Design And Performance Of Cobalt-based Electrocatalytic Materials Derived From Metal-organic Frameworks

Due to increased depletion of fossil-fuel and environmental issues,clean and renewable energy resources have attracted much attention.Among the possible renewable energy technologies,fuel-cells,metal-air batteries and water-splitting systems are in a leading position in the storage and energy conversion due to their potential to create energy with zero emission.Despite the high activity of noble-metal-based electrocatalysts for the key reactions(hydrogen evolution reaction,oxygen evolution reaction and oxygen reduction reaction),weak durability and high cost impedes its practical application at industrial level.As compared to conventional noble metal-based catalysts,the low cost and high mass transfer efficiency of MOFs have a broad application prospect in the field of energy.In many studies,the stability of the structure and chemistry and the discrete catalytic sites of MOFs are the main factors limited MOFs electrocatalytic activity.In this paper,a series of MOFs composite nanomaterials are prepared to study their electrochemical properties,and applied to electrocatalytic oxygen reduction and overall water splitting experiments.The work is performed following:(1)A simple pyrolysis process using ZIF-67 and CNTs as precursors to obtain N-doped carbon wrapped Co nanoparticles core-shell nanostructures grafted on carbon nanotubes(Co@NC@CNTs).Most importantly,this unique structure of Co@NC@CNTs is beneficial to increase the contact area of N-doped carbon and Co,inhibit the aggregation of Co@NC core-shell nanoparticles and protect the Co from dissolution,thus improving the electrocatalytic performance and stability for Oxygen Reduction Reaction(ORR).(2)A facile method for synthesizing bifunctional electrocatalysts using Mo-doped polymetallic phosphide.The synergistic effect in multi-metallic phosphides can provide abundant active sites.Meanwhile,Mo-doped can effectively adjust the electronic structure and increase the electroactive center.Benefiting from the unique composition,Mo-Ni Co Fe P/NF has shown extremely competitive Oxygen Evolution Reaction(OER)and excellent Hydrogen Evolution Reaction(HER)performance.(3)A facile strategy is demonstrated to rationally construct Co Fe prussian blue analogues(PBA)@Co P cube-on-sheet hierarchical structure by etching reaction with intermediated Co O to form PBA nanocubes.Benefitted from rapid charge transfer of active species and the synergistic effect between each component to achieve tuned electronic structure and abundant electrocatalytic active sites.The Co Fe PBA@Co P presents remarkable electrocatalytic performance and good stability in 1.0 MKOH.