Rafizah Rahamathullah
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Preferred name
Rafizah Rahamathullah
Official Name
Rafizah, Rahamathullah
Alternative Name
Rahamathulla, Rafizah
Rahamathullah, R.
Main Affiliation
Scopus Author ID
55764144700
Researcher ID
DMZ-6313-2022

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Contribution of stilbene-imine additives on the structural, ionic conductivity performance and theoretical evaluation on CMC-based biopolymer electrolytes

2020 , Rafizah Rahamathullah , Wan M. Khairul , M.I.N Isa

New solid biopolymer electrolytes (SBEs) were prepared by integrating stilbene-imine derivatives bearing vinylene (–CH[dbnd]CH–) and azomethine (–CH[dbnd]N–) as additives in carboxymethyl cellulose (CMC) based electrolyte. The investigation on their spectroscopic and theoretical assessments were conducted to alter the energy level in improving the structural and ionic conductivity performance. The simulated results from frontier molecular orbitals (FMO) and Mulliken-charge analysis revealed that -CF3 and -NO2 substituents significantly reduce the HOMO-LUMO gap up to 0.68 eV. The highest ionic conductivity of SBEs achieved at ambient temperature was ∼8 × 10−3 Scm-1 upon the addition of additive, obeying an Arrhenius model with reciprocal of temperature (303 K–373 K). The coordination interaction of C–O bond and CH[dbnd]N band facilitated the dissociation of more cation (H+) of NH4Cl which permits alternative route for H+ to hop into coordinating site in CMC. The outcomes are ideal in the development of electrochemical devices.

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Chitosan based solid electrolyte doped with new azo-azomethine additive for electric double-layer capacitor (EDLCs)

2025-06-10 , Tuan Siti Fatimah Tuan Mohd Pauzi , Rafizah Rahamathullah , M.N. Hafiza , Qian Yee Ang , Wan M. Khairul , Artiqah Khairudin , M.I. Rosli , Fatin Saiha Omar

Biopolymer-based solid electrolytes are gaining attention for their potential in electric double-layer capacitors (EDLCs). However, their practical application is limited by drawbacks such as low electrical performance and increased corrosive reactivity due to excessive amount of plasticizers. This present study investigates the effect of an azo-azomethine (AI) additive featuring hybrid (-N=N-) and (-CH=N-) groups, incorporated into a chitosan biopolymer matrix as a novel electrolyte for enhancing EDLC performance. Simulated results of the molecular electrostatic potential (MEP) and frontier molecular orbitals (FMO) suggest that the nitrogen (N) and oxygen (O) atoms from the azo and alkoxy substituents modulate the energy level of AI by reducing the HOMO-LUMO gap to 2.17 eV. The interaction between AI additive and chitosan was assessed using FTIR and powder-XRD analyses. The ionic conductivity of the prepared SBEs also increased by eight orders of magnitude from 7.38 × 10−10 S/cm to 1.27 × 10−2 S/cm with the contribution of 8 wt% of the additive. The EDLC cell was constructed by placing the prepared SBE within carbon-based electrodes, resulting in a specific capacitance 2.05 × 10−5 F/g. Thus, these findings demonstrate promising potential for electrochemical device applications.

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