Modulating the photocatalytic activity of TiO2 (P25) with lanthanum and graphene oxide

Coelho, Leticya Lais; Hotza, Dachamir; Estrella, Arthur S.; Amorim, Suélen Maria de; Puma, Gianluca Li; Moreira, Regina de Fátima Peralta Muniz

doi:10.1016/j.jphotochem.2018.11.048

Cited by 17 publications

(5 citation statements)

References 49 publications

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Section: Resultssupporting

confidence: 67%

“…The significant decrease of k′ CBZ from pH 6.0 to 7.0 in the UV 365 /TiO 2 /chlorine process is mainly attributed to the significant decrease in steady-state concentrations of HO• and Cl• (Figure . 2) caused by change of the surface charge of TiO 2 , because TiO 2 has a point of zero charge of 6.2. 33 A similar decrease was also observed in the UV 365 /TiO 2 process (Figure S12) because of the same reason. Moreover, the highest k′ CBZ at pH 6.0 is also attributed to the production of highly reactive Cl• (Figure 2), whose secondorder rate constant (3.3 ± 0.26 × 10 10 M −1 s −1 ) toward CBZ is even higher than HO•.…”

Section: Methodssupporting

confidence: 68%

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Near-Ultraviolet Light-Driven Photocatalytic Chlorine Activation Process with Novel Chlorine Activation Mechanisms

2021

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In this study, the near-ultraviolet (near-UV) light-driven TiO2 photocatalytic chlorine activation process, termed as the UV365/TiO2/chlorine process, degrades a representative recalcitrant micropollutant, carbamazepine (CBZ), at an apparent first-order rate constant (k CBZ ′) that is 34.2 and 3.9 times higher than those without TiO2 and chlorine, respectively. In this process, chlorine serves a more important role as a catalyst to enhance the yield of hydroxyl radicals (HO·) without being consumed, in addition to its role as a radical precursor to produce HO· and reactive chlorine species. k CBZ ′ increased with increasing TiO2 dosages from 1.0 to 20.0 mg/L and light intensities from 0.1 to 0.33 mW/cm2 and with decreasing chlorine dosages from 5.0 to 1.0 mgCl2/L. Increasing pH increased the overall radical concentrations but transformed HO· and Cl· to less reactive ClO·, leading to a decreasing k CBZ ′ from pH 6.0 to 9.0. The dual roles of chlorine in the process enabled the rapid CBZ degradation at a chlorine dosage about 1/20 to that of the conventional UVC/chlorine process, at a TiO2 dosage about 1/200 to that of the UVC/TiO2 process and at an electrical energy per order of CBZ degradation at least 2-order of magnitude lower than those of the existing UVC-based processes.

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Section: Resultssupporting

confidence: 67%

Section: Methodssupporting

confidence: 68%

Near-Ultraviolet Light-Driven Photocatalytic Chlorine Activation Process with Novel Chlorine Activation Mechanisms

2021

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“…Lanthanum in its ionic form (La 3+ ) has the ability to generate surface defects and titanium and oxygen vacancies. This possibly occurs because La 3+ (1.15 Å) has a larger atomic radius than Ti 4+ (0.68 Å) [ 57 , 58 ]. Consequently, the La 3+ ion cannot replace the Ti 4+ ions in the semiconductor lattice, so it only adsorbs on the surface, forming Ti–O–Ln 3+ bonds with ionic/covalent characteristics [ 44 ], leading to an imbalance in the surface charges of the crystalline structure of TiO 2 .…”

Section: Discussionmentioning

confidence: 99%

La3+’s Effect on the Surface (101) of Anatase for Methylene Blue Dye Removal, a DFT Study

2022

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Density functional theory (DFT) is a widely used method for studying matter at the quantum level. In this study, the surface (101) of TiO2 (anatase phase) was considered to develop DFT calculations and explain the effect of lanthanum ion (La3+) on the electronic properties, adsorption capacity, and photocatalytic activity of this semiconductor. Due to the presence of the La3+ ion, the bandgap energy value of La/TiO2 (2.98 eV) was lower than that obtained for TiO2 (3.21 eV). TDOS analysis demonstrated the presence of hybrid levels in La/TiO2 composed mainly of O2p and La5d orbitals. The chemical nature of the La-O bond was estimated from PDOS analysis, Bader charge analysis, and ELF function, resulting in a polar covalent type, due to the combination of covalent and ionic bonds. In general, the adsorption of the methylene blue (MB) molecule on the surface (101) of La/TiO2 was energetically more favorable than on the surface (101) of TiO2. The thermodynamic stability of doping TiO2 with lanthanum was deduced from the negative heat-segmentation values obtained. The evidence from this theoretical study supports the experimental results reported in the literature and suggests that the semiconductor La/TiO2 is a potential catalyst for applications that require sunlight.

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“…Titanium dioxide (TiO 2 ) comprises a high fraction of nanoparticle production − due to its widespread use in consumer and industrial products. Potential environmental impacts of TiO 2 have been widely assessed under UV illumination because titania, a wide band-gap semiconductor (3.0–3.2 eV), only absorbs UV light (<5% of sunlight). − However, limited attention has been given to the effects of nTiO 2 upon exposure to visible light in the presence of photosensitizing dissolved organic matter (DOM) that abounds in natural waters.…”

Section: Introductionmentioning

confidence: 99%

Visible-Light Activation of a Dissolved Organic Matter–TiO₂ Complex Mediated via Ligand-to-Metal Charge Transfer

Bui¹,

Park

Alvarez

et al. 2022

Environ. Sci. Technol.

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Given the widespread use of TiO2, its release into aquatic systems and complexation with dissolved organic matter (DOM) are highly possible, making it important to understand how such interactions affect photocatalytic activity under visible light. Here, we show that humic acid/TiO2 complexes (HA/TiO2) exhibit photoactivity (without significant electron–hole activation) under visible light through ligand-to-metal charge transfer (LMCT). The observed visible-light activities for pollutant removal and bacterial inactivation are primarily linked to the generation of H2O2 via the conduction band. By systematically considering molecular-scale interactions between TiO2 and organic functional groups in HA, we find a key role of phenolic groups in visible-light absorption and H2O2 photogeneration. The photochemical formation of H2O2 in river waters spiked with TiO2 is notably elevated above naturally occurring H2O2 generated from background organic constituents due to LMCT contribution. Our findings suggest that H2O2 generation by HA/TiO2 is related to the quantity and functional group chemistry of DOM, which provides chemical insights into photocatalytic activity and potential ecotoxicity of TiO2 in environmental and engineered systems.

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Modulating the photocatalytic activity of TiO2 (P25) with lanthanum and graphene oxide

Cited by 17 publications

References 49 publications

Near-Ultraviolet Light-Driven Photocatalytic Chlorine Activation Process with Novel Chlorine Activation Mechanisms

Near-Ultraviolet Light-Driven Photocatalytic Chlorine Activation Process with Novel Chlorine Activation Mechanisms

La3+’s Effect on the Surface (101) of Anatase for Methylene Blue Dye Removal, a DFT Study

Visible-Light Activation of a Dissolved Organic Matter–TiO₂ Complex Mediated via Ligand-to-Metal Charge Transfer

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Modulating the photocatalytic activity of TiO2 (P25) with lanthanum and graphene oxide

Cited by 17 publications

References 49 publications

Near-Ultraviolet Light-Driven Photocatalytic Chlorine Activation Process with Novel Chlorine Activation Mechanisms

Near-Ultraviolet Light-Driven Photocatalytic Chlorine Activation Process with Novel Chlorine Activation Mechanisms

La3+’s Effect on the Surface (101) of Anatase for Methylene Blue Dye Removal, a DFT Study

Visible-Light Activation of a Dissolved Organic Matter–TiO2 Complex Mediated via Ligand-to-Metal Charge Transfer

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Visible-Light Activation of a Dissolved Organic Matter–TiO₂ Complex Mediated via Ligand-to-Metal Charge Transfer