Advanced Materials Research Vol. 1190

Abstract: Microbial fuel cells (MFCs) offer a sustainable solution for converting organic waste into electricity through electroactive microorganisms. However, their widespread implementation is hindered by low catalytic efficiency and the high cost of noble metal-based electrodes. This study addresses these challenges by conducting a comprehensive bibliometric analysis of research trends and scientific advances in MFC materials, with a focus on catalysts and electrode coatings as key determinants of system performance. Using analytical tools such as VOSviewer and RStudio, we systematically mapped publication trends, collaboration networks, and technological developments from 2007 to 2025. Beyond bibliometric metrics, the analysis highlights significant scientific breakthroughs, including the development of a CeO₂/Co₃O₄-PEDOT/CF nanocomposite anode, which increased voltage output by 74.9% and power density by 2.5-fold, and a Ni-Fe LDH/(DSP) cathode system that achieved 83.5% contaminant removal efficiency with notable antimicrobial activity. These findings demonstrate the potential of metal oxide-based and doped materials to replace costly platinum while maintaining high electrochemical performance. Furthermore, the integration of nanotechnology and artificial intelligence in material design is identified as an emerging trend driving future innovations. The study concludes that advancing MFC technology toward practical applications in wastewater treatment and decentralized energy systems will require enhanced global collaboration and the adoption of scalable, cost-effective materials.

Abstract: The conversion of energy through functional materials has gained significant relevance in recent years, particularly with the development of perovskites and graphene, which have demonstrated a substantial impact on photovoltaic technologies and energy storage. However, challenges remain, such as the stability of perovskites under adverse environmental conditions and the industrial scalability of graphene, highlighting the need for a bibliometric analysis to assess the state of research on these materials from 2010 to 2025. To achieve this, a systematic search was conducted in Scopus, applying specific selection criteria and utilizing tools such as VOSviewer and R Studio to visualize collaboration networks, bibliometric indices, and thematic evolution. The results reveal an exponential growth in scientific output, with Asian leadership spearheaded by Tsinghua University, reflected in citation metrics and publication quality. Perovskites have achieved efficiencies exceeding 25%, while graphene has enhanced its integration into storage devices. This bibliometric study provides key insights for guiding future research towards a more sustainable energy transition.

Abstract: In this study, the effect of external electric fields on the electronic and optical properties of silicene quantum dots (SiQDs) was investigated using density functional theory (DFT) within the Quantum Espresso package. The optimized SiQD structure shows a Si–Si bond length of about 2.25 Å in the central hexagon, a buckling height of 0.50 Å, and a cohesive energy of –4.05 eV/atom, confirming structural stability. When the external electric field increases from 0 to 3.0 V/Å, the Fermi level shifts significantly from –4.43 eV to –12.35 eV, while the bandgap gradually decreases, leading to an increase in the density of states at the Fermi level and a semiconductor–metal transition. Charge density and Bader charge analysis reveal uneven redistribution of electrons: atom Si1 accumulates up to 7.8 e at 3.0 V/Å, while Si4 and Si10 lose nearly all electrons in their Bader regions. For optical properties, both dielectric and absorption spectra exhibit a pronounced red-shift; the absorption peak around 1.8 eV decreases to about 1.5 eV at 3.0 V/Å, while the reflection intensity is strongly reduced in the 1–2 eV range. These results demonstrate the controllable tuning of the electronic and optical properties of SiQDs by external electric fields, highlighting their potential for optoelectronic devices, sensors, and next-generation solar technologies.

Abstract: Humidity sensors are crucial for monitoring and controlling environmental conditions in diverse sectors such as agriculture, food and beverage processing, pharmaceutical industries, electronics, healthcare and biomedical applications, building environments, automotive systems, meteorology, and research laboratories [1]. Excessively high or low humidity levels relative to the ideal range can pose detrimental effects on both the environment and human health. For example, in the food industry, uncontrolled humidity can cause product damage, promote microbial growth, accelerate chemical degradation, and reduce the quality of raw materials [2]. In healthcare and biomedical environments. When the relative humidity is too low, it may dry out the skin and respiratory passages, making people more prone to infections. On the other hand, when RH is too high,it can support the growth of microorganisms such as molds, bacteria, and viruses [3]. Therefore, humidity sensors for monitoring and controlling moisture levels are essential for ensuring human comfort and maintaining high product quality. In recent years, various efforts have been undertaken to enhance the performance of humidity sensors, particularly through the development of humidity-sensing materials capable of providing high sensitivity, high stability, a wide detection range, low hysteresis, and optimal dynamic response, including fast response and recovery times [4-5].

Abstract: Humidity sensors play a vital role in various industrial and environmental monitoring applications that require accurate and stable detection of moisture. In this study, La_0.9Mg_0.1FeO₃ perovskite was synthesized via a sol–gel method, in which Mg²⁺ ions were substituted at the A-site of lanthanum ferrite to enhance material performance. X-ray diffraction (XRD) analysis confirms the formation of a single-phase orthorhombic perovskite structure with a Pnma space group, indicating successful phase formation without detectable secondary phases. Scanning electron microscopy (SEM) observations reveal a relatively homogeneous surface morphology with nearly spherical or polygonal grains and well-defined grain boundaries. A sensing layer was fabricated by drop-casting the synthesized material onto an interdigital alumina (IDT) substrate, and its capacitance response was measured using an LCR meter over a relative humidity (RH) range of 11%–96% at room temperature. The sensor shows stable performance after 30 days of testing, with response and recovery times of 9.8 s and 1.7 s, respectively. These results suggest that A-site Mg²⁺ substitution modifies the structural and electrical characteristics of LaFeO₃ and supports the potential of La_0.9Mg_0.1FeO₃ for capacitive humidity sensing applications.

Abstract: The dielectric properties of Mg₄Nb₂O₉ – TiO₂ composites in the low-frequency range were evaluated under temperature variation. X-ray diffraction demonstrated that Mg₄Nb₂O₉ (MNO) reacted with the added TiO₂, resulting in the formation of Mg₅(Nb_0.625Ti_0.375)₄O₁₅ as a new phase. Using Complex Impedance Spectroscopy (CIS), it was possible to observe that the activation energy (Ea) varied between 1.16 and 1.64 eV with the addition of TiO₂. Thermal stability was evaluated through the Temperature Coefficient of Capacitance (TCC), and it was observed that the systems could function as Class 1 ceramic capacitors according to EIA RS-198 at various frequencies. The TCC values suggested that the Mg₄Nb₂O₉ – TiO₂ system would be a promising candidate for applications in the low-frequency range as a ceramic capacitor.

Abstract: Remazol Brilliant Blue R is an azo dye consisting of aromatic compounds with N-H groups and possesses carcinogenic properties, frequently utilized in the textile industry, particularly in batik. Therefore, it is imperative to develop biomass-based adsorbents to reduce harmful dyes. This work investigated the effectiveness of N-doped carbon modified with magnetite material in adsorbing Remazol Brilliant Blue R dye, focusing on adsorption isotherms and kinetics. N-doped carbon modified material made from cellulose-based palm empty fruit bunches was modified with magnetite using a solution of ammonia-urea-NaOH and FeCl₃, then freeze-dried and pyrolyzed. Adsorption of Remazol brilliant blue R dye using N-doped carbon based on palm empty fruit bunches modified with magnetite has shown promising results in enhancing the removal efficiency of this dye from wastewater. The incorporation of magnetite not only improves the adsorption capacity but also facilitates magnetic separation, making the process more efficient and environmentally friendly. Magnetite-modified N-doped carbon composites containing active N-H and O-H groups effectively adsorbed the dye Remazol Brilliant Blue R, following the Freundlich isotherm and pseudo-second-order adsorption kinetics. The adsorption capacity of magnetite-modified N-doped carbon attained 680.32 mg/g at real batik wastewater containing Remazol Brilliant Blue R.

Abstract: Diesel-based engines generate hazardous chemical compounds to the air. It is necessary to have filtration mechanism before the gas exerted. The current filter is made by inorganic polymer that needs hundreds of years to degrade after disposal. Many attempt to have alternative material for the filter that would not cause environmental problems. One of prominent candidates is cellulose based filter. However, those who work mostly focus on how effectively the filter decreases the pollutant concentration yet another important aspect to evaluate is their mechanical properties. This work examines Cellulose Acetate (CA) filtering mechanical properties. Three properties that are examined are roughness, tensile and hardness. Those parameters indicate physical integrity and durability of the filter, especially when working in high velocity flow and temperature. It was found that after exposure to exhaust gas of diesel engines, the CA filter mechanical properties change dramatically (2.5 MPa to 0.16 MPa) as a sign of deterioration after used. The exposure of high temperature and flow lead to a drastic reduction of CA filter mechanical properties.

Abstract: This study presents a comparative characterization of carbon materials derived from coconut shell and rice husk based on their structural, thermal, elemental, and optical properties. The materials were characterized using thermogravimetric–differential thermal analysis (TGA–DTA), X-ray fluorescence (XRF), X-ray diffraction (XRD), and ultraviolet–visible (UV–Vis) spectroscopy. TGA–DTA results indicate that coconut shell-derived carbon exhibits higher thermal stability, with minimal weight loss of approximately 6% up to 1000°C, whereas rice husk-derived carbon undergoes significant weight loss of approximately 60% due to residual organic matter decomposition. XRF analysis reveals distinct compositional differences: rice husk carbon is dominated by SiO₂ (95.06 wt%), while coconut shell carbon contains 9.66 wt% Fe₂O₃. XRD patterns confirm predominantly amorphous carbon structures in both materials, with partial graphitic features (d-spacing ~0.34 nm) observed in the coconut shell-derived carbon. UV–Vis spectroscopy demonstrates higher optical absorbance (~0.85) for coconut shell carbon in the wavelength range of 200–800 nm. Overall, coconut shell-derived carbon exhibits superior characteristics in terms of thermal stability, Fe₂O₃ content, partial graphitic ordering, and optical absorbance compared to rice husk-derived carbon.