Interfacial Regulation And Synergistic Catalysis Mechanism Of NiCo₂O₄/Mesoporous N-Graphene Composite For Reversible Oxygen Electrocatalysis

As the environment and energy issues become more and more serious,renewable clean energy is increasingly becoming a hot research topic.Among them,fuel cells and rechargeable zinc-air batteries have a good prospect.At present,the core of the current research is to find out a cheap and efficient non-precious metal-based reversible oxygen electrocatalyst to replace expensive commercial Pt/C and RuO2.Recently,spinel/carbon composite catalysts have attracted much attention due to excellent reversible oxygen electrocatalytic activity.The improved catalytic performace of composites is normally ascribed to the synergistic effect.However,the mechanism of synergistic catalytic effect is still not clear.In this thesis,the mesoporous structure of graphene oxide could be regulated by adjusting the energy of laser irradiation.As the laser energy increases,the pore volume increases from 0.033 cm³ g^-1 to 0.085 cm³ g^-1,and it will improve the content of pyridine nitrogen.Therefore,the mesoporous structure can regulate the content of pyridine nitrogen.XPS test results show that the content of pyridine nitrogen increases from 1.83%to 3.42%,and the reversible oxygen electrocatalytic activity of NiCo2O4/mesoporous N-graphene?NiCo/NLG?composite catalyst also increases.The synergistic effect of cobalt and nitrogen bonds is the reason why the composite catalyst has a high catalytic activity for reversible oxygen electrocatalysis.It was found that the catalytic activity of different configurations of nitrogen bonded with cobalt is different.The bonding of pyridine nitrogen and cobalt can improve the catalytic activity.The mechanism of the effect of different nitrogen configurations bonded with cobalt on the ORR/OER catalytic activities are revealed by the DFT calculation,which is consistent with the experimental results.It shows that pyridine nitrogen bonded with cobalt could improve the catalytic activity.At last,a Zn-air battery is assembled using NiCo/NLG as the catalyst for the oxygen electrode,and it displays superior charge/discharge performance.