Photoactivity improvement of TiO2 electrodes by thin hole transport layers of reduced graphene oxide
| Autor: | Ana M. Benito, Javier Hernández-Ferrer, Sandra Víctor-Román, Alejandro Ansón-Casaos, Wolfgang K. Maser, M.T. Martínez, Belén Villacampa, Olga Sanahuja-Parejo |
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| Přispěvatelé: | Ministerio de Economía, Industria y Competitividad (España), European Commission, Gobierno de Aragón, Hernández-Ferrer, Javier [0000-0002-6586-6935], Ansón Casaos, Alejandro [0000-0002-3134-8566], Víctor-Román, Sandra [0000-0003-0924-5840], Sanahuja-Parejo, Olga [0000-0002-1891-4324], Villacampa, Belén [0000-0001-9814-0834], Benito, Ana M. [0000-0002-8654-7386], Maser, Wolfgang K. [0000-0003-4253-0758], Hernández-Ferrer, Javier, Ansón Casaos, Alejandro, Víctor-Román, Sandra, Sanahuja-Parejo, Olga, Villacampa, Belén, Benito, Ana M., Maser, Wolfgang K. |
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Work (thermodynamics)
Titania Materials science Fabrication General Chemical Engineering Oxide 02 engineering and technology Hole-transport layer 010402 general chemistry 01 natural sciences Óxido de grafeno reducido law.invention chemistry.chemical_compound Photoelectrochemistry Depletion region law Electrochemistry Reduced graphene oxide Fotoelectroquímica business.industry Graphene 021001 nanoscience & nanotechnology Acceptor 0104 chemical sciences chemistry Electrode Optoelectronics Titanium dioxide Capa de conducción de agujeros 0210 nano-technology business Layer (electronics) Fotoelectrodos Photoelectrons |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname Zaguán. Repositorio Digital de la Universidad de Zaragoza |
| Popis: | 9 Figuras, 2 Tablas.-- Datos suplementarios de este artículo disponibles en línea en la página web del editor.-- © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ Nanostructured TiO2 and graphene-based materials constitute components of actual interest in devices related to solar energy conversion and storage. In this work, we show that a thin layer of electrochemically reduced graphene oxide (ECrGO), covering nanostructured TiO2 photoelectrodes, can significantly improve the photoactivity. In order to understand the working principle, ECrGO/TiO2 photoelectrodes with different ECrGO thicknesses were prepared and studied by a set of photoelectrochemical measurements. Methanol in alkaline conditions was employed as effective hole acceptor probe to elucidate the electronic phenomena in the electrode layers and interfaces. These studies underline the hole accepting properties of ECrGO and reveal the formation of a p-n junction at the interface between ECrGO and TiO2. It is shown for the first time that the resulting space charge region of about 10 nm defines the operational functionality of the ECrGO layer. Films thinner than the space charge region act as hole transport layer (HTL), which efficiently transfers holes to the liquid interface thus leading to enhanced photoactivity. Thicker films however act as hole blocking layer (HBL), resulting in a systematic decrease of the photoactivity. The finding of a thickness dependent threshold value for the operation of ECrGO as HTL and HBL is of general interest for the fabrication of optoelectronic devices with improved performance. The authors thank Prof. M.T. Martínez for AFM measurements and the Analysis Service of the Instituto de Carboquímica (ICB-CSIC) for XPS measurements. This work has received funding from the Spanish MINEICO (project grant ENE 2016-79282-C5-1-R), Gobierno de Aragón(Grupo ReconocidoDGA T03_17R), and associated EU Regional Development Funds. S.V. acknowledges Spanish MINEICO for her PhD grant (BES2014-068727 and associated EU Social Funds). |
| Databáze: | OpenAIRE |
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