Study Of Transition Metal-doped Porous Carbon-based Catalysts And Their Oxygen Electrode Properties

In recent years,the intensification of pollution and energy shortage have caused a research wave for green,renewable energy at home and abroad.However,the oxygen reduction and oxygen evolution key electrode reactions of these devices still face problems of sluggish kinetics,high overpotential,and low conversion efficiency.There are already commercial precious metal catalysts such as Pt/C and RuO₂/IrO₂,but their high cost and poor stability cannot satisfy the large-scale commercial applications.To resolve the above problems,a series of high-performance transition metal-based ORR/OER catalysts were prepared.The research contents are as follows:?1?A series of FeNi/NC catalysts were constructed through a high-temperature calcination process by using surfactant F127 as soft template,g-C₃N₄ as carbon and nitrogen source,and Fe?NO₃?₃·9H₂O and NiCl₂·6H₂O as Fe and Ni sources,respectively.The obtained FeNi/NC catalyst has a specific surface area of 399 m² g^-1,and FeNi nanoparticles are evenly distributed on the graphene-like structure surface.The optimized electrode potential gap ?E(?E=E(j _OER=10 mA cm^-2)–E(j _ORR=-3 mA cm^-2))of FeNi/NC catalyst in alkaline medium was 0.77 V,which was better than that of Pt/C+RuO₂?0.83 V?.?2?The ultra-high dispersion Cu/NC catalyst was prepared through a high-temperature calcination process by using g-C₃N₄ as a carrier,o-phenanthroline as carbon source and nitrogen source and Cu?NO₃?₂·3H₂O as a Cu source,respectively.Through the complexation of o-phenanthroline with Cu²⁺ions,the optimized Cu/NC forms a graphene-like structure.The highly dispersed Cu₂O nanoclusters have a mean size of 2³ nm and the nitrogen content was as high as 20.13 at.%.Electrochemical tests indicated that the ORR half-wave potential E_1/2 of Cu/NC catalyst was 0.82 V,which was close to Pt/C.The half-wave potential of the Cu/NC catalyst has no negative shift after 10,000 cycles of accelerated aging test,showing excellent stability.?3?The FeNi/NKb catalyst was obtained by high-temperature calcination by using Ketjenblack as a carrier and o-phenanthroline as a nitrogen source,and Fe?NO₃?₃·9H₂O and NiCl₂·6H₂O as the Fe and Ni sources.The porous FeNi/NKb catalyst has a specific surface area of 513 m² g^-1 and a large number of single-atom M-N_x active sites uniformly dispersed on the surface.Electrochemical tests show that the ORR onset potential E_onset of FeNi/NKb catalyst is1.05 V,which is higher than that of most ORR catalysts reported in the current literature.The oxygen electrode potential gap?E is 0.69 V,which is much lower than the commercialized Pt/C+RuO₂,and it is expected to realize industrial application due to its excellent stability.