Akfiny Hasdi Aimon

Incorporating graphene into Ni-rich cathode materials, such as the LiNi_0.815Co_0.15Al_0.035O₂ (NCA) cathode, has been frequently reported as an effective strategy to improve the performance of lithium-ion batteries. However, the influence of the oxidation degree of graphene on the electrochemical performance of the mixed NCA/graphene cathode remains largely unexplored. In this work, the oxidation degree of graphene was tuned by varying the electrolyte concentration during the electrochemical exfoliation process, and its impact on the performance of NCA/graphene cathodes was evaluated. The results show that the exfoliated graphene (EG) synthesized using 0.3 M (NH₄)₂SO₄ (denoted as EG 0.3) possesses the lowest oxidation degree among all the samples, which leads to the highest electrical conductivity and the lowest moisture content. When incorporated into the NCA cathode, EG 0.3 produced a composite (NCA/EG 0.3) with the best rate capability and cycling stability owing to the low degree of cation mixing and the lowest charge-transfer resistance in the resulting cathode. Electrochemical measurements revealed that the NCA/EG 0.3 cathode delivers the highest specific capacity of 191.32 mA h g⁻¹ at 0.1C, 67.72% capacity retention rate at 5C compared with 0.1C, and good cycling stability (85.13% capacity retention after 100 cycles at 0.2C), which outperformed other composite cathodes. This study demonstrates that the oxidation degree of graphene can govern the cation mixing degree and charge-transfer resistance in Ni-rich cathodes, offering insights into the design of graphene-based additives and protective layers for lithium-ion battery cathodes.

An integrated electrochemical exfoliation and electrophoretic deposition (EPD) method is developed to achieve a high‐performance graphene supercapacitor. The electrochemical delamination of graphite sheet has obtained a low‐defected few‐layer graphene adorned with oxygen‐containing functional groups. Then, the EPD process produced a binder‐free electrode to alleviate the graphene restacking problem. The electrode prepared using a deposition voltage of 5 V exhibits the highest specific capacitance of 145.95 F/g at 0.5 A/g from three‐electrode measurement. Moreover, this EPD‐prepared electrode also demonstrates superior electrochemical properties compared to electrodes fabricated using PVDF binder. In the real symmetrical cell, the EPD‐prepared electrode also shows excellent performance with a high rate capability of 82.31 % (from 0.5 A/g to 10 A/g), high cycling stability of 95.00 % (at 5 A/g) after 10,000 cycles, and rapid frequency response with short relaxation time ( ) of 9.73 ms. These results indicate that this integration method is beneficial to construct a high performance binder‐free supercapacitor electrode consisting of low‐defected graphene materials, low electrode resistance, and less agglomeration of graphene sheets by utilizing an environmentally friendly process.

Medan magnet merupakan salah satu fenomena fisika yang menarik dan banyak ditemukan dalam kehidupan sehari-hari. Banyak perkembangan teknologi saat ini yang merupakan aplikasi dari konsep medan magnet tersebut, seperti barang elektronik, motor listrik, kereta cepat dan lainnya. Pada penelitian ini, dilakukan pengembangan prototipe pengukuran medan magnet dengan bantuan sistem instrumentasi fisika. Prototipe ini, diharapkan dapat digunakan sebagai media eksperimen pengukuran medan magnet untuk pelajaran fisika di sekolah-sekolah. Pembuatan alat pengukuran medan magnet dapat dibuat dengan menggunakan bantuan sistem intrumentasi Fisika. Sehingga alat tersebut dapat digunakan sebagai media eksperimen pengukuran besar medan magnet pada magnet permanen dan kawat yang dialiri arus listrik. Prototipe alat dibuat dengan menggunakan sensor magnetik 49E. Prototipe ini diharapkan dapat menggantikan Gaussmeter dan/atau Teslameter yang harganya relatif mahal. Prototipe alat ukur medan magnet dikalibrasi dengan cara membandingkan besar kuat medan magnet yang terukur oleh sensor 49E dengan Gaussmeter Lutron GU-3001. Pengukuran dilakukan pada pusat objek dan sejajar dengan posisi alat ukur. Hasil pengukuran menunjukan rerata kuat medan magnet pada Gaussmeter dan sensor 49E adalah 246.7 μT dan 487.3 μT untuk magnet permanen dan 51.2 μT dan 96.9 μT untuk kawat melingkar.

Hydrogel is being broadly studied due to their tremendous properties, such as swelling behavior and biocompatibility. Numerous review articles have discussed hydrogel polymer types, hydrogel synthesis methods, hydrogel properties, and hydrogel applications. Hydrogel can be synthesized by physical and chemical cross-linking methods. One type of the physical cross-linking method is freeze-thaw (F–T), which works based on the crystallization process of the precursor solution to form a physical cross-link. To date, there has been no review paper which discusses the F–T technique specifically and comprehensively. Most of the previous review articles that exposed the hydrogel synthesis method usually mentioned the F–T process as a small part of the physical cross-linking method. This review attempts to discuss the F–T hydrogel specifically and comprehensively. In more detail, this review covers the basic principles of hydrogel formation in an F–T way, the parameters that influence hydrogel formation, the properties of the hydrogel, and its application in the biomedical field.

Tunable emissive solid-state carbon nanoparticles (CNPs) have been successfully synthesized by a facile synthesis through microwave irradiation.

Zero-dimensional Perovskite Magic-size Clusters play crucial roles in understanding and controlling nucleation and growth of semiconductor nanoparticles. However, their metastability behavior is a critical hindrance for reliable characterizations. Here, we report the first demonstration of using an excess amount of surface ligand and SiO₂ as novel passivation for synthesizing the magic-sized clusters (MSCs) by the Ligand-assisted reprecipitation method. A synergetic effect between an excessed surface ligand and SiO₂ inhibits the protonation and deprotonation reaction between amine-based and acid-based ligand, leading to enhanced PL stability. The obtained CH₃NH₃PbBr₃ PMSCs/SiO₂ retain 70% of its initial emission intensity in ambient conditions for 20 days. This passivation approach opens an entirely new avenue for the reliable characterizations of CH₃NH₃PbBr₃ PMSCs, which will significantly broaden their application for understanding and controlling nucleation and growth of semiconductor nanoparticles.

The effect of silica (SiO2) addition on optical properties of organometal halide perovskite PMMA composite film was studied. The organometal halide perovskite, MAPbBr3, was synthesis using ligand assisted re-precipitation (LARP) method, and then was compose to PMMA and SiO2 directly to make composite films. The absorbances, transmittances, and photoluminescence (PL) spectrum of the samples were characterised using UV Vis and PL spectroscopy. The result shows that the addition of silica leads blueshift on photoluminescence and absorbance spectra. The blue shift reveals one-dimensional confinement effect in perovskite.