Role of defects on TiO<sub>2</sub>/SiO<sub>2</sub> composites for boosting photocatalytic water splitting

Saputera, Wibawa Hendra; Rizkiana, Jenny; Wulandari, Winny; Sasongko, Dwiwahju

doi:10.1039/d0ra05745b

Cited by 13 publications

(7 citation statements)

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“…Titanium dioxide (TiO 2 ) is the most widely used semiconductor for photocatalyst due to its wide band gap, lower price, high photocatalytic activity, considerable photostability, non-toxicity, ample availability, insolubility in aqueous solution, and chemical and biological inertness [ 38 ]. Currently, TiO 2 materials are used for many applications, including water splitting [ 39 ], water treatment [ 40 ], air pollution treatment [ 10 ], solar cells [ 41 ], and many other applications ( Figure 12 ).…”

Section: Selection Of Materials For Photocatalytic Methane To Methano...mentioning

confidence: 99%

Recent Advances in Photocatalytic Oxidation of Methane to Methanol

et al. 2022

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Methane is one of the promising alternatives to non-renewable petroleum resources since it can be transformed into added-value hydrocarbon feedstocks through suitable reactions. The conversion of methane to methanol with a higher chemical value has recently attracted much attention. The selective oxidation of methane to methanol is often considered a “holy grail” reaction in catalysis. However, methanol production through the thermal catalytic process is thermodynamically and economically unfavorable due to its high energy consumption, low catalyst stability, and complex reactor maintenance. Photocatalytic technology offers great potential to carry out unfavorable reactions under mild conditions. Many in-depth studies have been carried out on the photocatalytic conversion of methane to methanol. This review will comprehensively provide recent progress in the photocatalytic oxidation of methane to methanol based on materials and engineering perspectives. Several aspects are considered, such as the type of semiconductor-based photocatalyst (tungsten, titania, zinc, etc.), structure modification of photocatalyst (doping, heterojunction, surface modification, crystal facet re-arrangement, and electron scavenger), factors affecting the reaction process (physiochemical characteristic of photocatalyst, operational condition, and reactor configuration), and briefly proposed reaction mechanism. Analysis of existing challenges and recommendations for the future development of photocatalytic technology for methane to methanol conversion is also highlighted.

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Section: Selection Of Materials For Photocatalytic Methane To Methano...mentioning

confidence: 99%

Recent Advances in Photocatalytic Oxidation of Methane to Methanol

et al. 2022

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“…In turn, the deconvolution of the O 1s core line revealed three components with their maxima centered at 530.1 eV, 531.8 eV, and 533.3 eV. The assignment of the lowest binding energy component is problematic due to the similar binding energy characteristics for Ag(I)O/Ag(II)O and/or TiO 2 , whereas the other two lines might be assigned to the adsorbed hydroxyl species (OH − ) on the titanium dioxide surface [53] or may correspond to the Si-O-Ti [54,55], respectively. However, considering that the samples were sintered at a high temperature, the probability of the adsorption of the OH − groups was minimal and might have been associated only with the surface.…”

Section: Pristinementioning

confidence: 99%

Innovative Bioactive Ag-SiO2/TiO2 Coating on a NiTi Shape Memory Alloy: Structure and Mechanism of Its Formation

et al. 2020

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In recent years, more and more emphasis has been placed on the development and functionalization of metallic substrates for medical applications to improve their properties and increase their applicability. Today, there are many different types of approaches and materials that are used for this purpose. Our idea was based on a combination of a chemically synthesized Ag-SiO2 nanocomposite and the electrophoretic deposition approach on a NiTi shape memory substrate. As a result, silver-silica coating was developed on a previously passivated alloy, which was then subjected to sintering at 700 °C for 2 h. The micrometer-sized coat-forming material was composed of large agglomerates consisting of silica and a thin film of submicron- and nano- spherical-shaped particles built of silver, carbon, and oxygen. Structurally, the coatings consisted of a combination of nanometer-sized silver-carbonate that was embedded in thin amorphous silica and siloxy network. The temperature impact had forced morphological and structural changes such as the consolidation of the coat-forming material, and the partial coalescence of the silver and silica particles. As a result, a new continuous complex ceramic coating was formed and was analyzed in more detail using the XPS, XRD, and Raman methods. According to the structural and chemical analyses, the deposited Ag-SiO2 nanocomposite material’s reorganization was due to its reaction with a passivated TiO2 layer, which formed an atypical glass-like composite that consisted of SiO2-TiO2 with silver particles that stabilized the network. Finally, the functionalization of the NiTi surface did not block the shape memory effect.

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“…Therefore, many papers have reported the improvement of the TiO 2 photocatalytic activity under visible light by different approaches including modifying the structure to nanoscale, introduction of additives such as carbon (C), silver (Ag), copper (Cu), silicon dioxide (SiO 2 ), and creation of heterostructures [11][12][13]. Recently, studies on the TiO 2 structures for improving the photocatalytic activity have been performed.…”

Section: Introductionmentioning

confidence: 99%

Enhanced visible light photocatalytic activity of nanostructured SiO₂-TiO₂ thin films through optimizing thickness

Darvish,

Masoudi,

Mortezaali

et al. 2023

Phys. Scr.

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Thin films of silicon dioxide-titanium dioxide (SiO2-TiO2) with different thicknesses were deposited by a simple dip-coating method in a repetition behavior followed by heating processes. Choosing the optimum thickness is accounted as an approach for improving photocatalytic and hydrophilicity properties of a thin film. The obtained results from FESEM and AFM characterizations showed that with increasing thickness, the surface roughness increases from 3.089nm to 132.8nm. The XRD patterns indicate the presence of anatase phase for the SiO2-TiO2 thin film. Optical measurements were used to calculate thickness, generation rate of photocarriers, band gap, and refractive index of the samples. Decrease of band gap with increasing thickness makes the layer more proper for photocatalytic activity under visible light. It is obtained that the generation rate of carriers has the highest value (17.16×1024 m-3s-1) for the thickness of 336 nm. PL spectra for the thickness of 336 nm confirmed the presence of defects which reduce the recombination rate and improve charge carrier separation. XPS was used to distinguish the chemical composition. Variation of defect concentrations, number of grain boundaries, and surface roughness with thickness were considered as the main parameters affecting the photocatalytic performance. The highest photodegradation was obtained for 336 nm thick film under illumination of visible light (100% degradation of 40 ml solution of 10 mg/L methylene blue (MB)). This research provides a systematic study on the structural and optical properties of the different thick SiO2-TiO2 films with goal of enhancing photocatalytic activity in the visible light region.

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Role of defects on TiO₂/SiO₂ composites for boosting photocatalytic water splitting

Abstract: Defect engineering of semiconductor photocatalysts is considered as an evolving strategy to adjust their physiochemical properties and boost photoreactivity of the materials.

Cited by 13 publications

References 43 publications

Recent Advances in Photocatalytic Oxidation of Methane to Methanol

Recent Advances in Photocatalytic Oxidation of Methane to Methanol

Innovative Bioactive Ag-SiO2/TiO2 Coating on a NiTi Shape Memory Alloy: Structure and Mechanism of Its Formation

Enhanced visible light photocatalytic activity of nanostructured SiO₂-TiO₂ thin films through optimizing thickness

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Role of defects on TiO2/SiO2 composites for boosting photocatalytic water splitting

Abstract: Defect engineering of semiconductor photocatalysts is considered as an evolving strategy to adjust their physiochemical properties and boost photoreactivity of the materials.

Cited by 13 publications

References 43 publications

Recent Advances in Photocatalytic Oxidation of Methane to Methanol

Recent Advances in Photocatalytic Oxidation of Methane to Methanol

Innovative Bioactive Ag-SiO2/TiO2 Coating on a NiTi Shape Memory Alloy: Structure and Mechanism of Its Formation

Enhanced visible light photocatalytic activity of nanostructured SiO2-TiO2 thin films through optimizing thickness

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Role of defects on TiO₂/SiO₂ composites for boosting photocatalytic water splitting

Enhanced visible light photocatalytic activity of nanostructured SiO₂-TiO₂ thin films through optimizing thickness