Preparation Of Ag-based Catalyst And Its Oxygen-evolving Catalytic Performance

Our world are threatened by increasingly energy crisis and environmental pollution,which makes hydrogen gradually becoming one of the most promising energy due to its plenty,cleaning and renewability.Water electrolysis with the advantage of simple process,easy operation and clean products has drawn extensive attention in the field of hydrogen production.However,there are still a lot of things in this area need to be improved,especially in high cost,high energy-consuming and low transformation efficiency.Safe and efficient water oxidation catalyst is the key to realize the water splitting technology.Our research group has studied novel silver oxygen-evolution catalysts,which have been investigated to further enhance its electrochemical reactivity.Ag based oxygen evolving catalysts operated under mild conditions have lower oxygen evolution overpotential and modulated structures,which are novel attracting oxygen evolving catalyst.However,it should be noted that the reported Ag-based oxygen evolution catalyst（OER）possess Low current density.As is known,low potential and high current density both are the important parameters of electrocatalysis.Thereby,we devoted great attention to further enhance its electrochemical reactivityHerein,we demonstrate a facile and efficient process to modify the Agbased catalyst from morphology,crystal plane and metal composite.Then analyze its structure and morphology by XRD and SEM,and the component and valence state of the catalyst by EDS and XPS.Finally,the oxygen evolution activity of five Ag-based catalysts was measured by a cyclic voltammetry method,a linear scanning voltamametric method and a potentiostatic method.The main research items in this dissertation are as follows:1.Under the system of organic carboxylic acid salt with NH₃H₂O,taking silver nitrate as a precursor,an Ag-based oxygen-evolving catalyst film for catalyzing water oxidation is prepared by potentiostatic electrodeposition.we select organic carboxylic acid salt with NH₃H₂O as buffer electrolytes not only the weak force of Ag+ and anion but also the formation of [Ag（NH₃）₂]⁺ complex,which plays a crucial role in successfully fabricating the Ag-based serving as intermediate medium.By a series of characterization,its active component is determined to AgO.Experiments indicated that Ag-based oxygen-evolving catalysts were formed in 0.1M potassium acetate with the different volume of ammonia and each one had a different face.The result show that when Ag⁺ has fully translated into [Ag（NH₃）₂]⁺and NH₃ did not exist in the solution,electrodeposited AgO exhibited the higher oxygen evolution performance.2.Under the system of potassium nitrate with NH₃H₂O,taking silver nitrate as a precursor,an Ag-based oxygen-evolving catalyst film exposed different planes for catalyzing water oxidation is prepared by potentiostatic electrodeposition.To decrease the bonding interaction between Ag+ and anion,we select potassium nitrate as electrolyte.On the other hand,NH₃ may serve as proton carrier in the electrolysis.By a series of characterization,its active omponent is determined to AgO.With the addition of ammonia quantity,the intensity of the（Ⅲ）peak increases relative to that of the（02）peak.Besides,Superior performance of AgO crystals with mainly（Ⅲ）exposed faces was observed in electrochemical water oxidation in comparison with AgO crystals with mainly（202）.3.Under the system of cobalt nitrate with NH₃H₂O,taking silver nitrate as a precursor,a Co-Ag bimetallic catalyst film for catalyzing water oxidation is prepared by potentiostatic electrodeposition.Therefore we added ammonia to cobalt nitrate,not only decreased the bonding interaction between Ag+ and anion,but also Co complexes could also been produced.The result showed that the electrodeposited CoAgOx exhibited the higher oxygen evolution performance when the added ammonia was 70μL.And they exhibited Co-Ag co-catalysis.