The Enhanced Energy Density of rGO/TiO2 Based Nanocomposite as Electrode Material for Supercapacitor

Design, Characterization, and Evaluation of Textile Systems and Coatings for Sports Use: Applications in the Design of High-Thermal Comfort Wearables

Exposure to high temperatures during indoor and outdoor activities increases the risk of heat-related illness such as cramps, rashes, and heatstroke (HS). Fatal cases of HS are ten times more common than serious cardiac episodes in sporting scenarios, with untreated cases leading to mortality rates as high as 80%. Enhancing thermal comfort can be achieved through heat loss in enclosed spaces and the human body, utilizing heat transfer mechanisms such as radiation, conduction, convection, and evaporation, which do not require initial energy input. Among these, two primary mechanisms are commonly employed in the textile industry to enhance passive cooling: radiation and conduction. The radiation approach encompasses two aspects: (1) reflecting solar spectrum (SS) wavelengths and (2) transmitting and emitting in the atmospheric window (AW). Conduction involves dissipating heat through materials with a high thermal conductivity. Our study focuses on the combined effect of these radiative and conductive approaches to increase thermal energy loss, an area that has not been extensively studied to date. Therefore, the main objective of this project is to develop, characterize, and evaluate a nanocomposite polymeric textile system using electrospinning, incorporating graphene oxide (GO) nanosheets and titanium dioxide nanoparticles (TiO2 NPs) within a recycled polyethylene terephthalate (r-PET) matrix to improve thermal comfort through the dissipation of thermal energy by radiation and conduction. The textile system with a 5:1 molar ratio between TiO2 NPs and GO demonstrates 89.26% reflectance in the SS and 98.40% transmittance/emittance in the AW, correlating to superior cooling performance, with temperatures 20.06 and 1.27 °C lower than skin temperatures outdoors and indoors, respectively. Additionally, the textile exhibits a high thermal conductivity index of 0.66 W/m K, contact angles greater than 120°, and cell viability exceeding 80%. These findings highlight the potential of the engineered textiles in developing high-performance sports cooling fabrics, providing significant advancements in thermal comfort and safety for athletes.

2D and 3D Nanostructured Metal Oxide Composites as Promising Materials for Electrochemical Energy Storage Techniques: Synthesis Methods and Properties

Due to population growth and global technological development, energy consumption has increased exponentially. The global energy crisis opens up many hotly debated topics regarding energy generation and consumption. Not only is energy production in short supply due to limited energy resources but efficient and sustainable storage has become a very important goal. Currently, there are energy storage devices such as batteries, capacitors, and super-capacitors. Supercapacitors or electrochemical capacitors can be very advantageous replacements for batteries and capacitors because they can achieve higher power density and energy density characteristics. The evolution and progress of society demand the use of innovative and composite nanostructured metal oxide materials, which fulfill the requirements of high-performance technologies. This review mainly addresses the synthesis techniques and properties of 2D and 3D metal oxide nanostructured materials, especially based on Ti, Fe, Ga, and Sn ions, electrochemical methods used for the characterization and application of 2D, and 3D nanostructured metal oxide structures in electrochemical storage systems of energy.

An Investigation into the Influence of Graphene Content on Achieving a High-Performance TiO2-Graphene Nanocomposite Supercapacitor

This study presents the synthesis of TiO2-graphene nanocomposites with varying mass ratios of graphene (2.5, 5, 10, 20 wt. %) using a facile and cost-effective hydrothermal approach. By integrating TiO2 nanoparticles with graphene, a nanomaterial characterized by a two-dimensional structure, unique electrical conductivity and high specific surface area, the resulting hybrid material shows promise for application in supercapacitors. The nanocomposite specimens were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman microscopy, field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Additionally, supercapacitive properties were investigated using a three-electrode setup by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) tests. Notably, the TiO2-20 wt. % rGO nanocomposite exhibited the highest specific capacitance of 624 F/g at 2 A/g, showcasing superior electrochemical performance. This specimen indicated a high rate capability and cyclic stability (93 % retention after 2000 cycles). Its remarkable energy density and power density of this sample designate it as a strong contender for practical supercapacitor applications.

Boosting Supercapacitor Efficiency with Amorphous Biomass-Derived C@TiO2 Composites

Carbon materials are readily available and are essential in energy storage. One of the routes used to enhance their surface area and activity is the decoration of carbons with semiconductors, such as amorphous TiO2, for application in energy storage devices.

Hybrid TiO2-RGO nanocomposite as high specific capacitance electrode for supercapacitor

This study describes the fabrication of composite electrodes comprising TiO2and reduced graphene oxide layers using a moderate-temperature hydrothermal method. The morphology, crystalline structure, chemical composition, and optical features of the prepared composites were analyzed by FE-SEM, x-ray diffraction, FTIR, and UV-visible spectroscopy. The cyclic voltammetry (CV) and Nyquist plots were used to assess the electrochemical and impedance responses of the composite electrodes, respectively. The analysis revealed that the incorporation of RGO reduced the TiO2bandgap to 3.87 eV 3.02 eV and improved the specific capacitance, enhancing the TiO2-RGO electrode's supercapacitive performance. CV studies highlight that the TiO2-RGO composite has a high specific capacitance of 152 F g-1at a substantially faster scan rate of 25 mV s-1in a 1.0 M-KOH dilute electrolyte. These findings confirmed the applicability of the fabricated electrodes as prospective supercapacitor electrodes.

Flower like-novel nanocomposite of Mg(Ti0.99Sn0.01)O3decorated on reduced graphene oxide (rGO) with high capacitive behavior as supercapacitor electrodes

In this study, ceramic materials of Mg(Ti0.99Sn0.01)O3were synthesized and decorated on reduced graphene oxide, forming a nanocomposite of rGO/Mg(Ti0.99Sn0.01)O3(rGO/MTS001). The successful synthesis results were confirmed by XRD, UV-vis analysis, FT-IR, and SEM-EDS. The MTS001 has a flower-like morphology from scanning electron microscopy (SEM) analysis, and the nanocomposites of rGO/MTS001 showed MTS001 particles decorated on the rGO's surface. The electrochemical performance of rGO/MTS001 and MTS001 was investigated by determining the specific capacitance obtained in 1 M H2SO4solution by cyclic voltammetry, followed by galvanostatic charge-discharge analysis using a three-electrode setup. The rGO/MTS001 achieved a specific capacitance of 361.97 F g‒1, compared to MTS001 (194.90 F g‒1). The capacitance retention of rGO/MTS001 nanocomposite also depicted excellent cyclic stability of 95.72% after 5000 cycles at a current density of 0.1 A g‒1. The result showed that the nanocomposite of ceramics with graphene materials has a potential for high-performance supercapacitor electrodes.

Multifunctional Dy2NiMnO6/Reduced Graphene Oxide Nanocomposites and Their Catalytic, Electromagnetic Shielding, and Electrochemical Properties

Multifunctional nanocomposites have shown great interest in clean energy systems and environmental applications in recent years. Herein, we first reported the synthesis of Dy2NiMnO6 (DNMO)/reduced graphene oxide (rGO) nanocomposites utilizing a hybrid approach involving sol-gel and solvothermal processes. Subsequently, we investigated these nanocomposites for their applications in catalysis, electromagnetic interference shielding, and supercapacitors. A morphological study suggests spherical-shaped DNMO nanoparticles of an average size of 382 nm that are uniformly distributed throughout the surface without any agglomeration. The as-prepared nanocomposites were used as catalysts to investigate the catalytic reduction of 4-nitrophenol in the presence of NaBH4. DNMO/rGO nanocomposites demonstrate superior catalytic activity when compared with bare DNMO, with the rate of reduction being influenced by the composition of the DNMO/rGO nanocomposites. In addition, novel multifunctional DNMO/rGO was incorporated into polyvinylidene difluoride (PVDF) to develop a flexible nanocomposite for electromagnetic shielding applications and exhibited a shielding effectiveness of 6 dB with 75% attenuation at a frequency of 8.5 GHz compared to bare PVDF and PVDF-DNMO nanocomposite. Furthermore, the electrochemical performance of DNMO/rGO nanocomposites was investigated as an electrode material for supercapacitors, exhibiting the highest specific capacitance of 260 F/g at 1 A/g. These findings provide valuable insights into the design of DNMO/rGO nanocomposites with remarkable performance in sustainable energy and environmental applications.

Highly Enhanced Photocatalytic Hydrogen Production Performance of Heterostructured Ti3C2/TiO2/rGO Composites

There has been a dire need for the exploration of renewable clean hydrogen energy recourses in recent years. In this work, we investigated the photocatalytic hydrogen production of heterostructured Ti₃C₂/TiO₂/rGO composites. Ti₃C₂/TiO₂/rGO heterojunction nanocomposites were synthesized using two-step calcination and hydrothermal methods, and the optimum in situ growth ratio of TiO₂ of 71.8% (n_Ti-O/n_Ti) and rGO mass ratio (m_RGO/m_TiO2/m_Ti3C2) of 12% were obtained. The target photocatalyst presented an outperforming photocatalytic hydrogen production performance of 1671.85 μmol·g^-1 hydrogen production capacity in 4 h, with the maximum hydrogen production rate of 808.11 μmol·g^-1·h^-1 in the first hour being 3.08 times the maximum hydrogen production rate of bare TiO₂ (262.66 μmol·g^-1·h^-1). The excellent hydrogen production performance was due to the formed rutile TiO₂ and the constructed heterojunction of Ti₃C₂/TiO₂/rGO, where rGO provided different electron transport channels, and made charge transfer easier, and restrained the recombination efficiency of electrons and holes.

Biogenic synthesis of reduced graphene oxide from Ziziphus spina-christi (Christ's thorn jujube) extracts for catalytic, antimicrobial, and antioxidant potentialities

In the current work, various concentrations of the aqueous extract of Ziziphus spina-christi were employed for the phytoreduction of graphene oxide (GO). The green synthesized reduced graphene oxide (rGO) was characterized through UV-Vis spectrometry, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy, and energy-dispersive X-ray spectroscopy (SEM-EDX). Gas chromatography-mass spectrometry (GC-MS) denoted the presence of numerous phytoconstituents including ketones, terpenoids, fatty acids, esters, and flavonoids, which acted as reducing and capping agents. The obtained results indicated the increase in rGO yield and shape with increasing the extract concentration. The optimized rGO was instantaneously ~100% removed methylene blue (MB) from the water at 5 mg L-1. However, the removal efficiency was slightly declined to reach 73.55 and 65.1% at 10 and 15 mg L-1, respectively. A powerful antibacterial activity for rGO particularly against gram-negative bacteria with a high concentration of 2 × 108 CFU mL-1 was confirmed. Furthermore, rGO demonstrated promising and comparable antioxidant efficiency with vitamin C against DPPH free radical scavenging. While vitamin C recorded 13.45 and 48.4%, the optimized rGO attained 13.30 and 45.20% at 12 and 50 μg mL-1, respectively.