Reduced graphene oxide supported PdNi alloy nanocrystals for the oxygen reduction and methanol oxidation reactions

Abstract

The research on electrocatalysts with relatively lower price than Pt and excellent electrocatalytic performance for the cathode oxygen reduction reaction (ORR) and anode methanol oxidation reaction (MOR) is vital for the development of direct methanol fuel cells (DMFCs). In this work, we develop a cyanogel-reduction method to synthesize reduced graphene oxide (rGO) supported highly dispersed PdNi alloy nanocrystals (PdNi/rGO) with high alloying degree and tunable Pd/Ni ratio. The large specific surface area and the d-band center downshift of Pd result in excellent activity of Pd4Ni1/rGO nanohybrids for the ORR. The modification of Pd electronic structure can facilitate the adsorption of CH3OH on Pd surface and the highly oxophilic property of Ni can eliminate/mitigate the COads intermediates poisoning, which make PdNi/rGO nanohybrids possess superior MOR activity. In addition, rGO improve the stability of PdNi alloy nanocrystals for the ORR and MOR. Due to high activity and stability for the ORR and MOR, PdNi/rGO nanohybrids are promising to be an available bifunctional electrocatalyst in DMFCs. Keywords: Cyanogel reduction, Reduced graphene oxide, PdNi alloy nanocrystals, Oxygen reduction reaction, Methanol oxidation reaction