In this study, the three structures of the symmetric paper supercapacitors based on the carbon nanotubes (CNTs), graphite nanoparticles (GNPs) and graphene electrodes have been fabricated. In the supercapacitors was used of polyvinyl alcohol (PVA)/phosphoric acid (H3PO4) as a gel electrolyte and the BaTiO3 film as a separator film. The carbon nanomaterials, gel electrolyte surface, and electrode films were characterized by scanning electron microscopy (SEM) and transmission electron microscope (TEM). The specific capacitance of the symmetric paper supercapacitors using charge-discharge technique and C-V curves at the voltage scan rates 20 mV/s and 150 mV/s have been investigated. The symmetric paper supercapacitor based on the CNTs electrode showed higher specific capacitance 411 F g- 1, compared to GNPs and graphene supercapacitors. Also by electrochemical impedance spectroscopy, the Nyquist curves of the symmetric paper supercapacitors have been plotted. For the symmetric paper supercapacitors based on the GNPs, graphene and CNTs electrodes the equivalent series resistance (ESR) resistance was 210 Ω, 96 Ω and 101 Ω respectively. The flexible symmetric paper supercapacitor based on BaTiO3/PVA/CNTs structure denotes a new type of the flexible supercapacitor that can be applied to the soft electronic.

Comparison of power density as a function of energy density for supercapacitors based on Ni-materials/carbon nanocomposites and keyword analysis of Ni material-based supercapacitors using VOSviewer.

Carbon nanotubes (CNTs), due to mechanical, electrical, and surface area properties and their ability to adapt to different nanocomposite structures, are very substantial in supercapacitor electrodes. In this review, we have summarized high-performance, flexible, and symmetry CNT supercapacitors based on the CNTs/graphene, CNTs/metal, and CNTs/polymer electrodes. To present recent developments in CNT supercapacitors, we discuss the performance of supercapacitors based on electrical properties such as specific capacitance (SC), power and energy densities, and capacitance retention (CR). The comparison of supercapacitor nanocomposite electrodes and their results are reported for future researchers.

In this study, fabrication of highly sensitive PdNPs/SiO2/Si hydrogen gas sensor using experimental and theoretical methods has been investigated. Using chemical method the PdNPs are synthesized and characterized by X-ray diffraction (XRD). The average size of PdNPs is 11 nm. The thickness of the oxide film was 20 nm and the surface of oxide film analyzed using Atomic-force microscopy (AFM). The C-V curve for the PdNPs/SiO2/Si hydrogen gas sensor in 1% hydrogen concentration and at the room temperature has been reported. The response time and recovery time for 1% hydrogen concentration at room temperature were 1.2 s and 10 s respectively. The response (R%) for PdNPs/SiO2/Si MOS capacitor hydrogen sensor was 96%. The PdNPs/SiO2/Si MOS capacitor hydrogen sensor showed very fast response and recovery times compared to SWCNTs/PdNPs, graphene/PdNPs, nanorod/PdNPs and nanowire/PdNPs hydrogen gas sensors. Keywords: Sensitive, Oxide film, Capacitive, Resistanc

Background: In this paper, the supercapacitor based on the carbon nanotubes (CNTs) electrodes has been fabricated. Objective: The Polyvinylidene Fluoride (PVDF) and Polyvinyl Alcohol (PVA) were used as a gel electrolyte. Methods: The electrodes and electrolytes thin films were characterized by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The specific Capacitance (Cs) of the CNTs-based supercapacitor has been measured using the cyclic voltammetry and galvanostatic methods. For the scan rate, 20 mV s^-1 the Cs of the CNTs-based supercapacitor was 173 F g^-1. Results: Using the electrochemical impedance spectroscopy the Nyquist curve has been plotted. The reactance capacitance and the equivalent series resistance of the CNTs-based supercapacitor with PVDF/PVA gel electrolytes were 90 Ω and 25 Ω respectively. Conclusion: Also, few patents for the CNTs-based supercapacitor have been reviewed and cited. The CNTs-based supercapacitor proposed a new structure solid-state and flexible supercapacitor with high performance.

We investigated the multifaceted gas sensing properties of porous silicon thin films electrodeposited onto (100) oriented P-type silicon wafers substrates. Our investigation delves into morphological, optical properties, and sensing capabilities, aiming to optimize their use as efficient gas sensors. Morphological analysis revealed the development of unique surfaces with distinct characteristics compared to untreated sample, yielding substantially rougher yet flat surfaces, corroborated by Minkowski Functionals analysis. Fractal mathematics exploration emphasized that despite increased roughness, HF/ethanol-treated surfaces exhibit flatter attributes compared to untreated Si sample. Optical approaches established a correlation between increased porosity and elevated localized states and defects, influencing the Urbach energy value. This contributed to a reduction in steepness values, attributed to heightened dislocations and structural disturbances, while the transconductance parameter decreases. Simultaneously, porosity enhances the strength of electron‒phonon interaction. The porous silicon thin films were further tested as effective gas sensors for CO₂ and O₂ vapors at room temperature, displaying notable changes in electrical resistance with varying concentrations. These findings bring a comprehensive exploration of some important characteristics of porous silicon surfaces and established their potential for advanced industrial applications.