Study On Preparation And Its Water Decomposition Performance Of RuO₂/Co?OH?₂ Bifunctional Electrocatalyst

Clean renewable energy has attracted widespread attention due to the intensification of the energy crisis.Hydrogen energy which is considered as the most potential energy carrier with its high energy density,clean and pollution-free characteristics,especially electrolytic water technology becomes the most eye-catching among many of the hydrogen production technologies.However,nowadays the commercial high-efficiency catalysts are still precious metals and related oxides.But the corresponding industrial development of electrolyzed hydrogen evolution is unsustainable when solely based on precious metals owing to the presence of less-storage and high-price.On the other hand,transition metals and their compounds possess controllable morphology and easily adjustable electronic structure,showing great potential in electrocatalysis.As we know,the metal cobalt has tremendous advantages in abundant reserves,high designability as well as,more active sites exposed because of the layered structure of Co(OH)2.Co(OH)2 becomes one of the most promising catalysts to replace the precious metals for full hydrolysis hydrogen production.As reported that the preparation of synthetic Co(OH)2 with high catalytic performance usually relies on high temperature or the complicated preparation process.Therefore,it is necessary to design and synthesize high-efficiency Co(OH)2 materials by a simple preparation method at room temperature.In addition,since acidic electrolytes can corrode electrolytic cell equipment,it is necessary to develop low-cost,renewable,and high-efficiency catalysts suitable for alkaline electrolytes.Co(OH)2 materials usually show poor hydrogen evolution performance in alkaline electrolytes,while precious metals still have high catalytic activity in alkaline electrolytes.At present,although some positive experimental results were obtained through the strategies of improving the catalytic performance by noble metal compounding,there are few studies more extensively.Using a simple method to prepare Co(OH)2 material with efficient OER performance and compound with noble metal composite to overcome the poor HER performance,is a theoretically feasible strategy to achieve efficient overall electrolysis of water under alkaline electrolyte.Therefore,this dissertation focuses on the synthesis of Co(OH)2 electrode materials at room temperature.The synthesis conditions are explored to control its morphology and composition and obtain Co(OH)2 nanomaterials with the best OER performance.In addition,RuO2 nanoparticles are incorporated in Co(OH)2 to further optimize the materials.The specific research work is as follows:(1)Preparation of self-assembled clusters of hierarchical Co(OH)2 ultrathin nanosheets and study on electrolyzed water performance:Co(OH)2 electrolytic water catalyzed nanomaterials with excellent OER performance was synthesized by a simple liquid phase method at room temperature.The prepared sample is a porous,cross-linked nano-clusters with honeycomb structure.The material has good dispersibility and the presence of metal cobalt.The effects of reaction solvent,reaction time,and NaBH4 concentration on morphology and electrocatalytic performance of Co(OH)2 materials were investigated respectively.The results indicated that the best OER performance of Co(OH)2 material was obtained in the case of reaction with 50 ml C2H6O and 0.05 M NaBH4 lasted for 3 hours.When the current density of the sample reaches to 10 mA/cm2 in 1 M KOH solution,the OER overpotential is merely 355 mV.(2)Preparation of RuO2/Co(OH)2 composite nanomaterials and research on electrolyzed water properties:Using liquid phase method to compound RuO2 on the surface of Co(OH)2 ultra-thin nanosheet clusters obtained in work(1)and obtaind RuO2/Co(OH)2 nanomaterials.The effect of the amounts of RuCl3·xH2O on the morphology and microstructure of materials were explored.The results showed that the sample which is prepared by adding 0.25 mmol RuCl3·xH2O,achieved both optimal OER and HER performance.It was found that the sample still maintained the morphology of the Co(OH)2 sample,and the sample was a kind of heterogeneous catalyst with a combination of three components:RuO2,Co(OH)2,and Co.When the composite electrode material reaches a current density of 10 mA/cm2 in 1 M KOH solution,the oxygen evolution overpotential is only 192 mV(vs.RHE),and the hydrogen evolution overpotential is 197 mV(vs.RHE)with superb stability of electrode material.When it was assembled into a fully hydrolytic cell,the current density of 10 mA/cm2 could be obtained in 1 M KOH solution under the condition of only 1.58 V(vs.RHE)operating voltage.