Structural Regulation Of Metal Phosphide/carbon Composite Catalysts And Their Application In Zinc-air Batterie

Zinc-air batteries are attracting attention because of their high energy density,low cost and high safety.Owing to the slow kinetic processes of oxygen reduction reaction（ORR）and oxygen evolution reaction（OER）,bifunctional electrode catalysts capable of catalyzing both reactions are required at the air electrode.Presently,the precious metal catalysts containing elements such as Pt and Ru are used with single function and high cost.Therefore,there is a need to develop inexpensive and efficient bifunctional catalysts for zinc-air batteries.In this paper,the excellent OER activity of bimetallic phosphide nanoparticles and the excellent ORR activity of phosphorus and nitrogen double-doped carbon were compounded together to construct a highly efficient bifunctional catalyst.Two different approaches were used to regulate the catalyst structure and to effectively improve the catalytic activity.The catalysts were used to construct an excellent performance of zinc-air battery.The main contents of the paper are as follows:（1）FeNiP nanoparticles/N,P double-doped carbon composite catalysts were prepared（FeNiP@C-200）.The result revealed that the introduction of oleylamine in the preparation processed modulated the amount of the catalytic active sites of ORR and OER.The addition of oleylamine increased the content of ORR active sites on graphite-N in carbon substrates and OER active sites on M-OH/M-OOH on the surface of FeNiP nanoparticles.The FeNiP@C-200 obtained after this surface structures modulation exhibited higher half-wave potential（0.879 V）and larger limit current density in the catalytic of ORR.The OER performance of FeNiP@C-200 exhibited an overpotential of 280 m V at a current density of 10 m A cm^-2.Both FeNiP@C-200-based assembled liquid and solid-state zinc-air batteries exhibited high power density and stable cycling performance.（2）Se-doped FeNiP nanoparticles/N,P double-doped carbon composite catalysts were prepared（FeNiP/Se NPC-2）.The results revealed that the Se-doped modulated the crystal structure and pore structure of the composite catalysts and improve the catalytic activities of ORR and OER.The Se-doped in the crystal structure of FeNiP caused the change of crystal plane spacing and adjusted the electronic structure,which contributed to improve the performance of OER.Meanwhile,the Se-doped also changed the pore structure of the carbon substrate,which exposed more active sites and improved the mass transfer efficiency,effectively enhanced the performance of ORR.The structural regulation caused by Se-doped caused to the ORR performance of FeNiP/Se NPC-2 exhibited high half-wave potential and large limiting current density.The OER performance of FeNiP/Se NPC-2exhibited an overpotential of 269 m V at a current density of 10 m A cm^-2.Both FeNiP@C-200-based assembled liquid and solid-state zinc-air batteries exhibited high power density and stable cycling performance.This paper demonstrated that FeNiP nanoparticles/N,P double-doped carbon composite catalyst is a category efficiently dual-energy catalyst.The catalytic activity of the catalysts can be improved through the means of structural modulation,which provided a new approach for the design of high-performance bifunctional catalysts and laid the foundation for the development of metal-air batteries with excellent performance.