Inorganic matter in rice husk derived carbon and its effect on the capacitive performance

Porous carbons were obtained from rice husk using two different chemical activation methods and they were investigated as supercapacitors.Their properties were studied using X-ray photoelectron spectroscopy,thermal analysis,potentiometric titration,and nitrogen adsorption isotherm.The specific capacitance measured in both H_(2) SO_(4) and KOH electrolytes in two-electrode cell was up to-150 F/g.The activation method used affected the resulting carbons’features.As expected,the dependence of the capacitance on porosity was found.The ash content reached 36 wt.%and that inorganic mater blocked some pores and limited their accessibility to electrolyte ions and increased the charge transfer resistance.Nevertheless,the main ash constituents such as CaCO_(3),MgCO_(3),Ca_(3)(PO_(4))2(or P_(2)O_(5)),and Fe-and Zn-containing species did not affect the specific capacitance to a large extent.Especially SiO2,even in a relatively large amount(~20 wt.%)T did not play a detrimental role in the capacitance behavior.The results showed that in spite of a high ash content,carbon can exhibit a good capacitive performance provided that it has a favorable porosity and is rich in sp_(2) configurations.

A bi-As-capped and tetra-V-substituted arsenomolybdate:synthesis,structure,capacitive and electrocatalytic properties

A bi-As-capped and tetra-V-substituted arsenomolybdate(Hbib)_(2)(biyb)_(3)[As^(Ⅲ)_(2)As^(Ⅴ)Mo^(Ⅵ)8V^(Ⅴ)_(4)O_(40)]_(2)·H_(2)O(1)(bib=1.4-Bis(imidazoly)butane;biyb=1,4-bis(imidazol-1-ylmethyl)benzene)has been constructed through hydrothermal methods and characterized by conventional method.Compound 1 is a tetra-V substituted{AsMo^(Ⅵ)_(8)V^(Ⅴ)_(4)O_(4)}polyanions capped by two AsⅢcations at two symmetrical ditch in{AsO_(4)}rectangular pyramid geometry.It exhibits higher specific capacitance,capacitance retention,and electrocatalytic activities for oxidizing ascorbic acid and reducing peroxide hydrogen.

Capacitance Performances of Supramolecular Hydrogels Based on Conducting Polymers

The capacitance performances of poly（3,4-ethylenedioxythiophene）-poly（styrenesulfonate）（PEDOT-PSS） supramolecular hydrogels have been investigated systematically. The materials show a specific capacitance of 67 F/g and display excellent rate capability at the scan rate as high as 5000 m V/s in the cyclic voltammogram measurements, accompanied by good cycle stability. On the basis of the measurements of the microscale morphologies, specific areas and electrical conductivities, the mechanisms for the improvement of the electrochemical properties are discussed and ascribed to the novel porous microstructures of the hydrogels and the synergetic effect of the rigid PEDOT and soft PSS components. Furthermore, polyaniline（PAn） is compounded with the PEDOT-PSS hydrogels through an interfacial polymerization process, endowing the hydrogel materials with a higher specific capacitance of 160 F/g at the scan rate of 5000 m V/s. The significance of this work lies in the demonstration of a novel method to solve the problems of conducting polymers in electrochemical applications.

Simulation and structure optimization of triboelectric nanogenerators considering the effects of parasitic capacitance

Parasitic capacitance is an unavoidable and usually unwanted capacitance that exists in electric circuits, and it is the most important second-order non-ideal effect that must be considered while designing a triboelectric nanogenerator （TENG） because its magnitude is comparable to the magnitude of the TENG capacitance. This paper investigates the structure and performance optimization of TENGs through modeling and simulation, taking the parasitic capacitance into account. Parasitic capacitance is generally found to cause severe performance degradation in TENGs, and its effects on the optimum matching resistance, maximum output power, and structural figures-of-merit （FOMs） of TENGs are thoroughly investigated and discussed. Optimum values of important structural parameters such as the gap and electrode length are determined for the different working modes of TENGs, systematically demonstrating how these optimum structural parameters change as functions of the parasitic capacitance. Additionally, it is demonstrated that the parasitic capacitance can improve the height tolerance of the metal freestanding-mode TENGs. This work provides a theoretical foundation for the structure and performance optimization of TENGs for practical applications and promotes the development of mechanical energy-harvesting techniques.