Lamellar Nanoporous Intermetallic Cobalt-Titanium Multisite Electrocatalyst with Extraordinary Activity and Durability for the Hydrogen Evolution Reaction

Constructing well-defined multisites with high activity and durability is crucial for the development of highly efficient electrocatalysts toward multiple-intermediate reactions. Here we report negative mixing enthalpy caused intermetallic cobalt-titanium (Co₃Ti) nanoprecipitates on a lamellar hierarchical nanoporous cobalt skeleton as a high-performance nonprecious multisite electrocatalyst for an alkaline hydrogen evolution reaction. The intermetallic Co₃Ti as a robust multisite substantially boosts the reaction kinetics of water dissociation and hydrogen adsorption/combination by unisonous adsorptions of hydrogen and hydroxyl intermediates with proper binding energies. By virtue of a bicontinuous and hierarchical nanoporous cobalt skeleton that enables sufficiently accessible Co₃Ti multisites and facilitates electron transfer and ion/molecule transportation, a self-supported nanoporous cobalt-titanium heterogeneous electrode exhibits extraordinary electrocatalytic activity and durability toward the hydrogen evolution reaction in 1 M KOH. It reaches a current density of as high as ∼3.31 A cm^-2 at a low overpotential of 200 mV and maintains exceptional stability at ∼1.33 A cm^-2 for >1000 h.