Structural and electronic properties of oxygen defective and Se-doped p-type BiVO⁠4(001) thin film for the applications of photocatalysis

This is the final version. Available on open access from Elsevier via the DOI in this record.There is another record in ORE for this publication: http://hdl.handle.net/10871/36011Monoclinic BiVO4 is being used as a photocatalyst due to its stability, cost-effectiveness, ease of synthesis, and narrow band gap. Although, the valence band maximum, VBM (∼−6.80 eV vs vacuum) of BiVO4 is well below the redox potential of water but having less positive conduction band minimum, CBM (−4.56 eV vs vacuum), responsible for its low efficiency. We have carried out a comprehensive periodic density functional theory (DFT) simulations for the pristine, Oxygen defective (Ov) and Se doped BiVO4, to engineer not only its CB edge position but the overall photocatalytic and charge carrier properties. Our theoretical method has nicely reproduced the experimental data of pristine BiVO4, which encouraged us to elaborate further its Ov and Se-doped characteristics. It is found that both the Ov (1% Oxygen vacancy) and Se-doped BiVO4 (1–2% Se) have ideal band edges, band gaps, and small effective masses of electrons and holes, responsible for high photocatalytic activities. Moreover, Se-doped BiVO4 behave as p-type semiconductor. Finally, the photocatalytic water-splitting behaviour of the selected surfaces were counterchecked with water interaction, where the strong water adsorption energy of about ∼−38 to −50 kcal/mol, confirms and predicts their higher efficiencies compared to that of parent BiVO4.The financial support was provided by Engineering and Physical Science Research Council, UK (EPSRC) under the research grant No EP/P510956/1

Structural and electronic properties of oxygen defective and Se-doped p-type BiVO⁠4(001) thin film for the applications of photocatalysis

This is the final version. Available on open access from Elsevier via the DOI in this record.There is another record in ORE fro this publication: http://hdl.handle.net/10871/30528Monoclinic BiVO4 is being used as a photocatalyst due to its stability, cost-effectiveness, ease of synthesis, and narrow band gap. Although, the valence band maximum, VBM (∼−6.80 eV vs vacuum) of BiVO4 is well below the redox potential of water but having less positive conduction band minimum, CBM (−4.56 eV vs vacuum), responsible for its low efficiency. We have carried out a comprehensive periodic density functional theory (DFT) simulations for the pristine, Oxygen defective (Ov) and Se doped BiVO4, to engineer not only its CB edge position but the overall photocatalytic and charge carrier properties. Our theoretical method has nicely reproduced the experimental data of pristine BiVO4, which encouraged us to elaborate further its Ov and Se-doped characteristics. It is found that both the Ov (1% Oxygen vacancy) and Se-doped BiVO4 (1–2% Se) have ideal band edges, band gaps, and small effective masses of electrons and holes, responsible for high photocatalytic activities. Moreover, Se-doped BiVO4 behave as p-type semiconductor. Finally, the photocatalytic water-splitting behaviour of the selected surfaces were counterchecked with water interaction, where the strong water adsorption energy of about ∼−38 to −50 kcal/mol, confirms and predicts their higher efficiencies compared to that of parent BiVO4.Engineering and Physical Sciences Research Council (EPSRC

Donor-acceptor polymer for the design of All-Solid-State dye-sensitized solar cells

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordDensity functional theory study has been carried out to design a new All-Solid-State dye-sensitized solar cell (SDSC), by applying a donor-acceptor conjugated polymer instead of liquid electrolyte. The typical redox mediator (I1−/I3−) is replaced with a narrow band gap, hole transporting material (HTM). The electronic and optical properties predict that donor and acceptor moieties in the polymeric body have increased the visible light absorption and charge transporting ability, compared to their parent polymers. A unique “upstairs” like band energy diagram is created by packing N3 between HTM and TiO2. Upon light irradiation on the proposed configuration, electrons will move from the dye to TiO2 and from HTM to dye (to regenerate dye), simultaneously. Our theoretical simulations prove that the proposed configuration will be highly efficient as the HOMO level of HTM is 1.19 eV above the HOMO of sanitizer (dye); providing an efficient pathway for charge transfer. High short-circuit current density and power conversion efficiency is promised from the strong overlapping of molecular orbitals of HTM and sensitizer. A low reorganization energy of 0.21 eV and exciton binding energy of 0.55 eV, confirm the high efficiency of HTM. Finally, a theoretical open-circuit voltage of 1.49 eV would results high quantum yield while, the chemical stability of HTM towards oxidation can be estimated from its high ionization potential value (4.57 eV)

Density Functional Theory Study of Selenium-Substituted Low-Bandgap Donor-Acceptor-Donor Polymer

This is the author accepted manuscript. The final version is available from American Chemical Society via the DOI in this recordTheoretical study of an optically transparent, near-infrared-absorbing low energy gap conjugated polymer, donor-acceptor-donor (D-A-D), 2,1,3-benzosele-nadiazole (A) as acceptor and 3,4-ethylenedioxyselenophene (D) as donor fragments, with promising attributes for photovoltaic application is reported herein. The D and A moiety on the polymeric backbone has been found to be responsible for tuning the band gap, optical gap, open circuit (VOC), and short-circuit current density (JSC) in the polymers solar cells. D-A-D has a key role in charge separation and molecular architecture which ultimately influences the charge transport. Reduction in the band gap, high charge transformation, and enhanced visible light absorption in the D-A-D system is because of strong overlapping of molecular orbitals of D and A. The polaron and bipolaron effects are also investigated which has a direct relation with visible light photocurrent generation. In addition, the enhanced planarity and weak steric hindrance between adjacent units of D-A-D resulted in red-shifting of its onset of absorption. The simulated band gap of the D-A-D has excellent correlation with experimentally reported values for closely related systems, which validates the level of theory used. Finally, PSC properties of the designed D-A-D was modeled in the bulk heterojunction solar cell, which gives a theoretical VOC of about 1.02 eV. (Graph Presented)

Electronic properties of Β-TaON and its surfaces for solar water splitting

This is the final version of the article. Available from Elsevier via the DOI in this record.Recently, oxynitrides materials such as β-TaON has been using as a photoanode material in the field of photocatalysis and is found to be promising due to its suitable band gap and charge carrier mobility. Computational study of the crystalline β-TaON in the form of primitive unit cell, supercell and its N, Ta, and O terminated surfaces are carried out with the help of periodic density functional theory (DFT). Optical and electronic properties of all these different species are simulated, which predict TaON as the best candidate for photocatalytic water splitting contrast to their Ta 2 O 5 and Ta 3 N 5 counterparts. The calculated bandgap, valence band, and conduction band edge positions predict that β-TaON should be an efficient photoanodic material. The valence band is made up of N 2p orbitals with a minor contribution from O 2p, while the conduction band is made up of Ta 5d. Turning to thin films, the valence band maximum; VBM (−6.4 eV vs. vacuum) and the conduction band minimum; CBM (−3.3 eV vs. vacuum) of (010)-O terminated surface are respectively well below and above the redox potentials of water as required for photocatalysis. Charge carriers have smaller effective masses than in the (001)-N terminated film (VBM −5.8 and CBM −3.7 eV vs. vacuum). However, due to wide band gap (3.0 eV) of (010)-O terminated surface, it cannot absorb visible wavelengths. On the other hand, the (001)-N terminated TaON thin film has a smaller band gap in the visible region (2.1 eV) but the bands are not aligned to the redox potential of water. Possibly a mixed phase material would produce an efficient photoanode for solar water splitting, where one phase performs the oxidation and the other reduction.We acknowledge the financial support of Engineering and Physical Science Research Council, UK (EPSRC)under the research grant Nos. EP/P510956/1, EP/P003435/1 and EP/R512801/1. S.K acknowledges the Notur Norwegian supercomputing facilities through project nn4608k and the HyMatSiRen project 272806 by the Research Council of Norway. We also acknowledge Prof. Neil Allan and Dr. Sergio C. Espindola for their help in completing this work

A novel stand-alone solar-powered agriculture greenhouse-desalination system; increasing sustainability and efficiency of greenhouses

This is the author accepted manuscript.The countries in the Middle East and North Africa (MENA) region are suffering from the scarcity of freshwater resources. With the economic development and population growth, planning the additional water supplies is critical for this region. Desalination of saline water is, therefore, considered as a strategic alternative water resources and technology to be adopted in MENA region. On the other hand, open field agriculture in such conditions is not economical particularly with high ambient temperature and solar intensity. Agriculture Greenhouses (GH) present a suitable alternative for different plants growth for the region’s desert. In most cases GHs can reduce about 90% of irrigating water demand compared open field. With the available high solar energy, integration of solar – GH – desalination presents a real challenge and is the field of newly funded N-M R&D proposal. This paper presents an integration of solar energy, agriculture GH and suitable desalination processes targeting the development and pilot testing of a novel stand-alone system that grows its energy and irrigation water demand.British CouncilScience & Technology Development Fund (STDF), Egyp

Immunotherapy for arterial ischaemic stroke in childhood: a systematic review

BACKGROUND: There is little evidence about either prevention or treatment of childhood arterial ischaemic stroke (AIS). However, drugs that regulate the immune and inflammatory response could theoretically prevent occurrence or recurrence of AIS. Additionally, as an acute treatment, they may limit the neurological damage caused by AIS. Here, we systematically review the evidence on the use of immunotherapy in childhood AIS. DESIGN: A systematic review of publications in databases Embase and Medline from inception. All types of evidence were included from trials, cohorts, case-control and cross-sectional studies and case reports. RESULTS: 34 reports were included: 32 observational studies and 2 trials. Immunotherapy was used in two key patient groups: arteriopathy and acute infection. The majority were cases of varicella and primary angiitis of the central nervous system. All three cohorts and 80% of the case studies were treated with steroids. Recurrence rates were low. Analytical studies weakly associated steroids with lower odds of new stroke and neurological deficits, and better cognitive outcomes in the context of Moyamoya disease and tuberculosis. CONCLUSIONS: Immunotherapies are used in children with AIS, mainly as steroids for children with arteriopathy. However, there is currently little robust evidence to either encourage or discourage this practice. There is weak evidence consistent with the hypothesis that in certain children at risk, steroids may both reduce the risk of occurrent/recurrent stroke and enhance neurological outcomes. As the potential benefit is still uncertain, this indicates that a trial of steroids in childhood AIS may be justified

An optimal climate-adaptable hydrogel-filled smart window for the energy-saving built environment

This is the final version. Available on open access from the Royal Society of Chemistry via the DOI in this record It is highly desirable to secure the net-zero targets by employing sustainable building materials that can store and release their energy depending on the weather. Conspicuously, windows can play a pivotal role in controlling the energy used in the building by reducing the use of energy-consuming areas that devour massive energy for air conditioning or heater appliances. Presently, the comfort performance of window materials is reaching its storage and processing limit, causing a significant push to find smart materials that can be used in the next generation of the built environment. An innovative solution for sustainable glazing has established an understanding of pH-temperature-transparency modulation. This work uses hydroxypropyl cellulose and polyacrylic acid-based hydrogel as a rational energy stimulus for double-glazed windows, enriching a comfortable indoor daylight environment without sacrificing aesthetic appeal. Hydrogel maintains thermal comfort across various outdoor temperatures from 4 oC to 60 oC. The developed hydrogel-filled prototype glazing’s indoor thermal comfort performance and durability were analsyzed, where hydrogel intermolecular gap and porosity play a pivotal role across various pHs.Engineering and Physical Sciences Research Council (EPSRC

Enhanced photoactivity and hydrogen generation of LaFeO 3 photocathode by plasmonic silver nanoparticle incorporation

This is the author accepted manuscript. The final version is available from ACS via the DOI in this record.A plasmonic LaFeO3-Ag (LFO-Ag) photocathode was synthesised by incorporating Ag nanoparticles to excite surface plasmon resonances (SPR) for enhanced light harvesting to drive photoelectrochemical (PEC) hydrogen evolution. The Ag nanoparticles were modelled using finite difference time domain (FDTD) simulations and the results show an optimal dimension of 50-80 nm for SPR enhancement. Nanostructured LFO films were prepared by a novel and inexpensive spray pyrolysis method and the Ag nanoparticles were dispersed uniformly on to the films by simple spin coating method. The LFO-Ag photocathode exhibited strong light absorption capability and high current density, twice that than of its untreated counterpart. This subsequently led to enhanced PEC hydrogen evolution, doubling the volume of hydrogen generated compared to untreated LFO. The enhancement is ascribed to the strong SPR effect and the synergy between the Ag nanoparticles and nanostructured LFO photocathode.We acknowledge UKIERI-DST2016-17-0089 project and Engineering and Physical Science Research Council, UK (EPSRC) under the research grant EP/R512801/1 for financial support. A.E. and S.S. would like to thank the Council of Scientific and Industrial Research (CSIR) for the award of Senior Research Fellowship. NSG Pilkington Glass Ltd. is acknowledged for kindly providing the FTO substrates for this work

The metformin in tuberous sclerosis (MiTS) study: A randomised double-blind placebo-controlled trial

Background: Tuberous Sclerosis Complex (TSC) is a genetic disorder characterised by the development of benign tumours secondary to loss of inhibitory regulation of the mTOR (mechanistic Target of Rapamycin) intracellular growth pathway. Metformin inhibits the mTOR pathway. We investigated whether metformin would reduce growth of hamartomas associated with tuberous sclerosis complex. / Methods: In this multicentre randomized, double-blind, placebo-controlled trial, patients with a clinical diagnosis of tuberous sclerosis, aged over 10 years and with at least one renal angiomyolipoma of greater than 1 cm in diameter were enrolled. Participants were randomly allocated (1:1) by a secure website to receive metformin or placebo for 12 months. The primary outcome was percentage volume change of renal angiomyolipomas (AML) at 12 months compared to baseline. Secondary outcomes were percentage change at 12 months from baseline in volume of cerebral Subependymal Giant Cell Astrocytomas (SEGA); appearance of facial and ungual hamartomas; frequency of epileptic seizures; and adaptive behaviour. The trial is registered with The International Standard Randomised Controlled Trial Number (ISRCTN), number 92545532, and the European Union Drug Regulating Authorities Clinical Trials (EUDRACT), number 2011-001319-30. / Findings: Between 1 November 2012 and 30 September 2015 72 patients were screened and 55 were randomly assigned to metformin (28) or placebo (27). Four participants withdrew between randomisation and starting treatment. All 51 patients who started therapy completed the trial and were assessed for outcome at 12 months. The median percentage change in angiomyolipoma (AML) volume was +7.6% (IQR -1.8% to +42.6%) for the placebo group and +8.9% (IQR 1.3% to 19.5%) for the metformin group (p = 0.28). Twenty-seven patients had SEGAs: 13 received placebo and 14 metformin. The median percentage change in SEGA volume was +3.0% (IQR -22.8% to +27.7%) for the placebo group and – 20.8% (IQR – 47.1% to - 5.0%) for the metformin group (p = 0.03). Twenty-one patients were assessed for seizure frequency: 9 received placebo and 12 received metformin. In the metformin group, a mean reduction of 43.7% from baseline in seizures was observed and in the placebo group a 3.1% mean reduction was observed, with a difference in response of 40.6% (95% CI -3.1% to +84.2%, p = 0.03). There were no significant differences between metformin and placebo groups for the other secondary outcomes. There were no deaths. Three serious adverse events (SAEs) occurred during the trial (all patients on metformin). / Interpretation: Metformin did not reduce AML volume. Metformin did reduce SEGA volume and seizure frequency compared with placebo. There may be a role for metformin in slowing or reversing growth of some life-threatening hamartomas in TSC and for reducing seizure frequency. Further study is justified. / Funding: This study was funded by the National Institute for Health and Research (NIHR) through the The Research for Patient Benefit Programme (RfPB)