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Highly visible-light-active S,N-codoped anatase−rutile heterojunctions are reported for the first time. The formation of heterojunctions at a relatively low temperature and visible-light activity are achieved through thiourea modification... more
Highly visible-light-active S,N-codoped anatase−rutile heterojunctions are reported for the first time. The formation of heterojunctions at a relatively low temperature and visible-light activity are achieved through thiourea modification of the peroxo−titania complex. FT-IR spectroscopic studies indicated the formation of a Ti−thiourea complex upon reaction between peroxo−titania complex and thiourea. Decomposition of the Ti−thiourea complex and formation of visible-light-active S,N-codoped TiO2 heterojunctions are confirmed using X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and UV/vis spectroscopic studies. Existence of sulfur as sulfate ions (S) and nitrogen as lattice (N−Ti−N) and interstitial (Ti−N−O) species in heterojunctions are identified using X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopic techniques. UV−vis and valence band XPS studies of these S,N-codoped heterojunctions proved the fact that the formation of isolated S 3p, N 2p...
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Abstract As antibiotic resistant bacteria and genes become more prevalent, novel methods to remove them from the environment need to be developed. Here we hope to give the case for the use of 2D nanomaterials that exhibit photocatalytic... more
Abstract As antibiotic resistant bacteria and genes become more prevalent, novel methods to remove them from the environment need to be developed. Here we hope to give the case for the use of 2D nanomaterials that exhibit photocatalytic properties for their removal, what they can do and what the future could potentially hold for them. Why 2D materials should be used will be examined, what makes them useful and their effectiveness. The morphological effects of the crystals on photocatalytic activity will be discussed, looking at particle size effects and shape. Recent advances in the field will be highlighted, investigating novel developments in treatment and degradation. Finally, the challenges that 2D nanomaterials face for further development will be addressed, what issues they have and hurdles they need to overcome.
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Anaerobic digestion (AD) has been recognised as an effective means of simultaneously producing energy while reducing greenhouse gas (GHG) emissions. Despite having a large agriculture sector, Ireland has experienced little uptake of the... more
Anaerobic digestion (AD) has been recognised as an effective means of simultaneously producing energy while reducing greenhouse gas (GHG) emissions. Despite having a large agriculture sector, Ireland has experienced little uptake of the technology, ranking 20th within the EU-28. It is, therefore, necessary to understand the general opinions, willingness to adopt, and perceived obstacles of potential adopters of the technology. As likely primary users of this technology, a survey of Irish cattle farmers was conducted to assess the potential of on-farm AD for energy production in Ireland. The study seeks to understand farmers’ motivations, perceived barriers, and preferred business model. The study found that approximately 41% of the 91 respondents were interested in installing AD on their farming enterprise within the next five years. These Likely Adopters tended to have a higher level of education attainment, and together, currently hold 4379 cattle, potentially providing 37,122 t y...
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Atomic and molecular level interactions in solutions dictate the structural and functional attributes of crystals. These features clearly dictate the properties of materials and their applicability in technologies. However, the... more
Atomic and molecular level interactions in solutions dictate the structural and functional attributes of crystals. These features clearly dictate the properties of materials and their applicability in technologies. However, the microscopic phenomena of particle formation—nucleation and growth—in real systems are still not fully understood. Specifically, crystallisation occurring in closed systems are largely unproven. Combining coherent experimental data, we here demonstrate a fundamental nucleation-growth mechanism that occurs in a model zinc oxide system when particles are formed under continuous, rapid heating under closed reaction conditions. Defying all previous reports, we show that the nucleation commences only when the heating is terminated. A prenucleation clusters pathway is observed for nucleation, followed by crystallite assembly-growth. We show that the nucleation-growth processes result from temporal and dynamic activity of constituent ions and gaseous molecules in sol...
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Abstract This work outlines a systematic and detailed study of the modification of anatase TiO2 with tungsten (W). The impact this coupling has on the temperature of the anatase to rutile phase transition and the photocatalytic... more
Abstract This work outlines a systematic and detailed study of the modification of anatase TiO2 with tungsten (W). The impact this coupling has on the temperature of the anatase to rutile phase transition and the photocatalytic degradation of 1,4-dioxane, a highly toxic compound that is increasingly present in water bodies is also studied. TiO2 composite photocatalysts with 2, 4, 8 and 16 mol. % W, respectively, were produced using a sol-gel process and then calcined between 500-1000 °C. The crystallinity and phase composition of pure and W - TiO2 photocatalysts were examined using X-ray Diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). All W-TiO2 composite photocatalysts demonstrated 100% anatase crystalline phase at calcination temperatures as high as 800 °C. Due to the retention of 26% anatase after calcination at 950 °C, 8 mol. % W was established as the optimum W loading for the development of high temperature stable anatase W-TiO2 composite photocatalysts. The % anatase content also significantly impacts the photocatalytic activity of the W - TiO2 composite photocatalysts. In the presence of solar light, 100% of 1,4-dioxane was successfully degraded by 2-W-TiO2, 4-W-TiO2 and 8-W-TiO2 composite photocatalysts, respectively, calcined at 800 °C. However, as the calcination temperature increases and the % anatase content decreases, only 70% of 1,4-dioxane was degraded when using 4-W-TiO2 and 8-W-TiO2 calcined at 900 °C. The highest % removal of 1,4-dioxane was also achieved using 8-W-TiO2 calcined at both 800 and 900 °C. 8-W-TiO2 is therefore considered the optimum sample for both photocatalysis and phase transition temperature.
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2D material based strategies for adsorption and conversion of CO2 to value-added products.
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The introduction of new energy levels in the forbidden band through the doping of metal ions is an effective strategy to improve the thermal stability of TiO2. In the present study, the impact of Ta doping on the anatase to rutile... more
The introduction of new energy levels in the forbidden band through the doping of metal ions is an effective strategy to improve the thermal stability of TiO2. In the present study, the impact of Ta doping on the anatase to rutile transition (ART), structural characteristics, anion and cation vacancy formation were investigated in detail using Density Functional Theory (DFT) and experimental characterisation including, X-ray diffraction (XRD), Raman, and X-ray photoelectron spectroscopy (XPS). The average crystallite size of TiO2 decreases with an increase in the Ta concentration. At high temperatures, more oxygen atoms entered the crystal lattice and occupy the vacancies, leading to lattice expansion. Importantly, we find that Ta doping preserved the anatase content of TiO2 up to annealing temperatures of 850 °C which allows anatase stability to be maintained at typical ceramic processing temperatures. The substitution of Ti4+ by the Ta5+ ions increased the electron concentration i...
Graphene oxide (GO) has broad potential in the biomedical sector. The oxygen-abundant nature of GO means the material is hydrophilic and readily dispersible in water. GO has also been known to improve cell proliferation, drug loading, and... more
Graphene oxide (GO) has broad potential in the biomedical sector. The oxygen-abundant nature of GO means the material is hydrophilic and readily dispersible in water. GO has also been known to improve cell proliferation, drug loading, and antimicrobial properties of composites. Electrospun composites likewise have great potential for biomedical applications because they are generally biocompatible and bioresorbable, possess low immune rejection risk, and can mimic the structure of the extracellular matrix. In the current review, GO-containing electrospun composites for tissue engineering applications are described in detail. In addition, electrospun GO-containing materials for their use in drug and gene delivery, wound healing, and biomaterials/medical devices have been examined. Good biocompatibility and anionic-exchange properties of GO make it an ideal candidate for drug and gene delivery systems. Drug/gene delivery applications for electrospun GO composites are described with a number of examples. Various systems using electrospun GO-containing therapeutics have been compared for their potential uses in cancer therapy. Micro- to nanosized electrospun fibers for wound healing applications and antimicrobial applications are explained in detail. Applications of various GO-containing electrospun composite materials for medical device applications are listed. It is concluded that the electrospun GO materials will find a broad range of biomedical applications such as cardiac patches, medical device coatings, sensors, and triboelectric nanogenerators for motion sensing and biosensing.
The outbreak of COVID-19 has spread rapidly across the globe, greatly affecting how humans as a whole interact, work and go about their daily life. One of the key pieces of personal protective equipment (PPE) that is being utilised to... more
The outbreak of COVID-19 has spread rapidly across the globe, greatly affecting how humans as a whole interact, work and go about their daily life. One of the key pieces of personal protective equipment (PPE) that is being utilised to return to the norm is the face mask or respirator. In this review we aim to examine face masks and respirators, looking at the current materials in use and possible future innovations that will enhance their protection against SARS-CoV-2. Previous studies concluded that cotton, natural silk and chiffon could provide above 50% efficiency. In addition, it was found that cotton quilt with a highly tangled fibrous nature provides efficient filtration in the small particle size range. Novel designs by employing various filter materials such as nanofibres, silver nanoparticles, and nano-webs on the filter surfaces to induce antimicrobial properties are also discussed in detail. Modification of N95/N99 masks to provide additional filtration of air and to deac...
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European Union’s INTERREG VA Programme and Department of Jobs, Enterprise and Innovation, Ireland (Renewable Engine (RE) project funded by European Union’s INTERREG VA Programme, managed by the Special EU Programmes Body (SEUPB), with... more
European Union’s INTERREG VA Programme and Department of Jobs, Enterprise and Innovation, Ireland (Renewable Engine (RE) project funded by European Union’s INTERREG VA Programme, managed by the Special EU Programmes Body (SEUPB), with match funding provided by the Department of Economy, Department of Jobs, Enterprise and Innovation in Ireland); Science Foundation Ireland ((SFI through the ERA.Net for Materials Research and Innovation (M-ERA.Net 2), SFI Grant Number SFI/16/M-ERA/3418 (RATOCAT)); SFI funded computing resources at Tyndall Institute and the SFI/HEA funded Irish Centre for High End Computing)); European Cooperation in Science and Technology (COST Action CM1104 “Reducible Metal Oxides, Structure and Function”); Universidad de Valladolid and Banco Santander (“Movilidad UVa-BANCO SANTANDER 2019”); Universidad de Valladolid (Research initiative “Catedra de Conocimiento e Innovacion” from “Caja Rural de Soria”)
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The advanced electrochemical properties, such as high energy density, fast charge–discharge rates, excellent cyclic stability, and specific capacitance, make supercapacitor a fascinating electronic device. During recent decades, a... more
The advanced electrochemical properties, such as high energy density, fast charge–discharge rates, excellent cyclic stability, and specific capacitance, make supercapacitor a fascinating electronic device. During recent decades, a significant amount of research has been dedicated to enhancing the electrochemical performance of the supercapacitors through the development of novel electrode materials. In addition to highlighting the charge storage mechanism of the three main categories of supercapacitors, including the electric double-layer capacitors (EDLCs), pseudocapacitors, and the hybrid supercapacitors, this review describes the insights of the recent electrode materials (including, carbon-based materials, metal oxide/hydroxide-based materials, and conducting polymer-based materials, 2D materials). The nanocomposites offer larger SSA, shorter ion/electron diffusion paths, thus improving the specific capacitance of supercapacitors (SCs). Besides, the incorporation of the redox-ac...
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Abstract The effect of chalcogens such as sulphur (S), selenium (Se), and tellurium (Te) on the anatase to rutile phase transition (ART) of titanium dioxide (TiO2) was investigated. 2 mol % of chalcogen doped TiO2 was synthesised via a... more
Abstract The effect of chalcogens such as sulphur (S), selenium (Se), and tellurium (Te) on the anatase to rutile phase transition (ART) of titanium dioxide (TiO2) was investigated. 2 mol % of chalcogen doped TiO2 was synthesised via a sol–gel technique. The as-synthesised samples were calcined at different temperatures from 500 °C to 800 °C for 2 h. X-ray diffraction (XRD) and Raman spectroscopy were used to study the ART of TiO2. Te -TiO2 showed the highest anatase phase (44%) at 750 °C as compared to other samples. X-ray photoelectron spectroscopy (XPS) and UV–visible diffuse reflectance spectroscopy (UV-DRS) was further utilised to investigate the oxidation state and optical properties. UV-DRS results showed that the substitutional doping of chalcogens in the TiO2 lattice enhanced visible light absorption. The photocatalytic efficiency was tested for the disinfection of Escherichia coli (E.coli) under visible light irradiation. It is noted that while the chalcogen modified TiO2 improved the anatase stability the antimicrobial activity is not significantly enhanced compared to pure anatase TiO2 under visible light illumination. Te-TiO2 attained 100% disinfection within 70 min of visible light irradiation and maintained equal antibacterial efficiency as pure TiO2 at 750 °C.
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Abstract A simple one-pot aqueous phase chemical reduction has been used for the successful synthesis of flower-like Cu-CuO-Ni heterostructures. X-ray diffraction analysis and X-ray photoelectron spectroscopy confirms the presence of... more
Abstract A simple one-pot aqueous phase chemical reduction has been used for the successful synthesis of flower-like Cu-CuO-Ni heterostructures. X-ray diffraction analysis and X-ray photoelectron spectroscopy confirms the presence of metallic copper, nickel and monoclinic copper oxide (CuO) in the sample with traces of Cu(OH)2. Scanning electron microscope images confirms the flower like morphology of the Cu-CuO-Ni nanoheterostructures. For the first time, Cu-CuO-Ni nanocrystals were employed as a new heterogeneous efficient nanocatalyst for the hydrogenation reduction of 4-nitrophenol (4-NP) and reduction of chromium (VI) (Cr) to chromium (III). The synthesized Cu-CuO-Ni nanocrystals showed highest catalytic properties with an activity factor of 0.0088 s−1 mg−1for reduction of 4-nitrophenol and 0.057 min−1for chromium reduction reaction. The XRD and XPS analysis of the catalytically recycled samples suggests the higher catalytic stability of Cu-CuO-Ni nanocrystals. In comparison to the bare CuO and CuO- Ni nanocrystals the maximum catalytic activity was shown by Cu-CuO-Ni nanocrystals. The improved catalytic activity was found to be due to the combined effect of morphological and compositional differences. The commendable catalytic efficiency along with the facile synthetic approach and the use of low-cost copper and nickel significantly reduces the cost of the catalytic process. The stability of the Cu-CuO-Ni catalyst system for the chromium reduction reactions was monitored by conducting recyclability test for three times. Therefore, the developed Cu-CuO-Ni nanocatalyst offers significant applications in waste water treatment systems and other industrial applications.
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Abstract The collection of intrinsic properties possessed by graphene family nanomaterials (GFNs) results in their continuous exploitation for biomedical applications. The materials biomedical potential has motivated an upsurge in green... more
Abstract The collection of intrinsic properties possessed by graphene family nanomaterials (GFNs) results in their continuous exploitation for biomedical applications. The materials biomedical potential has motivated an upsurge in green preparation routes for the production of graphene like materials with limited toxicity. A number of bio-friendly reducing agents have been utilized for the preparation of chemically reduced graphene oxide (GO), and their resulting cytotoxic effects examined. However, the toxicology effects of one of the first biomolecules implemented for the reduction of GO, ascorbic acid (AA) has yet to be investigated. Herein, the toxicity of three distinct GFNs; GO, hydrazine reduced GO (H.rGO) and AA.rGO, prepared through diverse chemical routes are studied, to demonstrate the cytotoxic activity of a green reducer, in comparison to an established reduction method using hydrazine hydrate. The variation in atomic structure of GO, H.rGO and AA.rGO resulting from different synthesis techniques demonstrates the dependence of toxicity on particle shape and size. All GFNs induced high levels of alveolar cell toxicity. Interaction of AA.rGO with the A549 human lung epithelial carcinoma cell line resulted in increased leakage of lactate dehydrogenase, indicative of diminished cell membrane integrity. The uncharacteristic shape of the AA.rGO may be responsible for this proliferated release of the essential protein. The presented data therefore demonstrates that modification of synthetic processes significantly alter the biological activities of GFNs.
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Sol-gel processing facilitates effortless control of the composition, properties, and architecture of nanosystems. For this reason, the technology has been adapted as a popular route for the preparation of nanostructures. The process... more
Sol-gel processing facilitates effortless control of the composition, properties, and architecture of nanosystems. For this reason, the technology has been adapted as a popular route for the preparation of nanostructures. The process supports the preparation of intricate three-dimensional networks extended throughout a liquid phase (a gel) through the agglomeration of nanoparticles dispersed within a colloidal suspension (sol). In order to gain a greater understanding of the process before exploring the possible applications of the technology, this chapter outlines the activities involved in sol-gel processing. The formation of sol-gel materials is explained by briefly focusing on the mechanisms of hydrolysis and condensation, in addition to ageing and drying of wet gels. Sol-gel processing can be used to form a range of architectures from fibres and films to fine powders and monoliths, however this chapter will focus on sol-gel processing for aerogels specifically.
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In pure synthetic titanium dioxide, the anatase to rutile phase transition usually occurs between the temperatures of 600 °C and 700 °C.
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Titania nanotubes decorated with Pd nanoparticles were synthesised by a hydrothermal method. The increased amounts of Pd concentration is found to facilitate the anatase to rutile crystalline phase transformation as well as in collapse of... more
Titania nanotubes decorated with Pd nanoparticles were synthesised by a hydrothermal method. The increased amounts of Pd concentration is found to facilitate the anatase to rutile crystalline phase transformation as well as in collapse of the morphology as revealed by X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopy. The presence of metallic as well as the oxidized form (PdO2) of surface metal ions was characterized by using XPS. The catalytic activity of the Pd loaded titania nanotubes has been demonstrated by studying the reduction of p-nitrophenol to p-aminophenol. The 1.0 mol% Pd loaded titania nanotubes has been found to exhibit optimum catalytic activity (rate constant of 0.7072 min−1) while those with higher amounts of Pd loading showed lower catalytic activity. It is observed that retention of tubular morphology and higher anatase content play significant roles in their catalytic activity.Graphical Abstract
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ABSTRACT ZnO nanomaterials are grown in-situ on graphene oxide (GO) materials by a facile hydrothermal method at a temperature of 100 °C. These ZnO–graphene composite materials display a strong and broad absorption in the visible region... more
ABSTRACT ZnO nanomaterials are grown in-situ on graphene oxide (GO) materials by a facile hydrothermal method at a temperature of 100 °C. These ZnO–graphene composite materials display a strong and broad absorption in the visible region besides an intense UV absorption peak. The enhanced fluorescent quenching observed for the graphene hybrids compared to ZnO, indicates the photoinduced electron transfer between ZnO and graphene layers, which in-turn reduces the recombination of charge carriers. In order to understand the mechanism of improved photocatalytic properties, reagents such as a radical scavenger t-BuOH and a hole scavenger EDTA-2Na were employed. The addition of t-BuOH did not show any appreciable changes in the photo-degradation properties of the ZnO–graphene hybrids. However, the addition of EDTA-2Na significantly reduced the photocatalytic activities of the ZnO–graphene hybrids indicated that photo-generated holes are the main reactive oxidative species responsible for the photocatalytic reaction. It has been concluded that the excellent absorption range, efficient charge transportation and separation and high surface area make the ZnO–graphene hybrids a better photocatalyst under UV and visible light.
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The use of adsorbents for the recovery and reuse of metal complex based persulphate activator is demonstrated.
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The simultaneous existence of visible light photocatalytic activity and high temperature anatase phase stability up to 900 C in undoped TiO 2 is reported for the fi rst time. These properties are achieved by the in-situ generation of... more
The simultaneous existence of visible light photocatalytic activity and high temperature anatase phase stability up to 900 C in undoped TiO 2 is reported for the fi rst time. These properties are achieved by the in-situ generation of oxygen through the thermal decomposition of peroxo-titania complex (formed by the precursor modifi cation with H 2 O 2). Titania containing the highest amount of oxygen (16 H 2 O 2-TiO 2) retains 100% anatase phase even at 900 C, where as the control sample exists as 100% rutile at this ...
Advanced Oxidation technologies (AOTs) are gaining attention as an effective waste water treatment methodology capable of degrading diverse spectrum of recalcitrant organic contaminants and microbes. Undoubtedly, photocatalysis is a... more
Advanced Oxidation technologies (AOTs) are gaining attention as an effective waste water treatment methodology capable of degrading diverse spectrum of recalcitrant organic contaminants and microbes. Undoubtedly, photocatalysis is a promising AOT to alleviate the problem of water pollution. Despite recent research into other photocatalysts (e.g. ZnO, ZnS, Semiconductor-Graphene composites, perovskites, MoS 2, WO 3 and Fe 2 O 3), titanium dioxide (TiO 2) remains the most popular photocatalyst due to its low cost, nontoxicity and high oxidising ability. Moreover, titania photocatalysts can easily be immobilized on various surfaces and be scaled up for large scale water treatment. The current review aims to highlight recent advancements in photocatalytic AOTs with main emphasis on TiO 2 photocatalysis. This review also discusses the use of TiO 2 photocatalysis for water and waste treatment, treating contaminants of emerging concern (CECs), pesticides, endocrine disrupters (EDs) and bacteria using both UV and visible light irradiations. It was concluded that with efficient photoreactor configuration and further studies on the photocatalyst regeneration, TiO 2 photocatalysis is a viable option for the reclamation of agricultural/irrigational waste water. Novel doped photocatalysts such as ZnS-CuS-CdS, carbon spheres/CdS, g-C 3 N 4-Au-CdS, ZnS-WS 2-CdS, C 3 N 4-CdS and Pd-Cr 2 O 3-CdS have also been discussed. Finally, the advances in the actively studied metal organic framework based photocatalysts that are emerging as effective alternate for metal oxide based photocatalysts is also discussed in detail.
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The photocatalytic water splitting technique is a promising alternative to produce hydrogen using a facile and proficient method. In the current Review, recent progress made in photocatalytic hydrogen evolution reaction (HER) using 2D... more
The photocatalytic water splitting technique is a promising alternative to produce hydrogen using a facile and proficient method. In the current Review, recent progress made in photocatalytic hydrogen evolution reaction (HER) using 2D nanomaterials (NMs) and composite heterostructures is described. The strong in-plane chemical bonds along with weak van der Waals interaction make these materials lucrative for surface-related applications. State-of-the-art protocols designed for the synthesis of 2D NMs is discussed in detail. The Review illustrates density functional theory (DFT)-based studies against the new set of 2D NMs, which also highlights the importance of structural defects and doping in the electronic structure. Additionally, the Review describes the influence of electronic, structural, and surface manipulation strategies. These impact the electronic structures, intrinsic conductivity, and finally output toward HER. Moreover, this Review also provides a fresh perspective on the prospects and challenges existing behind the application and fabrication strategies.
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The conversion of carbon dioxide (CO 2) into fuels and value-added products is one of the most significant inventions to address the global warming and energy needs. Photoelectrochemical (PEC) CO 2 conversion can be considered as an... more
The conversion of carbon dioxide (CO 2) into fuels and value-added products is one of the most significant inventions to address the global warming and energy needs. Photoelectrochemical (PEC) CO 2 conversion can be considered as an artificial photosynthesis technique that produces formate, formaldehyde, formic acid, methane, methanol, ethanol, etc. Recent advances in electrode materials, mechanisms, kinetics, thermodynamics, and reactor designs of PEC CO 2 conversion have been comprehensively reviewed in this article. The adsorption and activation of CO 2 /intermediates at the electrode surface are the key steps for improving the kinetics of CO 2 conversion. PEC efficiency could be upgraded through the utilization of 2D/3D materials, plasmonic metals, carbon-based catalysts, porous nanostructures, metal−organic frameworks , molecular catalysts, and biological molecules. The defect engineered (by cation/anion vacancy, crystal distortion, pits, and creation of oxygen vacancies) 2D/3D materials, Z-scheme heterojunctions, bioelectrodes, and tandem photovoltaic−PEC reactors are suitable options to enhance the efficiency at low external bias.
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The thermal stability of anatase titanium dioxide (TiO2) is a prerequisite to fabricate photocatalyst coated indoor building materials for use in antimicrobial and self-cleaning applications under normal room light illumination. Metal... more
The thermal stability of anatase titanium dioxide (TiO2) is a prerequisite to fabricate photocatalyst coated indoor building materials for use in antimicrobial and self-cleaning applications under normal room light illumination. Metal doping of TiO2 is an appropriate way to control the anatase to rutile phase transition (ART) at high processing temperature. In this present work, ART of indium (In) doped TiO2 (In-TiO2) was investigated in detail in the range of 500 °C-900 °C. In-TiO2 (In mol % = 0 to 16) was synthesized via a modified sol-gel approach. These nanoparticles were further characterized by means of powder X-ray diffraction (XRD), Raman, photoluminescence (PL), transient photocurrent response, and X-ray photoelectron spectroscopy (XPS) techniques. XRD results showed that the anatase phase was maintained up to 64 % by 16-mol % of In doping at 800 °C of calcination temperature. XPS results revealed that the binding energies of Ti 4+ (Ti 2p1/2 and Ti 2p3/2) were red-shifted by In doping. The influence of In doping on the electronic structure and oxygen vacancy formation of anatase TiO2 was studied using density functional theory corrected for on-site Coulomb interactions (DFT+U). First principles results showed that the charge compensating oxygen vacancies form spontaneously at sites adjacent to the In dopant. DFT+U calculations revealed the formation of In-5s states in the band gap of the anatase host. The formation of In2O3 at the anatase surface was also examined using a slab model of the anatase (101) surface modified with a nanocluster of composition In4O6. The formation of a reducing oxygen vacancy also has a moderate energy cost and results in charge localisation at In ions of the supported nanocluster. PL and photocurrent measurements suggested that the charge carrier recombination process in TiO2 was reduced in the presence of In dopant. The photocatalytic activity of 2 % In-TiO2 calcined at 700 °C is more comparable with that of pure anatase.
Owing to their atomically thin structure, large surface area and mechanical strength, 2D nanoporous materials are considered to be suitable alternatives for existing desalination and water purification membrane materials. Recent progress... more
Owing to their atomically thin structure, large surface area and mechanical strength, 2D nanoporous materials are considered to be suitable alternatives for existing desalination and water purification membrane materials. Recent progress in the development of nanoporous graphene based materials has generated enormous potential for water purification technologies. Progress in the development of nanoporous graphene and graphene oxide (GO) membranes, the mechanism of graphene molecular sieve action, structural design, hydrophilic nature, mechanical strength and antifouling properties and the principal challenges associated with nanopore generation are discussed in detail. Subsequently, the recent applications and performance of newly developed 2D materials such as 2D boron nitride (BN) nanosheets, graphyne, molybdenum disulfide (MoS 2), tungsten chalcogenides (WS 2) and titanium carbide (Ti 3 C 2 T x) are highlighted. In addition, the challenges affecting 2D nanostructures for water purification are highlighted and their applications in the water purification industry are discussed. Though only a few 2D materials have been explored so far for water treatment applications, this emerging field of research is set to attract a great deal of attention in the near future.
Research Interests: Graphene and 2d Materials
Advanced Oxidation technologies (AOTs) are gaining attention as an effective waste water treatment methodology capable of degrading diverse spectrum of recalcitrant organic contaminants and microbes. Undoubtedly, photocatalysis is a... more
Advanced Oxidation technologies (AOTs) are gaining attention as an effective waste water treatment methodology capable of degrading diverse spectrum of recalcitrant organic contaminants and microbes. Undoubtedly, photocatalysis is a promising AOT to alleviate the problem of water pollution. Despite recent research into other photocatalysts (e.g. ZnO, ZnS, Semiconductor-Graphene composites, perovskites, MoS 2, WO 3 and Fe 2 O 3), titanium dioxide (TiO 2) remains the most popular photocatalyst due to its low cost, nontoxicity and high oxidising ability. Moreover, titania photocatalysts can easily be immobilized on various surfaces and be scaled up for large scale water treatment. The current review aims to highlight recent advancements in photocatalytic AOTs with main emphasis on TiO 2 photocatalysis. This review also discusses the use of TiO 2 photocatalysis for water and waste treatment, treating contaminants of emerging concern (CECs), pesticides, endocrine disrupters (EDs) and bacteria using both UV and visible light irradiations. It was concluded that with efficient photoreactor configuration and further studies on the photocatalyst regeneration, TiO 2 photocatalysis is a viable option for the reclamation of agricultural/irrigational waste water. Novel doped photocatalysts such as ZnS-CuS-CdS, carbon spheres/CdS, g-C 3 N 4-Au-CdS, ZnS-WS 2-CdS, C 3 N 4-CdS and Pd-Cr 2 O 3-CdS have also been discussed. Finally, the advances in the actively studied metal organic framework based photocatalysts that are emerging as effective alternate for metal oxide based photocatalysts is also discussed in detail.
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Photocatalysis has recently been emerged as an effective green solution for antimicrobial disinfection applications. Photocatalytic disinfection has been observed to be efficient in deactivation of extensive varieties of organisms.... more
Photocatalysis has recently been emerged as an effective green solution for antimicrobial disinfection applications. Photocatalytic disinfection has been observed to be efficient in deactivation of extensive varieties of organisms. Numerous gram positive and gram negative bacterial strains such as Escherichia coli, Staphylococcus aureus, Streptococcus pneumonia etc. have been studied. Similarly, fungal strains such as Aspergillus niger, Fusarium graminearum, algal (Tetraselmis suecica, Amphidinium carterae etc.) and viral strains have also been examined in the last decades. The present review sketches the photocatalytic mechanism and provides a brief account of several model organisms used for the disinfection studies. It presents an overview of the major kinetic models such as the Chick's model, Chick-Watson model, delayed Chick-Watson model and Hom's with modified Hom's model. Furthermore, it summarises the importance of operational parameters on the inactivation kinetics and discusses the recent advances of the disinfection results by novel composites and progress in structural or morphological improvements in conventional catalyst. The current review presents a brief overview of the state of the art commercial products utilising photocatalytic antibacterial property. Finally, it details the major international testing standards (ISO, JIS, CEN and ASTM) for photocatalytic antimicrobial applications.
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The photocatalytic activities of reduced titanium dioxide (TiO2) materials have been investigated by measuring their ability to produce hydroxyl radicals under UV and visible light irradiation. Degussa P25 TiO2 was doped with nitrogen... more
The photocatalytic activities of reduced titanium dioxide (TiO2) materials have been investigated by measuring their ability to produce hydroxyl radicals under UV and visible light irradiation. Degussa P25 TiO2 was doped with nitrogen (N), fluorine (F), and/or phosphorus (P) and then subjected to surface modification employing a thermo-physicochemical process in the presence of reducing agent sodium borohydride (NaBH4). The reduced TiO2 materials were characterized by a number of X-ray, spectroscopic and imaging methods. Surface doping of TiO2 was employed to modulate the band gap energies into the visible wavelength region for better overlap with the solar spectrum. Hydroxyl radical generation, central to TiO2 photocatalytic water purification applications, was quantitated using coumarin as a trap under UV and visible light irradiation of the reduced TiO2 materials. At 350 nm irradiation, the yield of hydroxyl radicals generated by the reduced forms of TiO2 was nearly 90% of hydroxyl radicals generated by the Degussa P25 TiO2. Hydroxyl radical generation by these reduced forms of TiO2 was also observed under visible light irradiation (419 and 450 nm). These results demonstrated that simple surface modification of doped TiO2 can lead to visible light activity, which is important for more economical solar-driven applications of TiO2 photocatalysis.