Core-Shell Pd₉Ru@Pt on Functionalized Graphene for Methanol Electrooxidation

Abstract

A simple but effective electrochemical route to functionalize graphene is demonstrated. Cyclic voltammetric sweeps (CV) are performed in a 0.5 M H 2 SO 4 aqueous solution on electrodes consisting of carbon cloth, graphene, and Nafion ionomer. Upon exposure to ambient oxygen, the formation of hydroxyl radicals from the oxygen reduction reaction during the CV cycles initiates the decomposition of the Nafion ionomer, which produces oxygenated functional groups on the graphene surface. Using contact angle measurements and X-ray photoelectron spectroscopy, various amounts of Nafion ionomer are explored to determine the optimum conditions for graphene functionalization. Afterwards, Pd 9 Ru nanoparticles with an average size of 3-4 nm are synthesized and impregnated on functionalized graphene (FGN). To prepare core-shell electrocatalysts, Pd 9 Ru/FGN is subjected to Cu underpotential deposition followed by a galvanic displacement reaction to deposit a Pt monolayer on the Pd 9 Ru surface (Pd 9 Ru@Pt). The assynthesized sample (Pd 9 Ru@Pt/FGN) exhibits enhanced performance in methanol electrooxidation, which includes a better activity and lower susceptibility to poisoning by intermediates. The electrochemically active surface area (ECSA) of Pd 9 Ru@Pt/FGN shows a value that is 1.5-fold larger than that of Pd 9 Ru@Pt on untreated graphene (Pd 9 Ru@Pt/GN). In the durability tests, Pd 9 Ru@Pt/FGN and Pd 9 Ru@Pt/GN demonstrate losses in the ECSA of 14.9% and 30.3%, respectively.

Platinum-Cobalt Nanowires for Efficient Alcohol Oxidation Electrocatalysis

“…The Pt 27 Co 73 /C exhibited the highest SA of 3.31 mA/cm 2 , which was 1.655, 2.98, 5.02 and 4.60 times higher than those of Pt 53 Co 47 /C (2.00 mA/cm 2 ), Pt 70 Co 30 /C (1.11 mA/cm 2 ), Pt/C (0.66 mA/cm 2 ), and commercial Pt/C (0.72 mA/cm 2 ), respectively ( Figure 3 b). Pt 27 Co 73 /C and Pt 53 Co 47 /C displayed higher activity for the MOR ( Table 1 ) in comparison to the literature [ 32 , 33 , 34 , 35 ]. The EOR performance of commercial Pt/C and Pt n Co 100−n /C catalysts is evaluated in Figure 3 c,d.…”

Facile Synthesis of Co3O4@CoO@Co Gradient Core@Shell Nanoparticles and Their Applications for Oxygen Evolution and Reduction in Alkaline Electrolytes

“…So far, the preparation of core@Pt nanoparticles is often achieved via a galvanic displacement reaction in which corrosive-prone atoms are pre-coated on selective cores, which was followed by their oxidative dissolution for reducing Pt ions from the electrolyte. For example, in our group, we adopted a Cu under-potential-deposition (UPD) to synthesize Pd 9 Ru@Cu nanoparticles and engaged the displacement reaction to fabricate Pd 9 Ru@Pt nanoparticles for ORR and methanol electro-oxidation activities in acidic electrolytes [33,34]. In the literature, the UPD process is a powerful tool to fabricate a core@shell microstructure by first depositing a Cu monolayer, which is followed by a displacement reaction in which the Cu is corrosively dissolved in conjunction with the reduction of selective ions from the electrolyte [35,36].…”

Conformal Deposition of RuO2 on Cu via a Galvanic Cementation Reaction

“…The galvanic displacement reaction has been employed to enable the formation of core-shell nanoparticles, and thin films with monolayered thickness. [26][27][28][29] In the case of CVD and ALD for RuO 2 thin film, the RuO 4 has been widely used as the precursor because its decomposition products are simpler than alternative metalorganics. 30,31 The RuO 4 is a volatile compound with a strong oxidizing power, and it dissolves easily in an aqueous solution.…”