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Issue 11, 2012
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Hydrogen-evolution characteristics of Ni–Mo-coated, radial junction, n+p-silicon microwire array photocathodes

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Abstract

The photocathodic H2-evolution performance of Ni–Mo-coated radial n+p junction Si microwire (Si MW) arrays has been evaluated on the basis of thermodynamic energy-conversion efficiency as well as solar cell figures of merit. The Ni–Mo-coated n+p-Si MW electrodes yielded open-circuit photovoltages (Voc) of 0.46 V, short-circuit photocurrent densities (Jsc) of 9.1 mA cm−2, and thermodynamically based energy-conversion efficiencies (η) of 1.9% under simulated 1 Sun illumination. Under nominally the same conditions, the efficiency of the Ni–Mo-coated system was comparable to that of Pt-coated n+p-Si MW array photocathodes (Voc = 0.44 V, Jsc = 13.2 mA cm−2, η = 2.7%). This demonstrates that, at 1 Sun light intensity on high surface area microwire arrays, earth-abundant electrocatalysts can provide performance comparable to noble-metal catalysts for photoelectrochemical hydrogen evolution. The formation of an emitter layer on the microwires yielded significant improvements in the open-circuit voltage of the microwire-array-based photocathodes relative to Si MW arrays that did not have a buried n+p junction. Analysis of the spectral response and light-intensity dependence of these devices allowed for optimization of the catalyst loading and photocurrent density. The microwire arrays were also removed from the substrate to create flexible, hydrogen-evolving membranes that have potential for use in a solar water-splitting device.

Graphical abstract: Hydrogen-evolution characteristics of Ni–Mo-coated, radial junction, n+p-silicon microwire array photocathodes

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Publication details

The article was received on 16 Aug 2012, accepted on 13 Sep 2012 and first published on 08 Oct 2012


Article type: Paper
DOI: 10.1039/C2EE23192A
Citation: Energy Environ. Sci., 2012,5, 9653-9661
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    Hydrogen-evolution characteristics of Ni–Mo-coated, radial junction, n+p-silicon microwire array photocathodes

    E. L. Warren, J. R. McKone, H. A. Atwater, H. B. Gray and N. S. Lewis, Energy Environ. Sci., 2012, 5, 9653
    DOI: 10.1039/C2EE23192A

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