Faheem K. Butt

Enhanced photocatalytic performance of CeO 2 –TiO 2 nanocomposite for degradation of crystal violet dye and industrial waste effluent

This study presents the synthesis of CeO2–TiO2 nanocomposite and its potential application for the visible light-driven photocatalytic degradation of model crystal violet dye as well as real industrial waste water. The ceria–titania (CeO2–TiO2) nanocomposite material was synthesised using facile hydrothermal route without the assistance of any template molecule. As-prepared composite was characterised by SEM, TEM, HRTEM, XRD, XPS for surface features, morphological and crystalline characters. The formed nanostructures were determined to possess crystal-like geometrical shape and average size less than 100xa0nm. The as-synthesised nanocomposite was further investigated for their heterogeneous photocatalytic potential against the oxidative degradation of CV dye taken as model pollutant. The photo-catalytic performance of the as-synthesised material was evaluated both under ultra-violet as well as visible light. Best photocatalytic performance was achieved under visible light with complete degradation (100%) exhibited within 60xa0min of irradiation time. The kinetics of the photocatalytic process were also considered and the reaction rate constant for CeO2–TiO2 nanocomposite was determined to be 0.0125 and 0.0662xa0min−1 for ultra-violet and visible region, respectively. In addition, the as-synthesised nanocomposite demonstrated promising results when considered for the photo-catalytic degradation of coloured industrial waste water collected from local textile industry situated in Faisalabad region of Pakistan. Enhanced photo-catalytic performance of CeO2–TiO2 nanocomposite was proposed owing to heterostructure formation leading to reduced electron–hole recombination.

Elucidating the First-Principles Calculations of SnO 2 Within DFT Framework and Beyond: A Library for Optimization of Various Pseudopotentials

In the present work detailed electronic, structural and optical properties of rutile-type SnO2 are presented based on plane-wave ultrasoft pseudopotential technique within Density Functional Theory (DFT) and beyond using LDA, GGA, HSE03, HSE06, LDA(HSE03), LDA(HSE06), GGA(HSE03) and GGA(HSE06) respectively. The results show that the calculated lattice constants and volumes are very close to the experimental values. The bandgap obtained from LDA(HSE06) is quite close to the experimental values. Conversely, the bandgaps calculated by HSE03 and HSE06 are also close to 3.6 eV. However, density of state and optical properties calculated from each type of potential is mostly alike in qualitative investigations, and the numerical values have a little difference. The graphs have been plotted for eight exchange correlation potentials to depict the properties of SnO2 in detail. These studies elucidate the first principles calculations of SnO2 using various pseudopotentials and provide a complete library for their optimization.

Engineering the electronic band structures of novel cubic structured germanium monochalcogenides for thermoelectric applications

Germanium mono-chalcogenides have received considerable attention for being a promising replacement for the relatively toxic and expensive chalcogenides in renewable and sustainable energy applications. In this paper, we explore the potential of the recently discovered novel cubic structured (π-phase) GeS and GeSe for thermoelectric applications in the framework of density functional theory coupled with Boltzmann transport theory. To examine the modifications in their physical properties, the across composition alloying of π-GeS and π-GeSe (such as π-GeS1-xSex for xu2009=0, 0.25, 0.50, 0.75, and 1) has been performed that has shown important effects on the electronic band structures and effective masses of charge carriers. An increase in Se composition in π-GeS1-xSex has induced a downward shift in their conduction bands, resulting in the narrowing of their energy band gaps. The thermoelectric coefficients of π-GeS1-xSex have been accordingly influenced by the evolution of the electronic band structures and effective masses of charge carriers. π-GeS1-xSex features sufficiently larger values of Seebeck coefficients, power factors and figures of merit (ZTs), which experience further improvement with an increase in temperature, revealing their potential for high-temperature applications. The calculated results show that ZT values equivalent to unity can be achieved for π-GeS1-xSex at appropriate n-type doping levels. Our calculations for the formation enthalpies indicate that a π-GeS1-xSex alloying system is energetically stable and could be synthesized experimentally. These intriguing characteristics make π-GeS1-xSex a promising candidate for futuristic thermoelectric applications in energy harvesting devices.Germanium mono-chalcogenides have received considerable attention for being a promising replacement for the relatively toxic and expensive chalcogenides in renewable and sustainable energy applications. In this paper, we explore the potential of the recently discovered novel cubic structured (π-phase) GeS and GeSe for thermoelectric applications in the framework of density functional theory coupled with Boltzmann transport theory. To examine the modifications in their physical properties, the across composition alloying of π-GeS and π-GeSe (such as π-GeS1-xSex for xu2009=0, 0.25, 0.50, 0.75, and 1) has been performed that has shown important effects on the electronic band structures and effective masses of charge carriers. An increase in Se composition in π-GeS1-xSex has induced a downward shift in their conduction bands, resulting in the narrowing of their energy band gaps. The thermoelectric coefficients of π-GeS1-xSex have been accordingly influenced by the evolution of the electronic band structures and e...

Solution growth of 3D MnO 2 mesh comprising 1D nanofibres as a novel sensor for selective and sensitive detection of biomolecules

This work is the first report describing the solution grown 3D manganese oxide nanofibrous (MnO2 NFs) mesh and its potential for the simultaneous detection of biomolecules such as ascorbic acid and uric acid. The mesh is synthesized by a facile, one-pot, and cost-effective hydrothermal approach without using any template or structure directing compound. The morphology consists of randomly placed nanofibres possessing a diameter in the range of 10-25u202fnm, and length of several micron; constituting a highly porous and flexible material. The electrochemical potential was examined by recording cyclic voltammetry signals towards ascorbic acid and uric acid. The special mesh morphology offers a large surface area to promote enhanced electrochemical activity, and also provided a macroporous network that supported efficient mass transport. Additionally, the strong electronic cloud and roughness of MnO2 NFs mesh facilitated the fast oxidation of species at very low potential. The lower detection limit was found to be 1.33u202fµM (S/Nu202f=u202f3) and 1.03u202fµM (S/Nu202f=u202f3) for ascorbic acid and uric acid, respectively. The MnO2 NFs mesh modified electrodes can robustly differentiate both of them by giving well separate signals (Δu202f=u202f500u202fmV) indicating capability of the material towards selective detection. The sensor has been successfully applied to human blood and urine samples and the recoveries were found statistically significant. These results demonstrate the practical feasibility of 3D mesh to develop sensors for the accurate diagnosis of clinically important molecules.