Comparison of the performance of cop-coated and pt-coated radial junction n+p-silicon microwire-array photocathodes for the sunlight-driven reduction of water to H2(g)

Christopher W. Roske, Eric J. Popczun, Brian Seger, Carlos G. Read, Thomas Pedersen, Ole Hansen, Peter Christian Kjærgaard Vesborg, Bruce S. Brunschwig, Raymond E. Schaak, Ib Chorkendorff, Harry B. Gray, Nathan S. Lewis

Research output: Contribution to journalJournal articleResearchpeer-review


The electrocatalytic performance for hydrogen evolution has been evaluated for radial-junction n+p-Si microwire (MW) arrays with Pt or cobalt phosphide, CoP, nanoparticulate catalysts in contact with 0.50 M H2SO4(aq). The CoP-coated (2.0 mg cm-2) n+p-Si MW photocathodes were stable for over 12 h of continuous operation and produced an open-circuit photovoltage (Voc) of 0.48 V, a light-limited photocurrent density (Jph) of 17 mA cm-2, a fill factor (ff) of 0.24, and an ideal regenerative cell efficiency (ηIRC) of 1.9% under simulated 1 Sun illumination. Pt-coated (0.5 mg cm-2) n+p-Si MW-array photocathodes produced Voc = 0.44 V, Jph = 14 mA cm-2, ff = 0.46, and η = 2.9% under identical conditions. Thus, the MW geometry allows the fabrication of photocathodes entirely comprised of earth-abundant materials that exhibit performance comparable to that of devices that contain Pt.
Original languageEnglish
JournalThe Journal of Physical Chemistry Letters
Issue number9
Pages (from-to)1679-1683
Number of pages5
Publication statusPublished - 2015


  • Cobalt phosphide
  • Hydrogen evolution
  • Microwires
  • Platinum
  • Silicon
  • Solar fuel

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