Preparation And Performance Study Of Co-Based Non-Noble-Catalysts For Fuel Cells

In contemporary society,the environmental pollution and energy shortage have become two major issues that threaten the survival of mankind,so the researchment of new energy is particularly important.Hydrogen energy has attracted much attention due to its high efficiency,non-pollution,and other advantages.Fuel cells can use hydrogen energy directly,safely,and environmentally friendly,and have high energy conversion efficiency.Therefore,they have a large potential to replace the internal combustion engine as a new generation of power systems.At present,the normal running of proton exchange membrane fuel cells is extremely dependent on platinum-based catalysts,and the cost and storage of platinum elements greatly limit its large-scale application.Alkaline membrane fuel cell can use non-precious metal catalysts instead of platinum-based catalysts,but it requires the non-precious metal catalysts have very high activity and stability.Therefore,in order to speed up the large-scale application of the fuel cell,it is very important to develop a non-precious metal catalyst that contain inexpensive and high ORR activity simultaneously.Based on the above research background,this paper prepared three different systems of non-precious metal catalysts:(1)A melamine formaldehyde gel with a network structure was synthesized by a sol-gel method.Cobalt oxide was coated with this gel,and then carbon black was used to wrap the above material and worked as a carrier.Finally,a series of Co2O3@MF-C catalysts were obtained by pyrolying the precursor at high temperaturethe.We also investigated the effect of cobalt oxide content and calcinating temperature on the ORR activity of the catalyst.Finally,we found that the optimal preparation conditions of the catalyst were that the cobalt oxide content is 20%and the calcination temperature is 650?.In other words,20%Co2O3@MF-C-650 has the most excellent ORR activity,and its initial reduction potential and half-wave potential under acidic conditions were 0.79 V and 0.60 V,respectively,and its initial reduction potential and half-wave potential under alkaline conditions were 1.02 V and 0.94 V,respectively.The electron transferred number of 20%Co2O3@MF-C-650 under acidic and alkaline conditions are 3.67 and 3.96,respectively,which are based on 4-electron reaction process,and the test results also indicate the prepared catalysts have better stability and methanol resistance;(2)A series of novel Co-bpdc crystals(Metal-organic frameworks,abbreviated as MOFs)with cuboid structure were synthesized by heating and stirring method.A series of catalysts were obtained by high-temperature calcination and it was found that Co-bpdc-600 has the most excellent ORR activity under alkaline conditions.On this basis,Co-bpdc/MWCNTs composites were synthesized under the same reaction conditions.The composites were calcined at 600?,and the effect of MWCNTs content on ORR activity was investigated.It was found that cobalt atoms were uniformly distributed on the surface of MWCNTs and the Co-bpdc/MWCNTs-100 has the most excellent ORR activity,and its initial reduction potential and half-wave potential under acidic conditions were 0.79 V and 0.60 V under acidic conditions,and its initial reduction potential and half-wave potential of 0.98 V and 0.92 V under alkaline conditions.The electron transferred number of Co-bpdc/MWCNTs-100 under acidic and alkaline conditions were 3.73 and 3.98,respectively,which were based on 4-electron reaction process,and the test results also indicate the prepared catalysts have better stability and methanol resistance;(3)A novel sheet-like Co-phen crystal was synthesized by stirred at room temperature method and carbon aerogel with high specific surface area was synthesized by sol-gel method.We use carbon aerogel wrap Co-phen,and then A series of high specific surface area catalysts were prepared by calcinating it at high temperature.We also investigated the effect of the ratio of Co-phen and carbon aerogels and calcinating temperature on the activity of the catalyst.we found that the optimal preparation conditions of the catalyst were that the ratio of Co-phen and carbon aerogel was 4:10 and the calcination temperature was 700?.In other words,4Co-phen@l0CA-700 has the most excellent ORR activity,and its initial reduction potential and half-wave potential under acidic conditions were 0.82 V and 0.75 V,respectively,and its initial reduction potential and half-wave potential under basic conditions were 0.99 V and 0.91 V,respectively.The electron transferred number of 4Co-phen@10CA-700 under acidic and alkaline conditions is 3.93 and 3.97,respectively,which are based on the 4-electron reaction process,and the test results also indicate the prepared catalysts have better stability and methanol resistance...