Preparation And Electrochemical Performance Of Ni-based Electrocatalyst For Direct Methanol Fuel Cell

As a new energy,fuel cell has the advantages of economy,environment friendly and high utilization.However,it is difficult to accomplish the commercialization of fuel cell due to the limitation of noble metal catalysts.Therefore,three types of non-noble metal Ni based catalysts with economic and practical high-performance were prepared by the different methods to study their catalytic effects on methanol fuel cell.The main contents are as follows:（1）The mixed precursor of nickel acetylacetonate（Ni（acac）₂）and metal organic framework ZIF8 was prepared by solvothermal method,and then the NiNC electrocatalyst was obtained by high temperature carbonization.The Ni（acac）₂ is limited in ZIF8 framework confirmed by UV absorption spectrum analysis.The morphology of NiNC sample is a cube of about 100 nm,which has sub-nano Ni metal particles of about 2.51 nm inside determined by SEM and TEM.The pore structure and specific surface area of NiNC were determined by specific surface area and pore size analysis.The graphitization degree of carbon in the sample was determined by Raman test.The catalytic oxidation performance of NiNC samples with different Ni（acac）₂ content for methanol was investigated.The experimental results show that the sample NiNC3 prepared with 3mmol Ni（acac）₂ has the best performance.At 0.7 V vs.Ag/AgCl,the methanol oxidation peak current density is 140 mA/cm²,but the stability of the sample is not satisfied.（2）The catalyst（NBC）with carbon nanotube（CNT）as catalyst carrier and aniline carbonization coated metal Ni was obtained by the high temperature carbonization method.The effects of carbonization temperature and NB:CNT ratio on the catalytic performance of methanol were studied.The morphology was observed by SEM and TEM.The experimental results show that the CNT with curved tubular clusters are attached with Ni catalyst coated by aniline carbonization.When the carbonization temperature is 800℃and the mass ratio of NB:CNT is 2,the oxidation peak current density for methanol oxidation is 165 mA/cm² at 0.7 V vs.Ag/AgCl.The current density remains 72%after 2000 s as initial current density is 125.7 mA/cm² in I-T test,indicating that the sample has good chemical stability.The electrochemical active area,surface species coverage and proton transfer coefficient of the samples were 707.75 cm² and 3.15×10^-6 mol/cm² and 3.17×10^-6 cm²/s,respectively。（3）Binary NiCuand ternary NiCuSnelectrocatalysts were prepared by the hydrothermal method.The composition and morphology of the samples were studied by XRD,XPS and TEM.The catalytic oxidation performance of binary NiCuelectrocatalyst with different proportions for methanol was investigated（the content of Ni remained unchanged,and the addition amount of CuCl₂·2H₂O was 0.2-1.0 g）.The results show that the sample NiCu0.6exhibits the favorable performances.The current density of MOR oxidation peak is 88 mA/cm² at 0.7 V vs.Ag/AgCl.The ternary NiCuSncatalyst（SnCl₂·2H₂O addition amount is 0.1-0.3 g）was prepared by introducing Sninto the NiCu0.6.It is found that the size of ternary NiCuSnsample is 368 nm.The sample with SnCl₂·2H₂O addition of 0.2 g NiCuSn0.2 showed the best catalytic performance of MOR.The MOR oxidation activity was 101.28mA/cm² at 0.7 V vs.Ag/AgCl.I-T curves shows that the sample has good stability.The electrochemical active area,surface species coverage and proton transfer coefficient of the samples were 63.75 cm²,2.11×10^-6 mol/cm² and1.69×10^-6cm²/s,respectively。...