Synthesis Of MOFs Derived Nanocatalyst As Advanced Electrocatalysts For Over Water Splitting

Environmental pollution and energy crisis have become major problems in today's society.Water electrolysis for hydrogen production is considered an effective way to solve these problem.The key to the large-scale commercial application of hydrogen energy is the development of low cost non-precious metals electrocatalyst with high catalytic activity and stability.Based on MOFs derived nanocatalyst in the application of water electrolysis,this work designed and modified MOFs materials,prepared two highly efficient bifunctional electrocatalysts,and systematically analyses the influence catalyst structure on catalytic activity.The main contents are summarized as follows.1.Hollow bimetallic cobalt-based selenide polyhedrons derived from metal–organic framework as efficient bifunctional electrocatalystsMetal organic frameworks?MOFs?is a new kind of crystalline porous material,which have the advantages of simple synthesis,stable structure,large specific surface area,regular and orderly control of morphology and pore structure.Based on these facts,in this part of work,we mainly used cobalt-based bimetallic MOFs as a template to hollow synthesize cobalt-based bimetallic selenide series catalyst M_xCo_1-xSe₂?M=Zn,Ni,Cu?through a simple one-step hydrothermal selenization method.When they were used in electrolyzed water experiments,the hollow M_xCo_1-xSe₂polyhedrons,particularly Zn_0.1Co_0.9Se₂,exhibit excellent electrocatalytic performances with overpotentials of–140 mV and 340 mV at a current density of 10 mA cm^-2,small Tafel slopes of49.9 mV dec^-1 and 43.2 mV dec^-1 for both HER in acidic and OER in basic solutions,respectively.At the same time it also has a very strong stability,can be stabilized run over 30 h.These excellent electrocatalytic properties could be attributed to the special specific surface area and hollow porosity of Zn_0.1Co_0.9Se₂ and the Jahn–Teller effect resulting from the introduction of the second transition metal ion.2.MOFs derived CoTe₂ encapsulated on nitrogen-doped carbon nanotubes frameworks:a high-efficiency bifunctional electrocatalyst for overall water splittingIn the presence of a small amount of hydrogen,the ZIF-67 will produce high-nitrogen-doped carbon nanostructure framework after inert atmosphere calcination.In this work,we for the first time report a high-efficiency electrocatalysts Cobalt Telluride encapsulated on nitrogen-doped carbon nanotubes frameworks?CoTe₂@NCNTFs?derived metal organic framework ZIF-67,which was synthesized via a straightforward telluride process under hydrogen atmosphere.Notably,benefiting from the hollow carbon nanotubes polyhedral structural framework,the target catalyst CoTe₂@NCNTFs has excellent OER performance with overpotential of 330 mV at 10 mA cm^-2 in1.0 M KOH solution.The Tafel slope is only 82.8 mV dec^-1,and can catalyze stability for more than35 h.At the same time,whether in acidic medium?0.5 M H₂SO₄?or in alkaline conditions?1.0 M KOH?,CoTe₂@NCNTFs have good HER properties.The overpotentials of 10 mA cm^-2 are 240 mV and 208 mV,the Tafel slope are 61.67 mV dec^-1 and 58.04 mV dec^-1,respectively.In addition,when the CoTe₂@NCNTFs was used bifunctional electrocatalysts as anode and cathode materials for electrolysis water reaction,their performance is almost the same as commercial IrO₂-Pt/C combination,and it also has very good stability.