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

Emily L. Warren, James R. McKone, Harry A. Atwater, Harry B. Gray, Nathan S Lewis

Research output: Contribution to journalArticle

150 Citations (Scopus)

Abstract

The photocathodic H 2-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 (V oc) of 0.46 V, short-circuit photocurrent densities (J sc) 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 (V oc = 0.44 V, J sc = 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.

Original languageEnglish
Pages (from-to)9653-9661
Number of pages9
JournalEnergy and Environmental Science
Volume5
Issue number11
DOIs
Publication statusPublished - Nov 2012

Fingerprint

Photocathodes
Silicon
Photocurrents
Energy conversion
Sun
silicon
Conversion efficiency
Hydrogen
hydrogen
Catalysts
Electrocatalysts
Open circuit voltage
Precious metals
Short circuit currents
Solar cells
Lighting
Earth (planet)
Thermodynamics
Membranes
light intensity

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Environmental Chemistry
  • Pollution
  • Nuclear Energy and Engineering

Cite this

Hydrogen-evolution characteristics of Ni-Mo-coated, radial junction, n +p-silicon microwire array photocathodes. / Warren, Emily L.; McKone, James R.; Atwater, Harry A.; Gray, Harry B.; Lewis, Nathan S.

In: Energy and Environmental Science, Vol. 5, No. 11, 11.2012, p. 9653-9661.

Research output: Contribution to journalArticle

Warren, Emily L. ; McKone, James R. ; Atwater, Harry A. ; Gray, Harry B. ; Lewis, Nathan S. / Hydrogen-evolution characteristics of Ni-Mo-coated, radial junction, n +p-silicon microwire array photocathodes. In: Energy and Environmental Science. 2012 ; Vol. 5, No. 11. pp. 9653-9661.
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