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Gap-plasmon enhanced water splitting with ultrathin hematite films: The role of plasmonic-based light trapping and hot electrons

Abstract

Hydrogen is a promising alternative renewable fuel to meet the growing energy demand of the world. Over the past few decades, photoelectrochemical water splitting has been widely studied as viable technology for hydrogen production with solar energy. A Solar-to-Hydrogen (STH) efficiency of 10% is considered to be sufficient for practical applications. Amongst the wide class of semiconductors studied for solar water splitting, iron oxide (α-Fe2O3) or hematite is one of the promising candidate materials with a theoretical STH efficiency of 15%. In this work, we experimentally show that by utilizing gold nanostructures supporting gap-plasmon resonances together with a hematite layer, we can enhance the water oxidation photocurrent by two times compared to a bare hematite film at wavelengths above the hematite bandgap. Moreover, we achieve a six-fold enhancement in the oxidation photocurrent at the near-infrared wavelengths which is attributed to hot electron generation and decay in the gap-plasmon nanostructures. Theoretical simulations confirmed that the used metamaterial geometry with gap plasmons allows us to confine electromagnetic fields inside the hematite semiconductor and to enhance surface photochemistry.

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Publication details

The article was accepted on 07 Nov 2018 and first published on 15 Nov 2018


Article type: Paper
DOI: 10.1039/C8FD00148K
Citation: Faraday Discuss., 2018, Accepted Manuscript
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    Gap-plasmon enhanced water splitting with ultrathin hematite films: The role of plasmonic-based light trapping and hot electrons

    A. Dutta, A. Naldoni, F. Malara, A. O. Govorov, V. Shalaev and A. Boltasseva, Faraday Discuss., 2018, Accepted Manuscript , DOI: 10.1039/C8FD00148K

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