Interfacial Water Activation by Single-Atom Co-N3 Sites Coupled with Encapsulated Co Nanocrystals for Accelerating Electrocatalytic Hydrogen Evolution

Using high-efficiency and low-cost catalyst to replace noble metal platinum for electrocatalytic hydrogen evolution reaction (HER) provides a broad prospect for the development of renewable energy technology, which is an important task yet to be solved. Herein, we proposed an efficient doping-adsorption-pyrolysis strategy for constructing a robust coupling catalyst composed of single-atom Co-N-3 sites anchored on an N-doped carbon (N-C) layer and encapsulated Co nanocrystals (NCs) to activate the interfacial water for accelerating HER Beneficial to the strong synergistic effect of Co-N-3 sites and Co NCs, the optimized CoNC-SA/N*-C catalyst showed excellent HER activity and stability in both acidic and alkaline electrolytes. In situ attenuated total reflectance-surface-enhanced infrared absorption spectroscopy revealed that the rigid interfacial water layer of Co-N-3 sites inhibited the transport of H2O*/OH*, while Co NCs promoted the transport of H2O*/OH* and increased the amount of available H2O* on Co-N-3 sites by disordering the rigid interfacial water network. Theoretical calculation showed that the coupling interface structure destroyed the rigid interfacial network, and Co NCs modified the electronic structure of Co-N-3 sites, which is beneficial to H2O dissociation and H adsorption, thus accelerating the HER process. This work opens up new avenues for the construction of coupling catalysts from the atomic scale to activate the interfacial water for boosting HER electrocatalysis.