Graphene Supported Pillared Ni-Co Metal-Organic Framework as an Efficient Electrocatalyst for the Water Oxidation Reaction

The oxygen evolution reaction (OER) plays a criticalrole in theoverall efficiency of water electrolysis. To address the ongoing challengeof creating electrocatalysts with high current density, low overpotential,and durable performance, we present a potential electrocatalyst forwater oxidation in an alkaline medium in the form of a composite ofpillared metal-organic framework (MOF) and graphene (G), designatedas Ni2Co(bdc)(2)D@G. The bimetallic MOF was synthesizedvia a solvothermal approach, using nickel and cobalt metal ions thatcoordinate with 1,4-benzenedicarboxylic acid (bdc) and 1,4-diazobicyclo[2.2.2]-octane(DABCO, D) as a pillared ligand. The as-synthesized MOF was then combinedwith graphene to form the composite. Our electrochemical analysisrevealed that the Ni2Co(bdc)(2)D@G composite exhibitssuperior catalytic activity to that of Ni2Co(bdc)(2)D, with an overpotential of 350 mV at 10 mA cm(-2) and a Tafel slope of 42.7 mV dec(-1), as opposedto 420 mV at 10 mA cm(-2) and a Tafel slope of 84.4mV dec(-1) for Ni2Co(bdc)(2)D.Furthermore, the MOF@G composite required only 400 mV to achieve acurrent density of 50 mA cm(-2). This significantimprovement in performance is attributed to the synergistic effectsbetween the MOF and graphene, resulting in enhanced current densityand reduced overpotential. The high electrocatalytic performance ofthe composite was attributed to the strong & pi;-& pi;interaction between the MOF and G, as well as the high surface areaof the composite. Additionally, during the OER, the composite facilitatedthe formation of Ni(OH)(2)/NiOOH and Co(OH)(2)/CoOOHspecies, which further contributed to the overall efficiency of theelectrocatalyst.

Automated summary

In this study, a novel water electrolysis catalyst in the form of a composite of pillared metal-organic framework (MOF) and graphene (G), denoted as Ni2Co(bdc)(2)D@G, was proposed. The electrochemical analysis showed that the Ni2Co(bdc)(2)D@G composite exhibited superior catalytic activity compared to Ni2Co(bdc)(2)D, with lower overpotential and higher current density. This improvement in performance was attributed to the synergistic effects between the MOF and graphene, the high surface area of the electrocatalyst, and the π-π interaction between the MOF and G.