３次元ナノ多孔質炭素金属複合材料による高効率電極材料の開発

要約のみTohoku University小山裕課

Pt Nanoparticles Embedded in Colloidal Crystal Template Derived 3D Ordered Macroporous Ce_0.6Zr_0.3Y_0.1O₂: Highly Efficient Catalysts for Methane Combustion

Three-dimensionally ordered macro/mesoporous Ce_0.6Zr_0.3Y_0.1O₂ (3DOM CZY) supported high-dispersion Pt nanoparticles (<i>x</i> wt % Pt/3DOM CZY, <i>x</i> = 0.6, 1.1, and 1.7) were successfully synthesized via the cetyltrimethylammonium bromide/triblock copolymer P123 assisted gas bubbling reduction route. The 3DOM CZY and <i>x</i> wt % Pt/3DOM CZY samples exhibited a high surface area of 84–94 m²/g. Pt nanoparticles (NPs) with a size of 2.6–4.2 nm were uniformly dispersed on the surface of 3DOM CZY. The 1.1 wt % Pt/3DOM CZY sample showed excellent catalytic performance, giving a <i>T</i>_90% value at 598 °C at gas hourly space velocity (GHSV) of 30000 mL/(g h) and the highest turnover frequency (TOF_Pt) of 6.98 × 10^–3 mol/(mol_Pt s) at 400 °C for methane combustion. The apparent activation energy (64 kJ/mol) over 1.1 wt % Pt/3DOM CZY was much lower than that (95 kJ/mol) over Bulk CZY. The effects of water vapor and SO₂ on the catalytic activity of 1.1 wt % Pt/3DOM CZY were also examined. It is concluded that the excellent catalytic activity of 1.1 wt % Pt/3DOM CZY was associated with its high oxygen adspecies concentration, good low-temperature reducibility, and strong interaction between Pt NPs and CZY as well as large surface area and unique nanovoid-walled 3DOM structure

Manganese Oxides with Rod-, Wire-, Tube-, and Flower-Like Morphologies: Highly Effective Catalysts for the Removal of Toluene

Nanosized rod-like, wire-like, and tubular α-MnO₂ and flower-like spherical Mn₂O₃ have been prepared via the hydrothermal method and the CCl₄ solution method, respectively. The physicochemical properties of the materials were characterized using numerous analytical techniques. The catalytic activities of the catalysts were evaluated for toluene oxidation. It is shown that α-MnO₂ nanorods, nanowires, and nanotubes with a surface area of 45–83 m²/g were tetragonal in crystal structure, whereas flower-like spherical Mn₂O₃ with a surface area of 162 m²/g was of cubic crystal structure. There were the presence of surface Mn ions in multiple oxidation states (e.g., Mn³⁺, Mn⁴⁺, or even Mn²⁺) and the formation of surface oxygen vacancies. The oxygen adspecies concentration and low-temperature reducibility decreased in the order of rod-like α-MnO₂ > tube-like α-MnO₂ > flower-like Mn₂O₃ > wire-like α-MnO₂, in good agreement with the sequence of the catalytic performance of these samples. The best-performing rod-like α-MnO₂ catalyst could effectively catalyze the total oxidation of toluene at lower temperatures (<i>T</i>_50% = 210 °C and <i>T</i>_90% = 225 °C at space velocity = 20 000 mL/(g h)). It is concluded that the excellent catalytic performance of α-MnO₂ nanorods might be associated with the high oxygen adspecies concentration and good low-temperature reducibility. We are sure that such one-dimensional well-defined morphological manganese oxides are promising materials for the catalytic elimination of air pollutants

Lithium intercalation into bilayer graphene

The mechanism of lithium storage in graphenic carbon remains a fundamental question to be addressed. Here the authors employ suitable bilayer graphene foam to investigate various physiochemical phenomena of lithium intercalation and propose a storage model

Three-Dimensionally Ordered Macroporous La_0.6Sr_0.4MnO₃ Supported Ag Nanoparticles for the Combustion of Methane

A series of Ag nanoparticles (NPs) supported on three-dimensionally ordered macroporous (3DOM) La_0.6Sr_0.4MnO₃ (<i>y</i>Ag/3DOM La_0.6Sr_0.4MnO₃; <i>y</i> = 0, 1.57, 3.63, and 5.71 wt %) were successfully prepared with high surface areas (38.2–42.7 m²/g) by a facile novel reduction method using poly methacrylate colloidal crystal as template in a dimethoxytetraethylene glycol (DMOTEG) solution. Physicochemical properties of these materials were characterized by means of numerous techniques, and their catalytic activities were evaluated for the combustion of methane. It is shown that the <i>y</i>Ag/3DOM La_0.6Sr_0.4MnO₃ materials possessed unique nanovoid-like 3DOM architectures, and the Ag NPs were well dispersed on the inner walls of macropores. Among the La_1–<i>x</i>Sr_<i>x</i>MnO₃ (<i>x</i> = 0.2, 0.4, 0.6, 0.8) and <i>y</i>Ag/3DOM La_0.6Sr_0.4MnO₃ (<i>y</i> = 0, 1.57, 3.63, and 5.71 wt %) samples, 3.63 wt % Ag/3DOM La_0.6Sr_0.4MnO₃ performed the best, giving <i>T</i>_10%, <i>T</i>_50%, and <i>T</i>_90% (temperatures corresponding to methane conversion =10, 50, and 90%) of 361, 454, and 524 °C, respectively, and the highest turnover frequency (TOF_Ag) value of 1.86 × 10^–5 (mol/mol_Ag s) at 300 °C. The apparent activation energies (39.1–37.5 kJ/mol) of the <i>y</i>Ag/3DOM La_0.6Sr_0.4MnO₃ samples were much lower than that (91.4 kJ/mol) of the bulk La_0.6Sr_0.4MnO₃ sample. The effects of water vapor and sulfur dioxide on the catalytic activity of the 3.63 wt % Ag/3DOM La_0.6Sr_0.4MnO₃ sample were also examined. It is concluded that its super catalytic activity was associated with its high oxygen adspecies concentration, good low-temperature reducibility, large surface area, and strong interaction between Ag and La_0.6Sr_0.4MnO₃ as well as the unique nanovoid-walled 3DOM structure