Ni/Co/Co₃O₄@C nanorods derived from a MOF@MOF hybrid for efficient overall water splitting

Abstract

The design of nanostructured materials for efficient bifunctional electrocatalysts has gained tremendous attention, yet developing a fast and effective synthesis strategy remains a challenge. Here, we present a fast and scalable synthetic method of Ni/Co/Co₃O₄@C nanorods for efficient overall water splitting. Using microwave synthesis, we first produced a unique Ni-MOF@Co-MOF in a few minutes. Subsequently, we transformed the MOF@MOF into hybrid Ni/Co/Co₃O₄ nanoparticles covered with graphitic carbon in a few seconds using laser-scribing. The prepared bimetallic catalysts showed remarkably low overpotentials of 246 mV for the oxygen evolution reaction (OER) and 143 mV for the hydrogen evolution reaction (HER) at a current density of 30 mA cm^-2. An electrolyzer assembled with the bimetallic catalysts delivered a high current density of 20 mA cm^-2 at a voltage of 1.6 V and exhibited good durability (nearly 91.6% retention even after a long-running operation of 24 h at a voltage of 1.52 V). Our proposed method could serve as a powerful method for creating various multimetallic hybrid nanocatalysts with unique hierarchical structures from diverse MOFs.