School Of Basic And Applied Sciences

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Author: search.filters.author.Pandey, RavindraHas files: No

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    Photocatalytic properties of anisotropic ?-PtX2 (X = S, Se) and Janus ?-PtSSe monolayers
    (Royal Society of Chemistry, 2022-09-01T00:00:00) Jamdagni, Pooja; Kumar, Ashok; Srivastava, Sunita; Pandey, Ravindra; Tankeshwar, K.
    The highly efficient photocatalytic water splitting process to produce clean energy requires novel semiconductor materials to achieve a high solar-to-hydrogen energy conversion efficiency. Herein, the photocatalytic properties of anisotropic ?-PtX2 (X = S, Se) and Janus ?-PtSSe monolayers were investigated based on the density functional theory. The small cleavage energy for ?-PtS2 (0.44 J m?2) and ?-PtSe2 (0.40 J m?2) endorses the possibility of mechanical exfoliation from their respective layered bulk materials. The calculated results revealed that the ?-PtX2 monolayers have an appropriate bandgap (?1.8-2.6 eV) enclosing the water redox potential, light absorption coefficient (?104 cm?1), and exciton binding energy (?0.5-0.7 eV), which facilitates excellent visible-light-driven photocatalytic performance. Remarkably, the inherent structural anisotropy leads to an anisotropic high carrier mobility (up to ?5 � 103 cm2 V?1 S?1), leading to a fast transport of photogenerated carriers. Notably, the required small external potential to realize hydrogen evolution reaction and oxygen evolution reaction processes with an excellent solar-to-hydrogen energy conversion efficiency for ?-PtSe2 (?16%) and ?-PtSSe (?18%) makes them promising candidates for solar water splitting applications. � 2022 The Royal Society of Chemistry.
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    Optoelectronic and photocatalytic properties of stable pentagonal B2S and B2Se monolayers
    (Elsevier B.V., 2022-06-01T00:00:00) Katoch, Neha; Kumar, Jagdish; Kumar, Ashok; Ahluwalia, P.K.; Pandey, Ravindra
    Boron-based 2D monolayers have attracted tremendous interest due to their unique physical and chemical properties. In this paper, we report novel pentagonal monolayers, B2S and B2Se, which are predicted to be energetically, dynamically, and thermally stable based on density functional theory. At the HSE06 level of theory, they exhibit a moderate indirect bandgap of (e.g., 1.82 eV for Penta-B2S and 1.94 eV for Penta-B2Se). Strain-induced indirect-to-direct bandgap transition, high hole mobility (~103 Cm2V-1S-1) and strong optical absorption (? ~105 Cm-1) in the visible region are observed for these monolayers. Moreover, the electronic band structures and optical spectra are tunable by mechanical strains suggesting their visible light-harvesting capabilities for optoelectronic applications. In this way, the pentagonal family of 2D materials is now expanded to include boron-containing photocatalytic materials for water splitting applications. � 2022
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    Engineering 2D Materials for Photocatalytic Water-Splitting from a Theoretical Perspective
    (MDPI, 2022-03-21T00:00:00) Jakhar, Mukesh; Kumar, Ashok; Ahluwalia, Pradeep K.; Tankeshwar, Kumar; Pandey, Ravindra
    Splitting of water with the help of photocatalysts has gained a strong interest in the scientific community for producing clean energy, thus requiring novel semiconductor materials to achieve highyield hydrogen production. The emergence of 2D nanoscale materials with remarkable electronic and optical properties has received much attention in this field. Owing to the recent developments in highend computation and advanced electronic structure theories, first principles studies offer powerful tools to screen photocatalytic systems reliably and efficiently. This review is organized to highlight the essential properties of 2D photocatalysts and the recent advances in the theoretical engineering of 2D materials for the improvement in photocatalytic overall water-splitting. The advancement in the strategies including (i) single-atom catalysts, (ii) defect engineering, (iii) strain engineering, (iv) Janus structures, (v) type-II heterostructures (vi) Z-scheme heterostructures (vii) multilayer configurations (viii) edge-modification in nanoribbons and (ix) the effect of pH in overall watersplitting are summarized to improve the existing problems for a photocatalytic catalytic reaction such as overcoming large overpotential to trigger the water-splitting reactions without using cocatalysts. This review could serve as a bridge between theoretical and experimental research on next-generation 2D photocatalysts. � 2022 by the authors. Licensee MDPI, Basel, Switzerland.
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    Electronic and optical properties of boron-based hybrid monolayers
    (IOP Publishing Ltd, 2021-06-24T00:00:00) Katoch, Neha; Kumar, Ashok; Kumar, Jagdish; Ahluwalia, P.K.; Pandey, Ravindra
    Anisotropic 2D Dirac cone materials are important for the fabrication of nanodevices having direction-dependent characteristics since the anisotropic Dirac cones lead to different values of Fermi velocities yielding variable carrier concentrations. In this work, the feasibility of the B-based hybrid monolayers BX (X = As, Sb, and Bi), as anisotropic Dirac cone materials is investigated. Calculations based on density functional theory and molecular dynamics method find the stability of these monolayers exhibiting unique electronic properties. For example, the BAs monolayer possesses a robust self-doping feature, whereas the BSb monolayer carries the intrinsic charge carrier concentration of the order of 1012 cm?2 which is comparable to that of graphene. Moreover, the direction-dependent optical response is predicted in these B-based monolayers; a high IR response in the x-direction is accompanied with that in the visible region along the y-direction. The results are, therefore, expected to help in realizing the B-based devices for nanoscale applications. � 2021 IOP Publishing Ltd Printed in the UK