Hydrothermal synthesis of nanostructured Cr-doped hematite with enhanced photoelectrochemical activity

[EN] Using the easily applicable hydrothermal method Cr-doped hematite thin films have been deposited polycrystalline on conductive glass substrates. The hydrothermal bath consisted of an aqueous solution containing a mixture of FeCl3.6H(2)O and NaNO3 at pH = 1.5. The samples were introduced in an autoclave and heated for a fixed time at a fixed temperature and then annealed in air at 550 degrees C. The concentration of the incorporated Cr atoms (Cr4+ ions) was controlled by varying the concentration of the Cr(ClO4)(3) precursor solution, varied from 0% to 20%. All samples followed morphological and structural studies using field-emission scanning electron microscopy, high-resolution transmission electron microscopy and X-ray diffraction. Chronoamperometry measurements showed that Cr-doped hematite films exhibited higher photoelectrochemical activity than the undoped films. The maximum photocurrent density and incident photon conversion efficiencies (IPCE) were obtained for 16 at.% Cr-doped films. This high photoactivity can be attributed to both the large active surface area and increased donor density caused by Cr-doping in the alpha-Fe2O3 films. All samples reached their best IPCE at 400 nm. IPCE values for 16 at.% Cr-doped hematite films were thirty times higher than that of undoped samples. This high photoelectrochemical performance of Cr-doped hematite films is mainly attributed to an improvement in charge carrier properties. (C) 2017 Elsevier Ltd. All rights reserved.This work was supported by the Ministry of Higher Education and Scientific Research, Tunisia and Ministerio de Economia y Competitividad (ENE2016-77798-C4-2-R) and Generalitat Valenciana (Prometeus 2014/044).Bouhjar, F.; Mollar García, MA.; Chourou, M.; Marí, B.; Bessais, B. (2018). Hydrothermal synthesis of nanostructured Cr-doped hematite with enhanced photoelectrochemical activity. Electrochimica Acta. 260:838-846. https://doi.org/10.1016/j.electacta.2017.12.049S83884626