Enhanced photocatalytic degradation rates at rutile TiO2 photocatalysts modified with redox co-catalysts

Neubert, Susann; Pulišová, P.; Wiktor, Christian; Weide, Philipp; Mei, Bastian; Guschin, Dmitrii A.; Fischer, Roland A.; Beránek, Radim

doi:10.1016/j.cattod.2013.11.046

Cited by 32 publications

(35 citation statements)

References 43 publications

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“…The optimum amount (actual loading) of Cu and Fe leading to maximum photocatalytic degradation rates of a test organic pollutant (4-chlorophenol, 4-CP) was found to be very low: 0.12 wt% for Cu and 0.13 wt% for Fe. 38 For comparison, rutile TiO 2 decorated with Pt nanoparticles (optimum Pt loading of 0.34 wt%) was prepared by conventional photoreduction method [44][45][46] and served as a benchmark. After 3 hours of simulated solar irradiation ( > 320 nm) the TiO 2 (R)-Cu and TiO 2 (R)-Fe induced 4-CP degradation of 80% and 54%, respectively (Figure 2a), a significant enhancement as compared to the photoactivity of pristine rutile TiO 2 (25%).…”

Section: Photocatalytic Activitymentioning

confidence: 99%

“…In a similar vein to the work of Ohno et al 28 and Hashimoto et al, [29][30][31][32] we have recently impregnated rutile TiO 2 powders with small amounts of copper(II) or iron(III) nitrate. 38 After a mild heat treatment, such surface-modified rutile photocatalysts exhibited highly enhanced activity, as compared to pristine rutile TiO 2 , in photocatalytic degradation of 4-chlorophenol (4-CP) in aqueous phase under simulated solar light irradiation ( > 320 nm). We tentatively suggested that small CuO x and FeO x clusters were formed on the TiO 2 surface after impregnation and drying, and that these small clusters allowed for improved catalysis of dioxygen reduction by photogenerated electron, leading to enhanced photoactivity.…”

Section: Introductionmentioning

confidence: 99%

“…We tentatively suggested that small CuO x and FeO x clusters were formed on the TiO 2 surface after impregnation and drying, and that these small clusters allowed for improved catalysis of dioxygen reduction by photogenerated electron, leading to enhanced photoactivity. 38 Herein we report our further detailed structural, spectroscopic, and theoretical investigations of these surface-modified rutile materials, and compare their photoactivity with rutile TiO 2 modified by conventional deposition of platinum nanoparticles. Most importantly, we provide a conclusive experimental evidence for the presence of single Cu(II) and Fe(III) cocatalytic sites in our highly active photocatalysts, which differentiates them from conventional composites of TiO 2 with metal or metal oxide particles.…”

Section: Introductionmentioning

confidence: 99%

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Highly efficient rutile TiO₂photocatalysts with single Cu(ii) and Fe(iii) surface catalytic sites

et al. 2016

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Highly active photocatalysts were obtained by impregnation of nanocrystalline rutile TiO 2 powders with small amounts of Cu(II) and Fe(III) ions, resulting in the enhancement of initial rates of photocatalytic degradation of 4-chlorophenol in water by the factor of 7 and 4, compared to pristine rutile, respectively. Detailed structural analysis by EPR and X-ray absorption spectroscopy (EXAFS) revealed that Cu(II) and Fe(III) are present as single species at the rutile surface. The mechanism of the photoactivity enhancement was elucidated by a combination of DFT calculations and detailed experimental mechanistic studies including photoluminescence measurements, photocatalytic experiments using scavengers, OH radical detection, and photopotential transient measurements. The results demonstrate that the single Cu(II) and Fe(III) ions act as effective cocatalytic sites, enhancing the charge separation, catalyzing "dark" redox reactions at the interface, improving thus the normally very low quantum yields of UV light-activated TiO 2 photocatalysts. The exact mechanism of the photoactivity enhancement differs depending on the nature of the cocatalyst. Cu(II)decorated samples exhibit fast transfer of photogenerated electrons to Cu(II/I) sites, followed by enhanced catalysis of dioxygen reduction, resulting in improved charge separation and higher photocatalytic degradation rates. At Fe(III)-modified rutile the rate of dioxygen reduction is not improved and the photocatalytic enhancement is attributed to higher production of highly oxidizing hydroxyl radicals produced by alternative oxygen reduction pathways opened by the presence of catalytic Fe(III/II) sites. Importantly, it was demonstrated that excessive heat treatment (at 450 °C) of photocatalysts leads to loss of activity due to migration of Cu(II) and Fe(III) ions from TiO 2 surface to the bulk, accompanied by formation of oxygen vacancies. The demonstrated variety of mechanisms of photoactivity enhancement at single site catalyst-modified photocatalysts holds promise for developing further tailored single-site-modified photocatalysts for various applications. 19calculations that have the surface exposed to vacuum. Furthermore, the oxygen atom of the cluster forms a short bond of 1.79 Å with a fivefold coordinated titanium atom of the surface, closing a TiO 6 octahedra. Figure 10. (a) DOS of the TiO 2 (R)-Cu system, spin-up channel only, aligned to the DOS of the ideal TiO 2 (R) surface. (b) The spin up channel DOS of the final relaxed electron polaron system for the TiO 2 (R)-Cu system. Cu contribution shown. The zero of the x-axis is fitted to the VBM for both plots.The electronic structure of TiO 2 (R)-Cu is shown in Figure 10a. The Cu atom has a significant presence on the CBE. This is primarily due to the Cu d-states. Further, we compare the position of the decorated rutile TiO 2 surface to the bare rutile surface, by comparison and alignment of the electrostatic potential in the vacuum region. 61 When the alignment is taken into action, the Cu-state is margi...

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Section: Photocatalytic Activitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Highly efficient rutile TiO₂photocatalysts with single Cu(ii) and Fe(iii) surface catalytic sites

et al. 2016

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“…Many researchers at photocatalytic field are focusing [16,17]. On the other hand, efforts to investigate photocatalytic activity of rutile TiO 2 or mixedphase of these crystal phases are continued [18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Influence of oxidation process on photocatalytic activity of photocatalyst coatings by mechanical coating technique

Kobayashi

Hao

et al. 2015

Materials Science in Semiconductor Processing

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“…Nanocrystalline rutile TiO 2 powders were modified with small amounts of CuO x and FeO x clusters by impregnation and drying. The modified rutile samples exhibited drastically enhanced photocatalytic degradation of 4-chlorophenol under UV-vis irradiation [32]. Nakamura et al [36] showed improvement of visible light responsivity of rutile TiO 2 nanorods by site-selective modification of iron (III) ion on newly exposed faces formed by chemical etching treatment.…”

Section: Introductionmentioning

confidence: 99%

Preparation and optical properties of iron-modified titanium dioxide obtained by sol–gel method

et al. 2015

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Enhanced photocatalytic degradation rates at rutile TiO2 photocatalysts modified with redox co-catalysts

Cited by 32 publications

References 43 publications

Highly efficient rutile TiO₂photocatalysts with single Cu(ii) and Fe(iii) surface catalytic sites

Highly efficient rutile TiO₂photocatalysts with single Cu(ii) and Fe(iii) surface catalytic sites

Influence of oxidation process on photocatalytic activity of photocatalyst coatings by mechanical coating technique

Preparation and optical properties of iron-modified titanium dioxide obtained by sol–gel method

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Enhanced photocatalytic degradation rates at rutile TiO2 photocatalysts modified with redox co-catalysts

Cited by 32 publications

References 43 publications

Highly efficient rutile TiO2photocatalysts with single Cu(ii) and Fe(iii) surface catalytic sites

Highly efficient rutile TiO2photocatalysts with single Cu(ii) and Fe(iii) surface catalytic sites

Influence of oxidation process on photocatalytic activity of photocatalyst coatings by mechanical coating technique

Preparation and optical properties of iron-modified titanium dioxide obtained by sol–gel method

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Highly efficient rutile TiO₂photocatalysts with single Cu(ii) and Fe(iii) surface catalytic sites

Highly efficient rutile TiO₂photocatalysts with single Cu(ii) and Fe(iii) surface catalytic sites