Abstract
We report the first results in which ALD-TiO2 layers electronically couple silicon to an overlying catalyst coating while inhibiting corrosion during brine splitting, a reaction that is capable of generating not only a fuel (H2) but also a disinfectant (Cl2 or NaOCl). An n-type silicon photoanode, and a p+-silicon anode are protected by a 1.7 nm coating of amorphous TiO2 and 2 nm coating of Ir. The p+-Si/TiO2/Ir anode is able to effect the oxidation of chloride (0.5 M H2SO4, 3.5 M NaCl) in the dark with a low overpotential compared to that for oxidation of water (0.5 M H2SO4). The 0.294 V overpotential difference occurs despite the difference in standard redox potentials, ΔE = (E°(Cl2/Cl−) - E°(O2/H2O)), of 130 mV. Under 1 sun irradiation a photovoltage of ca. 0.566 V is achieved by comparing the illuminated n-Si/TiO2/Ir photoanode with the dark p+-silicon anode. Although the n-Si/TiO2/Ir photoanode is only one half of an eventual tandem cell needed for photosynthetic brine splitting, its ABPE for chloride oxidation is 1.42%, ca. 28 times that for water oxidation. The illuminated n-Si/TiO2/Ir photoanode remained stable at 1 mA cm−2 during a six-day chronopotentiometry test.
Original language | English |
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Pages (from-to) | H1072-H1079 |
Number of pages | 8 |
Journal | Journal of the Electrochemical Society |
Volume | 165 |
Issue number | 16 |
DOIs | |
Publication status | Published - 29 Dec 2018 |
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Silicon Photoanodes for Solar-Driven Oxidation of Brine: A Nanoscale, Photo-Active Analog of the Dimensionally-Stable Anode
Mills, A. (Creator), O'Rourke, C. (Creator), Tang-Kong, R. (Creator) & McIntyre, P. (Creator), Queen's University Belfast, 18 Dec 2018
DOI: 10.17034/129f2400-dce5-4727-9e2d-f575354a67df
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