Papers by Keyword: Electrode

Abstract: In this study, SnO₂ was successfully synthesized using spray pyrolysis method. Knowing that lanthanides has the capability to enhance the performance of metal oxides in supercapacitor application, Samarium was loaded to Tin Dioxide (SnO2) at different percent weight concentrations (0.5%, 1%, 3% 5%). XRD diffractograms shows the formation of tetragonal rutile structure with prominent peaks at 26.6°, 34.08°, 51.94° that corresponds to (110), (101), and (211) respectively and no additional peaks was detected with the incorporation Sm³⁺ ions which. The data obtained from Energy Dispersive X-ray Spectroscopy confirm the presence of Sm on the spray pyrolyzed SnO2. Scanning electron micrograph revealed that the increase in loading of Sm changes the morphology of the samples from 1D to 2D structures. Faradaic reactions indicated by the oxidation and reduction peaks were monitored using cyclic voltammetry in 1M KOH electrolyte. The specific capacitances were determined by analyzing the galvanostatic charge discharge profile of each sample. SnO₂ with 0.5% Sm yield the the highest specific capacitance, energy density and power density of 54.55 F/g, 1.60 WHr/kg, and 230 W/kg respectively. The results from this research offers a valuable information in synthesizing binder-free electrode and modifying its properties by incorporating samarium. These electrodes can be used for advanced applications such as electrochemical energy storage device, electrochemical sensors, and electrocatalytic applications.

Abstract: As the demand for energy and technological advancements continues to grow, the need for efficient and high-capacity energy storage devices is also increasing. Supercapacitors have emerged as a potential solution, offering advantages such as high specific capacitance, shorter charging times, and longer lifespan. Metal-Organic Framework (MOF) materials have shown promise potential as various electrodes applications due to their superior surface area and porosity. This study focuses on the development of MOF materials based on HKUST-1 with bimetallic modification at a 1:1 ratio, using cobalt and nickel as the metal center. The synthesis, characterization, and electrochemical testing were conducted to evaluate the potential of each material as an electrode for supercapacitor applications. The synthesis was carried out using the coprecipitation method. SEM and XRD characterizations revealed poor crystallinity, with a morphological change to polyhedral shapes with the addition of Ni and elongated shapes with the addition of Co. Electrochemical tests using cyclic voltammetry and galvanostatic charge discharge techniques demonstrated poor supercapacitor performance, with non-ideal voltammetry curves and relatively low specific capacitance compared to common supercapacitor materials. The trend shows that secondary metals improves the characteristics of HKUST-1 as supercapacitor. It is shown that the HKUST-1 which has been added with Co and Ni is better than regular HKUST-1, with Co being the best out of all three. This trend is also supported by DFT calculations which shows stronger adsorption in Co active sites, followed by Ni and lastly Cu.

Abstract: Piezoelectric materials possess a special property to produce electricity from mechanical motion and are therefore it is suitable for green energy solutions. In our project, we fabricated a flexible piezoelectric device through a simple, non-vacuum process. We prepared the device by a solution casting process with a thin poly (vinylidene fluoride) (PVDF) film. Under mechanical stress, the device shows a clear electrical response, confirming its functionality. This indicates that piezoelectric materials can be fabricated to utilize as a low-cost, eco-friendly, and efficient means to harvest energy. This device can also be used as a sensor in robots and robot-related applications. This device can sense movement, which can be used in autonomous robots to sense movement, feed back, or even to harvest energy to power robotic sensors. In the future, we can improve the device performance by modifying the film thickness, using more efficient electrode materials, and making it stable to operate in different conditions.

Abstract: In the search for environmentally acceptable and sustainable energy storage solutions, biomass-derived biochar materials are becoming popular in supercapacitor applications. Rice straw is regularly disposed of as agricultural waste, but it is an intriguing biomass precursor for synthesizing activated biochar suitable for supercapacitor electrodes. This study exhibited the utilization of activated biochar synthesized from rice straw through pyrolysis and potassium hydroxide (KOH) activation for supercapacitor applications. Structural examination, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), and nitrogen (N₂) adsorption and desorption, showed the activated rice straw-derived biochar‘s distinct crystal structure, morphological structure, pore structure, and surface area. Rice straw-derived biochar revealed an amorphous structure, nanosheet-like or multilayered morphology, and hierarchical pore structure. Electrochemical characterization showed that the activated rice straw-derived biochar has high specific capacitances of 116.48 F/g at 1 A/g and 84.58 F/g at 5 A/g, respectively. The amorphous character, hierarchical pore structure, and nanosheet-like morphology of the rice straw-derived biochar provided favorable properties for effective ion transfer for high electrochemical performance. These findings exhibited the prospects of rice straw as a sustainable and economical biomass precursor to produce excellent electrode material in supercapacitor applications.

Abstract: Asymmetric supercapacitors have been fabricated using nanostructured AC// AC-NiCo₂O₄ composite electrodes. The aim was to determine the performance of a modified electrode based on AC as the anode and AC-NiCo₂O₄ as the cathode. NiCo₂O₄ has been successfully synthesized using the co-precipitation method. FTIR, XRD, and SEM characterized the material. The NiCo₂O₄ confirmed the crystalline structure assigned to cubic spinel with nanospheres morphologies. The electrochemical properties of the prepared composite electrodes and fabricated supercapacitor cells have been studied using charge-discharge (CD) and cyclic voltammetry (CV) in 1M Et₄NBF₄ as an electrolyte_. The optimized composition is AC-NiCo₂O₄ (15%), exhibiting a superior power density of 42.56 W kg^-1. These results showed that AC-NiCo₂O₄ material could be a great candidate as an active material for supercapacitors.

Abstract: Developing energy storage systems has become a significant focus in supporting advancing renewable energy technologies and electric vehicles. Supercapacitors are a critical device in this endeavor, known for their high capacitance and low internal resistance. Although carbon-based supercapacitors have been widely used, they have low energy density. This research addresses the development of activated carbon (AC) and polyaniline (PANi) composite-based supercapacitors to improve the performance of energy storage devices. AC/PANi composites were synthesized in various ratios of (20:80)%, (50:50)%, and (80:20)% using in-situ polymerization method. Supercapacitor electrodes were prepared by mixing AC/PANi composite, acetylene black, and polyvinylidene fluoride (PVDF) with a mass ratio of (80:10:10)%. Furthermore, coin-type supercapacitor cells were assembled using AC/PANi composite electrodes, 1 M Et4NBF4 electrolyte, and polypropylene separator. Supercapacitor performance was evaluated using Cyclic Voltammetry (CV) methods. The results of FTIR analysis showed that the AC/PANi composite was successfully synthesized, with absorption peaks corresponding to the characteristics of AC and PANi. X-ray diffraction patterns showed that the AC/PANi composite exhibited amorphous properties. The CV test results show that the coin cell based on the AC/PANi composite (20%:80%) indicates the highest performance with significant specific capacitance. Thus, supercapacitor electrodes based on the AC/PANi composite show potential as active materials for supercapacitor devices.

Abstract: In recent years, the EU policy identified the hydrogen as one of the main energy vectors to support the power production from renewable sources. Coherently, electrolysis is suitable to convert energy in hydrogen with no carbon emission and high purity level. Among the electrolysis technologies, the anion exchange membrane (AEM) seems to be promising for the performance and the development potential at relatively high cost. In the present work, AEM electrolysers, and their technological bottlenecks, have been investigated, in comparison with other electrolysers’ technology such as alkaline water electrolysis and proton exchange membranes. Major efforts and improvements are investigated about innovative materials design and the corresponding novel approach as main focus of the present review. In particular, this work evaluated new materials design studies, to enhance membrane resistance due to working cycles at temperatures close to 80 °C in alkaline environment, avoiding the employment of toxic and expensive compounds, such as fluorinated polymers. Different strategies have been explored, as tailored membranes could be designed as, for example, the inclusion of inorganic nanoparticles or the employment of not-fluorinated copolymers could improve membranes resistance and limit their environmental impact and cost. The comparison among materials’ membrane is actually limited by differences in the environmental conditions in which tests have been conducted, thereafter, this work aims to derive reliable information useful to improve the AEM cell efficiency among long-term working periods.

Abstract: A two-stage hydrothermal method was used to prepare rapid-switching electrochromic WO₃/ZnO composite electrodes. The morphology of the nanorods was altered by changing the precursor concentration. A higher precursor concentration inhibited the growth of crystals and declined the crystallinity of nanorods. Nanorods with a diameter of 48 nm, height of 92.5 nm, and transmittance greater than 80% were grown when the precursor concentration in the second step was 1.5 times that in the first step. The electrochromic electrode demonstrated rapid coloring and bleaching speeds (5 and 0.8 s, respectively), which were faster than those of the electrode prepared using the one-stage process.

Abstract: Poly (3,4-ethylene dioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) is a promising conductive polymer to be the next-generation electrode for medical purposes. However, PEDOT:PSS exhibits low conductivity (~1×10−3 S cm−1); hence, incorporating silver nanoparticles (SNP) with PEDOT:PSS will improve the electrical conductivity. This paper aims to investigate the electrical properties differences between PEDOT:PSS doped SNP-based films and hydrogels. The two different states of PEDOT:PSS/SNP serves its particular purpose as an electrode. Initially, the PEDOT:PSS/SNP solution was prepared by homogeneously mixing at constant stirring. Then, the solution was drop-casting onto a glass substrate to produce a film, while another part of the solution was undergoing a freeze-thaw method to produce hydrogel. Surface resistance measurement exhibits lower resistance values for a film (0.11 kΩ) than hydrogel (0.59 kΩ). A scanning electron microscope (SEM) was utilized to observe the morphology of the films, while an optical microscope (OM) observed the surface of the hydrogel since they are in different states. Fourier Transform Infrared (FTIR) spectra display prominent peaks that described the successful blending between PEDOT:PSS and SNP for both films and hydrogels. These findings demonstrate that varying processing methods of preparing PEDOT:PSS/SNP in films or hydrogels may influence its properties like the electrode, which should provide a valuable contribution to the bioelectronic areas.

Abstract: In this paper, a color-tunable light emitting diode LED with two laterally arranged single quantum wells (SQWs) is designed, and simulated. In this work, III-nitride materials are used. The structure has been numerically investigated using the ATLAS simulation software. The proposed structure has three electrodes. This gives the opportunity to emit violet (420 nm) or green (560 nm) light individually. Furthermore, it can emit simultaneously a mixture of both colors, and at a certain mixture ratio the white light is obtained with chromaticity coordinates ( x = 0.3113, y = 0.3973). The lateral arrangement of the two SQWs reduces the negative effect of photon absorption; which will give good external quantum efficiency (EQE). The structure has a big importance in the application of the solid-state lighting, especially in the white light generation.