Structural Optimization And Electrocatalytic Performance Of Heteroatom Doped Carbon Catalyst

With the ever-increasing demand for next generation renewable and sustainable energy,the new energy storage and conversion device attracts people's attention because of its environmental friendliness,high specific energy and long cycle life.However,the use of these devices requires a catalyst to assist in the completion.The best catalysts are precious metal catalysts,but their wide range of uses are limited due to their high cost,scarcity and poor stability.Therefore,it is urgent and meaningful to develop sustainable catalysts with high performance from earth abundant materials.Carbon materials are promising alternatives due to their rich earth content,tailorable porous structures,high surface area,resistance to acids and bases,high-temperature stability,and environmental friendliness.However,due to the inherent properties of carbon materials,it cannot directly act as an excellent catalyst to promote electrocatalytic reactions.The incorporation of heteroatoms?such as P or N?can adjust the electronic properties of carbon,giving carbon an optimized charge-carrier concentration and provide a large number of catalytic active sites,significantly enhancing the electrochemical activity of the original carbon.However,the performance of heteroatom-doped carbon under acidic conditions is poor,and the catalytic activity under acidic conditions can be improved by the introduction of metal Fe and Mn.This paper mainly uses the heteroatom doping to modify the activity of carbon substrates,thereby improving the application of these materials in carbon dioxide reduction and oxygen reduction electrocatalytic reactions.The main work is as follows:?1?N,P co-doped fullerene carbon?N,P-FC?for CO₂ reduction and oxygen reduction performance.P and N-codoped fullerene-like carbon?N,P-FC?was constructed via a soft-template pyrolysis method.Density functional theory?DFT?calculation results reveal the interesting fact that P-doping neighboring C site is more active for CO₂ reduction reaction?CO₂RR?,while N-doping neighboring C site is responsible for oxygen reduction reaction?ORR?and oxygen evolution reaction?OER?in this catalyst.As expected,N,P-FC shows excellent performance for catalyzing CO₂RR?83%Faraday efficiency and 24 mA cm-2 high current density?and much higher than the N,P-doped graphene-like carbon?N,P-GC?.The activity of the fullerene-like carbon material for CO₂ reduction is strongly dependent on the P/N atomic ratio.Furthermore,it shows excellent catalytic activities toward ORR and OER,and Zn-air batteries,with a half-wave potential 79 mV higher than commercial Pt/C,and also higher than all of the carbon-based ORR catalysts described.This work highlights a new-concept for modulating the surface charge redistribution by heteroatom codoping and morphology control toward designing efficient and low-cost electrocatalysts.?2?Fe,Mn modified N,P co-doped porous carbon?Fe,Mn/N,P-C?for electrocatalytic oxygen reduction performance.Highly active and stable isolated monoatomic Fe,Mn/N,P co-doped porous carbon?Fe,Mn/N,P-C?catalysts were prepared by in-situ pyrolysis.HAADF-STEM and XPS analysis demonstrated the formation of a metal-nitrogen-carbon active site,which was beneficial to the catalytic oxygen reduction reaction.As expected,the catalyst showed excellent ORR performance with a half-wave potential(E_1/2)of 0.93 V in 0.1 M KOH,which outperformed commercial Pt/C and most non-precious-metal catalysts reported to date.It has similar catalytic activity to Pt/C in 0.1 M HClO4(E_1/2 = 0.8 V).It also has good methanol tolerance and excellent stability.The assembled zinc-air battery also showed excellent performance?the charge and discharge cycle performance remained good after 105 h?.The present investigation opens the avenue for simple synthesis of catalysts with efficient acid-base oxygen reduction performance.