Electrochemical Dealloying of PdCu₃ Nanoparticles to Achieve Pt-like Activity for the Hydrogen Evolution Reaction

Manipulating the d-band center of the metal surface and hence optimizing the free energy of hydrogen adsorption (ΔG_H ) close to the optimal adsorption energy (ΔG_H =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 (ΔG_H =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.