Preparation And Electrocatalytic Properties Of Transition Metal Compound Carbon Nanotube Composites

Oxygen reduction reaction(ORR)is a cathode reaction occurring in new energy storage devices,such as metal-air batteries and fuel cells,which directly affects the energy efficiency of such devices.Therefore,how to speed up the kinetics of oxygen reduction reaction,and overcome the problems caused by kinetic lag such as overpotential,low power density,low charge-discharge stability,etc.,is very critical.Are now known to cathodic reaction catalyst are mostly based on precious metals platinum and its alloys,precious metals is expensive,and poor stability,restrict its application in business.This is the main reason why we develop non-platinum ORR catalysts.Carbon-based materials because of its wide range of element distribution,and have been widely used at low cost.In order to improve its catalytic properties in the carbon materials doped N,B,F heterogeneous impurity atoms,such as can change its electronic structure and electrochemical properties.Filled with transition metal elements,the reserves of low cost,easy and homogeneous element combination,at the same time in carbon material surface to form a variety of active site,expanding activity area,the activity of catalyst.In this paper,we have realized the co-doping of various heteroatoms through the slow temperature-raising method,and obtained a transition metal,fluorine and nitrogen co-tuning modified carbon nanotubes composite material,as a new low-cost,high activity oxygen reduction electrode catalyst.The composite FePc/FCNT800(Eonset 1.05V vs.RHE,E1/2 0.9V vs.RHE)exhibited the best catalytic activity among the composites obtained at various experimental temperatures.The catalytic activity remained good after a 5000 cycle CV test and a 20-hour I-T test.At the same time,we applied this process to other transition metal elements and obtained MnPc/FCNT800,CoPc/FCNT800 and NiPc/FCNT800 with excellent catalytic activity.Among them,MnPc/FCNT800 showed the best performance(Eonset 1.03 V vs.RHE,E1/20.89V vs.RHE).It also has good stability.The ORR catalytic activity of FePc/FCNT800 and MnPc/FCNT800 are both superior to that of commercial Pt/C catalyst,which proves the effective modification effect of the heterogeneous atom co-doping on carbon-based materials,and opens a new door for future electrochemical catalyst research.