Boosted electrocatalytic oxidation of formic acid at CoOx/Pd/Au nanoparticle-based ternary catalyst

Tailoring and designing of an efficient catalyst for the direct formic acid fuel cell industry is very imperative. Herein, various Pd-based electrocatalysts for formic acid electro-oxidation (FAO) are introduced. The ternary CoOx/Pd/Au catalyst, in which Au nanoparticles (nano-Au), Pd nanoparticles (nano-Pd) and cobalt oxide nanoparticles (nano-CoOx) are, sequentially, electrodeposited onto a glassy carbon (GC) substrate offering a boosted catalysis towards formic acid electro-oxidation (FAO). This study reveals that the electrocatalytic activity of the catalyst toward FAO depends on the catalyst's composition, loading level, and sequence of deposition. FE-SEM, EDS, and XRD are used to determine the surface morphology, composition, and crystallographic orientation, respectively. Cyclic voltammetry is employed to probe the electrochemical surface area (ECSA) of the various electrodes and to probe their activity. Compared to Pd/GC, Au/Pd/GC and Pd/Au/GC catalysts, the ternary CoOx/Pd/Au/GC catalyst features a higher oxidation peak current for FAO, I-p (ca. Eightfold), a better reversibility ratio, I-p(f)/I-P(B) (congruent to 1), and a significant negative shift in the onset potential, E-onset (ca. 70 mV) of FAO together with a higher stability of FAO current. Capacitance (C-re-G(im)) measurements reveal the superiority of the ternary catalyst over the other catalysts in terms of higher capacitance which is in line with the order of the observed catalytic activity. That is the capacitance of CoOx/Pd/Au/GC electrode/electrolyte interface is ten times higher than that of Pd/GC electrode. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.