Engineering crystalline CoMP-decorated (M = Mn, Fe, Ni, Cu, Zn) amorphous CoM LDH for high-rate alkaline water splitting

Abstract

Rational design of non-noble metal catalysts for alkaline electrochemical water splitting under large current densities is of great significance for realizing hydrogen economy and remains a daunting challenge. Herein, a series of crystalline CoMP-decorated (M = Mn, Fe, Ni, Cu, Zn) amorphous CoM LDH nanomaterials in-situ grown on nickel foam (denoted as c-CoMP/a-CoM LDH/NF) is developed as highly efficient and stable alkaline water splitting electrocatalysts. Crystalline CoMP encountered amorphous CoM LDH structure brings the increased catalytic active sites without sacrificing charge transfer rates, more optimal intermediate adsorption/dissociation capability, and the synergistic effects between binary transition metals, leading to more favorable reaction kinetics, thus enhancing catalytic performance for oxygen evolution reaction and hydrogen evolution reaction. As a result, the optimized cell assembled by the as-proposed electrocatalysts only requires ultralow cell voltages of 1.655 and 1.722 V to drive current densities of 100 and 500 mA cm−2 in 1.0 M KOH and exhibits excellent durability over 85 h (under 100 mA cm−2), which is originated from the well-retentive hybrid crystalline/amorphous nanostructure even after undergoing surface reconstruction. The presented work deepens the insights of crystalline/amorphous heterostructure catalysts and provides a new inspiration in the design of bifunctional electrocatalysts for high-rate alkaline water splitting.