Department Of Physics

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Subject: search.filters.subject.II-VI semiconductors

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    Ab Initio Modeling of the ZnO-Cu(111) Interface
    (American Chemical Society, 2021-12-31T00:00:00) Mondal, Krishnakanta; Megha; Banerjee, Arup; Fortunelli, Alessandro; Walter, Michael; Moseler, Michael
    The morphology at the catalytically active interfacial site of ZnO/Cu in the commercial ZnO/Cu/Al2O3 catalyst for CO2 hydrogenation to methanol is still an open question. In the present study, we employ ab initio density functional theory based methods to gain insight into the structure of the ZnO-Cu interface by investigating the morphology of supported ZnO nano-ribbons at the interface with the Cu(111) surface in the presence of hydrogen and water molecules. We find that the stabilities of free-standing ZnO nano-ribbons get enhanced when they are supported on the Cu(111) surface. These supported nano-ribbons are further stabilized by the adsorption of hydrogen atoms on the top of O atoms of the nano-ribbons. Interestingly, the hydrogenated nano-ribbons are found to be equally stable and they appear to be an array of independent chains of ZnOH motifs, suggesting that the hydrogenated nano-ribbons are structurally fluxional. The edge of these fluxional nano-ribbons is stabilized via a triangular reconstruction with a basic composition of Zn6O7H7 in the presence of water molecules. Such a triangular structure gets further stabilized when it is attached to a bulk-like part of the ZnO/Cu(111) system. Furthermore, we find that the triangular reconstruction is energetically favorable even at the methanol synthesis conditions. Therefore, we propose that, under methanol synthesis conditions, the motif Zn6O7H7 represents a stable form at the interface between the bulk-like part of ZnO and the Cu(111) surface in the ZnO/Cu/Al2O3 based commercial catalyst. � 2021 American Chemical Society
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    Flexible zinc oxide photoelectrode for photo electrochemical energy conversion
    (Springer, 2021-05-18T00:00:00) Shiyani, T.; Banerjee, I.; Mahapatra, Santosh K.; Ray, Asim K.
    Photoelectrochemical properties have been investigated for flexible photoelectrodes containing 310�nm thick ZnO film on spin-coated ITO/PET. The high crystalline structure of ZnO was studied using x-ray diffraction pattern. A value of 3.4�eV has been estimated for optical band gap from its absorption spectra. The flexible ZnO photoelectrode was demonstrated to generate photoelectrochemical current. The photocurrents are enhanced by 4% whereas flat-band potential is shifted by 8�V due to the illumination. Values of 1.022 and 0.714 AW?1 were found to be for photo switching and photoresponsivity, respectively. ZnO/ITO/PET can be used as a substrate for making flexible hybrid PEC devices to generate solar power and solar fuels. � 2021, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.