Stabilization of n-cadmium telluride photoanodes for water oxidation to O2(g) in aqueous alkaline electrolytes using amorphous TiO2 films formed by atomic-layer deposition

Michael F. Lichterman, Azhar I. Carim, Matthew T. McDowell, Shu Hu, Harry B. Gray, Bruce S. Brunschwig, Nathan S. Lewis

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80 Citations (Scopus)

Abstract

Although II-VI semiconductors such as CdS, CdTe, CdSe, ZnTe, and alloys thereof can have nearly ideal band gaps and band-edge positions for the production of solar fuels, II-VI photoanodes are well-known to be unstable towards photocorrosion or photopassivation when in contact with aqueous electrolytes. Atomic-layer deposition (ALD) of amorphous, "leaky" TiO2 films coated with thin films or islands of Ni oxide has been shown to robustly protect Si, GaAs, and other III-V materials from photocorrosion and therefore to facilitate the robust, solar-driven photoelectrochemical oxidation of H2O to O2(g). We demonstrate herein that ALD-deposited 140 nm thick amorphous TiO2 films also effectively protect single crystalline n-CdTe photoanodes from corrosion or passivation. An n-CdTe/TiO2 electrode with a thin overlayer of a Ni-oxide based oxygen-evolution electrocatalyst produced 435 ± 15 mV of photovoltage with a light-limited current density of 21 ± 1 mA cm-2 under 100 mW cm-2 of simulated Air Mass 1.5 illumination. The ALD-deposited TiO2 films are highly optically transparent and electrically conductive. We show that an n-CdTe/TiO2/Ni oxide electrode enables the stable solar-driven oxidation of H2O to O2(g) in strongly alkaline aqueous solutions, where passive, intrinsically safe, efficient systems for solar-driven water splitting can be operated.

Original languageEnglish
Pages (from-to)3334-3337
Number of pages4
JournalEnergy and Environmental Science
Volume7
Issue number10
DOIs
Publication statusPublished - Oct 1 2014

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ASJC Scopus subject areas

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

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