Heterogeneous core-shell Co(PS)@CoP nanowires with accelerated surface reconstruction for efficient electrocatalytic seawater oxidation.

The design of pre-catalysts and the rational manipulation of corresponding electrochemical reconstruction are vitally important to construct the highly durable and active catalysts for seawater oxidation, but rather challenging. Herein, a novel core-shell catalyst of Co(PS)@CoP (labeled as CoPS) by epitaxial growth of amorphous cobalt phosphide (CoP) on crystalline cobalt phosphorous trichalcogenide (Co(PS)) is firstly designed as a pre-catalyst for alkaline seawater oxidation. Various characterization techniques are employed to demonstrate that the unique amorphous-crystalline nanowire structure (CoPS) achieves the rapid surface reconstruction into active CoOOH and diversiform oxyanions species (labeled as CoPS-R). Theoretical simulations uncover that the in situ derived oxyanions (PO, SO and SO) on the surface of CoOOH can tune the electron distribution of Co site, thereby optimizing the chemisorption of oxygen evolution reaction (OER) intermediates on CoOOH and reducing the energy barrier of determining step. Consequently, in an alkaline natural seawater solution, the reconstructed CoPS-R catalyst exhibits small overpotentials of 357 and 402 mV for OER at 200 and 500 mA cm, respectively, together with an impressive durability over 500 h at a large current density of 500 mA cm benefiting from the strong repulsive effect of the derived PO, SO and SO oxyanions. This work offers a new insight for comprehending the relationship of structure-composition-activity and develops a new approach toward the construction of efficient and robust OER catalysts for seawater electrolysis.