Preparation And Electrochemical Catalytic Performance Of Nickel-iron Hydrotalcite/Carbon Composites

In order to alleviate the shortage of fossil fuels and the environmental pollution caused by combustion,people are committed to developing alternative new energy sources.High expectations are placed on efficient and environmentally friendly hydrogen energy.Water electrolysis is a green way to produce hydrogen,and the kinetics of the ORE process in the two half-reactions is sluggish,which restricts the efficiency of water electrolysis.Precious metal catalysts are expensive and scarce,so it is crucial to build high-performance and low-cost catalysts.Nickel-iron hydrotalcite has attracted extensive attention due to its excellent properties,but its catalytic performance is limited due to its poor electrical conductivity.Therefore,in this paper,nickel iron hydrotalcite is taken as the research object,and it is compounded with different conductive carbon materials,and the electrochemical catalytic performance of the compound is studied.The research contents are as follows:(1)Nickel-iron hydrotalcite was synthesized by hydrothermal method,exfoliated into few-layers nanosheets by ultrasonic method,self-assembled with monolayer graphene oxide and and then reduced.the electron transfer at the heterointerface causes a strong interaction between the two,which is the key factor for the improved catalytic performance.The recombination ratio was optimized to obtain Ni3Fe-LDHs@rGO50 with the most excellent OER performance,with?₁₀and?₅₀of only203 m V and 258 m V in 1 M KOH,and good electrochemical stability.At the same time,the local electron accumulation of rGO also enhances its own HER performance.Ni3Fe-LDHs@rGO50 was used as both cathode and anode for overall water splitting test,it required 1.68 V to reach a current density of 10 m A cm^-2.In addition,it was found that when the content of Ni in the composite is more,the electrochemical performance at high OER potential is improved more significantly,and when the content of Fe is more,it is more conducive to improve the HER performance of the composite.(2)A series of carbon microspheres were obtained by the method of hydrothermal glucose.Add the carbon microspheres to the precursor solution of NiFe hydrotalcite,and NiFe-LDH@CS composites were obtained after hydrothermal treatment.The study found that the carbon microspheres prepared under different conditions had different degrees of improvement in the performance of nickel-iron hydrotalcite.The optimal synthesis conditions of carbon spheres are:glucose concentration 0.6 M,hydrothermal temperature 180?,hydrothermal time 5 h.The carbon spheres synthesized under these conditions have a certain degree of graphitization and small particle size,and the best OER performance is obtained after compounding them with hydrotalcite,with an?₁₀of only 196.7 m V and a Tafel slope of 36.82 m V dec^-1,and the results show that high load rate is more conducive to the improvement of OER performance...