In Situ Formation of an Oxygen-Evolving Catalyst in Neutral Water Containing Phosphate and Co 2+
Tóm tắt
The utilization of solar energy on a large scale requires its storage. In natural photosynthesis, energy from sunlight is used to rearrange the bonds of water to oxygen and hydrogen equivalents. The realization of artificial systems that perform “water splitting” requires catalysts that produce oxygen from water without the need for excessive driving potentials. Here we report such a catalyst that forms upon the oxidative polarization of an inert indium tin oxide electrode in phosphate-buffered water containing cobalt (II) ions. A variety of analytical techniques indicates the presence of phosphate in an approximate 1:2 ratio with cobalt in this material. The pH dependence of the catalytic activity also implicates the hydrogen phosphate ion as the proton acceptor in the oxygen-producing reaction. This catalyst not only forms in situ from earth-abundant materials but also operates in neutral water under ambient conditions.
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Tài liệu tham khảo
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Materials and methods videos of an active electrode and figs. S1 to S4 are available as supporting material on Science Online.
In a typical experiment >40 C are passed over 8 hours whereas oxidation of all the Co 2+ in solution requires 1.9 C per oxidation-state change.
K. D. Bomben J. F. Moulder P. E. Sobol W. F. Stickel in Handbook of X-Ray Photoelectron Spectra: A Reference Book of Standard Spectra for Identification J. Chastain Ed. (Perkin Elmer Eden Prairie MN 1992).
This work was supported by a grant from the NSF Chemical Bonding Center (CHE-0802907). M.W.K. is supported by a Ruth L. Kirchenstein National Research Service Award postdoctoral fellowship provided by NIH (F32GM07782903). We thank E. Shaw for obtaining XPS spectra G. Henoch for providing the videos in the supporting online material and Y. Surendranath for many productive discussions.