Preparation And Electrochemical Performance Of Ag-loading Micron Diamond

Micron diamond powders possess excellent chemical and physical properties,including ultrahigh hardness,chemical and electrochemistry stability,resistance to acid and alkali corrosion etc.Micron diamond can be prepared with a great yield by airflow crushing method.Currently,the micron diamond powders are mainly applied in the grinding and polishing fields.To extend the application range,the micron diamond powders were used as substrate materials and the silver nanoparticles were loaded by the reduction of Ag+ with the reaction of glucose and silver ammonia,and the electrocatalytic activities of AgNPS loading diamond samples were also investigated.The silver nanoparticles were loaded on several different sizes diamond surface.Surface morphology,composition and structure of the electrocatalysts were characterized by several experimental apparatus,such as XRD,SEM and TEM et al.The electrocatalytic activities of diamond with different content of silver electrocatalysts were studied by the rotating disk electrode technique.The results showed that the silver nanoparticles were uniformly loaded on the surface of diamond and a good performance of electrochemical properties.While the silver content is 10 wt.%,compared with the pristine diamond,the disk current density value of the oxygen reduction reaction(ORR)increased from 2.81 mA/cm2 to 4.10 mA/cm2;the disk current density value of the oxygen evolution reaction(OER)increased from 14.25 mA/cm2 to 27.49 mA/cm2.In order to further improve the conductive ability of diamond powders,the Spark plasma sintering(SPS)was applied.Combine with XRD and SEM,it found that the anealing time,anealing temperature,and the size of diamond powder factors have influence to the graphitization degree of diamond powders.When the sintering condition is definited,the bigger size the diamond particles is the lighter graphitization degree the samples are.When the sintering temperature is 1400? and the sintering time is 15 min,the sample 1400-15 min has the appropriate degree of graphitization with a core-shell structure,the performance is that the core of sample particle is still the diamond and the outer layer is graphite.The BET result showed that the specific surface area increased from pristine diamond 3.39 to 1400-15 min sample 25.98 m2/g.The electrochemical performances of silver modified 1400-15 min sample were studied,the results showed that the ORR,AC impedence et al performances improved obviously.The disk current density value of ORR up to 3.53 mA/cm2.In summary,10 wt.% Ag/Dia sample can be used as an excellent non platinum bifunctional catalyst material,and Ag/1400-15 min sample is a promising material for the ORR electrocatalysts.