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Catalysts 2018, 8(11), 497; https://doi.org/10.3390/catal8110497

Surface Modification of Hematite Photoanodes for Improvement of Photoelectrochemical Performance

1
Operando Characterization of Solar Fuel Materials (EE-NOC), Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
2
Physikalische Chemie, Universität Bielefeld, Universitätsstr. 25, 33615 Bielefeld, Germany
*
Author to whom correspondence should be addressed.
Received: 26 September 2018 / Revised: 18 October 2018 / Accepted: 20 October 2018 / Published: 26 October 2018
(This article belongs to the Special Issue Photocatalytic Water Splitting)
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Abstract

Solar water splitting is a promising method for producing renewable fuels. Thermodynamically, the overall water splitting reaction is an uphill reaction involving a multiple electron transfer process. The oxygen evolution reaction (OER) has been identified as the bottleneck process. Hematite (α-Fe2O3) is one of the best photoanode material candidates due to its band gap properties and stability in aqueous solution. However, the reported efficiencies of hematite are notoriously lower than the theoretically predicted value mainly due to poor charge transfer and separation ability, short hole diffusion length as well as slow water oxidation kinetics. In this Review Article, several emerging surface modification strategies to reduce the oxygen evolution overpotential and thus to enhance the water oxidation reaction kinetics will be presented. These strategies include co-catalysts loading, photoabsorption enhancing (surface plasmonic metal and rare earth metal decoration), surface passivation layer deposition, surface chemical etching and surface doping. These methods are found to reduce charge recombination happening at surface trapping states, promote charge separation and diffusion, and accelerate water oxidation kinetics. The detailed surface modification methods, surface layer materials, the photoelectrochemical (PEC) performances including photocurrent and onset potential shift as well as the related proposed mechanisms will be reviewed. View Full-Text
Keywords: hematite; photoelectrochemical; water oxidation; surface modification; flatband potential; onset potential; photocurrent; kinetics; photoanode hematite; photoelectrochemical; water oxidation; surface modification; flatband potential; onset potential; photocurrent; kinetics; photoanode
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Xi, L.; Lange, K.M. Surface Modification of Hematite Photoanodes for Improvement of Photoelectrochemical Performance. Catalysts 2018, 8, 497.

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