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 CoOx and in situ formed porous carbon, and the presence of nitrogen in the catalyst may also be attributed to its high catalytic activity.