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

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.