Journal of Material and Metamaterial Sciences

Energy storage device utilising garlic skin and carbon fibre derived from agricultural and industrial waste

Ayu Atmanda — Tue, 11 Feb 2025 00:00:00 +0700

Carbon quantum dots (CQDs) are small-sized nanoparticles (1 – 10 nm) with unique properties such as high conductivity, thermal stability, and fluorescence capability, making them superior materials for energy applications. This research develops an energy storage device based on garlic skin waste and carbon fiber from agricultural and industrial waste. Garlic peel was processed into CQDs using pyrolysis method, while carbon fiber was obtained from methylcellulose. Analytical results showed that CQDs increased the specific capacitance of the gel electrolyte to 110.57 F/g, with excellent cycling stability reaching 96% after 2000 cycles. In addition, the carbon fiber-based electrode showed the highest specific capacitance of 155.58 F/g, energy density of 10.59 Wh/kg, and power density of 4047 W/kg, making it an economical alternative to carbon nanotubes and graphene. Material characterization via TGA, UV-Vis, FTIR, SEM, and TEM confirmed the high thermal stability and quasi-round particle morphology with an average size of 7 nm. The results of this study highlight the potential of CQDs from garlic skin as a sustainable solution for advanced energy storage applications, particularly supercapacitors.

Nano rod-shaped core-shell TiO2-SiO2 coating exhibiting superior self-cleaning capabilities under visible light

Dea Stefani — Tue, 11 Feb 2025 00:00:00 +0700

Titanium dioxide (TiO₂) is a photocatalytic material widely used in self-cleaning applications due to its ability to decompose organic compounds with free radicals under UV irradiation. However, its limitations in stability and efficiency make it necessary to combine with other materials such as silicon dioxide (SiO₂). This combination forms a core-shell structure where TiO₂ becomes the active core, while SiO₂ acts as a shell that improves stability, extends the absorption spectrum to visible light, and reduces particle agglomeration. This study examines the synthesis and characterization of rod-shaped TiO₂-SiO₂ core-shell nanoparticles that have superior self-cleaning ability under visible light. The synthesis was carried out using a modified hydrothermal method. Structure analysis using SEM showed uniform particle distribution, while XRD analysis confirmed the presence of anatase phase in TiO₂. Self-cleaning evaluation was performed through methylene blue degradation and water contact angle measurement. Results show that this core-shell layer has better photocatalytic activity and hydrophilic properties than pure TiO₂. With these characteristics, this material has great potential to be applied in environmental purification, waste treatment, and renewable energy technologies.

Biosynthesis and characterisation of silver nanoparticles utilising tin (ficus carica) leaf extracts

Dinda Pratiwi — Tue, 11 Feb 2025 00:00:00 +0700

Silver nanoparticles (AgNPs) are materials with various potential applications, ranging from catalysts to antibacterial agents. This study aims to synthesize and characterize AgNPs using tin leaf extract (Ficus carica) as a bioreduction agent in a green synthesis method. The synthesis process was carried out by utilizing AgNO₃ as a precursor and evaluated using UV-Vis spectroscopy, X-ray diffraction (XRD), and scanning transmission electron microscopy (STEM). UV-Vis results showed a characteristic absorption peak at a wavelength of 419 nm, indicating the successful synthesis of AgNPs. XRD analysis identified a face-centered cubic structure with an average particle size of 22.6 nm. STEM revealed a spherical particle morphology with sizes ranging from 11.97 to 20.31 nm. This green synthesis approach provides an environmentally friendly, efficient, and cost-effective solution in the production of silver nanoparticles, with broad potential applications in the medical and technological fields.

Synthesis and characterisation of SrCoxFe12-xO19 composite magnetic material (x = 0 – 0.3)

Meiyuli Simanullang — Tue, 11 Feb 2025 00:00:00 +0700

SrCo_xFe_12-xO₁₉ is a composite magnetic material that has wide applications in the field of modern technology. This study aims to synthesize and characterize SrCo_xFe_12-xO₁₉ (x = 0 – 0.3) using coprecipitation technique and high temperature sintering. The results showed that increasing cobalt (Co) concentration enhanced the magnetic properties of the composite, including saturation magnetization up to a peak value of 42.5 emu/g at x = 0.3, as well as higher coercivity due to morphological anisotropy and valence change of Fe²⁺ to Fe²⁺. XRD characterization revealed a magnetoplumbite-type crystal structure with a hexagonal M phase, while FTIR analysis identified Fe-O and Co-O bond vibrations that became more intense with the addition of Co. SEM showed morphological changes from lamellar shapes to small spherical particles as Co increased. VSM analysis confirmed the strong interaction between the hard (SrFe₁₂O₁₉) and soft (CoFe₂O₄) magnetic phases, which supports the application of this composite as a microwave absorbing material. These findings highlight the potential of SrCo_xFe_12-xO₁₉ as an advanced magnetic material with characteristics that can be optimized for high-tech applications.

Analysis of physical and electrochemical properties of activated carbon derived from bamboo charcoal utilising diverse electrolytes for supercapacitor applications

Seli Novalina Sawitri — Tue, 11 Feb 2025 00:00:00 +0700

Activated carbon is a highly porous material that is widely used in energy applications, such as supercapacitors, as it has a large specific surface area and good electrical conductivity. Bamboo, as one of the abundant biomasses, can be processed into high-quality activated carbon through chemical activation process. With its natural carbon-rich structure and pores, bamboo provides a great opportunity to improve the energy storage performance of supercapacitors. This study analyzes the physical and electrochemical properties of activated carbon synthesized from bamboo charcoal using KOH activation for supercapacitor applications. Structural characterization was performed using X-ray diffraction and field emission scanning electron microscopy, which showed an amorphous structure with high porosity. Electrochemical studies via cyclic voltammetry and galvanostatic charge-discharge revealed that the electrolyte mixture (Na₂SO₄ 1 M and KOH 0.5 M) yielded the best performance with a maximum specific capacitance of 290 F/g at a current density of 1 A/g. These results indicate that bamboo-based activated carbon has great potential for environmentally friendly energy storage applications.