• NAVEEN KUMAR

Articles written in Bulletin of Materials Science

• Study on thermodynamic, electronic and magnetic properties of RE$_2$Cu$_2$Cd (RE $=$ Dy $−$Tm) intermetallics: first-principle calculation

RE$_2$Cu$_2$Cd (RE $=$ heavy rare earth elements: Dy, Ho, Er, Tm) intermetallics show the interesting physical, magnetic and chemical properties with reference to magnetocaloric effect. To explore the relevant complex performance of RE$_2$Cu$_2$Cd materials, which crystallizes in Mo$_2$B$_2$Fe-type structure with space group P4/$mbm$; electronic, magnetic and thermodynamic properties have been studied using first principle theory. Electronic properties, i.e. spin-polarized electron dispersion curves (band structure) and density of state calculations showthat (Dy/Ho/Er/Tm)$_2$Cu$_2$Cd compounds aremetallic with dominant character of Dy-f spin down channels. Whereas magnetic and electron spin-polarization calculations show that studied materials behave like metallic ferromagnet having nearly fully spin-polarized characteristics. The effect of temperature on bulk modulus, $B$, volume of unit cell, $V$, entropy, $S$ and specific heat, $C_{\rm v}$ has also been studied using quasi-harmonic Debye model.

• New age monolithic design-based visible light responsive and reusable photocatalyst material using iron oxide-modified mesoporous titania framework

In this work, we report a facile route for the synthesis of worm-like mesoporous Fe$_2$O$_3$-doped TiO$_2$ monolithic composites through a direct template sol–gel method, for the photocatalytic degradation of textile dye (acid blue 113) pollutants. The monolith surface morphology and structural properties have been characterized using p-XRD, HR-SEM–EDAX, HR-TEM–SAED, TGA, UV–Vis–DRS, PLS, FTIR, XPS and BET analyses. The stoichiometric doping of Fe$_2$O$_3$ unleashes visible light photocatalytic activity through a red shift in the light absorption character of TiO$_2$, thereby narrowing the energy band gap, and an eventual increase in e$^−$$/$h$^+$ separation centres. The monolithic photocatalyst exhibits better properties in terms of surface area, pore volume and diameter. The physico-chemical parameters, such as solution pH, dopant stoichiometry, catalyst quantity, dye concentration, photo-sensitizers and light intensity have been optimized to enhance the photocatalysis efficiency. The photocatalyst exhibits complete dye mineralization within 0.5 h, and also reusable for five continuous cycles.

• Monolithic heterojunctions of CeO$_2$/La$_2$O$_3$/TiO$_2$ nanocomposites as visible-light capturing photoactive materials for fast and efficient clean-up of persistent pharmaceutical pollutants

We report the first of its kind synthesis of CeO$_2$/La$_2$O$_3$ nanocomposites that are with integrated mesoporous TiO$_2$ monoliths, with well-defined structural and surface properties, to act as visible-light responsive photocatalysts. Thes tructural features of the photocatalyst materials are defined using HR-TEM, p-XRD, FE-SEM, SAED, EDAX, XPS, PLS, TGA, IR, UV–Vis–DRS and BET/BJH analyses. The stoichiometric infusion of CeO$_2$/La$_2$O$_3$ nanocomposites with themonolithic TiO$_2$ network reduces the bandgap energy from 3.26 to 2.52 eV, thus promoting excellent visible-light photocatalysis. To evaluate the photocatalytic efficiency of the proposed photoactive materials, two antimicrobial drugs namely, moxifloxacin and ciprofloxacin are selected as target pollutants. It is observed that the uniform and continuous porous monolithic network ensures easy transport of pollutant molecules to the photoactive sites, thereby felicitating their faster dissipation. The influence of various physico-chemical parameters has been studied by photolysis and photocatalysis procedures, and the extent of drug degradation is quantitatively analysed by using a robust HPLC-DAD method. The photocatalysis results reveal that the monolithic photocatalyst can serve efficiently for environmental remediation applications, with excellent reusability character.

• # Bulletin of Materials Science

Volume 44, 2021
All articles
Continuous Article Publishing mode

• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020