Nanostructural Modulation Of Cobalt-based And Zinc-based Compounds For Electrochemical Energy Applications

With the increasing energy crisis,new energy generation and storage systems have become one of the focal points of scientific research.Supercapacitors and electrochemical catalysts have been considered as important ways to solve these problems,due to the high efficiency and safty.Although noble metal materials have been widely accepted as the most active materials for supercapacitors and electrocatalysts,these noble-metal-based materials are scarcity and high cost,which greatly limit their widespread application.Developing non-noble mateials is a big challenge for new energy devices.In this paper,design and modulate the nanostructure of transition metal(Co,Zn)compounds as electrode and uesd for high performacne supercapacitors and electrocatalysts.(1)CuCo2O4/NiO nanotrees with a mesoporous,hierarchical composite nanostructure were hydrothermally grown on nickel foam.The composite nanostructure exhibits excellent synergistic reaction as electrode for supercapacitors.The specific capacitances of composite electrode were 2199 and 1296 F g"1 at current densities of 1 and 20 A g-1,respectively,and long-term capacity retention of?95.3%after 10000 cycles at 20 A g-1.(2)Highly twinned structured ZnSe nanorods were prepared by ion exchange method.A mount of Zinc vacancies were existence in ZnSe nanorods,which plays an important role to adsorb N2 and improve the catalytic activity for electrochemical nitrogen reduction reaction.The Faraday efficiengy can reach 3.65%at-0.5 V,exhibiting a superior stability during the testing for 10 hours.(3)FeCo2O4 nanoparticles rich in oxygen vacancies was first synthetised by a laser fractured method.The oxygen vacancies play an important role to improve the catalytic activity.Modulating the concentration of oxygen vacancy can adjust the catalysts to achieve the best performance.Furthermore,the FeCo2O4 nanoparticles also exhibited superior discharge performance and long life-time for zinc-air battery.(4)Monocrystal CoO with abundant oxygen vancies was synthesized by ion exchange method.The CoO NRs as air electrode for zinc-air battery delivers a voltage of up to 1.25 V at the current density of 10 mA cm-2.The battery equipped with CoO NRs shows very stable charging(1.89 V)and discharging(1.09 V)voltages at charge current densities of 2 mA cm-2 and discharge current densities of 20 mA cm-2.Moreover,the CoO NRs based battery exhibits 60 stable charge-discharge cycles without noticeable degradation of performance.Based on the above results,designing and modulating the nanostructured of non-noble metal compounds is an effective way to improve their electrochemical activities,and enhance their performance for electrochemical energy.