Preparing LaMnO3 nanocrystals on surface graphitized micro-diamond for efficient oxygen reduction

Abstract Electrocatalysts for oxygen reduction reactions are the key to metal–air batteries. In this work, surface graphitized microdiamond (GMD) with a diamond core and graphitic carbon shell are prepared by spark plasma sintering technique. Perovskite-type LaMnO3 (LMO) nanoparticle/surface GMD samples are prepared by a sol–gel method using GMD as support. The LMO/GMD hybrid catalyst exhibits higher electrocatalytic activity than pure LMO and LMO/graphene. The suitability of the hybrid catalyst is tested for primary zinc–air batteries. Results demonstrate that the hybrid catalyst shows a high voltage plateau and slow decay rate. The excellent electrochemical performance is ascribed to the corrosion resistance of diamond, the coral-like structure of composite, the formation of electron transfer connector, and the spill effect of oxygen-containing species. Comparing the performance of differently sized graphitized diamond components in the catalysts proves that approximately 1 μm diamonds are extremely important for improving electrocatalytic activity.