Fabrication of rGO/α-Fe2O3 electrodes: characterization and use in photoelectrocatalysis

• Published in: Journal of materials science. Materials in electronics 2020-10, Vol.31 (19), p.16882-16897
• Main Authors: Leão-Neto, Vanildo Souza, da Silva, Aruã Clayton, Camargo, Luan Pereira, Da Silva Pelissari, Marcelo Rodrigues, da Silva, Paulo Rogério Catarini, Parreira, Paulo Sergio, Segatelli, Mariana Gava, Dall′Antonia, Luiz Henrique
• Format: Article
• Language: English
• Subjects: Bilayers; Characterization and Evaluation of Materials; Chemistry and Materials Science; Decoloring; Electrodes; Fourier transforms; Glass substrates; Graphene; Hematite; Indium oxides; Indium tin oxides; Infrared analysis; Iron oxides; Materials Science; Methylene blue; Optical and Electronic Materials; Photoelectric effect; Photoelectric emission; Polyelectrolytes; Raman spectroscopy; Spectrum analysis; Thermogravimetric analysis
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-020-04244-3

In the current study, the synthesis of hematite ( α -Fe 2 O 3 ) at different temperatures (750 and 900 °C), and reduced graphene oxide (rGO), obtained from an adaptation to the Hummers’s method, was evaluated. These materials were characterized by X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, among others. The deposition of samples on the conductive surface of tin-doped indium oxide coated glass substrate, was performed by the Layer-by-Layer technique. The films were prepared with 1- and 4-bilayers α -Fe 2 O 3 , using a cationic polyelectrolyte diallyldimethylammonium chloride (PDDA) or rGO. It was observed that the rGO/ α -Fe 2 O 3 films presented higher photocurrent and less resistivity when compared to the PDDA/ α -Fe 2 O 3 films. The largest photocurrent was obtained with the 4-bilayers rGO/ α -Fe 2 O 3 at 900 °C film, with 2.15 µA cm −2 . In addition, a kinetic study for photoelectrocatalytic decolorization of the methylene blue dye under visible light was performed. The electrode that showed the greatest photoelectroactivity was the 4-bilayers rGO/ α -Fe 2 O 3 at 900 °C film, resulting in k obs  = 11.90 × 10 −3  min −1 and about 78% decolorization after 120 min.