Hierarchical cobalt-molybdenum layered double hydroxide arrays power efficient oxygen evolution reaction

Abstract

Transition metal-based layered double hydroxides (LDHs) have been capable of working efficiently as catalysts in the basic oxygen evolution reaction (OER) for sustaining hydrogen production of alkaline water electrolysis. Nevertheless, exploring new LDH-based electrocatalysts featuring both remarkable activity and good stability is still in high demand, which is pivotal for comprehensive understanding and impressive improvement of the sluggish OER kinetics. Here, a series of bimetallic (Co and Mo) LDH arrays were designed and fabricated via a facile and controlled strategy by incorporating a Mo source into presynthesized Co-based metal-organic framework (MOF) arrays on carbon cloth (CC), named as ZIF-67/CC arrays. We found that tuning the Mo content resulted in gradual differences in the structural properties, surface morphology, and chemical states of the resulting catalysts, namely CoMox-LDH/CC (x representing the added weight of the Mo source). Gratifyingly, the best-performing CoMo0.20-LDH/CC electrocatalyst demonstrates a low overpotential of only 226 mV and high stability at a current density of 10 mA·cm−2, which is superior to most LDH-based OER catalysts reported previously. Furthermore, it only required 1.611 V voltage to drive the overall water splitting device at the current density of 10 mA·cm−2. The present study represents a significant advancement in the development and applications of new OER catalysts.