School Of Basic And Applied Sciences

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    Stability, optoelectronic and thermal properties of two-dimensional Janus ?-Te2S
    (IOP Publishing Ltd, 2022-02-14T00:00:00) Singh, Jaspreet; Jakhar, Mukesh; Kumar, Ashok
    Motivated by recent progress in the two-dimensional (2D) materials of group VI elements and their experimental fabrication, we have investigated the stability, optoelectronic and thermal properties of Janus ?-Te2S monolayer using first-principles calculations. The phonon dispersion and MD simulations confirm its dynamical and thermal stability. The moderate band gap ( 1/41.5 eV), ultrahigh carrier mobility ( 1/4103 cm2 V-1 s-1), small exciton binding energy (0.26 eV), broad optical absorption range and charge carrier separation ability due to potential difference ( "V = 1.07 eV) on two surfaces of Janus ?-Te2S monolayer makes it a promising candidate for solar energy conversion. We propose various type-II heterostructures consisting of Janus ?-Te2S and other transition metal dichalcogenides for solar cell applications. The calculated power conversion efficiencies of the proposed heterostructures, i.e. ?-Te2S/T-PdS2, ?-Te2S/BP and ?-Te2S/H-MoS2 are 1/421%, 1/419% and 18%, respectively. Also, the ultralow value of lattice thermal conductivity (1.16 W m-1 K-1) of Janus ?-Te2S makes it a promising material for the fabrication of next-generation thermal energy conversion devices. � 2022 IOP Publishing Ltd.
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    Pressure and electric field tuning of Schottky contacts in PdSe2/ZT-MoSe2 van der Waals heterostructure
    (Institute of Physics Publishing, 2020) Jakhar, M; Singh, J; Kumar, A; Tankeshwar, K.
    A two-dimensional van der Waals (vdW) heterostructure (PdSe2/ZT-MoSe2) has been investigated through vdW corrected density functional theory. ZT-MoSe2 acts as a Dirac material with an anisotropic Dirac cone and variable Fermi velocity (0.52-1.91 105 ms-1). The intrinsic Schottky barrier height can be effectively tuned by applying external pressure and an electric field to the heterostructure. The p-type Schottky barrier transforms into a p-type ohmic contact at pressure P ? 16 GPa. A positive electric field induces p-type ohmic contact while a negative electric field results in the transition from p-type Schottky contact to n-type Schottky contact, and finally to n-type ohmic contact at the higher values of the field. Moreover, the external positive (negative) electric field induces n-type (p-type) doping of ZT-MoSe2 in the heterostructure and remarkably controls the charge carrier concentration. Our results demonstrate that controlling the external pressure and electric field in a PdSe2/ZT-MoSe2 heterostructure can result in an unprecedented opportunity for the design of high-performance nanodevices. � 2020 IOP Publishing Ltd.
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    NiO QDs /ZnO nanorods composite structure for catalytic reduction of Cr6+
    (Central University of Punjab, 2018) Ahmed, Imtiaz; Haldar, K.K
    Infront of the emerging interest and talent to search for new materials, we have synthesized Nickel oxide (NiO) nanoparticles decorated Zinc oxide (ZnO) nanorods composite (NiO/ZnO) nanostructure. By the X-ray powder diffraction and high-resolution transmission electron microscopy (HRTEM) the NiO/ZnO heterostructure formation was confirmed. The fabricated environmental affable NiO/ZnO composite nanostructure under UV-lights shows a well-defined photoreduction characteristic of hexavalent Chromium (Cr) (VI) to tri-valent Chromium (Cr) (III). Photoluminescence (PL) spectroscopy, photocurrent study, and electrochemical impedance spectroscopy, proved that the superior photoreduction property is ascribed due to the decreased electron-hole recombination process. In addition to the photocatalytic activity rate of the NiO decorated ZnO nanorods was much higher than that of exposed ZnO nanorods dfv for the reduction of chromium (VI) and their rate of activity is found to be 0.306 min?1 . All results have demonstrates that in the development of highperformance photocatalyst the suitable surface engineering may open up new opportunities.