Efficient photo-oxidation of NOx by Sn doped blue TiO2 nanoparticles

Martinez-Oviedo, Adriana; Ray, Schindra Kumar; Nguyen, Hong-Quang

doi:10.1016/j.jphotochem.2018.10.032

Cited by 33 publications

(11 citation statements)

References 32 publications

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“…Doping the TiO 2 surface, or forming a nano-composite with other species, such as noble metals, metal-oxides and carbon, is generally aimed at increasing the activity of the material, chiefly through shifting the band gap towards the visible region and preventing electron/hole recombination. There has been extensive research into this, with studies investigating doping with Fe [96,98,99], Fe 2 O 3 [100], Cu [98] , Sn [101], Zn [102], Zn-S [103], Au-N [104], Al 2 O 3 [105], Pd [88,106], Pt [107], Pt/Au [108], Ag [109,110], g-C 3 N 4 [111,112], graphene [113], Sn and Ce/Mn-graphene [114], other forms of carbon [53,115] and minerals from clay [116]. Many of these have previously been summarised in tables in Martinez et al [98,101].…”

Section: Dopingmentioning

confidence: 99%

A Review of Photocatalytic Materials for Urban NOx Remediation

et al. 2021

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NOx is a pervasive pollutant in urban environments. This review assesses the current state of the art of photocatalytic oxidation materials, designed for the abatement of nitrogen oxides (NOx) in the urban environment, and typically, but not exclusively based on titanium dioxide (TiO2). Field trials with existing commercial materials, such as paints, asphalt and concrete, in a range of environments including street canyons, car parks, tunnels, highways and open streets, are considered in-depth. Lab studies containing the most recent developments in the photocatalytic materials are also summarised, as well as studies investigating the impact of physical parameters on their efficiency. It is concluded that this technology may be useful as a part of the measures used to lower urban air pollution levels, yielding ∼2% NOx removal in the immediate area around the surface, for optimised TiO2, in some cases, but is not capable of the reported high NOx removal efficiencies >20% in outdoor urban environments, and can in some cases lower air quality by releasing hazardous by-products. However, research into new material is ongoing. The reason for the mixed results in the studies reviewed, and massive range of removal efficiencies reported (from negligible and up to >80%) is mainly the large range of testing practices used. Before deployment in individual environments site-specific testing should be performed, and new standards for lab and field testing should be developed. The longevity of the materials and their potential for producing hazardous by-products should also be considered.

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Section: Dopingmentioning

confidence: 99%

A Review of Photocatalytic Materials for Urban NOx Remediation

et al. 2021

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“…[27] Therefore, development of visible (VIS) lightresponsive photocatalysts with higher stability, selectivity and activity is highly desired. For this purpose, different strategies have been adopted to enhance the photocatalytic efficiency of TiO 2 in the VIS light region such as non-metal [28][29][30] and precious/non-precious metal [15,16,[31][32][33][34][35][36] doping, functionalization with quantum dots (QDs) [37][38][39] and surface modifications with polymers. [40,41] An important requirement in PHONOS applications is the high selectivity of the designed photocatalyst toward nitrate (NO 3 À ) formation, which is the preferred final storage product of the photocatalytic NO x abatement process.…”

Section: Introductionmentioning

confidence: 99%

Core‐crown Quantum Nanoplatelets with Favorable Type‐II Heterojunctions Boost Charge Separation and Photocatalytic NO Oxidation on TiO₂

et al. 2020

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Functionalization of TiO2 (P25) with oleic acid‐capped CdSe(core)/CdSeTe(crown) quantum‐well nanoplatelets (NPL) yielded remarkable activity and selectivity toward nitrate formation in photocatalytic NOx oxidation and storage (PHONOS) under both ultraviolet (UV‐A) and visible (VIS) light irradiation. In the NPL/P25 photocatalytic system, photocatalytic active sites responsible for the NO(g) photo‐oxidation and NO2 formation reside mostly on titania, while the main function of the NPL is associated with the photocatalytic conversion of the generated NO2 into the adsorbed NO3− species, significantly boosting selectivity toward NOx storage. Photocatalytic improvement in NOx oxidation and storage upon NPL functionalization of titania can also be associated with enhanced electron‐hole separation due to a favorable Type‐II heterojunction formation and photo‐induced electron transfer from the CdSeTe crown to the CdSe core of the quantum well system, where the trapped electrons in the CdSe core can later be transferred to titania. Re‐usability of NPL/P25 system was also demonstrated upon prolonged use of the photocatalyst, where NPL/P25 catalyst surpassed P25 benchmark in all tests.

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“…The promotion of TiO 2 photocatalysts with Sn species, either by doping with Sn ions or by composite formation with SnO x , has been successfully applied to numerous fields, such as the photocatalytic degradation of water [ 1 , 2 ] and air pollutants [ 3 , 4 , 5 ], photovoltaics [ 6 ], and hydrogen production [ 7 , 8 ]. Because one of the main disadvantages of TiO 2 photocatalysts is their limited activity in the visible region, due to the large band gap (≥3.0 eV) [ 9 ], doping with Sn 2+ species has raised interest as a strategy for promoting TiO 2 visible light activity [ 1 , 2 , 3 , 5 , 8 ]. Visible light absorption of TiO 2 doped with Sn 2+ has been related to a band gap narrowing caused by a shift in the position of the valence band, consisting of Sn 5s and O 2p orbitals [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

“…Visible light absorption of TiO 2 doped with Sn 2+ has been related to a band gap narrowing caused by a shift in the position of the valence band, consisting of Sn 5s and O 2p orbitals [ 3 ]. Martinez-Oviedo et al, on the contrary, reported an extensive formation of Ti 3+ species in Sn 2+ -doped TiO 2 , leading to a marked blue color [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

“…The reported syntheses of Sn 2+ -doped TiO 2 use SnCl 2 as a starting material and require reducing conditions [ 5 , 8 ], leading to materials with limited thermal stability [ 1 , 10 , 11 ]. As a matter of fact, thermal treatments in non-reducing atmosphere result in the conversion of Sn 2+ in Sn 4+ , leading to the loss of visible-light absorption.…”

Section: Introductionmentioning

confidence: 99%

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Role of Synthetic Parameters on the Structural and Optical Properties of N,Sn-Copromoted Nanostructured TiO2: A Combined Ti K-Edge and Sn L2,3-Edges X-ray Absorption Investigation

et al. 2020

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Sn-modification of TiO2 photocatalysts has been recently proposed as a suitable strategy to improve pollutant degradation as well as hydrogen production. In particular, visible light activity could be promoted by doping with Sn2+ species, which are, however, thermally unstable. Co-promotion with N and Sn has been shown to lead to synergistic effects in terms of visible light activity, but the underlying mechanism has, so far, been poorly understood due to the system complexity. Here, the structural, optical, and electronic properties of N,Sn-copromoted, nanostructured TiO2 from sol-gel synthesis were investigated: the Sn/Ti molar content was varied in the 0–20% range and different post-treatments (calcination and low temperature hydrothermal treatment) were adopted in order to promote the sample crystallinity. Depending on the adopted post-treatment, the optical properties present notable differences, which supports a combined role of Sn dopants and N-induced defects in visible light absorption. X-ray absorption spectroscopy at the Ti K-edge and Sn L2,3-edges shed light onto the electronic properties and structure of both Ti and Sn species, evidencing a marked difference at the Sn L2,3-edges between the samples with 20% and 5% Sn/Ti ratio, showing, in the latter case, the presence of tin in a partially reduced state.

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Efficient photo-oxidation of NOx by Sn doped blue TiO2 nanoparticles

Cited by 33 publications

References 32 publications

A Review of Photocatalytic Materials for Urban NOx Remediation

A Review of Photocatalytic Materials for Urban NOx Remediation

Core‐crown Quantum Nanoplatelets with Favorable Type‐II Heterojunctions Boost Charge Separation and Photocatalytic NO Oxidation on TiO₂

Role of Synthetic Parameters on the Structural and Optical Properties of N,Sn-Copromoted Nanostructured TiO2: A Combined Ti K-Edge and Sn L2,3-Edges X-ray Absorption Investigation

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Efficient photo-oxidation of NOx by Sn doped blue TiO2 nanoparticles

Cited by 33 publications

References 32 publications

A Review of Photocatalytic Materials for Urban NOx Remediation

A Review of Photocatalytic Materials for Urban NOx Remediation

Core‐crown Quantum Nanoplatelets with Favorable Type‐II Heterojunctions Boost Charge Separation and Photocatalytic NO Oxidation on TiO2

Role of Synthetic Parameters on the Structural and Optical Properties of N,Sn-Copromoted Nanostructured TiO2: A Combined Ti K-Edge and Sn L2,3-Edges X-ray Absorption Investigation

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Core‐crown Quantum Nanoplatelets with Favorable Type‐II Heterojunctions Boost Charge Separation and Photocatalytic NO Oxidation on TiO₂