Confined Sub-nanometer PtCo Cluster as a Highly Efficient and Robust Electrocatalyst for Hydrogen Evolution Reaction

Pt catalysts are the best potential hydrogen evolution reaction (HER) electrocatalysts for industrial applications, but the development of efficient Pt catalysts with low Pt loading and high utilization efficiency remains challenging. Herein, sub-nanometer PtCo clusters confined into the small pores of ZIF-8 derived N-doped nanomaterials are fabricated through the galvanic replacement method. Benefiting from the formation of sub-nanometer PtCo clusters confined in small pores and the synergic effect of bimetallic components, the optimal sub-nanometer PtCo clusters with only 1.2% Pt loading (1.2%PtCo/NPC) achieve an extraordinary HER catalytic activity and durability with a mass activity of 13.83 A mg−1 at an overpotential of 20 mV, which is more than 65 times greater than that of the commercialized Pt/C catalyst. Density functional theory (DFT) calculations reveal that the outstanding HER activity on the 1.2%PtCo/NPC electrocatalyst is attributed to the charge redistribution and the lower d-band center on Pt due to the enhanced coupling of electrons in the d orbitals between Pt and Co, which decreases the Gibbs free energy of H* adsorption and increases the HER kinetics and activity.