Nano Conductive Ceramic Wedged Graphene Composites As Highly Efficient Metal Supports For Oxygen Reduction

At present, carbon black (e.g., Vulcan XC-72R) has been the most widely-usedsupport for PEM fuel cell catalysts. Unfortunately, such carbon supports aresensitively oxidized under radically chemical and electrochemical oxidationconditions at cathode for fuel cells. This leads to a migration/aggregation of noblemetal (e.g., Pt) nanoparticles (NPs) and subsequent a serious decay of electrochemicalsurface area (ECSA). The insufficient stability of catalysts remains a major obstacleto the widespread commercialization of PEMFCs.A novel nano conductive ceramic/graphene composite is prepared by wedgingzirconium diboride (ZrB2) nanocrystals into the reduced graphene oxide (RGO) stackusing a simple solvothermal method to mitigate the re-stacking of RGO. TheRGO/ZrB2composite supported Pt nanoparticles (Pt/RGO-ZrB2) with a uniformdistribution shows very excellent electrochemical properties. Significantly, theelectrochemical surface area (ECSA) of the prepared catalyst is up to147.6m2g-1(very approaches the geometry surface area of154.9m2g-1), much greater than boththe Pt/RGO (102.8m2g-1) and Pt/C (91.2m2g-1) catalysts. Moreover, its massactivity is high as16.8mA mg-1, which is almost2times and5times that of thePt/RGO (8.6mA mg-1) and Pt/C (3.5mA mg-1) catalysts, respectively.On the other hand, the new catalyst demonstrates a predominant electrochemicalstability in comparison with the above catalysts as benchmarks. The great improvedperformance of the catalyst can be attributed to the wedge effect of ZrB2nanoparticles and the formed unique3D architecture of the RGO/ZrB2composite thatgreatly decreases the re-stacking of graphene nanosheets.