Synthesis And Properties Of Transition Metal Doped Electrocatalytic Materials

Renewable energy storage and conversion technologies have brought new hope to address current energy and environmental problems,in which electrocatalysis has received widespread attention.Oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)constitute the core of many energy conversion devices,such as fuel cells,metal-air batteries and the like.Platinum,ruthenium,iridium and other precious metals can be used as efficient catalysts for electrocatalytic ORR and OER reactions,but their high prices and resource scarcities limit the wide range of commercial applications.A growing number of researchers are committed to the development of partial or complete replacement of precious metal catalysts for new material catalysts,such as precious metal alloys,carbon-based catalysts,etc.,which has the advantages of low cost,abundant reserves,and relatively high catalytic activity.Based on the synthesis and properties of transition metal doped electrocatalytic materials,this thesis is composed of the following two aspects:1.Zn-doped Co-NC composite was synthesized via pyrolysis of Zn-doped ZIF-67.Due to the synergistic effect of N-doped carbon and Co nanoparticles,as well as the advantages of high nitrogen content and large specific surface area,the composite exhibited excellent electrocatalytic activity for ORR and OER in an alkaline environment.Notably,the doping of Zn contributes to the reduction of the size of Co nanoparticles,increasing the interaction between Co and N,and therefore enhancing the N content and the electrocatalytic activity.The primary Zn-air battery capacity based on the optimal Zn-doped Co-NC composite is 741 mAh gZn-1,and the energy density is 889 Wh gZn-1.The potential change in the charge and discharge process for the optimal Zn-doped Co-NC composite after 100 cycles is 0.1 V.The primary and rechargeable Zn-air batteries show better performance than those based on Pt/C catalyst.2.The Co-doped noble-metal Ir nanodendrite alloys were prepared by the one-step solvothermal method.The morphologies of Co-doped Ir nanodendrites were controlled by optimizing the ratio of Co/Ir and the ratio of the reducing agent(ethylene glycolgly)and the surfactant(oleylamine).The preparation of IrNi and IrCu nanodendrites using this synthesis method proved the universality of the method.The Co-doping of dendritic Ir-based alloy nanomaterials increased the exposure of the electrocatalytic sites.Compared with pure Ir,the IrCo nanodendrites showed better ORR and OER properties,providing potential applications for hydrogenation via water electrolysis,metal-air batteries,and so on.