Photoreduction of Mesoporous In2O3: Mechanistic Model and Utility in Gas Sensing - Wagner, Thorsten; Kohl, Claus-Dieter; Morandi, Sara; Malagù, Cesare; Donato, Nicola; Latino, Mariangela; Neri, Giovanni; Tiemann, Michael (Chemistry - A European Journal, 2012)
A model is proposed for the drop in electronic resistance of n-type semiconducting indium oxide (In2O3) upon illumination with light (350 nm, 3.5 eV) as well as for the (light-enhanced) sensitivity of In2O3 to oxidizing gases. Essential features of the model are photoreduction and a rate-limiting oxygen-diffusion step. Ordered, mesoporous In2O3 with a high specific surface area serves as a versatile system for experimental studies. Analytical techniques comprise conductivity measurements under a controlled atmosphere (synthetic air, pure N2) and temperature-resolved in-situ Fourier transform infrared (FTIR) spectroscopy. IR measurements reveal that oxygen vacancies form a donor level 0.18 eV below the conduction band.
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