Methanol Tolerant Oxygen Reduction Reaction Electrocatalysis using Size-Specific Triphenylphosphine-Ligated Gold Nanoclusters

Abstract

The development of a stable and efficient Oxygen Reduction Reaction (ORR) electrocatalysts with high methanol tolerance is crucial for Direct Methanol Fuel Cells (DMFCs). Herein, triphenylphosphine (PPh3)-ligated gold nanoclusters and complexes (AuNCs), Au101(PPh3)21Cl5, Au9(PPh3)8(NO3)3, and Au1(PPh3)Cl supported on reduced graphene oxide (rGO) have been explored as methanol tolerant ORR electrocatalysts. Electrocatalytic performance of each AuNCs-rGO was determined through linear sweep voltammograms (LSV) and cyclic voltammetry (CV) and compared with Pt/C. Size-dependent ORR activity was observed which followed the size trend of Au101NC-rGO>Au9NC-rGO>Au1NC-rGO. Repeated LSV and chronoamperometry measurements revealed that the long-term stability over 24 hours followed the trend Au101NC-rGO>Au9NC-rGO∼Au1NC-rGO and all were more stable than Pt/C. The methanol tolerance of each AuNCs-rGO was also evaluated via LSV and CV. Size-independent methanol tolerance with no noticeable change in ORR performance of AuNCs-rGO was observed in the presence of methanol. AuNCs-rGO nanocomposites are promising cathode electrocatalysts for DMFCs.