Browsing by Author "Shirodkar, Sharmila N."

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    Defining shapes of two-dimensional crystals with undefinable edge energies
    (Springer Nature, 2022) Wang, Luqing; Shirodkar, Sharmila N.; Zhang, Zhuhua; Yakobson, Boris I.
    The equilibrium shape of crystals is a fundamental property of both aesthetic appeal and practical importance: the shape and its facets control the catalytic, light-emitting, sensing, magnetic and plasmonic behaviors. It is also a visible macro-manifestation of the underlying atomic-scale forces and chemical makeup, most conspicuous in two-dimensional (2D) materials of keen current interest. If the crystal surface/edge energy is known for different directions, its shape can be obtained by the geometric Wulff construction, a tenet of crystal physics; however, if symmetry is lacking, the crystal edge energy cannot be defined or calculated and thus its shape becomes elusive, presenting an insurmountable problem for theory. Here we show how one can proceed with auxiliary edge energies towards a constructive prediction, through well-planned computations, of a unique crystal shape. We demonstrate it for challenging materials such as SnSe, which is of C2v symmetry, and even AgNO2 of C1, which has no symmetry at all.
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    Substitution of copper atoms into defect-rich molybdenum sulfides and their electrocatalytic activity
    (Royal Society of Chemistry, 2021) Wang, Zixing; Kannan, Harikishan; Su, Tonghui; Swaminathan, Jayashree; Shirodkar, Sharmila N.; Hernandez, Francisco C. Robles; Benavides, Hector Calderon; Vajtai, Robert; Yakobson, Boris I.; Meiyazhagan, Ashokkumar; Ajayan, Pulickel M.
    Studies on intercalation or substitution of atoms into layered two-dimensional (2D) materials are rapidly expanding and gaining significant consideration due to their importance in electronics, catalysts, batteries, sensors, etc. In this manuscript, we report a straightforward method to create sulphur (S) deficient molybdenum (Mo) sulfide (MoS2−x) structures and substitute them with zerovalent copper (Cu) atoms using a colloidal synthesis method. The synthesized materials were studied using several techniques to understand the proportion and position of copper atoms and the effect of copper functionalization. Specifically, the impact of change in the ratio of Cu : S and the hydrogen evolution reaction (HER) activity of the derived materials were evaluated. This technique paves the way for the synthesis of various functionalized 2D materials with a significant impact on their physical and chemical behavior making them potential candidates for catalysis and several other applications such as energy storage and the development of numerous functional devices.