Yahya Ismail - Academia.edu (original) (raw)

Papers by Yahya Ismail

Journal of Physical Chemistry C, Oct 3, 2022

RSC Advances, 2022

A polypyrrole/hydrogel hybrid film composed of macromolecular electrochemical machines fabricated... more A polypyrrole/hydrogel hybrid film composed of macromolecular electrochemical machines fabricated through an in situ chemical polymerization of pyrrole is considered here as a flexible model material of the intracellular matrix of ectothermic muscle cells which is aware of ambient thermal energy. The polypyrrole component imparts excellent electroactivity and good electronic conductivity for the hybrid film. The hybrid film can go through n consecutive fundamental conformational energetic states progressively and reversibly under electrochemical control and acts as a multi-step macromolecular motor. Under constant electrochemical stimulus (cyclic voltammetry), increasing available thermal energy promotes deeper conformational movements of the polymeric chains due to the cooperative actuation of the constitutive electrochemical machines leading to the exchange of greater amounts of counterions and solvent for charge compensation and osmotic balance. The closed coulovoltammetric responses of the hybrid film guarantee the reversible nature of the polypyrrole redox reactions and reveal the absence of simultaneous irreversible reactions taking place in the studied potential window. At any reaction time, the extension of the reaction defined by the coulovoltammetric charge varies as a semilogarithmic function of the inverse of the temperature and acts as a self-sensor of reaction thermal conditions (reaction self-awareness). The results offer the potential for biomimetic sensing motors (intelligent devices) based on a polypyrrole/chitosan hybrid film imitating biological functions in which the driving and sensing signals can be read at any time during the reaction, through the same two connecting wires.

ACS applied energy materials, Aug 9, 2021

The fabrication of a high energy density supercapacitor with electrodes bearing ultrahigh aspect ... more The fabrication of a high energy density supercapacitor with electrodes bearing ultrahigh aspect ratio active materials is still a big challenge. Here, we successfully developed ultralong and millimeter-thick supercapacitors, which enable practical applications due to the large electrochemical volumetric capacitance overcoming the limits of previous carbon-based materials. The gel graphene oxide fibers (GOFs) with an ultrahigh aspect ratio of over 20,000,000 were completely reduced at room temperature and biscrolled with a conductive Korean traditional paper used as the matrix material for the supercapacitors without any post-treatment. The average cell capacitance value of the yarn-type supercapacitors containing 80 reduced GOFs is maximized at a scan rate of 100 mV/s. The capacitance measured at a scan rate of 1000 mV/s is over 75% of that measured at 100 mV/s

Nanoscale advances, 2022

Please note that technical editing may introduce minor changes to the text and/or graphics, which... more Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal's standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains.

Encyclopedia of Polymer Science and Technology, Jul 27, 2023

Materials advances, 2022

A new class of near-infrared (NIR) reflecting yellow and orange cool pigments based on TiZn 2 O 4... more A new class of near-infrared (NIR) reflecting yellow and orange cool pigments based on TiZn 2 O 4 inverse spinels were synthesized. The colour tuning in pure TiZn 2 O 4 was made possible by the substitution of octahedral Zn 2+ ions by Cu 2+ and Fe 3+ ions separately. By the incorporation of Cu 2+ and Fe 3+ ions into the inverse spinel lattice in varying amounts, a series of pigment compositions having colours ranging from greenish-yellow to reddishbrown was obtained. The developed pigments exhibited moderate to high NIR reflectance ranging from 47.61 to 87.81%. The TiZn 2 O 4 based NIR reflecting pigment provided an interior 4.8 1C cooler than an uncoated roofed interior. Cu 2+ and Fe 3+ doped TiZn 2 O 4 systems were found to be highly stable and eco-friendly cool pigment candidates capable of achieving better thermal conditioning and impressive energy conservation. Experimental Materials Zinc nitrate (Zn(NO 3) 2 Á6H 2 O, Alfa Aesar, 98%), titanium isopropoxide (Ti(OCH(CH 3) 2) 4 , Aldrich Chemistry, 97%), cupric

RSC Advances, 2021

A facile two-step strategy has been reported for the preparation of a ternary 3D reduced graphene... more A facile two-step strategy has been reported for the preparation of a ternary 3D reduced graphene oxide/ Ni 0.5 Zn 0.5 Fe 2 O 4 /polyindole nanocomposite (GNP) and this composite is applied as an electrode material for supercapacitor applications. Remarkably, Ni 0.5 Zn 0.5 Fe 2 O 4 nanoparticles (NZF) decorated on reduced graphene oxide (GN2) are achieved by a facile hydrothermal method followed by coating with polyindole (PIN) through an in situ emulsion polymerization process. The structure, porosity, morphology, and thermal stability of the resulting ternary GNP hybrid material were characterized via X-ray diffraction (XRD), Raman spectroscopy, Brunauer-Emmett-Teller (BET) surface area measurements, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). This combination of hybrid material has a favorable mesoporous structure that enables high exposure of active sites for fast electron transport for supercapacitor applications. We demonstrate here that the ternary GNP hybrid electrode material is capable of delivering a favorable specific capacitance of $320 F g À1 at 0.3 A g À1 within the potential range from À0.1 to 1 V, with desirable rate stability and excellent cycling stability in the threeelectrode system. Furthermore, an asymmetric supercapacitor (ASC) of a two-electrode configuration was fabricated using 3D RGO and GNP as the negative and positive electrodes, respectively. Such a device manifests a favourable C sp of 48.9 F g À1 at 0.5 A g À1 and retains stability of 84% even after 2000 cycles. This ASC device exhibits a significant energy density of 16.38 W h kg À1 at a power density of 1784 W kg À1. The synergistic effects of pseudo and double layer capacitive contributions from PIN and GN2 make this ternary GNP hybrid electrode material of great promise in supercapacitor applications.

Plastics Rubber and Composites, Sep 23, 2021

Journal of Adhesion Science and Technology, Jul 14, 2020

Flexible electrode materials are inevitable for high-end applications such as wearable electronic... more Flexible electrode materials are inevitable for high-end applications such as wearable electronics, implantable microelectrodes, artificial muscles, various sensors, and biomedical devices. A simple and easy method for large scale preparation of mechanically stable and flexible electrode material using PANI and PVA films is presented. The hybrid films prepared through the chemical coating of PVA using an in-situ chemical polymerization of aniline were highly electroactive and comprised of coral-like nanowires of PANI grown on the surface of PVA films resulting large surface area and high porosity as evinced from SEM studies. FTIR spectra showed characteristic bands of PANI and PVA. Bandgap energies estimated were consistent with the electrical conductivity of the films. The doubly coated film showed an electrical conductivity as high as 4.0 Â 10 À2 S cm À1. The high electrochemical activity studied through cyclic voltammetry was attributed to the easy diffusion of ions through the porous nanowires of PANI on the surface of the films. Thermal studies revealed that hybrid films are thermally more stable. The tensile strength of the hybrid films was comparable with that of pure PVA film in the dry state while in the wet state the single coated film was mechanically more stable. Sorption studies showed that the mass swelling ratio of the hybrid films was decreased due to the incorporation of PANI into the hydrogel matrix. As the films were mechanically stable and highly electroactive and can be cut into pieces of any desirable size and shape we propose that they can be used as active electrode materials for sensors, supercapacitors, actuators, etc.

Journal of Energy Storage

Advances in Materials Science and Engineering, May 22, 2019

Nanoscale advances, 2021

Herein we first report surface basicity mediated rapid and selective adsorptive removal of organi... more Herein we first report surface basicity mediated rapid and selective adsorptive removal of organic pollutants over nanocrystalline mesoporous CeO 2. The role of surface features in controlling the selectivity and efficiency of adsorption is well known. Nevertheless, the possibility of tuning the adsorption capacity and selectivity of adsorbents through their surface characteristics remains less explored. In this work, the surface basicity of mesoporous CeO 2 nanoparticles was improved by Er 3+ doping under two different reaction conditions: via sol-gel and sol-hydrothermal methods. The nature and amount of surface basic sites were determined with the help of CO 2 temperature programmed desorption (TPD). The adsorption capacity and selectivity of four different CeO 2 samples were investigated using Congo red, methyl orange, and methylene blue as the model pollutants. From the adsorption studies, Er 3+ doped CeO 2 synthesized by the sol-gel method, having the highest amount of surface basic sites, proved to be the most efficient and highly selective adsorbent among the four developed variants of CeO 2 towards Congo red. According to the proposed mechanism, surface basicity can be employed as a controlling parameter capable of tuning the adsorption capacity as well as the selectivity of CeO 2 towards organic pollutants.

Materials Chemistry and Physics, Mar 1, 2022

Materials Research Bulletin, Aug 1, 2022

Materials Chemistry Frontiers, 2022

Conducting polymers can be considered as model materials for designing motors sensing working con... more Conducting polymers can be considered as model materials for designing motors sensing working conditions while working without additional connectivity as they mimic the electrochemical reactions of biological muscles comprising macro molecular motors.

Research on Chemical Intermediates

Materials Today: Proceedings, 2022

Materials Today: Proceedings, 2021

Journal of Materials Research, 2021

A faradaic supercapacitor electrode capable of sensing current is presented for the first time us... more A faradaic supercapacitor electrode capable of sensing current is presented for the first time using chitosan/poly-o-toluidine composites. The semiconducting and highly electroactive composites have an agglomerated nano granular morphology with sufficient porosity enabling efficient electrochemical reaction. A moderately high specific capacitance of 425 F g−1 was achieved for the composite at a scan rate of 5 mV s −1. The sensing abilities monitored through chronopotentiometry show that the consumed electrical energy during reactions varied as a linear function of the applied current which proves that the composites can function as a current sensing supercapacitor. The sensitivity with regard to current increases as the specific capacitance increases. The sensing ability is imparted through the electrochemical reaction of poly-o-toluidine, whose reaction rate (and potential) responds to and senses the electrical working condition (current). This finding suggests that any device based on conducting polymers driven by electrochemical reactions is capable of sensing electrical working conditions.