Reduced graphene oxide-supported Pd@Au bimetallic nano electrocatalyst for enhanced oxygen reduction reaction in alkaline media

• Published in: International journal of hydrogen energy Vol. 43; no. 8; pp. 4125 - 4135
• Main Authors: Raghavendra, P., Vishwakshan Reddy, G., Sivasubramanian, R., Sri Chandana, P., Subramanyam Sarma, L.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 22-02-2018
• Subjects: Core-shell nanoparticles; Electrocatalysis; Graphene oxide support; Oxygen reduction reaction; Core-shell nanoparticles; Electrocatalysis; Graphene oxide support; Oxygen reduction reaction
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2017.07.199

Rational design and synthesis of core-shell bimetallic nanoparticles with tailored structural and functional properties is highly sought to realize clean and energy-efficient fuel cell systems. Herein, PdAu bimetallic nanoparticles (NPs) with core-shell morphology (PdCore–AuShell) were fabricated on the surface of reduced graphene oxide (RGO) support by a facile two-step protocol. In the first step, PdCore–AgShell bimetallic NPs were synthesized on RGO support by reducing Pd2+and Ag+ ions with methyl ammonia borane (MeAB). Later, PdCore–AuShell bimetallic NPs were conveniently fabricated on RGO support via a galvanic replacement strategy involving sacrificial oxidation of metallic silver and reduction of gold ions. The resulting core/shell bimetallic NPs were characterized by X-ray diffraction (XRD), High-resolution transmission electron microscopy (HR-TEM), Energy dispersive X-ray spectroscopy (EDS), Fourier-Transform Infrared Spectroscopy (FT-IR) and cyclic voltrammetry (CV). The electrocatalytic performance of core/shell nanostructures for the room temperature oxygen reduction reaction (ORR) in alkaline media were systematically performed by CV. The electrode-area-normalized ORR activity of RGO-supported PdCore–AuShell NPs was higher than the corresponding commercially available carbon-supported Pt nanoparticles (Pt/C) at −0.8 V vs Ag/AgCl (satd. KCl) (6.24 vs 5.34 mA cm−2, respectively). Further, methanol-tolerant ORR activities of as-synthesized catalysts were also studied. The Au-on-Pd/RGO bimetallic NPs presented enhanced ORR activity both in presence and in the absence of methanol in comparison with a commercial Pt/C catalyst and as-synthesized Pd/RGO and Au/RGO catalysts. The enhanced catalytic activities of core/shell structures might be resulted owing to the optimized core/shell structure comprising of a small Pd core and a thin Au shell and synergistic effects offered by Pd and Au. The present synthesis protocol demonstrated for two-layer structure can be extended to multi-layered structures with desired functions and activities.
•Facile synthesis strategy for supported bimetallic nanoparticles.•Highly active electrocatalysts for oxygen reduction reaction in alkaline media.•Electrocatalysts for methanol-tolerant oxygen reduction reaction.