Observation of visible light activated photocatalytic degradation of stearic acid on thin films of tantalum oxynitride synthesized by aerosol assisted chemical vapour deposition

Cosham, Samuel D.; Celorrio, Verónica; Kulak, Alexander N.; Hyett, Geoffrey

doi:10.1039/c8dt04638g

Cited by 12 publications

(10 citation statements)

References 62 publications

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“…However, having stated this, such comparison can be made with an attempt to account for differences in light intensity, assuming a linear dependence on the rate. Prior work from this group under identical reaction conditions with a film of tantalum oxynitride found an initial rate 2.5 × 10 13 molecules min –1 or approximately half that observed with the co-catalyst-loaded SrNbO 2 N film reported here …”

Section: Resultssupporting

confidence: 59%

“…Prior work from this group under identical reaction conditions with a film of tantalum oxynitride found an initial rate 2.5 × 10 13 molecules min −1 or approximately half that observed with the co-catalyst-loaded SrNbO 2 N film reported here. 52 Prior work with visible light degradation of stearic acid on modified titanium dioxide has also been reported. Adjusting for light intensity, nitrogen-doped titania films have been reported with an initial rate of 0.03 × 10 13 molecules min −1 , while fluorinated titania films have a reported rate of 0.2× 10 13 molecules min −1 .…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Demonstration of Visible Light-Activated Photocatalytic Self-Cleaning by Thin Films of Perovskite Tantalum and Niobium Oxynitrides

Iborra-Torres

Kulak

Palgrave³

et al. 2020

ACS Appl. Mater. Interfaces

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Metal oxynitrides adopting the perovskite structure have been shown to be visible light-activated photocatalysts, and therefore, they have potential as self-cleaning materials where surface organic pollutants can be removed by photomineralization. In this work, we establish a route for the deposition of thin films for seven perovskite oxynitrides, CaTaO 2 N, SrTaO 2 N, BaTaO 2 N, LaTaON 2 , EuTaO 2 N, SrNbO 2 N, and LaNbON 2 , on quartz and alumina substrates using dip-coating of a polymer gel to form an amorphous oxide precursor film, followed by ammonolysis. The initially deposited oxide films were annealed at 800 °C, followed by ammonolysis at temperatures from 850 to 1000 °C. The perovskite oxynitride thin films were characterized using XRD and EDX, with band gaps determined using Tauc plots derived from UV−vis spectroscopic data. A cobalt oxide co-catalyst was deposited onto each film by drop casting, and the photocatalytic activity assessed under visible light using dichloroindophenol dye degradation in the presence of a sacrificial oxidant. The light source used was a solar simulator equipped with a 400 nm cut-off filter. The dye degradation test demonstrated photocatalytic activity in all samples except EuTaO 2 N and BaTaO 2 N. The three most active samples were SrNbO 2 N, CaTaO 2 N, and SrTaO 2 N. The cobalt oxide loading was optimized for these three films and found to be 0.3 μg cm −2 . Further, catalytic tests were conducted using stearic acid degradation, and this found the film of SrNbO 2 N with the cobalt oxide co-catalyst to be the most active for complete mineralization of this model pollutant.

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Section: Resultssupporting

confidence: 59%

Section: ■ Results and Discussionmentioning

confidence: 99%

Demonstration of Visible Light-Activated Photocatalytic Self-Cleaning by Thin Films of Perovskite Tantalum and Niobium Oxynitrides

Iborra-Torres

Kulak

Palgrave³

et al. 2020

ACS Appl. Mater. Interfaces

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“…The preference for HPPs is due mainly to their important, characteristic features which include: (i) ambient operating conditions, such as temperature and pressure (ii) potential mineralization of parent and transformation products without secondary pollution and (iii) economic feasibility and efficiency [44]. A broad class of semiconductor nanomaterials have been explored for HPP processes and could be broadly classified as metals, sulfides [45,46], oxides [47,48], nitrides [49,50], oxysulfides [51], oxyhalides [52,53] and oxynitrides [54,55]. The activity of semiconductors in light-induced redox process sensitization arise from the electronic structure of the metal atoms in chemical compounds.…”

Section: Therapeutic Classmentioning

confidence: 99%

Graphene-Based Composites as Catalysts for the Degradation of Pharmaceuticals

Olatunde

Onwudiwe

2021

IJERPH

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The incessant release of pharmaceuticals into the aquatic environment continues to be a subject of increasing concern. This is because of the growing demand for potable water sources and the potential health hazards which these pollutants pose to aquatic animals and humans. The inability of conventional water treatment systems to remove these compounds creates the need for new treatment systems in order to deal with these class of compounds. This review focuses on advanced oxidation processes that employ graphene-based composites as catalysts for the degradation of pharmaceuticals. These composites have been identified to possess enhanced catalytic activity due to increased surface area and reduced charge carrier recombination. The techniques employed in synthesizing these composites have been explored and five different advanced oxidation processes—direct degradation process, chemical oxidation process, photocatalysis, electrocatalyis processes and sonocatalytic/sono-photocatalytic processes—have been studied in terms of their enhanced catalytic activity. Finally, a comparative analysis of the processes that employ graphene-based composites was done in terms of process efficiency, reaction rate, mineralization efficiency and time required to achieve 90% degradation.

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“…A key component of the coating solution used to produce the initial haze is stearic acid, SA, possibly because it appears an appropriate test pollutant for self-cleaning glass, given it is one of the most common saturated fatty acids found in nature and is in all fingerprints [13]. Not surprisingly, therefore, in research, the photocatalytic mineralisation of SA, is one of the most commonly employed reactions used to demonstrate the self-cleaning action of new photocatalytic films [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]; the reaction associated with this process can be summarised as follows, where E bg is the bandgap energy of the photocatalyst, which is ca. 3.2 eV for anatase TiO 2 , for example.…”

Section: Introductionmentioning

confidence: 99%

“…3.2 eV for anatase TiO 2 , for example. Interestingly, the number of studies of the kinetics of Reaction (1) appear limited, with most focussed on a system in which the SA film is on top of the photocatalytic film [14][15][16][17][18][19][20][21][22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Kinetics of stearic acid destruction on TiO2 ‘self-cleaning’ films revisited

Alofi

O’Rourke

Mills

2022

Photochem Photobiol Sci

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The photocatalytic oxidation of stearic acid, SA, by O2 is a common test method used to assess the activity of new materials and underpins a standard test for self-cleaning activity. The kinetics of this process have been well-studied and are often interpreted using one of two simple models, which are revisited here in this overview. The first model is based on the common scenario of a SA layer on top of an all-photocatalyst layer which yields zero order kinetics, for which it is suggested that all the reaction sites are occupied by SA during the bulk of the photocatalytic process. An important, but rarely noted feature of this system is that the rate of SA removal depends directly upon the fraction of absorbed ultra-bandgap radiation, which suggests that the photocatalyst particles are extensively networked, thereby allowing the photogenerated electrons and holes to move rapidly and efficiently to the surface to effect the destruction of SA. The second kinetic model has been used to describe the first order kinetics of SA removal observed for mesoporous photocatalytic films comprised of isolated photocatalyst particles, in which the SA is inside (rather than on top) of the photocatalytic film, and is developed further here. It is shown that, contrary to previous reports, this model is not appropriate for porous photocatalytic films in which the particles are extensively networked, such as ones based on powders or sol–gel films, even though they too may exhibit decay kinetics where the order is > 0. The reason for the latter kinetics appears to be a distribution of reactivities through such films, i.e. high and low activity sites. Graphical abstract

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Observation of visible light activated photocatalytic degradation of stearic acid on thin films of tantalum oxynitride synthesized by aerosol assisted chemical vapour deposition

Abstract: Demonstration of photocatalytic stearic acid mineralisation by thin films of tantalum oxynitride.

Cited by 12 publications

References 62 publications

Demonstration of Visible Light-Activated Photocatalytic Self-Cleaning by Thin Films of Perovskite Tantalum and Niobium Oxynitrides

Demonstration of Visible Light-Activated Photocatalytic Self-Cleaning by Thin Films of Perovskite Tantalum and Niobium Oxynitrides

Graphene-Based Composites as Catalysts for the Degradation of Pharmaceuticals

Kinetics of stearic acid destruction on TiO2 ‘self-cleaning’ films revisited

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