Carbon Nanowalls as Anode Materials with Improved Performance Using Carbon Nanofibers.

In this paper, a new synthesis of carbon nanofibers (CNFs)/carbon nanowalls (CNWs) was performed to improve the characteristics of anode materials of lithium-ion batteries by using the advantages offered by CNWs and CNFs. Among the carbon-based nanomaterials, CNWs provide low resistance and high specific surface area. CNFs have the advantage of being stretchable and durable. The CNWs were grown using a microwave plasma-enhanced chemical vapor deposition (PECVD) system with a mixture of methane (CH4) and hydrogen (H2) gases. Polyacrylonitrile (PAN) and N,N-Dimethyl Formamide (DMF) were stirred to prepare a solution and then nanofibers were fabricated using an electrospinning method. Heat treatment in air was then performed using a hot plate for stabilization. In addition, heat treatment was performed at 800 °C for 2 h using rapid thermal annealing (RTA) to produce CNFs. A field emission scanning electron microscope (FE-SEM) was used to confirm surface and cross-sectional images of the CNFs/CNWs anode materials. Raman spectroscopy was used to examine structural characteristics and defects. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and constant current charge/discharge tests were performed to analyze the electrical characteristics. The synthesized CNFs/CNWs anode material had a CV value in which oxidation and reduction reactions were easily performed, and a low Rct value of 93 Ω was confirmed.

Two-Dimensional Heterostructure of PPy/CNT-E. coli for High-Performance Supercapacitor Electrodes.

The nano-biocomposite electrodes composed of carbon nanotube (CNT), polypyrrole (PPy), and E. coli-bacteria were investigated for electrochemical supercapacitors. For this purpose, PPy/CNT-E. coli was successfully synthesized through oxidative polymerization. The PPy/CNT-E. coli electrode exhibited a high specific capacitance of 173 F∙g-1 at the current density of 0.2 A∙g-1, which is much higher than that (37 F∙g-1) of CNT. Furthermore, it displayed sufficient stability after 1000 charge/discharge cycles. The CNT, PPy/CNT, and PPy/CNT-E. coli composites were characterized by x-ray diffraction, scanning electron microscopy, and surface analyzer (Brunauer-Emmett-Teller, BET). In particular, the pyrrole monomers were easily adsorbed and polymerized on the surface of CNT materials, as well as E. coli bacteria enhanced the surface area and porous structure of the PPy/CNT-E. coli composite electrode resulting in high performance of devices.

Preparation of Carbon Nanowall and Carbon Nanotube for Anode Material of Lithium-Ion Battery.

Carbon nanowall (CNW) and carbon nanotube (CNT) were prepared as anode materials of lithium-ion batteries. To fabricate a lithium-ion battery, copper (Cu) foil was cleaned using an ultrasonic cleaner in a solvent such as trichloroethylene (TCE) and used as a substrate. CNW and CNT were synthesized on Cu foil using plasma-enhanced chemical vapor deposition (PECVD) and water dispersion, respectively. CNW and CNT were used as anode materials for the lithium-ion battery, while lithium hexafluorophosphate (LiPF6) was used as an electrolyte to fabricate another lithium-ion battery. For the structural analysis of CNW and CNT, field emission scanning electron microscope (FE-SEM) and Raman spectroscopy analysis were performed. The Raman analysis showed that the carbon nanotube in composite material can compensate for the defects of the carbon nanowall. Cyclic voltammetry (CV) was employed for the electrochemical properties of lithium-ion batteries, fabricated by CNW and CNT, respectively. The specific capacity of CNW and CNT were calculated as 62.4 mAh/g and 49.54 mAh/g. The composite material with CNW and CNT having a specific capacity measured at 64.94 mAh/g, delivered the optimal performance.

Preparation and Electrical Properties of Silicone Composite Films Based on Silver Nanoparticle Decorated Multi-Walled Carbon Nanotubes.

The electrical properties of silicone composite films filled with silver (Ag) nanoparticle-decorated multi-walled carbon nanotubes (MWNT) prepared by solution processing are investigated. Pristine MWNT is oxidized and converted to the acyl chloride-functionalized MWNT using thionyl chloride, which is subsequently reacted with amine-terminated poly(dimethylsiloxane) (APDMS). Thereafter, APDMS-modified MWNT are decorated with Ag nanoparticles and then reacted with a poly(dimethylsiloxane) solution to form Ag-decorated MWNT silicone (Ag-decorated MWNT-APDMS/Silicone) composite. The morphological differences of the silicone composites containing Ag-decorated MWNT and APDMS-modified MWNT are observed by transmission electron microscopy (TEM) and the surface conductivities are measured by the four-probe method. Ag-decorated MWNT-APDMS/Silicone composite films show higher surface electrical conductivity than MWNT/silicone composite films. This shows that the electrical properties of Ag-decorated MWNT-APDMS/silicone composite films can be improved by the surface modification of MWNT with APDMS and Ag nanoparticles, thereby expanding their applications.

Nature inspired approach to mimic design for increased specific capacitance as supercapacitor electrodes.

In this study, the experiment was conducted assuming that the citrus fruits were contaminated with bacteria. Herein, orange peels (OP) and lemon peels (LP) can be used as a carbon source and have the advantage of using discarded materials and heteroatoms. Also, the nitrogen heteroatom is introduced by naturally doping the materials with bacteria (Escherichia Coli, E. coli). The as-prepared bacteria doped activated carbon showed an increase in nitrogen content and surface properties which led to an improvement in electrochemical properties. The specific capacitance of bacteria doped OP and LP was 92.4 and 139 Fg-1 compared to the bare samples with a specific capacitance of 60.9 and 49.6 Fg-1 at a current density of 0.2Ag-1 and capacity retention of 129% after 10,000 cycles for the bacteria-doped samples. This process which is simple, cheap, and environmentally friendly can be applied to discarded fruit peels for the fabrication of supercapacitor materials.

Combined Treatment on an Al Surface to Improve the Metal-Polymer Adhesion Strength.

The development of mobile industries and urban transportation today requires nanotechnology for research and processing of metallic surfaces. Here, aluminum alloys (Al) are the most common material with the best physical properties that need to be treated. The advantages of Al in manufacturing are obvious; however, the Al surface is sensitive to the presence of acid or base, and thus protecting the Al surface is mandatory. In this study, Al surfaces have been subjected to a new surface treatment process that includes sandblasting, anodizing, and subsequent post-etching steps. The treated surfaces are evaluated by surface morphology including contact angle measurement and polymer adhesion strength. The adhesion strength of blasted Al-polymer assemblies with and without an anodizing step have been performed with a single lap shear test. This clearly shows the profound effect of the combined treatment process. The results reveal that a combination of high surface roughness and area as well as a thick Al2O3 layer with micro-cavities created by a post-etch step can significantly improve the adhesion strength of the Al-polymer. This, in turn, enhances the quality of and longevity of Al surface in production and application.

Development of an anti-pollution coating process technology for the application of an on-site PV module.

This study aimed to apply annealing processes during the coating of photovoltaic (PV) module glasses to PV modules already installed through an easy and simple procedure. Three types of annealing treatments were applied to PV module glasses, i.e., furnace, rapid thermal annealing (RTA) and torch. Among these, torch annealing, which can be easily carried out at PV module installation sites, was applied to PV module glasses using different numbers of repetition. Light transmittance, contact angle, anti-pollution characteristics, adhesion and hardness of the functional coating films after using different annealing treatment times and methods were measured, and it was confirmed that these characteristics varied depending on the annealing treatment times and methods. Through this, it was possible to optimize the process conditions that provide excellent anti-pollution characteristics and could be easily utilized at on-site PV modules.

Non-aqueous approach to the preparation of reduced graphene oxide/α-Ni(OH)2 hybrid composites and their high capacitance behavior.

Reduced graphene oxide/α-Ni(OH)(2) composites present high electrochemical properties, with specific capacitance of 1215 F g(-1) at 5 mV s(-1) scan rate, since graphene as conductive matrix provides electronic conduction pathway.