Design And Construction Of Heteroatom/Cobalt Co-doped Carbon Composites For Oxygen Reduction Reaction Electrocatalysts

The depletion of traditional fossil energy supplies and the climate and environmentalchanges brought about by energy consumption make it imperative to develop clean energy.In the coming decades,clean and sustainable energy storage and conversion devices such as fuel cells,metal-air batteries will be the pivotal research topics.Among them,the proton exchange membrane fuel cell?PEMFC?,as one of the most important friendly energy technology,is broadly applied in various stages such as aerospace,transportation,communications,and portable power supplies.Platinum-based materials are widely perceived as the most effective catalysts for PEMFC under both acidic and alkaline media.However,the biggest bottleneck to their large-scale utilization is the scarcity and prohibitive cost of platinum.Therefore,it is imperative to develop a high-activity,low-cost,good durability oxygen reduction reaction?ORR?cathode non-precious metal catalyst.Currently,substantial attention has been dedicated to transition metals and heteroatom?N,S,P,etc?doped carbon materials due to their low cost,high stability and insensitive to methanol.Thus,M-N/C is highly evaluated as one of the most promising candidates for replacing Pt/C.In this work,a highly active electrocatalyst based on carbon nanotubes intercalatedCo/N-doped few layered carbon nanosheets?CNTs-Co/NC?are prepared through a facile method.By adding CTAB surfactant and adjusting the amount of carbon nanotubes,aniline monomer is polymerized on the surface of CNTs to form polyaniline long chain.After heat treatment,PANI forms carbon nanosheets and CNTs act as scaffolds to prop up carbon nanosheets to form a porous fluffy network structure.The as prepared CNTs-Co/NC displays the high specific surface area up to 1072 m²/g,and abundant mesopores which are favorable for exposing more intrinsic active sites,fascinating the diffusion and mass transport of reactants.As a consequence,CNTs-Co/NC exhibits an enhanced ORR activity,i-t measurements shows that CNTs-Co/NC exhibited slightly higher stability than commercial Pt/C catalysts in alkaline media and CO and methanol anti-poisoning performance.Moreover,as cathode electrodes for Zn–air batteries,it shows high power density and good durability under different discharge current densities,very suitable for practical application in portable electronic and electrochemical energy devices.In addition,we report the synthesis of a noval type of nitrogen and phosphorous co-doped porous carbon catalyst Co-P/NC derived from phosphonitrilic chloride trimer in one step.It has been demonstrated that two types of heteroatoms dual-doping could reinforce the ORR performance of the catalyst.As expected,Co-P/NC displays high ORR performance with an onset and a half wave potential of 0.92V and 0.805V?vs.RHE?,respectively,in alkaline media.Impressively,when used as a cathode catalyst for zinc-air batteries,Co-P/NC also exhibits a peak power density up to 86.5 mWcm^-2,as well as the long-term discharge stability for more than 20 hours under a discharge current density of 5 and 20 mAcm^-2.