Electrochemical Water Oxidation Catalyzed by an In Situ Generated α-Co(OH)2 Film on Zeolite-Y Surface.

The design and synthesis of an efficient and robust water-oxidation catalyst with inexpensive materials remains an important challenge in the context of artificial photosynthesis. Herein, a simple but unique technique is reported to in situ generate a thin-film of α-Co(OH)2 on the surface of zeolite-Y [hereafter referred to as Y-α-Co(OH)2 ] that acts as an efficient and stable catalyst for electrochemical water oxidation in alkaline medium. Catalyst Y-α-Co(OH)2 is so stable that it retains its catalytic activity even after 2000 cyclic voltammetric cycles of water oxidation. Expectedly, the chemical composition of α-Co(OH)2 on the surface of zeolite-Y remains same as that of parent Y-α-Co(OH)2 after 2000 electrocatalytic cycles. A Tafel slope as low as 59 mV decade-1 in 0.1 m KOH (pH 13) suggests faster oxygen evolution kinetics (overpotential=329 mV; turnover frequency=0.35 mol O2 (mol Co)-1  s-1 at 1 mA cm-2 ) than the existing α-Co(OH)2 -based electrocatalysts operating in alkaline medium.