A facile method for the synthesis of a porous cobalt oxide–carbon hybrid as a highly efficient water oxidation catalyst

Abstract

A main challenge for light-driven water splitting is the development of efficient and economical water oxidation catalysts (WOCs). Herein, we developed a facile approach for the preparation of a porous cobalt oxide–carbon hybrid, which was prepared by carbonizing in an inert atmosphere and subsequently air-calcining nanocrystals of zeolite imidazole framework-67 (ZIF-67), and utilized as an efficient WOC. Using Ru(bpy)₃(PF₆)₃ as an oxidant, we got a record catalytic turnover number (TON) and a turnover frequency (TOF) of 910 ± 21 and 14.6 ± 0.4 s⁻¹ per cobalt atom, respectively. In addition, the synthesized catalyst can also act as an efficient electrochemical WOC, with a low OER overpotential of 0.36 V at 10.0 mA cm⁻² in a pH 13 medium. The superior catalyst performance can be attributed to the homogeneous dispersion of CoO_x and in situ formed porous carbon, and the presence of nitrogen in the catalyst may also be attributed to its high catalytic activity.