Preparation And Performance For Water Splitting Of Co-MOF Compounds As Electrocatalysts

Developing pollution-free energy and high energy density energy is an important direction of China’s new energy materials.Hydrogen production by Water splitting technology is an efficient,clean and safe way,however,its practical application is mainly limited by the excessive potential of oxygen evolution reaction（OER）and hydrogen evolution reaction（HER）.The catalyst can accelerate the reaction rate.Existion high-efficiency precious metal catalysts hinder their large-scale application due to their high price and low earth content.Therefore,the development of high-quality,inexpensive and efficient OER and HER catalysts that can replace precious metals is necessary for the industrial application of hydrogen energy.Metal-organic frameworks,also as are porous coordination polymers,with a high specific surface area,large pore volume,tunable porous structure and controllable size and shape.They providing hopeful applications in the areas of batteries,gas storage and sepatation,heterogeneous catalysis and drug delivery.They provide chemists with creative opportunities.Also emerging MOF composites,with their excellent new properties and multifunctional capabilities with motivate neoteric applications in industry in important areas of technology.Based on appeal analysis,we have launched research based on the Co-MOF materials as OER and bifunctional electrocatalyst.This works is composed of the following content:（1）A Co-MOF was synthesized under room temperature conditions using Co²⁺and 2-methylimidazole.It as the precursor was coated with a layer of polyaminothiazole,which was then combined with graphene oxide and prepared by simple calcination under nitrogen.We prepared advanced and highly efficient electrocatalysis of oxygen evolution reaction using the cobalt sulfide（Co₉S₈）nanoparticles embedded in nitrogen,sulfur co-doped graphene（Co₉S₈/NSG）hybrid materials,which are obtained by coating Co-based metal-organic frameworks.The frameworks are grown in situ on graphene oxide using a facile pyro lysis method,with polydiaminothiazole,which server as both a nitrogen and a sulfur source in the system.The Co₉S₈/NSG hybrid materials exhibit outstanding OER performance in alkaline electrolytes.Its hace a small overpotential of 260 mV with a Tafer sl ope of 55 mV dec^-1 at a current density of 10 mA cm^-2 and they show long-term stability.The mechanism of the catalyst was analyzed,which may be due to the synergistic effect of the N-.S-co-doped graphene helps to enhance the conductivity of the hybrid,a nd the Co₉S₈ provides abundant catalytic active sites as well as mesoporous structure.This work provided a general and promising method for the design and synthesis of inexpensive and efficient OER electrocatalysts.（2）Co₉S₈-NSC,which was calcined by Co-MOF containing poly-2aminothiazole,was used as precursor,and then combined with molybdate to prepare a kind of high activity and stable bifunctional electrocatalyst under nitrogen pyrolysis.Co₉S₈ and Mo₂C were anchored in N,S co-doped in graphitized carbon to form Co₉S₈-NSC@Mo₂C hybrid material.The results show that the material exhibits excellent HER catalytic performance and excellent stability under acidic conditions,achieving a current density of 10 mA cm^-2 at an overpotential of 74 mV and maintaining long-term stability of 20 h.At the same time,it exhibited excellent OER activity in an alkaline solution,and has an overpotential of 293 mV at a current density of 10 mA cm^-2 and maintained a long-term stability of 20 h.In addition,our self-made alkaline cell with Co₉S₈-NSC@Mo₂C material assembled as the cathode and anode electrolyzed water,the device has a current density of only 1.61 V at 10mA cm^-2.This work provides a versatile method for designing and developing highly efficient and stable non-precious metal catalysts.