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Issue 30, 2014
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Energetics and efficiency analysis of a cobaloxime-modified semiconductor under simulated air mass 1.5 illumination

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Abstract

We report on the energetics and efficiency of a p-type (100) gallium phosphide (GaP) semiconductor functionalized with molecular hydrogen production catalysts via polymer grafting. The catalysts belong to the cobaloxime class of compounds that have recently shown promise in electrocatalysis and solar-to-fuel applications. Attachment of the complex to a semiconductor surface allows direct photoelectrochemical (PEC) measurements of performance. Under simulated air mass 1.5 illumination, the catalyst-modified photocathode yields a 0.92 mA cm−2 current density when operating at the equilibrium potential for the hydrogen production half reaction. The open circuit photovoltage (VOC) is 0.72 V vs. a reversible hydrogen electrode (RHE) and the fill factor (FF) is 0.33 (a 258% increase compared to polymer-modified electrodes, without cobaloxime treatment). The external quantum efficiency (EQE), measured under a reverse bias of +0.17 vs. RHE, shows a maximum of 67% under 310 nm illumination. Product analysis of the head-space gas yields a lower limit on the Faradaic efficiency of 88%. In addition, the near linear photoresponse of the current density upon increasing illumination indicates that photocarrier transport to the interface can limit performance. These results give insights into the design of improved photocatalytic constructs with additional performance gains.

Graphical abstract: Energetics and efficiency analysis of a cobaloxime-modified semiconductor under simulated air mass 1.5 illumination

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Publication details

The article was received on 02 Feb 2014, accepted on 11 Feb 2014 and first published on 12 Feb 2014


Article type: Paper
DOI: 10.1039/C4CP00495G
Author version available: Download Author version (PDF)
Citation: Phys. Chem. Chem. Phys., 2014,16, 15818-15824
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    Energetics and efficiency analysis of a cobaloxime-modified semiconductor under simulated air mass 1.5 illumination

    A. Krawicz, D. Cedeno and G. F. Moore, Phys. Chem. Chem. Phys., 2014, 16, 15818
    DOI: 10.1039/C4CP00495G

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