Bifunctional catalytic activity of Ni–Co layered double hydroxide for the electro-oxidation of water and methanol

Abstract

The development of nanostructured architectures using low-cost first–row transition metals with high electrocatalytic activity to replace noble-metal-based electrocatalysts has recently gained considerable attention in the field of clean and sustainable energy generation technology. In this study, highly efficient, binder-free, Ni–Co layered double hydroxide (NiCo-LDH) nanowires on a nickel foam (NF) substrate were fabricated via a simple, one-step hydrothermal synthesis procedure, and their use as electrocatalysts for the oxygen evolution reaction (OER) and methanol oxidation reaction (MOR) was studied. When NiCo-LDH was used as the OER electrocatalyst, the overpotential required to deliver a current density of 20 and 100 mA cm⁻², was only 270 and 410 mV (without iR correction), and it exhibited a long-term stability of 50 h in 1 M KOH. Moreover, the as-prepared NiCo-LDH nanowire electrocatalyst presented remarkable electrochemical performance for the MOR with a higher current density of 761 mA cm⁻² at 0.7 V vs. the saturated calomel electrode (SCE) and excellent stability in 1 M KOH with 0.5 M methanol. The vertically aligned NiCo-LDH nanowires presented numerous active sites and open structures and their synergism with the highly conductive NF substrate was responsible for the excellent electrochemical performance of the electrocatalyst.