Diamondoid Ni(II) Coordination Polymer as an Electrocatalyst for Hydrogen and Oxygen Evolution Reactions and Overall Water Splitting.

We have successfully synthesized a new Ni(II)-based coordination polymer (CP) [Ni 2 (cis-1,4-chdc) 2 (4,4'-bpy) 3 (H 2 O) 2 ] (1); (cis-1,4- H 2 chdc=cis-1,4-cyclohexanedicarboxylic acid and 4,4'-bpy=4,4'-bipyridine) employing slow diffusion method in a single pot technique. The connectivity of Ni(II) ions and bridging cis-1,4-chdc ligand gives rise to a three-dimensional (3D) framework with 2-fold interpenetrated diamondoid topology. Interestingly, the synthesized CP acts as efficient catalyst for electrocatalytic water splitting. The water oxidation activity of compound 1 exhibits Tafel slope equivalent to 361.48 mV.dec -1 for hydrogen evolution reaction (HER) and 353.53 mV.dec -1 for oxygen evolution reaction (OER) in an alkaline medium while almost similar values of Tafel slope for HER and OER equivalent to 287.33 mV.dec -1 and 289.93 mV.dec -1 respectively in acidic medium. Thus, the compound 1 has excellent efficacy in catalyzing HER and OER in acidic as well as alkaline medium, which is ascribed to its distinctive 3D architecture.