• MEYSAM NAJAFI

      Articles written in Bulletin of Materials Science

    • Sn-adopted fullerene (C$_{60}$) nanocage as acceptable catalyst for silicon monoxide oxidation

      RAZIEH RAZAVI SEYYED MILAD ABRISHAMIFAR MOHAMMAD REZA REZAEI KAHKHA ARASH VOJOOD MEYSAM NAJAFI

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      In recent years, the discovery of metal catalysts for the oxidation of silicon monoxide (SiO) has become extremely important. In first step, the Sn adoption of fullerene (C$_{60}$) was investigated and then activation of surface ofSn-C$_{60}$ via O$_2$ molecule was examined. In second step, the SiO oxidation on surface of Sn-C$_{60}$ via Langmuir Hinshelwood (LH) and Eley Rideal (ER) mechanisms was investigated. Results show that O$_2$-Sn-C$_{60}$ can oxidize the SiO molecule via Sn-C$_{60}$-O-O$^∗$ $+$ SiO $\to$ Sn-C$_{60}$-O-O$^∗$-SiO $\to$ Sn-C$_{60}$-O$^∗$ $+$ SiO$_2$ and Sn-C$_{60}$-O$^∗$ $+$ SiO $\to$ Sn-C$_{60}$ $+$ SiO$_2$ reactions.Results show that SiO oxidation via the LH mechanism has lower energy barrier than ER mechanism. Finally, Sn-C$_{60}$ is an acceptable catalyst with high performance for SiO oxidation in normal temperature.

    • C$_{32}$, Si$_{32}$ and B$_{16}$N$_{16}$ as anode electrodes of Li-, Na- and K-ion batteries: theoretical examination

      RAZIEH RAZAVI BEHNAM NASROLLAHZADEH SYED ABOLGHASEM MIRHOSSEINEI MILAD JANGHORBAN LARICHE MEYSAM NAJAFI

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      In this study, the potential of C$_{32}$, Si$_{32}$ and B$_{16}$N$_{16}$ nanocages as anode electrodes of Li-,Na- andK-ion batteries via density functional theory was investigated. The effects of halogen-adoption of C$_{32}$, Si$_{32}$ and B$_{16}$N$_{16}$ on potentials of metal-ion batteries were examined. Results showed that B$_{16}$N$_{16}$ as an anode electrode in metal-ion batteries has higher potential than C$_{32}$ and Si$_{32}$. Results illustrated that (i) a K-ion battery has higher cell voltage and higher performance than Li- and Na-ion batteries; (ii) halogen-adoption of nanocages increased the cell voltage of studied metal-ion batteries and (iii) F-adopted metal-ion batteries have higher cell voltage than Cl- and Br-adopted metal-ion batteries. Finally, F–B$_{15}$N$_{16}$ as an anode electrode in K-ion batteries has the highest performance and it can be proposed as novel metal-ion batteries.

    • Titanium-doped carbon and boron nitride nanocages (Ti–C$_{48}$ and Ti–B$_{24}$N$_{24}$) as catalysts for ClO $+$ 1/2O$_2$ $\to$ ClO$_2$ reaction: theoretical study

      CHAO SUI ZHIPING ZHANG XUE CAI QI ZHOU MEYSAM NAJAFI

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      The performances of Ti-doped carbon and boron nitride nanocages towards chloride monoxide (ClO) oxidation were examined. Details of mechanisms of oxidation of ClO on Ti-doped carbon and boron nitride nanocages were examined. Ti atoms of Ti–C$_{48}$ and Ti–B$_{24}$N$_{24}$ show catalytic activity towards ClO adsorption with low-barrier energies. Resultsdisplayed that the Ti-doped carbon and boron nitride nanocages oxidized ClO by the mechanisms of Eley–Rideal (ER) and Langmuir–Hinshelwood (LH). Catalytic activities in the LH path were limited by irremediable adsorption of chloridedioxide (ClO$_2$) on Ti–C$_{48}$ and Ti–B$_{24}$N$_{24}$.While, in the ER path, the first and second ClO$_2$ were separated, directly. Finally,the results proved that the Ti–C$_{48}$ and Ti–B$_{24}$N$_{24}$ show suitable catalytic abilities towards ClO oxidation via the ER path.

    • Theoretical examination of oxygen reduction reaction (ORR) on carbon nanocone (CNC) for fuel cells

      XIAOMIN SHANG MENG SUN MINGXIAO JIN XIAOQIU LIU MEYSAM NAJAFI

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      Recently, various studies were performed to propose and discover acceptable catalysts for oxygen reduction reaction (ORR) in various fuel cells. Here, performance of boron-doped carbon nanocone (CNC) as catalyst to ORR via theoretical methods is examined. The ORR paths through ER and LH mechanisms were studied. Results showed that onsetpotentialand over-potential on ORR of boron–CNC were 0.73 and 0.50 V, respectively. The calculated exchange current density and transfer coefficient of B–CNC were $ca.$ $6.5 \times 10^{−6}$ A cm$^{−2}$ and 0.52, respectively. Results demonstrate that boron-doped CNC is a high-potential catalyst to ORR.

    • Investigation of potentials of C$_{30}$ and Ge$_{30}$ as anode in metal-ion batteries

      ZENGCAI MI KAIJIN ZHU LIFENG DING MEYSAM NAJAFI

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      Performances of C$_{30}$ and Ge$_{30}$ nanocages for anode electrodes in metal-ion battery (MI-B) are studied. Abilities of halogens (F, Br and Cl) adsorption on C$_{30}$ and Ge$_{30}$ potential for anode electrodes of MI-Bs were investigated. Gibbs free energy, voltage of cell, adsorption energy and orbital energy values of studied complexes were calculated and werecompared. Results displayed the $V_{\rm cell}$ of K-Ge$_{30}$ was higher than Na- and Li-Ge$_{30}$ 0.15 and 0.29 V. $V_{\rm cell}$ of K, Na and Li onGe$_{30}$ were higher than C$_{30}$ 0.18, 0.17 and 0.15 V. The G$_{\rm ad}$ of halogens (F, Br and Cl) on Ge$_{30}$ were higher than C$_{30}$ 5.19,4.63 and 4.91 eV. $V_{\rm cell}$ of K-halogen-, Na-halogen- and Li-halogen-Ge$_{30}$ are higher than C$_{30}$ 0.39, 0.36 and 0.32 V. G$_{\rm ad}$ of2, 3 and 4 halogens (F, Br and Cl) on Ge$_{30}$ are higher than C$_{30}$ ca 5.12, 3.29 and 4.64 eV, respectively. Finally, the F-Ge$_{29}$ with high performance and $V_{\rm cell}$ was proposed as anode electrode of potassium ion battery.

    • A DFT investigation of performance of metal-doped nanotubes as acceptable catalysts to SiO oxidation

      WEI GAO LI YAN YINGFANG LI MEYSAM NAJAFI

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      The Fe-doped nanotubes can be considered as novel catalysts to SiO oxidation. The information of SiO oxidation on nano-catalysts is not clear. In this study, the SiO oxidation on Fe-carbon nanotube (CNT) and Fe-boron nitride nanotube (BNNT) is examined through Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) paths. The SiO joins in the Fe atom of Fe-surface-O$_2$$^*$ and Fe-surface-O$^*$ to create important structures with minor barrier energy. Cis-Fe-surface-OSiOO$^*$ in the ER is more stable than structures in LH pathway. In the LH and ER mechanisms the one and two SiO$_2$ are released at normal temperature, respectively. The abilities of Fe-CNT and Fe-BNNT to oxidation of SiO is investigated, and Fe-CNT and Fe-BNNT as novel metal-doped catalysts are proposed.

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    • 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

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

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      Posted on July 25, 2019

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