Wan Khairunnisa Wan Ramli
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Preferred name
Wan Khairunnisa Wan Ramli
Official Name
Wan Khairunnisa, Wan Ramli
Alternative Name
Ramli, W. K. W.
Ramli, Wan K. W.
Ramli, Wan Khairuzzaman Wan
Ramli, W. K. Wan
Main Affiliation
Scopus Author ID
18435070700
Researcher ID
DNN-0208-2022

Research Output

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  • Publication
    Exsolution enhancement of metal-support CO oxidation perovskite catalyst with parameter modification
    ( 2021-05-24)
    Lew G.L.
    ;
    Naimah Ibrahim
    ;
    Abdullah S.
    ;
    Wan Daud W.R.
    ;
    Wan Khairunnisa Wan Ramli
    This study aimed to further tune the capability of active metal exsolution onto the surface of the CO oxidative perovskite catalyst La0.7Ce0.1Co0.3Ni0.1Ti0.6O3 by tuning the reducing parameter. Under same calcination temperature of 800℃, XRD analysis shown that the precursors with calcination duration of 6 hours (S2T8H6) was able to achieve similar crystalline structure to those with calcination duration of 12 hours (S2T8H12). In order for the active metal (CoNi) to be exsolved onto the perovskite surface, reducing parameter such as temperature and duration are deemed crucial to the reduction process. The exsolution of the active metals was observed when the samples were treated under reducing condition with varying temperatures of 550℃ and 700℃ and duration from 200 to 300 minutes. Through comparison with their EDX readings, S2T8H6 treated under 700℃ and 300 minutes (S2T8H6-R7H5) achieved the highest weight percentage of surface Cobalt and Nickel of 3.83 and 2.81. It was clear that by tuning the temperature and duration of reduction, the exsolution of the active metals onto the surface of the perovskite could be improved resulting in better exposure and dispersion of active metals onto the surface of catalyst.
  • Publication
    Fe₃O₄-Doped polysulfane membrane for enhanced adsorption of copper from aqueos solution
    ( 2024-01-01)
    Wan Khairunnisa Wan Ramli
    ;
    Nur Maisyatul Syalina Abdul Wahab
    ;
    Siti Khalijah Mahmad Rozi
    ;
    Syumayyah Rasis
    ;
    Gavin Chew Tiong Chuen
    ;
    Lew Guo Liang
    Water pollution, especially from industrial wastewater has become one of the major global environmental problems. As the result of rapid industrialization, the expansion of industries such as the electroplating industry has resulted in an increase in heavy metals effluent, especially copper, in the wastewater, and this poses detrimental effects on the biodiversity and environment. The abatement of copper pollution has received widespread attention, and continuous research advancement has been observed in adsorption and membrane technology. Nanofiltration membranes with nanopores recorded higher suitability to remove ions but at the expense of membrane fouling as a result of the formation of contaminants on the surface layer that blocks the diffusion of contaminants into the membrane substructure. This research highlights the incorporation of Fe3O4 nanoparticles into the polysulfone (PSf) membrane matrix as an adsorptive membrane and their possible adsorption mechanism towards Cu, which can manifest the combined characteristics of both removal techniques. Fe3O4 nanoparticles were synthesized using the co-precipitation method. Fe3O4-doped PSf membranes were then synthesized with various concentrations of Fe via the Non-solvent Induced Phase Separation (NIPS) technique. The physicochemical properties of the Fe nanoparticles and the membranes were evaluated using X-ray diffraction (XRD), Scanning Electron Microscope (SEM), water contact angle and porosity testing. Crystal phase analysis confirmed the formation of magnetite Fe3O4 in a cubic structure. Agglomerations of Fe NPs on the membrane surface were observed for membranes with lower Fe concentrations, suggesting the possibility of poor blending and this contributed to the lower adsorption capability of these membranes. Membranes with 2 wt.% Fe concentration (Fe-2.0) exhibited the highest Cu(II) ions adsorption capacity of 637 mg/g, which is trifold of those recorded for pristine PSF membrane (Fe-0.0). The adsorption data of Cu adsorption were best fitted into the Temkin isotherm and pseudo-second-order models, suggesting an adsorption mechanism involving an exothermic chemical interaction between Cu ions and the Fe3O4 NPs within the membrane. This research confirms the potential of incorporating Fe3O4 in the PSf membrane backbone to enhance Cu removal as an adsorptive membrane, even at lower NP concentrations.
  • Publication
    Demonstration of chemistry at a point through restructuring and catalytic activation at anchored nanoparticles
    ( 2017)
    Dragos Neagu
    ;
    Evangelos I. Papaioannou
    ;
    Wan Khairunnisa Wan Ramli
    ;
    David N. Miller
    ;
    Billy J. Murdoch
    ;
    Hervé Ménard
    ;
    Ahmed Umar
    ;
    Anders J. Barlow
    ;
    Peter J. Cumpson
    ;
    John T. S. Irvine
    ;
    Ian S. Metcalfe
    Metal nanoparticles prepared by exsolution at the surface of perovskite oxides have been recently shown to enable new dimensions in catalysis and energy conversion and storage technologies owing to their socketed, well-anchored structure. Here we show that contrary to general belief, exsolved particles do not necessarily re-dissolve back into the underlying perovskite upon oxidation. Instead, they may remain pinned to their initial locations, allowing one to subject them to further chemical transformations to alter their composition, structure and functionality dramatically, while preserving their initial spatial arrangement. We refer to this concept as chemistry at a point and illustrate it by tracking individual nanoparticles throughout various chemical transformations. We demonstrate its remarkable practical utility by preparing a nanostructured earth abundant metal catalyst which rivals platinum on a weight basis over hundreds of hours of operation. Our concept enables the design of compositionally diverse confined oxide particles with superior stability and catalytic reactivity
      7  4
  • Publication
    Exsolution of nickel alloys anchored nanoparticles on perovskite oxides for CO oxidation
    (IOP Publishing, 2020)
    Wan Khairunnisa Wan Ramli
    ;
    E Papaioannou
    ;
    D Naegu
    ;
    I S Metcalfe
    Noble metals notably platinum (Pt), is a major element of heterogeneous catalysts, excel in catalysing an extensive number of important catalytic reactions in chemical and automotive industries. Since the increased use of these metals is severely limited because of their high cost and scarcity’s, there is therefore an urgent need for the search of alternative transition metal catalysts that are cheaper and more widely available. This can only be practical if the main drawbacks of these transition metals can be impeded for instance the agglomeration of particles under high temperatures operational conditions with their activity enhanced, such that they can directly replace Pt on a weight-to-weight basis. The exsolution of metallic nanoparticles mainly nickel (Ni) at the surface of perovskite oxides in situ has shown remarkable catalytic activity and durability towards carbon monoxide (CO) and nitric oxide (NO) oxidation and in fuel cells. In this study, for CO oxidation reaction, the catalytic capabilities of exsolved Ni nanoparticles can be further enhanced when iron (Fe) and cobalt (Co) are co-exsolved with Ni, as FeNi and CoNi alloy nanoparticles, forming mixed oxide nanoparticles. FeNi alloy nanoparticles exhibit almost ten times site activities as compared to the Ni nanoparticles, owing to the oxide layer formation which then aided the oxidation of CO. Interesting enough, the CoNi alloy nanoparticles exhibit slightly different morphological and chemical transformation due to the difference in oxidation mechanism and the degree of oxidation, which reveal greater site activities towards CO oxidation. These nanoparticles were also subjected to additional compressive strain when they expanded as a result of them being pinned to the support. These results pave the way for new approach in altering the activity of the exsolved materials for various reactions.
      2  3