Studies On The Catalysts Derived From Poly-aminobenzene For Fuel Cells

Fuel cell is a clean and efficient power technology,with a wide application.Direct Formic Acid Fuel Cell(DFAFC)is an equipment which can directly transform the chemical energy in Formic Acid into electric energy.It has a high theoretical open-circuit voltage,a low toxicity and a low fuel cross-over rate.However,the dependence on noble-metal catalysts increases its cost.And the fast decay of the anode activity shortens its lifetime.Therefore,this thesis makes a big effort on studying in-situ synthesis and electro-catalytic activity of non-noble-metal ORR catalysts.And the characteristics of formic acid oxidation reaction are also studied.Finally,DFAFC single cells are assembled to test the cataysts' generating abilities.Using polyaniline(PANI)as C,N precursor,nano-CaCO3 as pore templates,a non-noble-metal ORR catalyst is synthesized.And electrochemical analyses are implemented.As results show,nano-CaCO3 contributes to the porosity of the catalyst and increases its surface area and activity.Adding nitrates can also increase the ORR performance.And the affection of pyrolysis temperatures are studied.The catalyst heated at 850? owns the highest ORR potential.To further enhance the incorporation between supporter and transition metal,poly-o-phenylenediamine(PoPD)is used to replace PANI as precursor.Experiment demonstrates that o-phenylenediamine has a stronger complexation with cobalt,which improves the cobalt content and activity of catalyst.And the synthesis method is optimized.Freezing drying is applied to make the precursors more homogeneous.And the optimum amount of initiator and cobalt nitrate is decided.The catalyst has an ORR half-wave potential of 0.73 V(vs.RHE).In RDE test,it owns a very small difference on the ORR onset potential to commercial 28.6%Pt/C catalyst.And Pd/XC-72 catalyst is also synthesized to study the characteristics of formic acid oxidation reaction.Research shows,the reaction rate has a very fast decay.However,when apply a low potential to proceed HER on the catalyst,the activity can partially recover.Finally,single fuel cell is assembled to test its power density and polarization.And the working conditions are studied.When using 28.6%Pt/C for cathode catalyst,the maximum power density reaches 93 mW·cm-2 at 60 ?.When using PoPD-Co(NO3)2-MPC for cathode catalyst,the cell performance is nearly as well as using 10%Pt/C.And the maximum power density is 24 mW·cm-2 at 60?.