https://doi.org/10.1140/epjb/s10051-026-01138-x
Research - Condensed Matter
Uncovering photocatalytic activity of Co3O4 normal spinel thin films via barium doping for organic dye photodegradation
1
Laboratory of Nanomaterials, Nanotechnology and Energy, Faculty of Sciences of Tunis, University of Tunis El Manar, 2092, Tunis, Tunisia
2
Borj el Amri Aviation School, B. P 1142, Tunis, Tunisia
3
Mediterranean Institute of Technology, South Mediterranean University, Lake II, 1053, Tunis, Tunisia
4
IPEIT (Preparatory Institute for Engineering Studies of Tunis), University of Tunis, 2 Jawaharlal Nehru Street, Montfleury, 1089, Tunis, Tunisia
a
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Received:
19
December
2025
Accepted:
4
February
2026
Published online:
27
February
2026
Abstract
Using spray pyrolysis deposition technique, pure and Ba-doped Co3O4 thin films were successfully produced. Various experimental characterization methods were carried out to study their structural, morphological, vibrational, optical properties followed by an evaluation of their photocatalytic activity toward the removal of some organic dyes. The XRD results showed that the prepared un-doped and Ba-doped thin films exhibit a cubic normal spinel crystal structure. IR and Raman spectroscopy confirmed an inherent dynamic stability of all samples. The UV–vis–NIR analysis proved the presence of two absorption edges at 600 and 800 nm, which are attributed to the O2− → Co2+ and the O2− → Co3+ charge transfer processes where the main optical band gap varied with Ba doping from 1.89 to 2.16 eV. The photoluminescence (PL) study revealed that Ba-doped Co3O4 has pronounced peak intensity at 512 nm and an emission associated with oxygen vacancies deep-level defects. The SEM results confirmed that the synthesized thin films had an irregular, flower-like morphology. Their photocatalytic efficiency was assessed through the photo-degradation of methylene blue (MB) and methylene orange (MR) under solar light irradiation. After 2 h hours of solar irradiation, the sample doped with 4% of Ba exhibited the highest degradation efficiency. The kinetic removal of both dyes follows a nonlinear pseudo-first-order model with a constant values k = 0.014 min−1 for MB and k = 0.005 min−1 for (MO). Overall, the results indicate that barium doping and the presence of oxygen vacancies promote efficient photocatalytic activity of the obtained thin films toward MB and MO removal under sunlight irradiation. Thus, our catalyst demonstrated high photocatalytic activity for the removal of synthetic and natural organic pollutants from wastewater, offering a sustainable solution for water contamination issues.
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© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2026
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
