Axis 3 : Materials for the environment and health

Axis 3: Materials for the environment and health

Action 3.1: CO₂ capture by lithium and sodium oxides

At room temperature, the reactivity of lithiated oxides (Ruddlesden-Popper and garnets) towards water vapour induces a topotactic exchange of Li⁺ ions by H⁺ protons within their structures leading to a release of lithium hydroxide able to capture atmospheric CO₂, a greenhouse gas. It has been shown that Li₆BaLa₂Nb₂O₁₂ garnet, in addition to its instability in humid ambient atmosphere, could also capture CO₂ in dry atmosphere thanks to the irreversible exsolution of barium oxide at 500°C and its carbonation at T > 600°C [1]. After five hours at 500°C, this exsolution causes a reduction in the ionic conductivity of the garnet Li₆BaLa₂Nb₂O₁₂ of more than 60%.

It was also shown that the compound with structure 1D -Na₂TeO₄ exhibited a CO₂ capture rate close to 190 mg per gram of sorbent [2]. As for the lithiated oxides, the capture mechanism involves a Na⁺/H⁺ exchange that leads to a NaHTeO₄ phase (Fig. 1) whose structural study was performed by combining different techniques: X-ray diffraction, Raman and solid-state NMR [3]. Although the compound Na₂TeO₄ has been known since 1977, a reversible structural transition between the 2 crystalline forms (Low Temperature-Orthorhombic) and (High Temperature-Monoclinic) has been, for the first time, demonstrated. This transition is rather surprising because the HT form is generally the one with the highest crystal symmetry. Subsequently, the search for new CO₂ absorbers was extended to other soda oxides in the framework of a project financed by the IMMM Research Incentive Fund. This work has led to the discovery of new (oxy)carbonates, one of which, based on alkali, will be the subject of a study of its ionic conduction by impedance spectroscopy in molten medium.

Action 3.2: Photo-active semiconductor oxides

The semiconductor oxides TiO₂, BiVO₄ and NiTiO₃ catalyse the degradation of organic pollutants contained in water by absorbing UV or visible radiation from sunlight. Their photo-catalytic properties depend on their crystalline and electronic structure but also on their morphology (nanoparticles, dense or mesoporous thin films). In order to fine-tune the photoactivity of  the nanoparticles of these oxides in the visible range: 1) electronic band structure engineering was performed by doping with nitride anions (in NiTiO₃, [4]) or metal cations (Cu/Mo in BiVO₄ [5–7] and Cu/Ag in TiO₂ [8]), 2) metallic silver nanoparticles generating surface plasmons were associated to the oxide nanoparticles (Fig. 2 left, [9]) and finally 3) organic charge transfer molecules (D149) were grafted on the surface of mesoporous BiVO₄ films [10]. The photoactivity of the different architectures was evaluated and correlated with their electronic, structural and surfaces states. Numerical modelling and simulation approaches were used to validate the modifications of the electronic structures [5,11,12] or to analyse the photo-induced charge distribution at the D149-BiVO₄ interfaces measured by Kelvin probe microscopy ([10] and Fig. 2 right).

Fig. 2. TEM image of Ag doped BiVO₄ (left). Photo-induced charge distribution in D149-BiVO₄ measured by Kelvin probe microscopy (right).

Action 3.3: Inorganic Bactericidal Materials for Health

In order to prepare nanometer- or micrometer-sized bactericidal particles, simple, rapid and environmentally friendly synthetic routes are favoured as long as the chemical composition can be controlled. These particles are thoroughly characterised by (X-ray or neutron) diffraction, electron microscopy (SEM, TEM) and spectroscopies (NMR, EPR, UV-visible absorption, IR, etc.) allowing the crystal structure, chemical modification, morphology and size of the particles to be accurately determined.

As the bactericidal activity is evaluated in water (in collaboration with C. Roques from the University of Toulouse), particular attention is also paid to the hydration of particles as a function of their immersion time, by measuring the concentrations of released ions and the evolution of the pH or by ex-situ analysing immersed particles by diffraction or IR spectroscopy. Free oxygen radicals produced by particles are tracked and identified by EPR spin trapping experiments carried out by V. Brezová from the University of Bratislava. All these measurements provide precise knowledge regarding the toxicity of studied particles towards bacteria.

Related papers [13–16].

References

(1)       Galven, C.; Corbel, G.; Le Berre, F.; Crosnier-Lopez, M.-P. Instability of the Ionic Conductor Li₆BaLa₂B₂O₁₂ (B = Nb, Ta): Barium Exsolution from the Garnet Network Leading to CO₂ Capture. Inorg. Chem. 2016, 55 (24), 12872–12880. https://doi.org/10.1021/acs.inorgchem.6b02238.

(2)       Galven, C.; Mounier, D.; Bouchevreau, B.; Suard, E.; Bulou, A.; Crosnier-Lopez, M.-P.; Berre, F. L. Phase Transitions in the Ruddlesden–Popper Phase Li₂CaTa₂ O₇: X-Ray and Neutron Powder Thermodiffraction, TEM, Raman, and SHG Experiments. Inorg. Chem. 2016, 55 (5), 2309–2323. https://doi.org/10.1021/acs.inorgchem.5b02659.

(3)       Galven, C.; Pagnier, T.; Dittmer, J.; Le Berre, F.; Crosnier-Lopez, M.-P. CO₂ Capture by Na₂TeO₄: Structure of Na_{2– x} H_xTeO₄ and Kinetic Aspects. Inorg. Chem. 2019, 58 (13), 8866–8876. https://doi.org/10.1021/acs.inorgchem.9b01282.

(4)       Bellam, J. B.; Ruiz-Preciado, M. A.; Edely, M.; Szade, J.; Jouanneaux, A.; Kassiba, A. H. Visible-Light Photocatalytic Activity of Nitrogen-Doped NiTiO₃ Thin Films Prepared by a Co-Sputtering Process. RSC Adv. 2015, 5 (14), 10551–10559. https://doi.org/10.1039/C4RA12516A.

(5)       Merupo, V. I.; Velumani, S.; Oza, G.; Makowska-Janusik, M.; Kassiba, A. Structural, Electronic and Optical Features of Molybdenum-Doped Bismuth Vanadium Oxide. Materials Science in Semiconductor Processing 2015, 31, 618–623. https://doi.org/10.1016/j.mssp.2014.12.057.

(6)       Merupo, V.-I.; Velumani, S.; Ordon, K.; Errien, N.; Szade, J.; Kassiba, A.-H. Structural and Optical Characterization of Ball-Milled Copper-Doped Bismuth Vanadium Oxide (BiVO₄). CrystEngComm 2015, 17 (17), 3366–3375. https://doi.org/10.1039/C5CE00173K.

(7)       Merupo, V. I.; Velumani, S.; Abramova, A.; Ordon, K.; Makowska-Janusik, M.; Kassiba, A. Cu, Mo-Doped and Pristine-BiVO4 Thin Films Prepared by Rf Sputtering Process for Photocatalytic Applications. J Mater Sci: Mater Electron 2018, 29 (18), 15770–15775. https://doi.org/10.1007/s10854-018-9241-7.

(8)       Vargas Hernández, J.; Coste, S.; García Murillo, A.; Carrillo Romo, F.; Kassiba, A. Effects of Metal Doping (Cu, Ag, Eu) on the Electronic and Optical Behavior of Nanostructured TiO₂. Journal of Alloys and Compounds 2017, 710, 355–363. https://doi.org/10.1016/j.jallcom.2017.03.275.

(9)       Merupo, V. I.; Velumani, S.; Oza, G.; Tabellout, M.; Bizarro, M.; Coste, S.; Kassiba, A. H. High Energy Ball-Milling Synthesis of Nanostructured Ag-Doped and BiVO₄ -Based Photocatalysts. ChemistrySelect 2016, 1 (6), 1278–1286. https://doi.org/10.1002/slct.201600090.

(10)     Ordon, K.; Merupo, V. I.; Coste, S.; Noel, O.; Errien, N.; Makowska-Janusik, M.; Kassiba, A. hadi. Charge-Transfer Peculiarities in Mesoporous BiVO₄ Surfaces with Anchored Indoline Dyes. Appl Nanosci 2018, 8 (8), 1895–1905. https://doi.org/10.1007/s13204-018-0891-9.

(11)     Ruiz Preciado, M. A.; Kassiba, A.; Morales-Acevedo, A.; Makowska-Janusik, M. Vibrational and Electronic Peculiarities of NiTiO₃ Nanostructures Inferred from First Principle Calculations. RSC Adv. 2015, 5 (23), 17396–17404. https://doi.org/10.1039/C4RA16400H.

(12)     Ordon, K.; Kassiba, A.; Makowska-Janusik, M. Electronic, Optical and Vibrational Features of BiVO₄ Nanostructures Investigated by First-Principles Calculations. RSC Adv. 2016, 6 (112), 110695–110705. https://doi.org/10.1039/C6RA20605K.

(13)     Clavier, B.; Baptiste, T.; Massuyeau, F.; Jouanneaux, A.; Guiet, A.; Boucher, F.; Fernandez, V.; Roques, C.; Corbel, G. Enhanced Bactericidal Activity of Brucite through Partial Copper Substitution. J. Mater. Chem. B 2020, 8 (1), 100–113. https://doi.org/10.1039/C9TB01927H.

(14)     Clavier, B.; Baptiste, T.; Barbieriková, Z.; Hajdu, T.; Guiet, A.; Boucher, F.; Brezová, V.; Roques, C.; Corbel, G. Hydration and Bactericidal Activity of Nanometer- and Micrometer-Sized Particles of Rock Salt-Type Mg_1-xCu_xO Oxides. Materials Science and Engineering: C 2021, 123, 111997. https://doi.org/10.1016/j.msec.2021.111997.

(15)     Clavier, B.; Baptiste, T.; Zhadan, A.; Guiet, A.; Boucher, F.; Brezová, V.; Roques, C.; Corbel, G. Understanding the Bactericidal Mechanism of Cu(OH)₂ Nanorods in Water through Mg-Substitution: High Production of Toxic Hydroxyl Radicals by Non-Soluble Particles. J. Mater. Chem. B 2022, 10 (5), 779–794. https://doi.org/10.1039/D1TB02233D.

(16)      Clavier, B.; Zhadan, A.; Baptiste, T.; Boucher, F.; Guiet, A.; Porcher, F.; Brezová, V.; Roques C.; Corbel, G. Revisiting Mg solubility in CuO nanorods: limit probed by neutron diffraction and effect on the particle toxicity towards bacteria in water. Dalton transactions, 2022, 51, 8411-8424. https://doi.org/10.1039/d2dt00352j