Browsing by Author "Ekwere, Precious Idinma"

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    Microwave synthesized ruthenium antimony oxide-graphene nanocomposite materials for asymmetric supercapacitors
    (University of the Western Cape, 2022) Ekwere, Precious Idinma; Iwuoha, Emmanuel
    With the rapid rise in energy demand and ever-escalating environmental hazards, the need for transition from fossil fuel to renewable energy sources is of paramount importance, requiring better and efficient energy storage devices such as supercapacitors. Supercapacitors are energy storage devices with high power density and long cycle life, but relatively low energy density when compared to batteries. New and advanced electrode materials are required to improve the energy density requirements of next-generation supercapacitors. However, the search for new types of active materials to be used as supercapacitors' electrodes continues to be a tough challenge. Herein, ruthenium antimony oxide (RuSbO) and ruthenium antimony oxide graphene (RuSbO-G) were synthesized via the microwave-assisted method for the first time and tested as a possible electrode material for an asymmetric supercapacitor. Graphene oxide prepared by modified Hummer’s method was exfoliated at low temperature and used for the synthesis of RuSbO-G.
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    Novel heterojunction superstrate Cu2ZnInS4−x (CZIS) thin film kesterite solar cell with vertical arrays of hexagonal ZnO nanorods window layer
    (Elsevier, 2022-11-24) Yussuf, Sodiq Tolulope; Ramoroka, Morongwa Emmanuel; Mdluli, Siyabonga Beizel; Nwambaekwe, Kelechi Chiemezie; Ekwere, Precious Idinma; Uhuo, Onyinyechi Vivian; Ikpo, Chinwe Oluchi; Iwuoha, Emmanuel Iheanyichukwu
    Quaternary Cu2ZnInS4−x (CZIS) thin films have been prepared by a facile and cheap sol-gel spin coating technique. Low-temperature solution-based methods were used to fabricate a heterojunction solar cell in the superstrate architecture with CZIS thin film as the absorber, vertically aligned ZnO nanorod arrays, and CdS as the window and buffer layers respectively. ZnO nanorod arrays were prepared by hydrothermal technique and nanocrystal layer deposition technique were employed for the deposition of CdS-coated ZnO nanorod arrays. CZIS absorber layer was spin coated on the CdS-coated ZnO nanorod arrays and annealed at different temperatures. The vertically aligned ZnO nanorod arrays, and uniformly distributed CdS shell layer were confirmed from morphological studies. The device had a final configuration of Glass/ITO/ZnO NRs/CdS/ CZIS/Ag. HRSEM revealed a nanoflake-like morphology and a band gap between 1.5 and 1.77 eV for the CZIS thin films. CZIS superstrate solar cell had a power conversion efficiency of ∼ 0.61%, an open circuit voltage of ∼ 0.8 V, a short circuit current of ∼ 0.95 mA cm−2 and a fill factor of ∼ 61.35%. This method demonstrates a novel, facile and eco-friendly technique for synthesizing nanocrystalline CZIS thin films with promising photo response from the fabricated device indicating a proof of principle that this material can find application in solar cells.