Carbon Nanomaterials/Conjugated Polymers ?-? Conjugation Enhances Oxygen Reduction Reaction Performance

Zinc-air battery,as the power generation technology with the most potential to solve the energy crisis,has the attracted widespread attention due to its high efficiency and pollution-free advantages.However,because the cathodic oxygen reduction reaction?ORR?is a slow four-electron transfer process with a high overpotential,a large amount of Pt-based catalysts should be used to accelerate this process.But the shortcoming of Pt reserves,high cost,toxicity,poor stability,singly selectivity and other shortcomings seriously restrict the development of commercialization.Therefore,it is very important to develop non-precious metal catalysts or non-metal catalysts with high ORR performance and long-term stability.Although carbon nanomaterials show great potential as effective catalysts for ORR,the high specific surface energy leads to compact restacking of carbon atoms,resulting in poor long-term stability,which limits their performance.In order to overcome this problem,in this paper,carbon nanomaterials and conjugated polymers are assembled to prepare composite materials,which are used in zinc-air batteries.It has been found through research that conjugated polymers can improve the agglomeration of carbon nanomaterials,which enhances the ORR performance of composite materials,especially the long-term stability.The specific research contents are as follows:?1?An anti-agglormeration single-walled carbon nano-tubes catalyst by use poly-3,4-Ethylenedioxythiophene as upholder.Physical characters indicate that PEDOT efficient fill in the interweave zone or adhere to SWNTs surface.Furthermore,S atom can be doped into lattice and produce more defects.Electrochemical tests show that SWNTs@PEDOT has the similar catalytic activities toward ORR to SWNTs,both of them can realize a quasi-4e ORR pathway.Within a32,000s long-term practice,cathodic current of SWNTs toward ORR gradually decays to 58%of the initial value,by contrast,SWNTs@PEDOT shows excellent stability with several stages of rise,fall,rise to 105%of the initial current.?2?An anti-agglormeration reduced graphene oxide catalyst by use poly-3,4-Ethylenedioxythiophene as upholder.The physical characterization showed that PEDOT effectively adhered to rGO sheets and structural defects increased.Electrochemical tests show that the ORR performance of P-rGO-10 catalyst is superior to pure rGO.rGO is a two-electron pathway and P-rGO-10 is a quasi-four-electron ORR pathway.In the long-term stability test of 32000s,the ORR current of rGO gradually decayed to 52%of the initial value at 32000s,however,P-rGO-10 showed good stability and decayed to 84%of the initial value at 32000s,an increase of 32 percentage points over rGO.The P-rGO-10 catalyst was applied to a zinc-air battery,and compared with 20 wt%Pt/C,the peak power density of the P-rGO-10 catalyst was 77.9 mW cm^-22 higher than Pt/C(64.7 mW cm^-2).However,the specific capacity of P-rGO-10 is 718.7 mAhg^-1 and the corresponding energy density is 844.5 Whkg^-11 lower than Pt/C(specific capacity 827.9 mAhg^-11 and energy density927.5 Whkg^-1).Under different discharge current densities,the voltage of Pt/C drops much faster than P-rGO-10.?3?G-Fe PPc catalyst was prepared by assembling iron polyphthalocyanine?FePPc?and reduced graphene oxide.Physical characterization showed that the iron polyphthalocyanine particles on rGO obviously smaller and uniformly dispersed.Electrochemical tests shows that G-FePPc has better catalytic activity for ORR than FePPc.In the long-term stability test,the ORR current of G-FePPc decays to 62.3%of the initial value at 32000s,which is better than pure FePPc?35.6%?.The peak power density of G-FePPc is 61.2 mW cm^-22 is much higher than the peak power density of FePPc(16.0 mW cm^-2)The calculated specific capacity of the G-FePPc zinc-air battery is 698.6 mAhg^-1,and the corresponding energy density is 768.4Whkg^-1.