Issue 7, 2015

Zinc–cobalt oxides as efficient water oxidation catalysts: the promotion effect of ZnO

Abstract

Herein, we report the promotion effect of ZnO in water oxidation catalyzed by Co. Zinc–cobalt oxides—ZnCoxOy were prepared via the calcination of Zn–Cox-coordination polymers. The results of XRD, Co K-edge XANES and EXAFS show that the Co/Zn ratio greatly affected the oxidation state of Co and local structure of the ZnCoxOy oxides. With a Co/Zn ratio higher than 3.0, Zn(II) prefers to substitute in the lattice of Co3O4. The integrated ZnO and Co3O4 composites were formed at a Co/Zn ratio less than 2.0. The HR-TEM images show that ZnO and Co3O4 compactly contact to form the interfaces in the composites. In both the chemical water oxidation and the visible-light-driven photocatalytic water oxidation ([Ru(bpy)3]2+–persulfate system), Zn substituted in the spinel structured Co3O4 oxide cannot significantly improve the water oxidation activity and only the integrated ZnO and Co3O4 composites afford much higher TOFs than Co3O4. This suggests the existence of the cooperation effect between ZnO (water adsorption site) and Co3O4 (water oxidation site). Our results provide a facile approach to design composite catalysts for the water oxidation reaction.

Graphical abstract: Zinc–cobalt oxides as efficient water oxidation catalysts: the promotion effect of ZnO

Supplementary files

Article information

Article type
Paper
Submitted
28 Nov 2014
Accepted
03 Dec 2014
First published
03 Dec 2014

J. Mater. Chem. A, 2015,3, 4010-4017

Author version available

Zinc–cobalt oxides as efficient water oxidation catalysts: the promotion effect of ZnO

F. Rong, J. Zhao, P. Su, Y. Yao, M. Li, Q. Yang and C. Li, J. Mater. Chem. A, 2015, 3, 4010 DOI: 10.1039/C4TA06527A

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