A trinuclear cobalt-based coordination polymer as an efficient oxygen evolution electrocatalyst at neutral pH.

The dearth of an efficient, robust, abundant and cost-effective water oxidation catalyst is debatably the major hurdle for the technological advancement of artificial photosynthesis devices. Herein, a three dimensional (3D) cobalt-based coordination polymer {[Co3(pyz)(fa)3(dmso)2]·2H2O}n, (1) (pyz = pyrazine, fa = fumarate, dmso = dimethyl sulfoxide) has been synthesized and demonstrated to act as an efficient electrocatalyst towards water oxidation at neutral pH. Compound 1 displays a stair-like arrangement parallel to the b-axis, with the cobalt clusters arranged in a zigzag fashion, and contains small, honeycomb-like channels parallel to the c-axis. Compound 1 shows a remarkable activity for water oxidation and attains a current density of 1 mA.cm-2 at low overpotential (η = 257 mV) with a Tafel slope value of 80.5 mV.dec-1. This high performance of 1 in catalysing the water oxidation reaction is attributed to its unique 3-D architecture. The results of electrochemical investigations, including long-term and controlled potential electrolysis, are anticipated to guide the forthcoming advancement in creating efficient, cheap and noble metal (Pt/Ru/Ir) free catalysts for the water oxidation reaction.