Imidazolate-mediated assembled structures of Co-LDH sheets for efficient electrocatalytic oxygen evolution

Abstract

To fully achieve an eco-friendly means of storing electricity in the form of chemical fuels, the development of a green synthetic route to highly active oxygen evolution reaction (OER) electrocatalysts is required. In this work, imidazolate-induced production of cobalt layered double hydroxide (Co-LDH) electrocatalysts with different assembled structures is presented. Porous Co-LDHs exhibit a remarkable OER catalytic performance with a low overpotential of η₁₀ = 312 mV, while cage-like Co-LDHs prepared by the transformation of ZIF-67 show a slightly inferior performance. Such a phenomenon is attributed to the assembled structure difference, giving rise to a difference in electron transfer and mass transport as well as the number of accessible active sites. After disassembly, these disperse Co-LDH sheets give a similar catalytic performance (η₁₀: 288–290 mV) due to bearing similar components. Importantly, the reversible/cycling transformation between Co-LDHs and ZIF-67 provides an effective method to radically reduce pollutant release and resource consumption, from the point of view of material synthesis.