Novel cobalt-fumarate framework as a robust and efficient electrocatalyst for water oxidation at neutral pH

Abstract

The development of efficient and cost-effective electrocatalysts for oxygen evolution reaction is a priority research area. Metal-organic frameworks (MOFs) have recently captured attention as heterogeneous water oxidation catalysts. In spite of their robustness and stability under specific pH conditions, the relatively low current density achieved is their main drawback. Herein, we explored a cobalt based framework [Co(bpy)(fa)]n(DMF)0.25(bpy)0.25 (1) {bpy = 4,4ʹ-bipyridine, fa = fumarate, DMF = dimethylformamide} as an efficient electrocatalyst for the water oxidation reaction. Compound 1 exhibits excellent activity in a neutral phosphate buffer solution. Chronoamperometric studies show that 1 offers a current density of 10 mA cm−2 at only η = 382 mV. Onset over-potential of 248 mV is observed which holds a Tafel slope value of 84 mV dec−1. The catalyst showed a turnover frequency (TOF) of 2 × 10−3 s−1 for oxygen evolution reaction (OER) at 289 mV. Detailed electrochemical studies, including long-term electrolysis, indicates the potential of compound 1 to be utilized as heterogeneous catalyst toward the oxygen evolution reaction.