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Issue 5, 2016
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Understanding the origin of photoelectrode performance enhancement by probing surface kinetics

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Abstract

Photoelectrochemical (PEC) water splitting holds the potential to meet the challenges associated with the intermittent nature of sunlight. Catalysts have often been shown to improve the performance of PEC water splitting, but their working mechanisms are not well understood. Using intensity modulated photocurrent spectroscopy (IMPS), we determined the rate constants of water oxidation and recombination at the surface of three different hematite-based photoanodes. It was found that the best performing electrodes, in terms of photocurrent onset potential, exhibited the slowest water oxidation rate constants, which was a surprise. The performance of these photoelectrodes was enabled by the slow surface recombination. When amorphous NiFeOx, a water oxidation catalyst, was present, the rate of surface hole transfer actually slowed down; what was slowed more was the recombination rate at the hematite surface, resulting in better water oxidation performance. As such, NiFeOx primarily serves as a passivation layer rather than a catalytic layer. Together a better understanding of the role of catalytic overlayers for water oxidation has been achieved.

Graphical abstract: Understanding the origin of photoelectrode performance enhancement by probing surface kinetics

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Publication details

The article was received on 24 Nov 2015, accepted on 11 Feb 2016 and first published on 11 Feb 2016


Article type: Edge Article
DOI: 10.1039/C5SC04519C
Citation: Chem. Sci., 2016,7, 3347-3354
  • Open access: Creative Commons BY license
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    Understanding the origin of photoelectrode performance enhancement by probing surface kinetics

    J. E. Thorne, J. Jang, E. Y. Liu and D. Wang, Chem. Sci., 2016, 7, 3347
    DOI: 10.1039/C5SC04519C

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