Ni-based Nanomaterials Prepared By Cyanoacrylate And Their Electrocatalytic Properties

With the uninterrupted consumption of traditional fossil fuels,countries all over the world will gradually face an energy crisis and the ensuing environmental problems.Metal-air batteries are an efficient,clean and economical new energy source to address the current excessive consumption of fossil fuels and environmental problems.However,the development of metal air batteries is limited by the intrinsic kinetics of both the OER and ORR reactions at the air cathode.Ni-based catalysts are conventional transition metal-based catalysts and are potentially promising materials for the preparation of excellent electrocatalysts.The cyanogel method is a novel approach to prepare nanomaterials using a cyanogel,which results in materials with a highly homogeneous structure that has high catalytic activity.Therefore,the aim of this thesis is to use the cyanogel method to prepare nickel-based catalysts and to investigate their catalytic properties.The main research and findings of this thesis are as follows:（1）Preparation and electrocatalytic performance of two-dimensional porous Co Ni O nanosheets.Prussian blue analogs with two-dimensional nanosheet morphology was generated by Co Cl₂solution and K₂Ni（CN）₄solution hydrothermal method,and two-dimensional porous Co Ni O nanosheets were obtained by calcination.Studies have shown that the calcined product still maintains the structure of the entire two-dimensional nanosheet,and on this basis,micropores of 3-5 nm are formed.The unique two-dimensional nanosheet structure of the catalyst increases the specific surface area of the catalyst and provides a site for the adsorption and desorption of intermediates.The porous structure provides channels for gas extraction as well as electron and ion transport.Electrochemical results show that the performance of the porous nanosheets in the oxygen evolution reaction（OER）in alkaline solution is comparable to that of noble metal oxides（Ru O₂）,with an overpotential of only365 m V at 10 m A cm^-2,and after 3000 CV cycles After cycling,the overpotential increased by only 1 m V,indicating that the as-prepared 2D porous Co Ni O nanosheets showed excellent catalytic performance and long-term stability in the oxygen evolution reaction.（2）Preparation and Electrocatalytic Properties of Amorphous Ni Fe Nanomaterials.Three-dimensional amorphous Ni Fe nanomaterials are obtained by reacting cyano compound Na₄Fe（CN）₆solution and Ni Cl₂solution to form Ni Cl₂/Na₄Fe（CN）₆cyanogel,and then wet chemical reduction of newly prepared Na BH₄solution at room temperature.Using the cyanoacrylate’s own three-dimensional skeleton,the reduction process causes the material to grow along the skeleton,resulting in a three-dimensional structure.It was shown that the entry of nickel changed the electronic structure of the material and reduced the oxidation state content of the material.Furthermore,by varying the amount of Ni Cl2solution in the precursor,the optimum ratio of Ni to Fe was found to be 2:1.The electrochemical test results show that the oxygen evolution performance of Ni Fe-21 in alkaline solution is better than that of Ru O₂,and the overpotential is only 340 m V at a current density of 10 m A cm^-2,and after 3000 CV cycles,the overpotential increases by only 12 m V.In addition,in the subsequent chronoamperometry test,the attenuation of the current density of Ni Fe-21 is only 20%,which has a great advantage over Ru O₂.（3）Preparation and Electrocatalytic Properties of Ordered Pt₃Ni/C Intermetallic Compound.Using K₂Pt Cl₄solution,K₂Ni（CN）₄solution and activated carbon as precursors,nickel-supported platinum cyanide（C@Pt HCF）was synthesized by hydrothermal method,and finally ordered Pt₃Ni/C intermetallic compound was obtained by hydrogen thermal reduction.The research shows that the prepared Pt₃Ni alloy nanoparticles have ordered structure.The nanoparticles were uniformly distributed on the activated carbon without sintering,and the particle size was about 5 nm.Electrochemical results show that the ordered Pt₃Ni/C intermetallic compounds exhibit ORR and OER properties with a half-wave potential of 0.856 V and an overpotential of 350 m V at 10 m A cm^-2.In the zinc-air battery test,the open circuit voltage reaches 1.512 V,the power density is 92.46 m W cm^-2,and the specific capacity can reach 420 m Ah g^-1.