Based On The Preparation Of Nano Carbon Composite Electrocatalyst And Their Electrochemical Performance Toward Oer/orr Reactions

Metal-air batteries have attracted much attention in the field of energy conversion and storage application because of its theoretically high energy density,low cost and environmentally friendly.Electrocatalytic oxygen reduction reaction?ORR?and oxygen evolution reaction?OER?play the key roles in the development of this device,however,these two kinds of reactions belong to the sluggish kinetics,which reduces the performance of metal/air batteries.To solve this problem associated with ORR and OER in electrochemical systems,efficient and low electrocatalysts has an important role in promoting the commercialization of metal/air batteries.According to the latest research results,the transition metal doped with other elements have an excellent catalytic activity of OER/ORR.Therefore,in this paper,firstly,through high-temperature calcination in N2 atmosphere,transition metal Co was doped with MgO successfully,named Co/MgO/N-doped carbon electrocatalyst.They were characterized by X-ray diffraction,Raman spectra and X-ray photoelectron spectroscopy,they also have been studied as electrocatalysts in both oxygen evolution and oxygen reduction reactions,such as cyclic voltammetry.As the result,the catalyst exhibit superior electrocatalystic activity for OER/ORRs in alkaline media.Among all the samples in this series,The 10Co1Mg/NC-800 catalyst with Co:Mg molar ratio of 10:1 was calcined at 800 ? to obtain the best catalytic activity of OER/ORR,The OER Tafel slope is 91.0 mV·dec^-1,the potential value at 10 mA·cm^-2 is 0.704 V?vs.Ag/AgCl?;the onset potential of ORR is-0.07 V?vs.Ag/AgCl?,the ORR Tafel slope and half-wave potential?E1/2?are 56.2 mV·dec^-1 and-0.168 V,respectively.The catalytic activity of ORR/OER is similar to that of precious metal.Secondly,we used cobalt nitrate hexahydrate as metal salt,2-methyl imidazole as ligands and ammonia solution?25wt%?as the alkaline conditions to prepare precursor through a simple ligand synthetic process.And then,The precursor was calcined at a certain temperature in N2 atmosphere to obtain the corresponding electrocatalyst.As a results,we can find the Co-600 catalyst was calcined at 600 ? to obtain the best catalytic activity of OER/ORR,the OER Tafel slope is 103.5 mV·dec^-1,the potential value at 10 mA·cm^-2 is 0.643 V?vs.Ag/AgCl?;the onset potential of ORR is-0.07 V?vs.Ag/AgCl?,the ORR Tafel slope and half-wave potential?E1/2?are 64.1 mV·dec^-1 and-0.153 V,respectively.