| Metal organic frameworks(MOFs)are a kind of inorganic-organic hybrid porous materials composing of different metal nodes and organic ligands.MOFs have a wide range of application prospect in many research fields,for their regular pores/channels,large specific surface area and wide selection of coordination metals/functional ligands.In recent years,hybrid zeolite imidazole framework(HZIF),as a branch of metal-organic framework materials,has entered the field of view of scientists because of its special structure and functional characteristics.Its structure contains a large number of zeolite-like TO4 inorganic units,which is a kind of hybrid crystalline material between inorganic zeolite and zeolite imidazole framework materials.It possesses both advantages of the high stability for zeolite and the structural designability for MOF s.Moreover,with the introduction of high valent atoms,the framework is endowed with unique physical and chemical properties.Furthermore,HZIF as precursors have derived lots of transition metal nanomaterials,such as carbides,sulfides and phosphides,which displayed great performance in electrocatalytic hydrogen evolution reactions,oxygen evolution reactions,sodium storage,wave absorption,et al.Hence,further synthesis of more functional HZIF-based derivatives materials with different chemical composition and morphology are promising research aspects.Based on above,the main research work of this report is as follows:(1)A porous binary sulfide CoS/MoS2 electrocatalyst is synthesized from CoMo-bimetallic hybrid zeolite imidazole framework(HZIF-1-CoMo)under a hydrothermal reaction with thioacetamide which displays excellent catalytic activity towards evolution reaction(OER)and hydrogen evolution reaction(HER).The overpotentials of OER and HER to reach at the current density of 10mAcm-2 are 281 and 180 mV with the Tafel slopes of 79 and 65 mV dec-1,respectively.In addition,the catalyst is further supported on nickel foam for an overall water splitting catalysis.The low potential of 1.61 V at the current density of 10mAcm-2 are observed.The excellent catalytic performance is attributed to porous structure of CoS/MoS2 exposes more active sites and greatly enhances the mass transfer rate in catalysis process.(2)Transition metal sulfides(TMSs)are excellent electrocatalysts for boosting oxygen evolution reaction(OER)but their poor stability hinders the practical applications.Therefore,through a well-designed two-step synthesis strategy,using bimetallic hybrid zeolite imidazole framework(HZIF-1-CoMo)as the precursor,we design and synthesize a 20wt%CeO2 nanoparticle embedded on the mesoporous CoS/MoS2 polyhedron as the target catalyst(20%CeO2@CoS/MoS2)by sulfurizing first and then doping cerium oxide.Electrochemical experimental results indicate that dispersion of a proper amount of CeO2(20wt%)cocatalyst on the interface of CoS/MoS2 has activated abundant Co/Mo sites and induced oxygen vacancies/defects to boost the OER activity.20%CeO2@CoS/MoS2 displays excellent OER electrocatalytic performance in alkaline with an overpotential of 247 mV to reach the current density of 10mAcm-2 and a Tafel slope of 64 mV dec-1.More importantly,the embedded CeO2 particles have effectively prevented the binary metal sulfide from corrosion through Ce3+/Ce4+switching,thus enhancing its stability and displaying a 12-hours continuous OER electrocatalysis at 10mAcm-2. |
