ゼオライト鋳型炭素の構造制御と電気化学的エネルギー貯蔵への応用

要約のみTohoku University京谷隆課

The Influence of H2O2 on The Photocatalytic Pretreatment of Cellulose for 5-Hydroxymethyl Furfural (5-HMF) Production

Photocatalysis has been widely known as a simple green technology to be applied in the synthesis and degradation process of organic molecules. An application of photocatalysis in a biomass pretreatment for a 5-hydroxymethylfurfural (5-HMF) production was investigated in this study. The results have revealed that photocatalysis, applied during pretreatment, facilitates the breakdown of cellulose. The presence of oxidizing agent (H2O2) in the ratios to cellulose of 11:1, 18:1, and 37:1 mol.mol-1 has been investigated for its effect on the production of 5-HMF. The optimum conditions obtained for the pretreatment process was the presence of H2O2 at 37:1 mol.mol-1, which was followed by the process of evaporation of the remaining H2O2 after pretreatment. The 5-HMF yield from the hydrolysis process involving pretreatment was 13.07%, while the yield from the process without pretreatment was 9.79%. The application of the pretreatment has succeeded in increasing the 5-HMF yield by 25.09%. The progress in the pretreatment was also marked by the presence of the carboxyl groups in the pretreated samples which were observed by the Fourier Transforms Infrared spectroscopy (FTIR). Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Binderless thin films of zeolite-templated carbon electrodes useful for electrochemical microcapacitors with ultrahigh rate performance

Controlled nanozeolite deposits are prepared by electrochemical techniques on a macroporous carbon support and binderless thin film electrodes of zeolite-templated carbon are synthesized using the deposits as templates. The obtained film electrodes exhibit extremely high area capacitance (10–12 mF cm−2) and ultrahigh rate capability in a thin film capacitor.We thank the Generalitat Valenciana, and FEDER (PROMETEO/2009/047) and the Spanish Ministry of Economy and Competitiveness (Projects PRI-PIBJP-2011-0766, CTQ2012-31762 and MAT2010-15273). A.B.M. thanks the Spanish Ministry Science and Innovation for a Ramón y Cajal fellowship (RyC 2009-03913). This research was also supported by Strategic International Cooperative Program, Japan Science and Technology Agency (JST)

Estudio de la capacidad electroquímica mediante carbones nanomoldeados

The template carbonization technique enables the production of porous carbons and carbon-based composites with precisely designed, controlled pore structures. The resulting templated carbons are therefore useful to investigate and understand the relation between carbon nanostructure and electrocapacitive properties. In this short review paper, we introduce our works on electrochemical capacitance using zeolite-templated carbons and carbon-coated anodic aluminum oxide.La técnica de nanomoldeo mediante carbonización de plantillas sólidas infiltradas permite la preparación y el diseño de materiales carbonosos porosos, tanto puros como compuestos, donde las estructuras porosas son fácilmente definibles y controlables. Los carbones nanomoldeados resultantes son muy útiles como materiales modelo para estudiar las relaciones entre la nanostructura del carbón y sus propiedades electrocapacitivas. En este trabajo, realizamos una breve revisión de nuestros estudios sobre la capacidad electroquímica utilizando carbones nanomoldeados obtenidos como réplica de una zeolita o por recubrimiento de óxido de aluminio anodizado.This research was partially supported by the Strategic International Cooperative Program, Japan Science and Technology Agency (T.K.) and MINECO (Spanish-Japanese project PRI-PIBJP-2011-0766); and a Grant-in-Aid for Scientific Research (B), 26286020 (H.N.). This research was partially supported also by Nano-Macro Materials, Devices and System Research Alliance and by Network Joint Research Center for Materials and Devices

Carbon–carbon asymmetric aqueous capacitor by pseudocapacitive positive and stable negative electrodes

An asymmetric aqueous capacitor was constructed by employing zeolite-templated carbon (ZTC) as a pseudocapacitive positive electrode and KOH-activated carbon as a stable negative electrode. The asymmetric capacitor can be operated with the working voltage of 1.4 V, and exhibits an energy density that is comparable to those of conventional capacitors utilizing organic electrolytes, thanks to the large pseudocapacitance of ZTC. Despite relatively thick electrode (0.2 mm) configuration, the asymmetric capacitor could be well operated under a current density of 500 mA g −1.The authors would like to thank the Spanish MINECO, FEDER funds (Project MAT2010-15273 and PRI-PIBJP-2011-0766). This research was also supported by Strategic International Cooperative Program, Japan Science and Technology Agency

Pseudocapacitance of zeolite-templated carbon in organic electrolytes

Carbon and graphene-based materials often show some amount of pseudocapacitance due to their oxygen-functional groups. However, such pseudocapacitance is generally negligible in organic electrolytes and has not attracted much attention. In this work, we report a large pseudocapacitance of zeolite-templated carbon (ZTC) based on the oxygen-functional groups in 1 M tetraethylammonium tetrafluoroborate dissolved in propylene carbonate (Et4NBF4/PC). Due to its significant amount of active edge sites, a large amount of redox-active oxygen functional groups are introduced into ZTC, and ZTC shows a high specific capacitance (330 F g−1). Experimental results suggest that the pseudocapacitance could be based on the formation of anion and cation radicals of quinones and ethers, respectively. Moreover, ZTC shows pseudocapacitance also in 1 M lithium hexafluorophosphate dissolved with a mixture of ethylene carbonate and diethyl carbonate (LiPF6/EC+DEC) which is used for lithium-ion batteries and lithium-ion capacitors.This research was partially supported by the Strategic International Cooperative Program, Japan Science and Technology Agency (T.K.); a Grant-in-Aid for Scientific Research (A), 15H01999 (T.K.); a Grant-in-Aid for Scientific Research (B), 26286020 (H.N.); and the Spanish MINECO, FEDER funds (Project MAT2013-42007-P and PRI-PIBJP-2011-0766). This research was supported also by Nano-Macro Materials, Devices and System Research Alliance and by Network Joint Research Center for Materials and Devices

A Simple “Nano-Templating” Method Using Zeolite Y Toward the Formation of Carbon Schwarzites

Schwarzites have a three-dimensional sp2 carbon structure with negative Gaussian curvatures. They can be synthesized through the deposition of carbon by chemical vapor deposition on a zeolite template and may be formed by increasing the amount of carbon. In this research, the amount of carbon deposition was increased by shortening the length of the diffusion pathways of the template through the use of nano-sized zeolite Y (nano-FAU). It was found that significantly larger quantities of carbon could be deposited inside the pores of nano-FAU (40 nm), compared to the micro-sized zeolite Y (300 nm). It is thus confirmed that by shortening the diffusion pathways enables more carbon to infiltrate into the center of the template before the pore channels are blocked, which leads to larger carbon depositions. A low acetylene gas concentration (15% vol in N2) and a prolonged period for chemical vapor deposition (6 h) is preferable for effectively loading carbon into the template. The obtained carbon replica exhibits the ordered structure derived from zeolite Y with an unprecedented 72 carbon atoms per supercage, of which a model with a structure similar to schwarzite was proposed.This work was supported by Grant-in-Aid for Scientific Research (A), 17H01042 (HN); the Nano-Macro Materials, Devices and System Research Alliance; and the Network Joint Research Center for Materials and Devices. The support from Sirindhorn International Institute of Technology under the Excellent Thai Student Program (PB) and from the Research Grant for New Scholar (Grant No. MRG6080153) co-funded by the Thailand Research Fund (TRF); the commission on Higher Education, Thailand; and Thammasat University, are also acknowledged

Characterization of a zeolite-templated carbon by electrochemical quartz crystal microbalance and in situ Raman spectroscopy

Electrochemical quartz crystal microbalance was used to monitor the mass changes during the electrochemical characterization of a zeolite-templated carbon (ZTC) in 1 M H2SO4 medium. Under electrochemical oxidation conditions, a high anodic current and a net mass increase were recorded, resulting in the increase of the specific capacitance owing to the contribution of the pseudocapacitance, mainly derived from the hydroquinone–quinone redox couple. Under more severe electrochemical conditions, a net mass loss was observed, revealing that electrochemical gasification took place. Surface chemistry, before and after the electrochemical treatments, was analyzed through temperature programmed desorption experiments. Furthermore, in situ Raman spectroscopy was used to further characterize the structural changes produced in ZTC under the electrochemical conditions applied, supporting that high potential values produce the electrochemical oxidation and degradation of the carbon material.The authors would like to thank the MINECO (Spanish-Japanese project PRI-PIBJP-2011-0766, MAT2013-42007-P and CTQ2012/31762) and JST (Strategic International Cooperative Program) and Generalitat Valenciana and FEDER (PROMETEOII/2014/010). This work is also supported by the Nano-Macro Materials, Devices and System Research Alliance and by Network Joint Research Center for Materials and Devices. SLG thanks Generalitat Valenciana for a Fellowship for training of researchers and Spanish MECD for the thesis grant