Modulating Electronic Environment of Ru Nanoclusters via Local Charge Transfer for Accelerating Alkaline Water Electrolysis.

Abstract

Compared to platinum catalysts, ruthenium (Ru) is disclosed as a promising alternative for alkaline water electrolysis due to its similar hydrogen adsorption energy and relatively lower water dissociation barrier. However, in the challenging alkaline media, the dissatisfied Volmer step during water dissociation of Ru metal prohibits its practical applications. Here, a new pathway to modulate the electronic environment of Ru catalysts via a local charge transfer strategy for tuning the water dissociation kinetics and accelerating the alkaline water electrolysis is proposed. The obtained catalysts are engineered by assembling and subsequently pyrolyzing the layer-stacked and 2D porphyrin-based Ru-N coordination polymers on nanocarbon supports. Benefiting from the well-defined Ru nanocluster-Nx -coordination bonds (Runc -Nx ), unique electronic environments, and local charge transfer properties, the catalysts exhibit the exceptional activity of 17mV overpotential at 10mAcm-2 and robust stability in water, which is more efficient than state-of-the-art Ru catalysts. The theoretical calculation suggests that the Runc -Nx sites enhance the nucleophilic attack of water and weaken the HOH bond. This study manifests that tailoring the bond environments of Ru clusters can significantly modulate their intrinsic catalytic activities and stabilities, which may open new avenues for developing high-active and durable catalysts for water electrolysis.