Hierarchical structure of amorphous bimetallic hydroxide modified Co-metal organic framework catalyst efficient and robust for oxygen evolution reaction

Abstract

OER is a four-electron-proton coupling reaction, generating a high kinetic barrier and suffering from high overpotential and low efficiency. Developing long-time operational stability the oxygen evolution electrocatalysts under large catalytic current densities is a crucial step for efficient OER. Herein, an amorphous NiCo(OH)x modified Co-MOF octahedron assembled by ultra-thin nanosheets catalysts grow on nickel foam (labelled as NiCo(OH)x@Co-MOF/NF) with hierarchical structure is synthesized by a mild interfacial nucleation strategy. The obtained material exhibits an excellent catalytic activity and stability toward OER, a low overpotential of only 210 and 531 mV can be required at 10 and 1000 mA cm −2 current density with remarkable durability for >24 h and a smaller Tafel slope of 43 mV dec −1 in alkaline aqueous solution. The experimental studies demonstrate that the modification of amorphous NiCo(OH)x improves the electrical conductivity of Co-MOF. In addition, the hierarchical structure assembled by ultra-thin nanosheets possess a larger surface area and expose number of active sites, enhancing the charge transfer rate and catalytic performance.