Graphene quantum dots-anchored Au-Pt bimetallic nanoparticles: A benign electrocatalyst for sustainable fuel cell applications

In the present study, a graphene quantum dots (GQDs) supported Au-Pt bimetallic nanocatalyst is directly fabricated on a glassy carbon electrode via electroless deposition and their electrocatalytic efficiency towards oxygen reduction reaction (ORR) and methanol oxidation is studied. The presence of hydroxyl functionalities of GQDs triggered the polyol reduction of Au(III) and the carboxylic acid groups supported the stabilization of Au nanoparticles (AuNPs). The resultant GQDs capped AuNPs (30 nm) were self-assembled on a GC electrode and immersed in Pt(IV) for various time intervals to tune the Au-Pt composition. The fabrication of Pt on GC/Au-GQDs followed an electroless deposition of Pt(IV) to Pt(0) via Pt(II) by the reducing ability of GQDs. The formation of Au-Pt bimetallic assembly over the GQDs surface was confirmed from cyclic voltammetry, SEM, TEM, and XPS analysis. The kinetics of the oxygen reduction on Au-Pt/GQDs follow a four-electron pathway and catalyzed the methanol oxidation with good efficiency and stability. The structural stability and charge transfer analysis via computational studies are executed, which supports the anchoring of the Au-Pt bimetallic system on GQDs. The theoretical Bader charge analysis explains the redistribution of charge between GQDs and the Au-Pt system. Finally, the adsorption energies of reaction intermediates like O 2 , OH, OOH and CO are calculated.