The Fabrication Of Functionalized Non- Precious Metal Catalysts And Their Applications In Elecrocatalysis

Oxygen reduction reaction?ORR?and oxygen reaction?OER?are two key processes in the clean and highly efficient electrochemical energy conversion and storage devices of proton exchange membrane fuel cells and rechargeable metal-air battery.The corresponding efficiency and cost of energy conversion are highly depended on the catalyst of the above processes.Traditionally,precious metal platinum?Pt?is considered as a great electrocatalyst for ORR and precious metal oxide?Ir O2?is regarded as an excellent electrocatalyst for OER.However,the scarcity and high cost of precious metals greatly limit the large-scale commercial application of electrochemical energy conversion and storage devices.Therefore,it is a great demend to develop a novel and costeffective electrocatalysts.In this study,series of low cost,high catalytic activity of catalytic materials,including active cuprous sulfide?Cu2S?nanorod,ZIF-67 loaded on carbonized cotton and MnO₂ with oxygen vacancies,were successfully synthesized by the simple,high efficiency,energy conservation and environmental friendly methods.The scanning electron microscope,transmission electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,specific surface area analyzer and electrochemical workstation were conducted to investigate the relationship between catalytic performance and structure composition of obtained materials.The present works open up new ideas and provide a useful reference to find the facile strategy to prepare catalytic materials with low cost and environmentally friendly.The main contents of this paper are summarized as follows:?1?The polymer precursors were fabricated through a one-step method with the reaction of reduced graphene oxide,copper nitrate,trimesic acid,formaldehyde and urea under room temperature.After the high temperature calcination under inert gas,the active Cu2 S nanorod was finally obtained.The electrochemical measurements revealed that the active Cu2 S nanorod exhibited excellent oxygen evolution reaction catalytic activity,whish was even better than Ir O2.The contributions were mainly attributed to?I?the activation effect of trimesic acid on the nanorod structure in the synthesis process,which promoted the activity of oxygen reaction;?II?the effect of reduced graphene oxides to enhance the conductivity of the material,which could accelerate the formation of the rod structure and improve the electrochemical performance;?III?the increase of calcination temperature,which would enlarge the degree of graphitization and contribute to the synthesis of rod structure.Therefore,the active rod structure is the most important key to obtain the excellent electrochemical properties.?2?The metal organic framework ZIF-67 nanocrystals loaded on cotton were successfully fabricated with the reaction of cobalt nitrate,2-methyl imidazole and absorbent cotton.After the high temperature calcination,the obtained production was regarded as MOF-C-T.Furthermore,the effect of calcination temperature on the oxygen reduction performance of the material was systematically discussed.Interestingly,the sample calcinated at 900 °C exhibited the best onset potential and limited current density.More importantly,the working stability and tolerance to methanol crossover effect of obtained material were even better than commercial Pt/C.This excellent catalytic activity was mainly attributed to synergistic effect of high nitrogen content and rich mesoporous structure originated from the cotton.?3?The oxygen vacancies MnO₂ nanorod was firstly synthesized through the microwave heating process.The effect of microwave heating reaction time on the oxygen reduction performance of the material was evaluated.Fortunately,the obtained MnO₂-t exhibited good oxygen reduction electric catalytic activity.Especially,the sample with microwave treatment for 30 min exhibited the highest onset potential of LSV curves as well as the limit current density.More importantly,the catalytic stability,tolerance to methanol crossover effect of the obtained material was far superior to the commercial Pt/C.Based on a series of structural characterization,it could be concluded that the improvement of catalytic performance contributed to the synergistic effect of oxygen vacancy and Mn4+ ion.