Functionalization of Carbon Nanotube (CNT) plays an important role in creating CNT hybride material. In this study, integrated analysis of functional group sites on the pristine and modified Multi-Wall Carbon Nanotube (MWCNT) surface was comparably conducted to know the effect of acid solution on the surface after purification and functionalization process. Acid treatment removed rest of graphitic and residual catalytic metal particles and suffered degradation, such as nanotube shortening and additional defect generation in the graphitic network. Defects on the side wall due to functionalized group clearly shown in Transmission Electron Image (TEM) images cause a reduction in thermal stability. Functional group sited on the side wall was detected by Attenuated Total Reflectance (ATR) -Fourier Transform Infra Red (FTIR) with the relative concentration of oxygen-containing functional groups determined by Boehm titration.

No abstract

The role of the water structure present in hydrogels from nutlets of three species of salvias, S. miltiorrhiza (SM), S. sclarea (SS) and S. viridis (SV), was analyzed by differential scanning calorimetry (DSC). The sharp endothermic peaks that appeared at 5.9 o C (SM), 2.8 o C (SS) and 1.8 o C (SV) in each 1.0% hydrogel of 10.4-15.8% were not affected by addition of 0.1 M urea and alkali-metal salts. The order-disorder portions in the network were slightly affected by the distribution of freezable and non-freezable water in the hydrogel networks. The SV hydrogel was further used to investigate the effects of additives (0.1-8.0 M urea and 0.1-5.0 M NaCl) on its melting behavior. At 0.5-4.0 M urea and 1.0-3.0 M NaCl, two endothermic peaks appeared, corresponding to unbound (high temperature) and bound (low temperature) water in the gel networks, and eventually merged into one endothermic peak at 5.0-8.0 M urea and 4.0-4.5 M NaCl. After this merger, the endothermic peak shifted to 3.7, 4.0 and 5.6 o C at 5.0, 6.0 and 8.0 M urea, respectively. In the case of NaCl, a combination of peaks that occurred at 4.0-4.5 M were accompanied by a shift to lower temperature (-14.4 and 15.3 o C) and the endothermic peak finally disappeared at 5.0 M NaCl due to the strong binding of water in the gel networks.

Excellent transparent films were prepared from bacterial cellulose (BC) sheets by solubilization of its defibrillated freeze-dried specimens in a solvent of dimethylacetamide (DMAc) containing 8.0% (w/w) lithium chloride (LiCl), and their properties were compared with those of the native BC. Fibrillar structure of the native BC disappeared after dissolution, and the film formed after dissolution also loose this structure. Occurence of structural transformation from crystalline to amorphous state was also evidenced by X-ray diffraction, solid state cross polarization/magic angle spinning 13 C-NMR and attenuated total reflectance-Fourier transform infrared spectroscopic analyses. In addition, excellent 3D uniform structure of the transparent BC film was further evidenced by X-ray micro computed tomography. Plastic-like characteristic was enhanced by film formation after dissolving the BC specimens in the DMAc-LiCl solution as shown by changing mechanical properties, a slight decrease in tensile strength (67.2 to 59.6 MPa) and breaking stress (67.2 to 58.4 MPa) but significant increase in elongation at break from 3.4 to 10.5%, and improvement of work of fracture from 5.8 to 21.2 kJ/m 2 .

Graphite is a critical material for lithium-ion battery (LIB) anodes. However, its fabrication using a simple route and sustainable carbon sources still remains a great challenge. In this current work, we fabricate high graphitic carbon from coconut coir waste by combining potassium hydroxide (KOH) and a Ni-based catalyst in a one-pot graphitization process. The graphitic carbon (1200-ANi-KOH) shows good electrochemistry performance as the anode of LIB with a specific capacity of 397.60 mA h/g, exceeding commercial graphite (339.90 mA h/g) and a high graphitic degree of I G /I D (1.99) with a surface area of 162.31 m 2 /g. The synergistic effect of K and Ni metal interaction with amorphous carbon promotes internal heating and catalytic graphitization, resulting in an ordered carbon structure and a greater area of graphitic structure. Ion diffusion in the graphite interlayer was found to be the dominant ion storage mechanism at 1200-ANi-KOH, which is comparable to the commercial graphite mechanism. Finally, this simple one-pot graphitization process succeeded in converting coconut coir waste into a graphitic material with a high graphitization degree and excellent LIB anode performance.

No abstract

Nonprecious bifunctional oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) catalysts in wide pH electrolytes are crucial for the versatile use of electrochemical energy storage and conversion devices. Non-noble metal/nitrogendoped carbon (M−N/C) has been reported as a promising candidate for efficient and cost-effective bifunctional catalysts. Nevertheless, the stability and catalytic activity of M−N/C bifunctional catalysts in a wide pH range are still limited, especially in neutral and acidic electrolytes. Here, we synthesized directly grown N-doped bamboo-like carbon nanofiber-encapsulated cobalt nanoparticles on carbon flakes (Co−N/C fiber) via pyrolysis of 2D cobalt−zeolitic imidazolate framework and tubular g-C 3 N 4 . The in situ growth of N-doped carbon nanofiber incorporated with Co nanoparticles exposes large active sites and enhances charge transfer. Moreover, abundant mesopores with high loading of pyridinic-N, graphitic-N, Co@N/C, and Co−N x facilitate high catalytic activity in a wide pH condition. Co−N/C fiber shows superior ORR performance in alkaline, neutral, and acidic electrolytes with high onset potentials of 1.003, 0.820, and 0.800 V vs RHE, respectively. A comparable OER performance of Co−N/C fiber to the Ir/C benchmark in alkaline and neutral conditions can be obtained with 397 and 570 mV overpotentials at 10 mA cm −2 . Utilizing Co−N/ C fiber in alkaline and neutral Zn−air batteries exhibits power densities of 155 and 67 mW cm −2 , with excellent stability for over 180 h. This study offers a strategy for developing a bifunctional M−N/C catalyst that is applicable across a wide pH range via hybrid nanostructuring.

Nanofibrous cellulose as solid polymer electrolyte for lithium-ion battery applications.