode and MnCo₂O₄/CC as cathode drives 10 mA?cm^-2 at a cell voltage of 1.97 V with strong long-term electrochemical durability and 100%Faradaic efficiency.（3）We have made a preliminary attempt to combine the oxidation of inorganic ions and reduction of water.As an OER process of the electrolytic bottleneck,the dynamic constraints of the whole reaction are the result of the four electron transfer process.The anode half reaction product of the actual electrolysis process,which is oxygen,is of little value.In this case,if the inorganic ion oxidation is more oxidized than water,instead of traditional water oxidation,it will greatly reduce the energy consumption of the whole reaction system.We use Ti mesh as base,by using the method of conformal phosphate was prepared by the CoP NA/TM electrode,when there are 50 mm Na₂S in alkaline electrolyte,when reaching the same current density,such novel electrochemical system drops by 350 mV,cell voltage reduces 210 mv.Lower energy consumption of hydrogen production is implemented with the degradation of S^2-.（4）We also reported the strategy of using organic electrooxidation instead of traditional OER to achieve efficient hydrogen analysis.The Fe-CoP/CC electrode was prepared by the conformal phosphating technique,and the extract of aloe extract from 5mL was used in 45 mL alkaline solution as the new electrolyte.The Fe-CoP/CC||Fe-CoP/CC couple needs a cell voltage of 1.51 V to drive 20 mA^-2 in 1.0 M KOH containing aloe extracts,however 1.63 V is required to drive the same current density in the absence of aloe extracts.The study provides a novel way to develop electrolytic systems that develop hydrogen production based on biomass electrooxidation.