Tin Oxide as a Protective Heterojunction with Silicon for Efficient Photoelectrochemical Water Oxidation in Strongly Acidic or Alkaline Electrolytes

Ivan A. Moreno-Hernandez, Bruce S. Brunschwig, Nathan S. Lewis

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9 Citations (Scopus)


Photoelectrodes without a p–n junction are often limited in efficiency by charge recombination at semiconductor surfaces and slow charge transfer to electrocatalysts. This study reports that tin oxide (SnOx) layers applied to n-Si wafers after forming a thin chemically oxidized SiOx layer can passivate the Si surface while producing ≈620 mV photovoltage under 100 mW cm−2 of simulated sunlight. The SnOx layer makes ohmic contacts to Ni, Ir, or Pt films that act as precatalysts for the oxygen-evolution reaction (OER) in 1.0 m KOH(aq) or 1.0 m H2SO4(aq). Ideal regenerative solar-to-O2(g) efficiencies of 4.1% and 3.7%, respectively, are obtained in 1.0 m KOH(aq) with Ni or in 1.0 m H2SO4(aq) with Pt/IrOx layers as OER catalysts. Stable photocurrents for >100 h are obtained for electrodes with patterned catalyst layers in both 1.0 m KOH(aq) and 1.0 m H2SO4(aq).

Original languageEnglish
Article number1801155
JournalAdvanced Energy Materials
Issue number24
Publication statusPublished - Aug 27 2018



  • heterojunctions
  • photoanodes
  • photoelectrochemistry
  • water oxidation
  • water splitting

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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