Preparation And Electrocatalytic Performance Of LaMnO₃/Diamond Composites

The production of industrial diamond is huge.At present,diamond is mainly applied in the mechanical and electronic industry.Micro-diamond powers possess resistance to acid and alkali corrosion,ultrahigh hardness,high thermal conductivity etc.Compare to nanodiamond,micro-diamond is higher production capacity,lower cost and more uniform size.Perovskite-type oxides?ABO₃?have many advantages,such as low cost,simple preparation and excellent electrocatalytic performance,and among which lanthanum manganate?LaMnO₃?nanoparticles have high electrocatalytic activity and stability.In this paper,LaMnO₃-diamond composites were prepared by sol-gel method using micro-diamond as carrier.The analysis of XRD and SEM images show that LaMnO₃nanoparticles successfully nucleate and grow on the surface of diamond.The oxygen reduction reaction activities of prepared LaMnO₃-diamond composites were studied by the rotating disk electrode technique.Meanwhile,these sample was applied as a cathode catalyst to zinc-air battery and its electrochemical properties were also studied.The results show that the LMO/2Dia composite has the good catalytic activities and stability,in which the mass percent of lanthanum manganate is 33%.The graphitized diamond was prepared by spark plasma sintering?SPS?at different annealing temperature.Combine with XRD and SEM,it found that the GMD-1400 sample has a core-shell structure,it shows that a gauze-like graphite layer on the surface of diamond.Then a series of LaMnO₃-graphitized diamond composites were prepared by nucleation and growth of LaMnO₃ nanoparticles on the surface of graphitized diamond.The physical characterization and electrochemical experiments show that LMO/GMD-1400 has higher electrocatalytic activity and stability than LaMnO₃ and LaMnO₃/G.The prepared LMO/GMD-1400 composites was applied as a cathode catalyst to zinc-air battery,the results show that LMO/GMD-1400 has higher discharge voltage and lower decay rate.These excellent electrochemical properties are attributed to the core-shell structure of the graphitized diamond and the synergistic effect within the composite.Finally,By comparing the electrocatalytic performance of different sizes of graphitized diamond with LaMnO₃ composites,it confirms that the optimum size of industrial diamond used as carrier is 1-2?m.