Monodispersed PtCo alloy nanoparticles with a modulated d-band center exhibiting highly efficient hydrogen evolution

Abstract

To fully utilize the synergistic effects generated by a bimetal, which accelerates the dissociation of H₂O and the reduction of H⁺ in the electrocatalytic hydrogen evolution reaction (HER). Herein we report the preparation of monodispersed PtCo alloy nanoparticles loaded on nitrogen-doped porous carbon (PtCo-NC), which adopts a well intact dodecahedral structure. By utilizing spontaneous redox reduction and subsequent chemical reduction, the resultant PtCo-NC displays an reduced particle size of 2.03 nm and exhibits minimal overpotentials of 40 and 25 mV in acidic and alkaline solutions, respectively, at a current density of 10 mA cm⁻², which outperforms commercial Pt/C, even at a current density of 100 mA cm⁻². Furthermore, the PtCo alloy nanoparticles demonstrate enhanced electrochemical surface area, which was 4.9 times in acidic solution and 1.6 times in alkaline solution compared to Pt nanoparticles (Pt NPs). Density functional theory (DFT) calculations suggest that the incorporation of Co lowers the d-band center of the PtCo alloy, leading to a nearly zero Gibbs free energy of H* and OH* adsorption, therefore boosting the HER performance.