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Issue 10, 2013
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Photocatalytic water oxidation by very small cobalt domains on a silica surface

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Abstract

Small domains of cobalt on silica (CoSBA) were prepared by the reaction of Co[N(SiMe3)2]2 and SBA-15, resulting in a range of surface structures as the cobalt loading varied from 0.27 to 5.11 wt%. X-ray absorption spectroscopy (XAS) was employed to characterize these surface structures, which range from single-site cobalt atoms to small clusters of Co3O4. The CoSBA materials exhibit photochemical water oxidation catalysis, revealing distinct catalytic activities associated with characteristic types of surface structures that are dominant in particular concentration regimes. The catalytic turnover frequency for water oxidation of an isolated single-site cobalt atom (0.0143 s−1) is much greater than that observed for a surface atom of a small cluster Co3O4 on silica (0.0006 s−1). The CoSBA catalysts were recyclable for more than seven catalytic cycles (>200 turnovers) with additional sacrificial oxidant, and no leaching of cobalt was observed. Post-catalytic analysis of CoSBA by XAS revealed that the cobalt atoms were partially oxidized to Co3+, without exhibiting significant surface migration and aggregation of cobalt atoms.

Graphical abstract: Photocatalytic water oxidation by very small cobalt domains on a silica surface

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Publication details

The article was received on 19 Jun 2013, accepted on 27 Aug 2013 and first published on 28 Aug 2013


Article type: Paper
DOI: 10.1039/C3EE42067A
Citation: Energy Environ. Sci., 2013,6, 3080-3087
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    Photocatalytic water oxidation by very small cobalt domains on a silica surface

    H. S. Ahn, J. Yano and T. D. Tilley, Energy Environ. Sci., 2013, 6, 3080
    DOI: 10.1039/C3EE42067A

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