Guiding the Development of Efficient and Durable Electrodes for Electrochemical Energy Conversion Applications through Advanced Ion Beam Analysis

Surface-sensitive ion beam techniques, such as Secondary Ion Mass Spectrometry (SIMS) and Low-Energy Ion Scattering (LEIS), are making significant contributions to further our understanding of the materials’ performance and the degradation processes that occur under operating conditions. In this contribution, we explore how recent instrumental developments and analytical approaches have boosted the application of these powerful techniques for the characterization of surfaces and interfaces in energy conversion and storage devices.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

一酸化炭素の水素化用担持鉄-コバルト-ニッケル系合金触媒に関する研究

第1章 緒論 第2章 鉄-コバルト-ニッケル系合金触媒による一酸化炭素の水素化反応 第3章 COおよびH_2の吸着状態に及ぼす鉄-コバルトーニッケルの合金効果 第4章 添加物による一酸化炭素の水素化反応における生成物制御 第5章 コバルトーニッケル系合金触媒によるCO水素化に及ぼす担体酸化物の影響 第6章 コバルトーニッケル系合金触媒における複合酸化物の担体への応用 第7章 Co-Ni/MnO-ZrO_2触媒とゼオライト触媒との組合せによる一酸化炭素の水素化反応の生成物制御 第8章 本研究の総括Made available in DSpace on 2012-07-03T23:57:02Z (GMT). No. of bitstreams: 2 ishihara1.pdf: 11044617 bytes, checksum: aca2fcb8e138916ecf1f1f54cf732309 (MD5) ishihara2.pdf: 9352391 bytes, checksum: 4ee91a9eadc2f0ef3aead35e290c90eb (MD5) Previous issue date: 1991-02-2

Synergistic enhancement of H2 and CH4 evolution by CO2 photoreduction in water with reduced Graphene oxide–bismuth monoxide quantum dot catalyst

Photocatalytic water splitting or CO2 reduction is one of the most promising strategies for solar energy conversion into hydrogen-containing fuels. However, these two processes typically compete with each other, which significantly decreases the solar energy conversion efficiency. Herein, we report for the first time this competition can be overcome by modulation of reactive sites and electron transfer pathway of heterogeneous photocatalysts. As a prototype, BiO composite reduced graphene oxide quantum dots (RGO-BiO QDs) were synthesized, which can provide large amounts of photogenerated electrons as well as individual reactive sites for H+ and CO2 reduction. The productivity of H2, CH4, and CO by the RGO-BiO QDs catalyst were 102.5, 21.75, and 4.5 μmol/(g·h), respectively, in pure water without the assistance of any cocatalyst or sacrificial agent. The apparent quantum efficiency at 300 nm reached to 4.2%, which is more than 10 times higher than that of RGO-TiO2 QDs (0.28%) under the same conditions. In situ DRIFT, ESR, and photoelectrochemical studies confirmed that the unique circled electron transfer pathway (Evb(BiO) → Ecb(BiO) → Ef(RGO) → EVo•(BiO)) and the large amount of separated different reactive sites are responsible for the highly efficient simultaneous H2 evolution and CO2 reduction performance

Active photocatalysts for CO2 conversion by severe plastic deformation (SPD)

Excessive CO2 emission from fossil fuel usage has resulted in global warming and environmental crises. To solve this problem, photocatalytic conversion of CO2 to CO or useful components is a new strategy that has received significant attention. The main challenge in this regard is exploring photocatalysts with high activity for CO2 photoreduction. Severe plastic deformation (SPD) through the high-pressure torsion (HPT) process has been effectively used in recent years to develop novel active catalysts for CO2 conversion. These active photocatalysts have been designed based on four main strategies (i) oxygen vacancy and strain engineering, (ii) stabilization of high-pressure phases, (iii) synthesis of defective high-entropy oxides, and (iv) synthesis of low-bandgap high-entropy oxynitrides. These strategies can enhance the photocatalytic efficiency compared to conventional and benchmark photocatalysts by improving CO2 adsorption, increasing light absorbance, aligning the band structure, narrowing the bandgap, accelerating the charge carrier migration, suppressing the recombination rate of electrons and holes, and providing active sites for photocatalytic reactions. This article reviews recent progress in the application of SPD to develop functional ceramics for photocatalytic CO2 conversion

Electrocatalytic Oxidation of Dimethyl Ether

考察了负载于镓酸镧基电解质上的镍电极与镍 钐掺杂氧化铈复合电极电催化二甲醚氧化反应的特性 .结果表明 ,反应的主要产物均为CO ,H2 和CH4,同时生成少量完全氧化的产物H2 O和CO2 .在开路电位下二甲醚发生裂解反应 ,生成的CO ,H2 和CH4三种主要产物的比例接近于 1.在有电泵氧存在下 ,二甲醚的电催化氧化反应强烈地依赖于阳极及电解质材料的组成 .Ni/La0 9Sr0 1Ga0 8Mg0 2 O3 界面上发生的主反应是二甲醚的部分氧化 ,且存在有严重的积碳现象 .电极中掺入SDC( 15 %Sm3 + 掺杂的CeO2 )后 ,二甲醚完全氧化性能明显增强 ;随着电流的增大 ,氢的生成速率显著减小 ,并生成大量的H2 O .采用掺钴镓酸镧基电解质后 ,Ni SDC主要表现为催化二甲醚部分氧化反应 ,且显著抑制了积碳的发生 .Ni SDC/La0 8Sr0 2Ga0 8 Mg0 11Co0 0 9O3 上二甲醚电催化氧化反应的主要产物为 1∶1的CO和H2 .掺钴电解质引起Ni SDC具有特殊的催化性能 ,可能与电解质中 p型电导的存在有关As potential fuel for solid oxide fuel cells, electrocatalytic oxidation of dimethyl ether (DME) was studied on nickel and nickel samarium doped CeO 2 composite anodes supported on series lanthanum gallate electrolytes. The reaction was characterized in a single solid oxide fuel cell, and the electrolytes were La 0 8 Sr 0 2 Ga 0 8 Mg 0 11 Co 0 09 O 3 (LSGMC9), La 0 8 Sr 0 2 Ga 0 8 Mg 0 13 Co 0 07 O 3 (LSGMC7), La 0 8 Sr 0 2 Ga 0 8 Mg 0 15 Co 0 05 O 3 (LSGMC5), and La 0 9 Sr 0 1 Ga 0 8 Mg 0 2 O 3 (LSGM). The composition of composite anode was 75%Ni 25%SDC (SDC15%Sm 3+ doped CeO 2). The main products were CO, H 2 and CH 4 with small amounts of CO 2 and H 2O. DME was decomposed into CO, H 2, and CH 4 under open circuit voltage. The product distribution depended strongly on the composition of anode and electrolyte. The major reaction on Ni/LSGM was partial oxidation of DME, and significant coke deposition was observed during the reaction. With the addition of SDC into Ni anode, complete oxidation was preferred on the catalyst. The formation rate of H 2 decreased with the increase of current on Ni SDC/LSGM, and large amount of H 2O was formed in the reaction. While using Co doped LSGM electrolytes, the major reaction changed to partial oxidation of DME, and the coke deposition was significantly decreased. The main products on Ni SDC/LSGMC9 were CO and H 2. The special property of Co doped LSGM electrolyte could be due to the high p type conductivity. Ni SDC/LSGMC is a kind of ideal anode for electrocatalytic partial oxidation of DME.日本教育部资助项目 (12 3 0 7

Electrocatalytic oxidation of dimethyl ether

As potential fuel for solid oxide fuel cells, electrocatalytic oxidation of dimethyl ether (DME) was studied on nickel and nickel-samarium-doped CeO2 composite anodes supported on series lanthanum gallate electrolytes. The reaction was characterized in a single solid oxide fuel cell, and the electrolytes were La0.8Sr0.2Ga0.8Mg0.11Co0.09O3(LSGMC9), Lao(0.8)Sr(0.2)Ga(0.8)Mg(0.13)Co(0.07)O(3)(LSGMC7), La0.8Sr0.2Ga0.8Mg0.15Co0.05O3(LSGMC5), and La0.9Sr0.1Ga0.8Mg0.2O3(LSGM). The composition of composite anode was 75% Ni-25% SDC (SDC - 15% Sm3+-doped CeO2). The main products were CO, H-2 and CH4 with small amounts of CO2 and H2O. DME was decomposed into CO, H-2, and CH4 under open circuit voltage. The product distribution depended strongly on the composition of anode and electrolyte. The major reaction on Ni/LSGM was partial oxidation of DME, and significant coke deposition was observed during the reaction. With the addition of SDC into Ni anode, complete oxidation was preferred on the catalyst. The formation rate of H-2 decreased with the increase of current on Ni-SDC/LSGM, and large amount of H2O was formed in the reaction. While using Co-doped LSGM electrolytes, the major reaction changed to partial oxidation of DME, and the coke deposition was significantly decreased. The main products on Ni-SDC/LSGMC9 were CO and H-2. The special property of Co-doped LSGM electrolyte could be due to the high p-type conductivity. Ni-SDC/LSGMC is a kind of ideal anode for electrocatalytic partial oxidation of DME

Visible light-driven dye-sensitized photocatalytic hydrogen production by porphyrin and its cyclic dimer and trimer: effect of multi-pyridyl-anchoring groups on photocatalytic activity and stability

The monomer, dimer, and trimer of 5,15-diphenyl-10,20-di(pyridin-4-yl)porphyrin are used to investigate the multianchoring effect on TiO2 for visible light-driven photocatalytic hydrogen production in a water medium. Further, the porphyrin trimer is prepared and analyzed by nuclear magnetic resonance (NMR) spectroscopy, absorption spectroscopy, electrochemical voltammetry, fast atom bombardment (FAB) mass spectroscopy, and density functional theory (DFT) computation. The results of this study indicate that the peak intensities of the absorption spectra increase as the number of porphyrin units increases, while changes could be barely observed in the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gaps. The porphyrin dimer in a 1 wt % Pt-loaded TiO2 powder photocatalyst system exhibited optimal hydrogen production performance in a stable state over a period of 80 h and at a superior rate of 1023 μmol·g–1·h–1. Further, the stability of the photocatalytic system was systematically investigated using films containing dyes on 1 wt % Pt-loaded TiO2/FTO. For a film containing the dimer, almost no change was observed in the hydrogen-bond coordination mode of the dimer and the photocurrent during the photocatalytic reaction. However, the photocurrents of the monomer and trimer were altered during visible light irradiation without altering the coordination mode, indicating that the arrangements and orientations of the porphyrins on TiO2 surfaces were altered. These results indicate that the presence of multiple anchoring groups enhance the stability of the photocatalytic system and the rate of hydrogen production

Designing Optimal Perovskite Structure for High Ionic Conduction.

Solid-oxide fuel/electrolyzer cells are limited by a dearth of electrolyte materials with low ohmic loss and an incomplete understanding of the structure-property relationships that would enable the rational design of better materials. Here, using epitaxial thin-film growth, synchrotron radiation, impedance spectroscopy, and density-functional theory, the impact of structural parameters (i.e., unit-cell volume and octahedral rotations) on ionic conductivity is delineated in La0.9 Sr0.1 Ga0.95 Mg0.05 O3- δ . As compared to the zero-strain state, compressive strain reduces the unit-cell volume while maintaining large octahedral rotations, resulting in a strong reduction of ionic conductivity, while tensile strain increases the unit-cell volume while quenching octahedral rotations, resulting in a negligible effect on the ionic conductivity. Calculations reveal that larger unit-cell volumes and octahedral rotations decrease migration barriers and create low-energy migration pathways, respectively. The desired combination of large unit-cell volume and octahedral rotations is normally contraindicated, but through the creation of superlattice structures both expanded unit-cell volume and large octahedral rotations are experimentally realized, which result in an enhancement of the ionic conductivity. All told, the potential to tune ionic conductivity with structure alone by a factor of ≈2.5 at around 600 °C is observed, which sheds new light on the rational design of ion-conducting perovskite electrolytes