Electrochemical dealloying of PdCu₃ nanoparticles to achieve Pt‐like activity for the hydrogen evolution reaction

Abstract

Manipulating the d-band center of the metal surface and hence optimizing the free energy of hydrogen adsorption ((ΔGH) close to the optimal adsorption energy ((ΔGH=0) for hydrogen evolution reaction (HER), is an efficient strategy to enhance the activity for HER. Herein, we report a oleylamine-mediated (acting as the solvent, stabilizer, and reducing agent) strategy to synthesize intermetallic PdCu₃ nanoparticles (NPs) without using any external reducing agent. Upon electrochemical cycling, PdCu₃ transforms into Pd-rich PdCu (ΔGH=0.05 eV), exhibiting remarkably enhanced activity (with a current density of 25 mA cm⁻² at ∼69 mV overpotential) as an alternative to Pt for HER. The first-principle calculation suggests that formation of low coordination number Pd active sites alters the d-band center and hence optimal adsorption of hydrogen, leading to enhanced activity. This finding may provide guidelines towards the design and development of Pt-free highly active and robust electrocatalysts.