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Research Paper
- Modeling and Identification the Parameters of a Silicon-Based Solar Cell to Optimize Its Energy Recovery
- Nacera Mazouz, Moadh Kichene
- Genetic algorithms (GAs) are used to optimize solutions to problems, particularly those that are analytically impossible to solve. As their name suggests, …
- Genetic algorithms (GAs) are used to optimize solutions to problems, particularly those that are analytically impossible to solve. As their name suggests, they are inspired by the biological concepts of genetics and evolution. Our work aims to study and model a silicon-based photovoltaic generator (PVG). Among the various models available is that of the diode. Modeling was used to approximate the PVG output (voltage, current) as a function of two inputs: temperature and irradiation. The parameters of our model were identified using a real coding algorithm, with the cumulative square error was used for selection. To test the effectiveness of our model, we carried out simulation tests on the power-voltage (P-V) and current-voltage (I-V) characteristics of a wide range of irradiation and temperature variations. This study demonstrates the effectiveness and accuracy of the proposed approach (GAs) and validates the parameters obtained and used in the single-diode electrical model. The results indicate that the GA technique is a better conventional parameter extraction strategy in terms of convergence. It provides globally optimal solutions. - COLLAPSE
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Research Paper
- Comparative Characterization of Cupric Oxide Thin Film and Nanorod Photocathodes for Photoelectrochemical Water Splitting
- Jong-Hyun Park, Hyojin Kim
- Hydrogen production via photoelectrochemical water splitting relies on the effectiveness of the photoelectrodes. Preparing low-dimensional structures of oxide semiconductors is a promising …
- Hydrogen production via photoelectrochemical water splitting relies on the effectiveness of the photoelectrodes. Preparing low-dimensional structures of oxide semiconductors is a promising approach to fabricating effective photoelectrodes, by enhancing the surface-to-volume ratios of the photocatalytic materials. In this study, we performed a comparative investigation of the photoelectrochemical characteristics of p-type oxide semiconductor cupric oxide (CuO) photocathodes based on CuO thin film and nanorods. The CuO thin film was prepared via a facile method involving sputtering a Cu metallic film and subsequent thermal oxidation, while the CuO nanorods were grown via a seed-mediated hydrothermal synthesis method using a CuO nanoparticle seed layer. The structural, optical, and photoelectrochemical properties of the prepared CuO thin film and nanorods were comparatively examined. Our results confirmed that the CuO nanorod photocathode has a higher photocurrent density and better photoconversion efficiency than the CuO thin film photocathode for photoelectrochemical water splitting, implying a promising route to the fabrication of CuO-based photoelectrodes. - COLLAPSE
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Research Paper
- Enhanced Supercapacitive Charge Storage in a Nickel Oxide-Graphene Oxide Composite: Synergistic Effect
- Shital Bachankar, Aditi Kumbhar, Shaupik Mullani, Dhanaji Malavekar, Jaehyung Park, Chihoon Kim, Taeksoo Ji
- As the pace of technological advances accelerates, the role of electrical energy storage has become increasingly important. Among various storage solutions, supercapacitors …
- As the pace of technological advances accelerates, the role of electrical energy storage has become increasingly important. Among various storage solutions, supercapacitors are garnering significant attention. Their unique attributes, including high power density, rapid charge/discharge capabilities, and extended lifecycle, position them as a promising alternative to conventional batteries. This study investigates the synthesis of a nickel oxide (NiO) and nickel oxide/graphene oxide (NiO/GO) composite using a single-step hydrothermal method, to evaluate their potential as supercapacitor electrode materials. The synthesized NiO, graphene oxide (GO), and NiO/GO composite were comprehensively characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy to analyze their crystal structures and chemical bonding. The XRD analysis confirmed the formation of an NiO phase with a rhombohedral crystal structure, and no change after GO incorporation. SEM analysis revealed the formation of spherical NiO particles and porous morphology of the NiO/GO composite, which also exhibited a spherical shape. The GO displayed a randomly arranged wrinkled sheet-like structure. Electrochemical analysis of the NiO/GO composite exhibited a remarkable specific capacitance of 893 F g-1 at a current density of 1 A g-1, surpassing that of NiO and GO alone, demonstrating NiO/GO has promising performance for supercapacitor applications. The charge transfer resistance, derived from the Nyquist plot, suggests that the reduction in charge transfer resistance contributed significantly to the improved capacitance. Additional stability studies of over 5,000 cycles at 5 A g-1 revealed an 85 % initial capacitance retention, confirming the advantages of GO inclusion to improve material retention for superior long-term performance. The asymmetric supercapacitor (ASC) assembled using an electrode with the configuration NiO/GO//activated carbon (AC) showed a specific capacitance of 77.8 F g-1 obtained at a current density of 0.5 A g-1. - COLLAPSE
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Research Paper
- Calculation of Electronic Structures of Graphene Nanoflakes by Hückel Molecular Orbital Method: Exploration of the Shape, Size, and Edge Effects
- Jaemin Jeong, Woong Lee
- The electronic structures of graphene nanoflakes (GNFs) were estimated for various shapes, sizes, symmetries, and edge configurations. The Hückel molecular orbital (HMO) …
- The electronic structures of graphene nanoflakes (GNFs) were estimated for various shapes, sizes, symmetries, and edge configurations. The Hückel molecular orbital (HMO) method was employed as a convenient way of handling the variety of possible GNF structures, since its simplicity allows the rapid solution of large system problems, such as tailoring optoelectronic characteristics of molecule containing large number of carbon atoms. The HMO method yielded the electronic structures with respect to the energy state eigenvalues, with results comparable to those obtained by other approaches, such as the tight-binding method reported elsewhere. The analyses included the consideration of various types of edge configurations of 68 GNF systems grouped by their geometric shape, reflecting symmetry. It was inferred that GNFs in the small length scale regimes, below 1 nm, which are effectively small polycyclic aromatic hydrocarbon molecules, exhibit the optoelectronic characteristic of quantum dots. This is due to the widely spaced discrete energy states, together with large energy gaps between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). With increasing size this arrangement evolves into graphene-like ones, as revealed by the narrowing HOMO-LUMO gaps and decreasing energy differences between eigenstates. However, the changes in electronic structure are affected by the symmetries, which are related to the geometric shapes and edge configurations. - COLLAPSE
Journal Informaiton
Korean Journal of Materials Research
Korean Journal of Materials Research
Materials Research Society of Korea
한국재료학회
204, 202, Muhak-ro, Dongdaemun-gu, Seoul, Republic of Korea
Tel: +82-2-566-4496 / Fax: +82-2-566-4497 / E-mail: jmrs@mrs-k.or.kr Copyright© Materials Research Society of Korea. Powered by APUB
Tel: +82-2-566-4496 / Fax: +82-2-566-4497 / E-mail: jmrs@mrs-k.or.kr Copyright© Materials Research Society of Korea. Powered by APUB