• ASGHAR ALI

      Articles written in Bulletin of Materials Science

    • Synthesis of Ag$_2$Se–graphene–TiO$_2$ nanocomposite and analysis of photocatalytic activity of CO$_2$ reduction to CH$_3$OH

      ASGHAR ALI WON-CHUN OH

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      The present work deals with the development of a new ternary composite, Ag$_2$Se–G–TiO$_2$, using ultrasonic techniques as well as X-ray diffraction (XRD), scanning electron microscopy (SEM), high transmission electron microscopy(HTEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and UV–Vis diffuse reflectance spectra (DRS)analyses. The photocatalytic potential of nanocomposites is examined for CO$_2$ reduction to methanol under ultraviolet(UV) and visible light irradiation. Ag$_2$Se–TiO$_2$ with an optimum loading graphene of 10wt% exhibited the maximumphotoactivity, obtaining a total CH3OH yield of 3.52 $\mu$mol g$^{−1}$ h$^{−1}$ after 48 h. This outstanding photoreduction activity is due to the positive synergistic relation between Ag$_2$Se and graphene components in our heterogeneous system.

    • First-principles calculations of opto-electronic properties of IIIAs (III $=$ Al, Ga, In) under influence of spin–orbit interaction effects

      MALAK AZMAT ALI NADEEM KHAN FAROOQ AHMAD ASGHAR ALI MUHAMMAD AYAZ

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      In this article, we present first-principles calculations for structural and opto-electric properties of IIIAs (III $=$ Al, Ga, In) in the zinc-blende phase. Our calculations are based on the full potential-linearized augmented planewave method implemented in the WIEN2k code. We employed Perdew–Burke–Ernzerhof generalized gradient and modified Becke–Johnson approximations as exchange–correlation potentials. Our calculated structure parameters are found to be in reasonable agreement with the available literature. It was found that the inclusion of spin–orbit interaction effect shifts the conduction band minima towards the Fermi level and provides band gaps very close to their experimental values. The optical properties such as complex dielectric functions, complex refractive indices, reflectivities, energy loss functions, optical conductivities and absorption coefficients at varied frequencies were investigated in detail. We found that static real part of dielectric functions and refractive index decreases with increase in band gap. Our calculated critical point energies (eV) are consistent with the experimental results.

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