Materials Science for Energy Technologies最新文献

Carbon nanofiber (CNF) derived from carbonization of bacterial cellulose (BC), with a unique three-dimensional porous nanostructure, has received significant interest in electrochemical applications. In this study, CNF samples were physically activated in CO₂ at different temperatures and durations. Raman spectroscopy and FTIR analysis showed that CO₂ activation caused hexagonal lattice defects, disorder, and oxygen-related functional groups in an amorphous carbon structure. CNF surface morphology changed after physical activation, reducing fiber diameter to 55 nm and introducing mesopores. Through activation temperature and time adjustments, surface area (870.1 m²/g) and micropore surface area (535.6 m²/g) and pore volume (0.2148 cm³/g) increased. EDX elemental analysis showed that activated CNF had a carbon concentration of > 90 %, while XPS analysis showed surface functional groups like C-C (sp²) and C-C (sp³) hybridization, which could improve electrolyte ion adsorption and accessibility. Electrochemical properties improved owing to CO₂ activation. The optimal activation condition of 800 ℃ for 60 min resulted in the highest specific area capacitance of 552 mF cm⁻² at 1 mA cm⁻². This activated CNF electrode retained capacitance nearly unchanged up to 3,000 cycles. It also achieved the highest energy density of 76.7 mWh cm⁻² at 500 mW cm⁻². This study demonstrates the efficacy of CO₂ physical activation for enhancing the electrochemical properties of CNF electrodes. The findings also highlight the importance of tailoring activation conditions, providing valuable insights for the design of advanced energy storage materials.

Solid oxide fuel cells (SOFCs) are efficient electrochemical energy device that converts the chemical energy of fuels directly into electricity. It has a high power and energy density and a sustainable source of energy. The electrode (cathode and anode) materials are essential for the efficient operation of SOFCs. Several electrode materials have been studied in the last two decades, mainly perovskite materials. The investigated materials have resulted in improved electrochemical performance of SOFCs, increased commercial viability, and reduced operational costs. However, the sustainability of most of the material compositions (heteroatoms) used as electrodes in SOFCs has never been investigated. The present study examines the recent progress, challenges, and constraints associated with electrode material development in SOFCs from a sustainable perspective. Heteroatoms majorly employed for doping in electrode materials’ long-term availability on the earth’s surface was established. The study also provides an overview on the current state of electrode materials development for symmetrical solid oxide fuel cells. This is intended to address the complexities of different materials development for the anode and cathode.

Manganese dioxide-multiwall carbon nanotube (MnO₂-MWCNT) nanocomposites were synthesized via one-pot synthesis method with varying concentrations of 1 mg/ml, 4 mg/ml, and 10 mg/ml MWCNT. The synthesized nanocomposites were characterized using x-ray diffraction (XRD), transmission electron microscopy (TEM), and electrochemical measurements. The intent of studying different concentrations is, ultimately, to correlate the effect of the concentration of multiwall carbon nanotube on the electrochemical performance of the MnO₂-MWCNT nanocomposites_. Two primary phenomena were observed as CNT concentration increased. First, less crystalline MnO₂ adsorption onto individual CNTs occurred. Subsequently, CNT agglomeration became the primary feature of the nanostructures of high CNT concentration. The electrochemical studies reveal that the specific capacitance of MnO₂ increases from 124 F/g to 145 F/g by the addition of 1 mg/ml MWCNTs and decreases to 102 F/g for MnO₂-10 mg/ml MWCNT nanocomposite.

In this research has been conducted on manufacturing ceramic materials based on Belanda Teak wood powder and bentonite using Solid State Reaction method. The composition variation of Belanda Teak wood powder with bentonite is 4:5, 5:5 and 6:5, then activated at 1000°C. Then, mixed using ball milling at 500 rpm for 30 min. Density analysis was conducted to determine the density. The density analysis obtained was 2.20 gr/cm³, 2.32 gr/cm³, and 2.33 gr/cm³ for samples 4:5, 5:5, and 6:5. The characterization analysis was SEM-EDX, XRD, and DTA. The results of XRD analysis obtained a hexagonal crystal structure. The size of the crystal diameter will increase as the teak wood powder mass ratio decreases in each sample. SEM-EDX results obtained morphology in the 4:5 composition is better than the 5:5 and 6:5 samples, and the optimum composition spectrum is 6:5, which has a maximum weight and atomic percentage and there are no other elements mixed beside the main elements. The DTA results stated that the sample phase start from 95.05°C, and there is an endothermic peak at a temperature of 427.54 °C with a mass loss of 9.14 mg and there is an increase in temperature to 534.29 °C with a mass loss of 4.34 mg due to recrystallization. Based on the results of this research, these materials can be recommended to become making ceramics materials.

In this study, S and Bi Co-doped carbon quantum dots were synthesized and their application for Cd(II) removal was investigated. All the experiments were performed in batch mode and effect Bi/S ratio on pH was investigated. It was observed that 12 pH is most suitable for fast removal of Cd²⁺. The optimized Bi/S ratio was further investigated for effect of adsorbent dosage, initial concentration of Cd(II). Addition of four scavenger solvent namely formaldehyde, acetic acid, ethanediamine and methanol was investigated for enhancement in the photocatalytic activity. Maximum removal efficiency was observed with ethandiamine ∼94% at 300 ppm as compared to formaldehyde (∼90.3%), methanol (∼86.7%) and acetic acid(∼86.3%) indicating that amine group is more suitable as scavenger molecule. Adsorption isotherms of Cd(II) on Bi/S doped on CQD were fitted for different adsorption isotherm model namely Langmuir, Freundlich and Temkin isotherms. Both Lanmguir and Temkin isotherm were observed to fit well with R² value above 98% as compared to Freundlich with lower R² value (∼95.3%), indicating that a combination of chemisorption phenomenon as well as availability of energy of electron could be responsible for the Cd(II) removal. Thermodynamic parameters both enthalpy change and entropy change were estimated as −10.76 kJ/mol and −11.2 kJ/mol K. All three parameters were negative indicating that the process was spontaneous and exothermic.