HIGHLY EFFICIENT GRAPHENE BASED CATALYST FOR OXYGEN REDUCTION REACTION

摘要

Hitherto, the low electrochemical stability of the catalyst is one of the big issues hindering the commercial application of proton exchange membrane fuel cells (PEMFCs) . In this work, more stable support materials based on functionalized graphene nanosheets (GNS), porous GNS, heteroatom doped GNS, and alternative GNS composites including GNSano-carbon (or nano-ceramics) sandwiches, nanoceramic wedged GNS, and core-shell graphene and amorphous carbon composites are prepared and applied in catalysts towards oxygen reduction reaction (ORR). based on the idea of bifunction of GNS to Pt catalysts, highly active and stable Pt/reduced graphene oxide (RGO) catalysts are developed by tuning the O/C atom ratio of RGO supports where the optimized O/C atom ratio of 0.14 is determined. Meantime, both perfluorosulfonic acid (PFSA) functionalized GNS and sulfonic acid group-grafted RGO supported Pt catalysts show a higher catalytic activity and a lower loss rate of electrochemical active area (ECA) in comparison with that of the plain Pt/GNS and conventional Pt/C catalysts. In addition, the N-doped RGO supported Pt catalyst (Pt/NRGO) is synthesized using a lyophilisation-assisted N-doping method, revealing a higher catalytic activity and a lower ECA loss of the Pt/NRGO catalyst to compare with that of the Pt/GO and Pt/C catalysts. In addition, to tackle the stacking issues of GNS which leads to the low mass transport property, the porous GNS are synthesized. Besides, we also describe a new strategy to synthesize GNS hybrids including GNSano-carbon (nano-creamics) sandwiches and nano-ceramic wedged GNS architectures. These unique architectures with highly dispersed Pt NPs exhibit much high catalytic activities towards ORR and an excellent electrochemical stability. At last, a new graphene @ amorphous carbon core-shell material also shows an excellent electrochemical property. This work was supported financially by the National Natural Science Foundation of China (NSFC) (No. 51372186), and the National Basic Research Development Program of China (973 Program) (No. 2012CB215504).