Functionalization of carbon and graphene quantum dots

In recent years, quantum dots (QDs) have been widely explored in the field of optoelectronics due to their exceptional physicochemical properties, including chemical stability, size-dependent optoelectronic properties (e.g., bandgap, and energy levels), high surface area, and mechanical flexibility. Furthermore, the QDs are biocompatible and environmentally friendly materials, which have garnered worldwide interests for use as fluorescent probes in bioimaging. This chapter aims to explain the recent findings on this growing topic and to disseminate critical insights, which would shed light onto the deployment of QDs-related technology, including carbon quantum dots and graphene quantum dots (GQDs) from fundamental research works and the applied sciences domain. Several QDs synthesis approaches and physicochemical property characterizations are explained from the perspectives of experimental and theoretical frameworks. The current trends of research, which would predict challenges, prospective candidates of precursors, fabrication technology and targeted size of the GQDs, are also discussed

Involvement of ethylene carbonate on the enhancement H+ carriers in structural and ionic conduction performance on alginate bio-based polymer electrolytes

This study investigates the structural and ionic conduction performance with the involvement of ethylene carbonate (EC) in a bio-based polymer electrolytes (BBPEs) system, based on alginate doped glycolic acid (GA). The solution casting technique was used to successfully prepare the BBPEs which were characterized with various approaches to evaluate their ionic conduction performance. It was revealed that at ambient temperature, an optimum ionic conductivity of 9.06 × 10−4 S cm−1 was achieved after the addition of 6 wt% EC, with an observed improvement of the amorphous phase and thermal stability. The enhancement of ionic conduction properties is believed to be due to the protonation (H+) enhancement, as proven by FTIR and TNM studies. The findings show that the developed alginate-GA-EC is a promising candidate for use as electrolytes in electrochemical devices that are based on H+ carriers

An Enhancement on Electrical Properties of Carboxymethyl Cellulose-NH4Br Based Biopolymer Electrolytes Through Impedance Characterization

In this work, the formulation of biopolymer electrolytes (BEs) system has been accomplished by incorporating various plasticizers with carboxymethyl cellulose–NH4Br through solution casting technique. The ionic conductivity at room temperature of BEs system was achieved at ∼10−4 S cm−1 with addition of 25 wt% NH4Br and enhanced to ∼10−3 S cm−1 when plasticizers were added. The temperature-dependence of the BEs system exhibits Arrhenius behavior. Jonschers power law was used to study the electrical properties and shows that the highest conducting BEs system can be represented by overlapping overlapping a large polaron tunneling model for poly(ethylene glycol) system a, small polaron hopping model for glycerol system, and a quantum mechanical tunneling model for ethylene carbonate system

Mapping of faults in the Libyan Sirte Basin by magnetic surveys

Magnetic surveys were carried out in Farigh area which is located in the eastern part of the Libyan Sirte basin. Interpretation of the onshore magnetic anomaly of this area, suggests that the high total magnetization may be caused by an intrusive body. Analysis of the magnetic power spectra indicates the presence of four sub-anomalies at depths of 340 m, 1400 m, and 2525 m which is probably related to the igneous rocks. The presence of igneous rock as basement at depth of 4740 m was confirmed by drilling. Assuming that all rock magnetization in the area is caused by induction in the present geomagnetic field, it strongly suggests that the causative structure has a remnant magnetization of declination (D) = −16° and inclination (I) = 23°. Based on pseudogravity data, the total horizontal derivative map shows high gradient values in NW-SW trends related to the structures in the eastern part of the Sirte basin. The 3D Euler deconvolution map derived from gravity data clearly indicates the location of igneous body in the study area as well as its tectonic trends and depth, which is estimated at 350 m to 1400 m below the surface. Depth of gravity anomalies at 1400 m to 2525 m is considered as anomalies in between shallow and deep. Anomaly at depth of approximately 4740 m below the surface is interpreted as basement rock. Geologically, the magnetic survey shows that the source of anomaly is a mafic igneous rock of Early Cretaceous age. The study also discovered a left-lateral sheared fault zone along the NW-SE of Hercynian age which was believed to be reactivated during Early Cretaceou

Electrical study on Carboxymethyl Cellulose-Polyvinyl alcohol based bio-polymer blend electrolytes

The present work deals with the formulation of bio-materials namely carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVA) for bio-polymer blend electrolytes (BBEs) system which was successfully carried out with different ratio of polymer blend. The biopolymer blend was prepared via economical & classical technique that is solution casting technique and was characterized by using impedance spectroscopy (EIS). The ionic conductivity was achieved to optimum value 9.12 x 10-6 S/cm at room temperature for sample containing ratio 80:20 of CMC:PVA. The highest conducting sample was found to obey the Arrhenius behaviour with a function of temperature. The electrical properties were analyzed using complex permittivity ε* and complex electrical modulus M* for BBEs system and it shows the non-Debye characteristics where no single relaxation time has observed

Electrochemical properties of CMC–PVA polymer blend electrolyte for solid state electric double layer capacitors

In this work, the electrochemical properties of polymer blend electrolyte (PBE) based CMC-PVA is presented for electrical double layer capacitance (EDLC) application. CMC-PVA PBE is incorporated in two different systems which contain an (1) ammonium nitrate (NH4NO3) ionic dopant (System I), and (2) ethylene carbonate (EC) plasticizer (System II). The ionic conductivity of PBE based on CMC (55 wt.%)–PVA (15 wt.%)–NH4NO3 (30 wt.%) and CMC (53 wt.%)–PVA (13 wt.%)–NH4NO3 (28 wt.%)–EC (6 wt.%) were optimized at room temperature with value of 1.70 × 10−3 S/cm and 3.92 × 10−3 S/cm, respectively. The ionic conduction for both systems shows Arrhenius behavior when tested at different temperatures. Electrochemical properties of the fabricated EDLC cell were analyzed for their electrochemical properties and System II showed higher specific capacitance than System I with values of 64.9 F/g and 89.1 F/g, respectively, based on a CV scan rate of 2 mV/s. Both fabricated EDLC show outstanding cycling stability over 10,000 cycles, which indicates that the present PBE based CMC–PVA has outstanding electrochemical performance and is a promising candidate for EDLC applicatio

Reducing crystallinity on thin film based CMCPVA hybrid polymer for application as a host in polymer electrolytes

The carboxymethyl cellulose and polyvinyl alcohol (CMC/PVA) based hybrid polymer (HPe) system with different ratio of composition have been prepared via solution casting. The features of interaction between CMC and PVA were investigated using X-ray diffraction (XRD), and infrared (IR) spectroscopy to disclose the reduction of crystallinity of the HPe system. Morphological properties observed by Scanning electron microscopy (SEM) confirmed the homogeneity of the HPe system. Differential scanning calorimetry (DSC) result explains the miscibility of the HPe system which was confirmed by means of variations in the glass transition temperature (Tg). Two degradation mechanisms were revealed by thermogravimetric analysis (TGA) in the HPe system attributed to the decarboxylation in CMC and degradation of bond scission in PVA backbone. The blend of 80:20 compositions of CMC/PVA HPe system was found to be the optimum ratio with an increase in conductivity of CMC/PVA by one magnitude order from 10−7 to 10−6 S/cm with the lowest in crystallinity