Abstract:
Manipulating the d-band center of the metal surface and hence optimizing the free energy of hydrogen adsorption (G(H)) close to the optimal adsorption energy (G(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 (G(H)=0.05eV), exhibiting remarkably enhanced activity (with a current density of 25mAcm(-2) at approximate to 69mV 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.
