Continuous Synthesis Of ZIF-67 And The Electrochemical Application Of Its Hybrid Derivatives

Under the background of rapid development of world economy and shortage of energy resources,it is very important to develop green,safe and environmentally friendly new energy conversion techniques.Hydrogen Evolution Reaction（HER）by electrolysis of water plays an important role in efficient and clean energy conversion and storage,the key step is to develop efficient and ideal electrocatalyst.ZIF-67（Co）shows great potential in the field of electrochemistry.The electrochemical performance of ZIF-67（Co）can be further improved by hybridize or modification.The application of ZIF-67 depends much on availability on a large scale.Therefore,developing a well-controlled scale-up synthesis methodology is required for the application of ZIF-67.In this thesis,the massive production of ZIF-67 was realized in microfluidic synthesis with a simple Y-mixer at ambient temperature and pressure.With a metal/ligand/triethylamine（TEA）ratio of 1/4/4,ZIF-67 can be produced with a high space-time yield（STY）of 57000 kg?m^-3?d^-1and a production rate of 285 g?h^-1in ethanol.It and can be produced with a similar STY in water solution as well.Given the importance of sustainable synthesis,the recycling process of the mother liquor was investigated.The mother liquor can be recycled 5 times with high yield and crystallinity in ethanol,but not applicable in water solution.The morphology and particle sizes of ZIF-67 can be regulated in a controlling manner in a water-ethanol mixed solvent.Moreover,the influence of TEA on the characteristic of the ZIF-67 structure was investigated in detail.It was proved that,TEA could easily enter into the pores and cause the reversible deformation of ZIF-67 structure,which is synthesized in water.The structure of zif-67 could be restored after the TEA was removed by high temperature activation.Tp Bpy/ZIF hybrid material was synthesized by using bipyridine-based COF framework as the carbon substrate,where ZIF-67 was anchored on the 2D framework by cooridination followed by secondary growth.A series of cobalt-based nitrogen doped carbon material,namely Co-NC_X,were prepared by high temperature pyrolysis.Compared with parent Tp Bpy,ZIF-67 and the physical mixture of Tp Bpy and ZIF-67,under the same pyrolysis temperature,the electrochemical HER performance of Co-NC_Xis much better than that of the other three materials.Co-NC₈₀₀has an overpotential of 261mv when the current density is 10 m A·cm^-2.The slope of Tafel obtained from LSV curve is the lowest,which is 112.8 mv/dec,which shows the best HER catalytic performance.Cyclic voltammetry test and i-t test showed that Co-NC₈₀₀has good HER catalytic stability.