Coupled Co and Ir nanocrystals on graphite as pH-wide and efficient electrocatalyst for hydrogen evolution

Abstract

Lacking pH-wide and efficient electrocatalysts restricts the practical application of hydrogen generation with water splitting technique. Here hetero-structure of coupled Ir with Co nanocrystals on graphite is designed as pH-universal catalyst for efficient hydrogen evolution reaction (HER). Graphite acts as effective matrix for the well dispersion of Ir and Co nanocrystals, benefiting the high exposure of active sites. Coupling Ir with Co generates large amounts of lattice distortion among the hetero-interface as active sites for improved catalysis. Importantly, the synergistic effect between hetero nanocrystals can greatly optimize the HER mechanism by accelerating the water dissociation and hydrogen desorption steps. The developed catalyst exhibits remarkably efficient and pH-universal catalysis activity toward HER, which generates a current density of 10 mA cm−2 with low overpotentials of 44 mV in acidic media, 49 mV in alkaline media, and 64 mV in neutral media. In addition, the developed dinuclear catalyst shows remarkably higher mass activities than Ir/C and even Pt/C in all pH conditions, indicating great potential for practical water splitting application.