Silver nanoparticles supported on graphitization micro-diamond as an electrocatalyst in alkaline medium

Graphitization micro-diamond composites are prepared by spark plasma sintering and which was modified by Ag nanoparticles subsequently. The samples are characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller analysis and Raman spectroscopy. Results show that the 1400-15 min diamond/graphite composite with core/shell structure has a more suitable thickness of graphite layer than other sintered samples. The silver nanoparticles are dispersed on the surface of graphitization micro-diamond in the form of elemental silver, with a size of approximately 15 nm. Electrocatalyst activities are investigated by cyclic voltammetry, linear sweep voltammetry, chronoamperometry and electrochemical impedance spectroscopy techniques. The test of the rotating disk electrode reveals the electrons transfer number of Ag/1400-15 min is about 3.90. Compared with pure micro diamond and 1400-15 min diamond/graphite composite, Ag/1400-15 min composites shows superior electrocatalytic activity and durability because of Ag particles facilitating charge transfer, and the core/shell structure of diamond/graphite can provide more active sites during the electrochemical reaction. The present results highly promise the silver-modified graphitization micro-diamond composite as a potential electrocatalyst.