Tunable metal–organic framework nanoarrays on carbon cloth constructed by a rational self-sacrificing template for efficient and robust oxygen evolution reactions

Abstract

Metal–organic frameworks (MOFs) are regarded as advanced materials for oxygen evolution reactions (OER) because of their large specific surface area, adjustable pore size and abundant intrinsic molecular/atomic metal active sites. However, their essential features, such as the organic-ligand-shielded metal centres and low conductivity, make their electrocatalytic potential far from being exploited. These undesired issues can be avoided by designing and constructing MOF nanoarrays (MOF NAs) on self-supporting and conductive substrates such as the carbon cloth. Transforming appropriate solid material nanoarrays into MOF NAs provides a possibility to unlock the bottleneck. Herein, we have successfully developed a general approach for the morphological and electronic modulation of Co/Ni-MOF-74 NAs with wall-like Co/Ni(OH)₂ NAs as the self-sacrificing template. The wall- or spindle-like morphology of MOF-74 NAs was modulated by changing the dosage of ligand. As a result, Co/Ni-MOF-74 NAs displayed superior activity and stability to those of Co/Ni-MOF-74 prepared without the template. The Co_0.5Ni_0.5-MOF-74 NAs delivered a low overpotential of 244 mV at a current density of 10 mA cm⁻² due to the high proportion of active high-valence Co(III) and Ni(III). The proposed strategy can be extended to obtain brick-like Ni-BDC NAs and needle-like Ni BTC MOF NAs on carbon cloth.