An infrared-responsive poly(acrylamide-co-butyl methacrylate)/polyacrylic acid/multi-wall carbon nanotube (MWCNT) interpenetrating network hydrogel was prepared, and its temperature response was observed. This hydrogel exhibits an upper critical solution temperature (UCST)-type temperature response; it swells at temperatures above the UCST and shrinks at temperatures below the UCST. Gravimetric measurements of the gels revealed that the infrared-induced temperature rise of the MWCNTs and subsequent cooling could be the cause of the recurrent swelling and shrinking. However, the degree of swelling was reduced by the addition of MWCNTs despite their exothermicity.

Because of worldwide industrialization and increasing population, we are facing a problem concerning the availability of clean water. Therefore, the desalination of saline water using a reverse osmosis (RO) membrane is very important technology for producing a large amount of clean water. RO membrane technology has been well developed over the past 50 years. Although remarkable progress has been made in the fabrication of membranes, there is still a challenge to produce reliable membranes with antifouling properties, high mechanical strength, high tolerance to chlorine attack and a minimum thickness of the membrane barrier layer to provide a high flux. Multi-wall carbon nanotubes (CNT) have been added to the active layer of aromatic polyamide (PA)-RO membranes, with interesting results, such as better robustness. This review considers recent work on the synthesis, structure, performance, etc. of CNT/PA nanocomposite membranes.

The ion adsorption/desorption behavior of single-wall carbon nanotube capacitor electrodes revealed by galvanostatic charge/discharge tests, cyclic voltammetry (CV), X-ray diffraction (XRD), Raman spectroscopy, and electrochemical quartz-crystal microbalance (EQCM) measurements are reviewed. It was found that capacitance of SWCNT capacitor electrodes depends not only on the surface area, but also on the electrical density of states (DOS) of the SWCNTs. It was also found that the inner tube space of SWCNTs is used for ion-storage. Smaller-diameter SWCNTs showed a higher gravimetric capacitance at low current densities. On the other hand, large diameter SWCNTs showed a better rate performance. The ion adsorption/desorption dynamics of SWCNT electrodes were examined by the EQCM method. The results obtained indicate that in addition to traditional ion adsorption-type charge compensation, ion desorption-type charge compensation dynamics occur inside the SWCNTs. The dependence of the rate performance of SWCNT electrodes on the tube-diameter can be explained by this mechanism. By combining the above knowledge, we propose a new type of electrochemical energy storage device which uses the redox reaction of iodine ions in the hollow space of SWCNTs.

Carbon nanotubes (CNTs) are known to be a material with excellent properties, and their use in various fields has been highly anticipated. However, the commercialization of CNT composites has not progressed as expected. The reason for this is that their appropriate use was not sufficiently defined. This report discusses some promising applications of CNT composite materials for the near future.

Recent progress in thermoelectric materials based on single-wall carbon nanotubes (SWCNTs) is considered from fundamental and practical points of view. This progress has recently been driven by social requirements in energy harvesting, as well as significant interest in terms of materials preparation and fundamental physical transport properties. The latest thermoelectric properties of SWCNT-based materials have achieved a figure of merit (zT) as high as ca. 0.1, comparable to those of inorganic semiconductors such as silicon. Along with structural control and doping chemistry, several exotic applications including thermal energy harvesting for the Internet of Things (IoT) and invisible sensing are described.

The performance of polymer electrolyte fuel cells (PEFCs) depends on the oxygen reduction reaction (ORR) at the cathode. Although platinum-supported carbon black has been used as the ORR catalyst in PEFCs, the use of platinum makes the cells expensive. Recently, platinum-free catalysts have been developed as cheap and long-life alternatives for excellent ORR catalytic activity. This review focusses on the acidic ORR catalytic activity of modified carbon nanotubes (CNTs) such as nitrogen-doped CNTs and defect-induced CNTs.

リチウムイオン電池(LIB)の負極活物質には黒鉛が広く使用され，黒鉛層間へのリチウムイオンの挿入脱離反応が進行する。黒鉛電極上では初回充電時に電解液が分解されることによりSolid electrolyte interphase (SEI)と呼ばれる表面被膜が形成される。SEIはリチウムイオン伝導性を有する一方で，電子伝導性は持たず，電解液のさらなる分解反応を速度論的に抑制するため，黒鉛上の負極反応には必要不可欠である。しかしながら，SEIはリチウムイオンの挿入反応が進行するエッジサイト上に形成されるため，界面イオン移動の反応サイト数の減少や界面抵抗の増大をもたらすと考えられる。さらに，SEIの性能向上のためにvinylene carbonate (VC)やfluoroethylene carbonate (FEC)に代表されるようなSEI形成剤が電解液に添加され，それにより構成成分や物理的性質も変化するが，これらの性質の違いが界面反応性を大きく左右することが予想される。つまり，形成されるSEIの性質は黒鉛電極表面の反応場に大きな影響を与え，LIBのレート特性やサイクル特性などにも影響があると考えられる。

従来のSEIに関する研究の多くは表面鋭敏な分光法を用いた成分分析や原子間力顕微鏡などを用いた物理的性質の解析が主たるものであり，これらの手法では界面でのリチウムイオン移動の反応性に関しての直接的な情報を得ることは困難であった。そこで本研究では，種々のプローブ分子を用いた電気化学的解析を用いることで，分光法では明らかにすることが困難であったSEI形成下における黒鉛／電解液界面での反応サイト数の評価やSEIの共挿入抑制能の評価を行い，SEIが黒鉛電極の表面反応場に与える影響を詳細に調べることで，良好な黒鉛／電解液界面を構築するために重要なSEIの要素に関して知見を得ることを目的とした。

本論文は，序論および2部の5章から構成される。序論では，SEIのこれまでの研究についてまとめた。第1部（1, 2章）では，SEIとリチウムイオンの電極／電解液界面移動反応速度の関係について考察し，第2部（3∼5章）では，SEIの性質の違いによる溶媒和リチウムイオンの共挿入抑制効果への影響とその発現理由について検討した。