Acetic acid‐assisted mild dealloying of fine CuPd nanoalloys achieving compressive strain toward high‐efficiency oxygen reduction and ethanol oxidation electrocatalysis

Abstract

Dealloying by which the transition metal is partially or completely leached from an alloy precursor is an effective way to optimize the fundamental effects for further enhancing the electrocatalysis of a catalyst. Herein, to address the deficiencies associated with the commonly used dealloying methods, for example, electrochemical and sulfuric acid/nitric acid treatment, we report an acetic acid-assisted mild strategy to dealloy Cu atoms from the outer surface layers of CuPd alloy nanoparticles to achieve high-efficiency electrocatalysis for oxygen reduction and ethanol oxidation in an alkaline electrolyte. The leaching of Cu atoms by acetic acid exerts an additional compressive strain effect on the surface layers and exposes more active Pd atoms, which is beneficial for boosting the catalytic performance of a dealloyed catalyst for the oxygen reduction reaction (ORR) and the ethanol oxidation reaction (EOR). In particular, for ORR, the CuPd nanoparticles with a Pd/Cu molar ratio of 2:1 after acetic dealloying show a half-wave potential of 0.912 V (vs. RHE) and a mass activity of 0.213 A mg Pd −1 at 0.9 V, respectively, while for EOR, the same dealloyed sample has a mass activity and a specific activity of 8.4 A mg −1 and 8.23 mA cm −2 , respectively, much better than their dealloyed counterparts at other temperatures and commercial Pd/C as well as a Pt/C catalyst.

Slowly Removing Surface Ligand by Aging Enhances the Stability of Pd Nanosheets toward Electron Beam Irradiation and Electrocatalysis

“…The cyclic voltammetry (CV) curves of the fresh, aged Pd NSs, and commercial Pd/C (Figure 4a) were measured in Ar‐saturated 0.1 M KOH. The integrated charge of the cathodic peak (0.45–1.0 V RHE ) represents the electroreduction of one monolayer of PdO to Pd [21] . From the CV curves, the ECSA of the aged NSs (91.2 m 2 g −1 ) is found to be higher than that of the fresh NSs (52.8 m 2 g −1 ), in agreement with the data obtained using the Cu UPD method (Table S1).…”

“…Chemie Forschungsartikel peak (0.45-1.0 V RHE ) represents the electroreduction of one monolayer of PdO to Pd. [21] From the CV curves, the ECSA of the aged NSs (91.2 m 2 g À 1 ) is found to be higher than that of the fresh NSs (52.8 m 2 g À 1 ), in agreement with the data obtained using the Cu UPD method (Table S1). We also derived their electrocatalytic activities toward EOR using CV measurements in Ar-saturated aqueous solution containing 0.1 M KOH and 0.1 M ethanol (Figure 4b).…”

Slowly Removing Surface Ligand by Aging Enhances the Stability of Pd Nanosheets toward Electron Beam Irradiation and Electrocatalysis

“…Chemie peak (0.45-1.0 V RHE ) represents the electroreduction of one monolayer of PdO to Pd. [21] From the CV curves, the ECSA of the aged NSs (91.2 m 2 g À 1 ) is found to be higher than that of the fresh NSs (52.8 m 2 g À 1 ), in agreement with the data obtained using the Cu UPD method (Table S1). We also derived their electrocatalytic activities toward EOR using CV measurements in Ar-saturated aqueous solution containing 0.1 M KOH and 0.1 M ethanol (Figure 4b).…”

Urchin-like Au/Pd Nanobranches for the Oxygen Reduction Electrocatalysis

“…Upon comparison, the Au/Pd-2 NBs/C catalyst shows the highest j m and j s , which are 8.8 and 8.9 times higher than those of Pt/C and 5.6 and 3.2 times higher than those of Pd/C, respectively. The activities of Au/Pd-2 NBs/C are also among the top of many other recently reported Pd-based nanocatalysts, − further demonstrating the excellent electrocatalytic performance (Table S3). Compared to the Pd NBs/C catalyst, the Au/Pd-1 NBs/C, Au/Pd-2 NBs/C, and Au/Pd-3 NBs/C catalysts all display much better electrocatalytic activities, which should be attributed to the appropriate introduction of the Au element and the successful constitution of the core–branch nanostructure.…”