The present study elucidates new perspectives regarding the Pt-CeO2 system for CO oxidation. The successful deposition of highly dispersed Pt-CeO2 species onto the surface of multiwalled carbon nanotubes (MWCNTs) led to the formation of abnormally active and water-resistant catalysts. The catalysts were investigated by structural (XRD, TEM), spectral (XPS), and kinetic (TPR-CO+O-2, TPR-CO, TPR-H-2) methods. The application of TPR-CO+O-2 revealed the remarkably high activity of all Pt-CeO2/MWCNTs catalysts at temperatures below 0 degrees C. The study of the catalysts at ambient temperature demonstrated high CO conversion in the presence of water vapor at a concentration of 100 ppm CO. The experimental findings suggest that active sites, comprising platinum structures stabilized directly on the surface of MWCNTs, play a pivotal role in the oxidation of CO under humid conditions. A dual-site approach was employed to develop a kinetic model that effectively describes the experimental data. This model provides valuable insights into the mechanism of wet CO oxidation.

В работе были исследованы композитные катализаторы, представляющие собой Rh-CeOx композиции, нанесенные на поверхность многостенных углеродных нанотрубок (МУНТ). Активные компоненты (Rh, Ce) были нанесены на поверхность МУНТ с сохранением постоянной загрузки родия и варьированием содержания церия в диапазоне соотношений Rhат./Ceат. = 0.085–0.34. Исследование полученных образцов проводилось комбинацией структурных (рентгеновская дифракция, просвечивающая электронная микроскопия (ПЭМ)), спектральных (рентгеновская фотоэлектронная спектроскопия (РФЭС)) и кинетических (температурно-программированная реакция с СО (ТПР-СО) и СО+О2 (ТПР-СО+О2)) методов. Обнаружено, что для всех изученных образцов наблюдается формирование высокодисперсных частиц CeO2 и RhOx. При изменении соотношения Rhат./Ceат. происходит формирование структур, проявляющих каталитическую активность в реакции окисления СО в различных температурных диапазонах. При низких соотношениях Rhат./Ceат. < 0.17 конверсия СО наблюдается при температурах выше 100°С. При увеличении соотношения Rhат./Ceат. в катализаторах Rh-CeO2/МУНТ происходит формирование центров, обладающих каталитической активностью при температурах ниже 0 °С. Исследование композитных катализаторов с высоким соотношением Rhат./Ceат. методами ПЭМВР и ТПР-СО указывает на то, что активными формами могут являться структуры на основе дисперсных окисленных форм родия, модифицированных ионами Ce3+.

Синтезированы новые координационные соединения – дигидрат транс-бис(оксалато)диакваиридата(III) натрия Na[Ir(H2O)2(C2O4)2]·2H2O и транс-бис(оксалато)диакваиридиевая кислота H5O2[Ir(H2O)2(C2O4)2]. Вещества охарактеризованы методами рентгеноструктурного и рентгенофазового анализа, инфракрасной спектроскопии. Кристаллографические данные для Na[Ir(H2O)2(C2O4)2]·2H2O: пространственная группа P-1, a = 5.2456(7) Å, b = 6.4999(8) Å, c = 8.237(1) Å, α = 98.162(6)°, β = 92.005(6)°, γ = 112.043(4)°, Z = 1. Кристаллографические данные для H5O2[Ir(H2O)2(C2O4)2]: пространственная группа P-1, a = 4.6903(2) Å, b = 6.0053(3) Å, c = 9.1527(5) Å, α = 75.843(2)°, β = 84.270(2)°, γ = 82.413(2)°, Z = 1. Координационная сфера атома иридия имеет геометрию искаженного октаэдра. Структура Na[Ir(H2O)2(C2O4)2]·2H2O по строению схожа со структурами оксалатов двухвалентных металлов состава MC2O4·2H2O (M = Mn, Fe, Co, Ni, Cu, Zn). Катион Цунделя H5O2+ в транс-бис(оксалато)иридиевой кислоте располагается дискретно.

Composite catalysts consisting of Rh-CeOx structures supported on the surface of multi-walled carbon nanotubes (MWCNTs) are studied. For supported active components (Rh, Ce) the rhodium content is maintained constant on the MWCNT surface and the cerium concentration is varied in the range Rh-at/Ce-at = 0.085-0.34. The obtained samples are investigated by a combination of structural (X-ray diffraction, transmission electron microscopy (TEM)), spectral (X-ray photoelectron spectroscopy (XPS)), and kinetic (temperature-programmed reaction with CO (TPR-CO) and CO+O-2 (TPR-CO+O-2)) techniques. Highly dispersed CeO2 and RhOx particles are found to form in all samples studied. When the Rh-at/Ce-at ratio is changed, structures are formed that exhibit the catalytic activity in the CO oxidation reaction for different temperature ranges. At low Rh-at/Ce-at ratios (< 0.17) the CO conversion is observed at temperatures above 100 degrees C. When the Rh-at/Ce-at ratio increases, centers exhibiting the catalytic activity at temperatures below 0 degrees C are formed in Rh-CeO2/MWCNT catalysts. HR-TEM and TPR-CO studies of composite catalysts with a high Rh-at/Ce-at ratio reveal that structures based on dispersed oxidized rhodium particles modified by Ce3+ ions can be active species.

Heteronuclear coordination compounds of d-metals are effective precursors for the production of bimetallic nanoalloys (Plyusnin et al., 2022) [1], which, in turn, are widely used in catalysis. Catalysts based on Rh and Cu, as well as Rh and Zn, are highly active in the process of steam reforming of hydrocarbons. Double oxalates of Rh with Cu and Rh with Zn with the general formula [(C2O4)(H2O)2Rh- (mu-C2O4)-M(H2O)2-(mu-C2O4)-Rh (H2O)2(C2O4)]& sdot;6H2O (M = Cu, Zn) are synthesized and structurally characterized. According to thermogravimetric analysis, the complexes completely decompose in He and H2 atmospheres already at 300 degrees C with the formation of the corresponding nanoalloys in the Cu-Rh and Zn-Rh systems. Calcination in an O2 atmosphere leads to the formation of a mixed oxide with a spinel structure. The Cu-Rh/Ce0.75Zr0.25O2 and Zn-Rh/ Ce0.75Zr0.25O2 catalysts were prepared by impregnation by moisture capacity on a porous support followed by calcination in a hydrogen atmosphere. The obtained catalysts were tested in propane steam reforming for hydrogen production at 300-480 degrees C and WHSV = 10 000-40 000 cm3 h- 1 center dot gcat- 1. At these conditions the Cu-Rh/ Ce0.75Zr0.25O2 and Zn-Rh/Ce0.75Zr0.25O2 catalysts demonstrated high selectivity for hydrogen (more than 70 %) compared to the monometallic catalyst Rh/Ce0.75Zr0.25O2 (less than 60%). Bimetallic catalysts make it possible to increase hydrogen productivity by reducing the reaction rate of methanation of carbon oxides, which is achieved due to the presence of Cu and Zn in the catalyst structure.

New coordination compounds, sodium trans-bis(oxalato)diaqua-iridate(III) dihydrate Na[Ir(H2O)2(C2 O4)2]·2H2O and trans-bis(oxalato)diaquairidic acid H5O2[Ir(H2O)2(C2O4)2], are prepared. The substances are characterized by single-crystal XRD, powder XRD, and IR spectroscopy. Crystal data for Na[Ir(H2O)2(C2O4)2]·2H2O: P1̅ space group, a = 5.2456(7) Å, b = 6.4999(8) Å, c = 8.237(1) Å, α = 98.162(6)°, β = 92.005(6)°, γ = 112.043(4)°, Z = 1; for H5O2[Ir(H2O)2(C2O4)2]: P1̅ space group, a = 4.6903(2) Å, b = 6.0053(3) Å, c = 9.1527(5) Å, α = 75.843(2)°, β = 84.270(2)°, γ = 82.413(2)°, Z = 1. The coordination sphere of iridium is a distorted octahedron. The Na[Ir(H2O)2(C2O4)2]·2H2O structure is similar to those of MC2O4·2H2O divalent metal oxalates (M = Mn, Fe, Co, Ni, Cu, Zn). The H_5O_2^+ Zundel cation in the trans-bis(oxalato)iridic acid is located discretely.

Composite catalysts consisting of Rh–CeOx structures supported on the surface of multi-walled carbon nanotubes (MWCNTs) are studied. For supported active components (Rh, Ce) the rhodium content is maintained constant on the MWCNT surface and the cerium concentration is varied in the range Rhat/Ceat = 0.085-0.34. The obtained samples are investigated by a combination of structural (X-ray diffraction, transmission electron microscopy (TEM)), spectral (X-ray photoelectron spectroscopy (XPS)), and kinetic (temperature-programmed reaction with CO (TPR-CO) and CO+O2 (TPR-CO+O2)) techniques. Highly dispersed CeO2 and RhOx particles are found to form in all samples studied. When the Rhat/Ceat ratio is changed, structures are formed that exhibit the catalytic activity in the CO oxidation reaction for different temperature ranges. At low Rhat/Ceat ratios (< 0.17) the CO conversion is observed at temperatures above 100 °C. When the Rhat/Ceat ratio increases, centers exhibiting the catalytic activity at temperatures below 0 °C are formed in Rh–CeO2/MWCNT catalysts. HR-TEM and TPR-CO studies of composite catalysts with a high Rhat/Ceat ratio reveal that structures based on dispersed oxidized rhodium particles modified by Ce3+ ions can be active species.

Проведен сравнительный кристаллохимический анализ о-[Pd(NH3)4]3Мо7O24·6H2O (а = 17.3472(3), b = 28.9064(4), с = 30.2463(4) Å, пр. гр. Ibca, V = 15166.9 Å3, Z = 16) и m-[Pd(NH3)4]3Мо7O24·3H2O (а = 10.6617(2), b = 20.5248(5), с = 16.4676(3) Å, b = 103.0792(10), пр. гр. P21/n, V = 3510.11(13) Å3, Z = 4). Изучены продукты термического разложения o-[Pd(NH3)4]3Мо7O24·6H2O. В атмосфере Н2 при 900°С образуется смесь разнометальных твердых растворов на основе ОЦК-решетки Мо и ГЦК-решетки Pd, а в атмосфере 90%Не/10%Н2 при 910°С - смесь твердого раствора на основе ОЦК-решетки Мо и Pd2Mo3N.

The [(Pt(NH 3 ) 4 ) x (Pd(NH 3 ) 4 ) 1– x ]CrO 4 single-phase solid solution ( x = 0.5-0.6) is prepared by the cocrystallization of [Pt(NH 3 ) 4 ](NO 3 ) 2 and [Pd(NH 3 ) 4 ](NO 3 ) 2 aqueous solutions with ammoniac (NH 4 ) 2 CrO 4 . The structure and parameters of the tetragonal ( I 4 1 / amd , Z = 4) unit cell ( a = 7.3091(1) Å, c = 15.2720(6) Å) of this compound and the molar fraction of Pt ( x = 0.568(7)) are determined using the single-crystal X-ray diffraction method. The unit cell parameters of the studied crystal are additionally refined by an original method ( a = 7.3207(9) Å, c = 15.2527(19) Å, V = 817.4(3) Å 3 ) and are further utilized to refine also the molar fraction of Pt using Zen′s law ( x = 0.57(1)). A single crystal of [(Pt(NH 3 ) 4 ) 0.57 (Pd(NH 3 ) 4 ) 0.43 ]CrO 4 and two samples of the synthesized product selected from the total mass are thermally decomposed in hydrogen. A study of thermolysis products by XRD, scanning and transmission electron microscopy methods demonstrates the formation of a Pt 0.49 Pd 0.38 Cr 0.13 nanoalloy included in the Cr 2 O 3 matrix in the form of blocks (~1 µm) and smaller (>2 nm) spherical formations.

This work presents a systematic study of the kinetic aspects of CO oxidation reaction catalyzed by platinum nanoparticles (NPs) supported on the surface of multiwalled carbon nanotubes (MWCNTs). The investigation presented is closely related to the actual practical task of air purification in enclosed spaces. Therefore, the catalytic reaction was carried out in the presence of an excess of oxygen (5 vol.%) and over a wide range of CO concentrations from 50 ppm to 1600 ppm. For the catalyst characterization, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were applied. Kinetic modelling based on the Langmuir–Hinshelwood and Mars-van Krevelen mechanisms was taken as a basis, using the results obtained on Pt foil. Simulation of CO oxidation reaction on platinum NPs at temperatures above 90 °C was carried out using a kinetic model describing the reaction mechanism on bulk platinum. The description of the kinetics of CO oxidation reaction on Pt NPs over the entire temperature range, including the low temperatures down to −40 °C, required the introduction of the steps characterizing an additional concerted mechanism related to CO-assisted O2 dissociation. Using the presented model, some predictions of the kinetic behaviour of the system were made.

The application of composite materials as catalysts for the oxidation of CO and other toxic compounds is a promising approach for air purification. In this work, the composites comprising palladium and ceria components supported on multiwall carbon nanotubes, carbon nanofibers and Sibunit were studied in the reactions of CO and CH4 oxidation. The instrumental methods showed that the defective sites of carbon nanomaterials (CNMs) successfully stabilize the deposited components in a highly-dispersed state: PdO and CeO2 nanoparticles, subnanosized PdOx and PdxCe1−xO2−δ clusters with an amorphous structure, as well as single Pd and Ce atoms, are formed. It was shown that the reactant activation process occurs on palladium species with the participation of oxygen from the ceria lattice. The presence of interblock contacts between PdO and CeO2 nanoparticles has an important effect on oxygen transfer, which consequently affects the catalytic activity. The morphological features of the CNMs, as well as the defect structure, have a strong influence on the particle size and mutual stabilization of the deposited PdO and CeO2 components. The optimal combination of highly dispersed PdOx and PdxCe1−xO2−δ species, as well as PdO nanoparticles in the CNTs-based catalyst, makes it highly effective in both studied oxidation reactions.

Herein, the highly dispersed palladium and ceria species were deposted on the surface of multi-walled carbon nanotubes (MWCNTs) by co-deposition from acetone solutions. The use of MWCNTs allowed varying Pd/Ce atomic ratio in a wide range, while maintaining a high dispersion of the active components. Application of physicochemical methods revealed the formation of various palladium species. Single Pd2+ ions dispersed in CeO2 lattice were the main Pd-Ce-Ox species at low Pdat/Ceat ratio. With an increase of the Pd content in the samples the preferential formation of PdO particles in a tight contact with CeO2 nanoparticles was observed. The size of PdO and CeO2 primary particles was in a range of 1-5 nm.The Pd-Ce-Ox/MWCNTs samples showed high activity in the CO oxidation reaction already at room tem-perature with a temperature of 50% CO conversion below 100 degrees C. The Pd2+-CeO2 and PdO-CeO2 species demonstrated the comparable activity in "dry" CO oxidation. However, the presence of water vapor in the re-action mixture resulted in the immediate deactivation of Pd2+-CeO2 species, while PdO-CeO2 species retained a high activity at 20 degrees C. The results of the work highlight the benefits of MWCNTs, Pd, and CeO2 combination for obtaining catalysts highly active in CO oxidation.

Heteronuclear coordination compounds of d-metals are suitable single-source precursors for bimetallic nanoalloys, which often show extraordinary catalytic properties due to synergetic effect. In particular, Ni- and Rh-based catalysts are highly effective in low temperature steam reforming processes. Double oxalates of Rh with Ni and Co of the formula {[Rh(H2O)(2)(C2O4)mu-(C2O4)](2)M(H2O)(2)}center dot 6H(2)O (M = Ni, Co) were synthesized and structurally characterized. According to thermogravimetric analysis, the complexes decompose completely in He and H-2 atmospheres to form corresponding nanoalloys at similar to 300 degrees C. The calcination in O-2 atmosphere leads to formation of spinel type mixed oxide. The supported Co-Rh/Al2O3 and Ni-Rh/Al2O3 catalysts were prepared by impregnation of double oxalate complexes in porous support with subsequent calcination and tested in propane low temperature steam reforming in CH4 excess. The Co-containing catalyst showed comparable activity regarding to pure Rh/Al2O3 sample, while bimetallic Ni-Rh/Al2O3 catalyst revealed to be appreciably more active, than monometallic catalysts with higher active component loadings. Rh-Ni catalyst allowed for complete propane conversion at T approximate to 350 degrees C, whereas for Rh catalyst the temperature was T approximate to 410 degrees C, and Rh-Co did not reach complete C3H8 conversion at all. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Nanocomposite catalysts based on highly dispersed platinum and ceria particles supported on carbon nanotubes were studied. The composites were prepared using the complex (Мe 4 N) 2 [Pt 2 (μ-OH) 2 (NO 3 ) 8 ] as the platinum precursor. This approach ensured stabilization of platinum nanoparticles, clusters, and single atoms/ions on the surface of both ceria and the carbon nanomaterial. Study of the catalytic activity of the samples showed that highly dispersed metallic platinum species stabilized directly on the surface of carbon nanotubes can efficiently oxidize CO present in low concentrations in a reaction mixture at room temperature, in particular, in the presence of water vapor. However, low-temperature CO oxidation at higher CO concentrations requires formation of new active sites through interaction of platinum ions with ceria particles.

Natural diamond crystals with a highly porous surface were used as substrates for synthesizing single-phase bimetallic Pt–Co nanoparticles at temperatures of 500 °C and 800 °C. The metal nanoparticles inside the pores were determined to take the form of single-phase Pt0.50Co0.50 solid solutions with different degrees of superstructure ordering. A detailed characterization of both nanoalloys revealed a tetragonal symmetry with a space group, P4/mmm. For the sample obtained at 500 °C, the lattice parameters were a = 2.673(2), c = 3.735(3) Å, and c/a = 1.397(1); for the samples obtained at 800 °C, the parameters were—a = 2.688(2), c = 3.697(3) Å, and c/a = 1.375(1). Within the experimental parameters, no significant chemical interaction of the diamond with the Pt–Co particles was identified. The results demonstrate a strong anchoring effect of the metallic material within the etching pores. The successful synthesis of bimetallic Pt–Co particles embedded inside the caverns can facilitate a study of their magnetic properties. The presence of Pt–Co in specific diamond compositions can also be used for marking diamond crystals as a means for their subtle identification, as well as confirming the possibility of capturing significant amounts of metal along with diamonds during their dissolution in the deep Earth.

В результате совместной кристаллизации водных растворов [Pt(NH3)4](NO3)2 и [Pd(NH3)4](NO3)2 с аммиачным раствором (NH4)2CrO4 получен однофазный твердый раствор [(Pt(NH3)4)x(Pd(NH3)4)1-x]CrO4 (x от 0.5 до 0.6). По результатам исследования отдельного монокристалла методом рентгеноструктурного анализа определены структура и параметры его тетрагональной (I41/amd, Z = 4) элементарной ячейки: a = 7.3091(1), c = 15.2720(6) Å и мольная доля Pt (x ≈ 0.568(7)). ПЭЯ исследуемого кристалла были дополнительно уточнены с использованием оригинальной методики (a = 7.3207(9), c = 15.2527(19) Å, V = 817.4(3) Å3), что в дальнейшем позволило уточнить также мольную долю Pt с использованием правила Зена (x = 0.57(1)). Термическое разложение монокристалла [(Pt(NH3)4)0.57(Pd(NH3)4)0.43]CrO4 и двух образцов, отобранных из общей массы синтезированного продукта проведено в токе водорода. Методами рентгенографического исследования продуктов термолиза ex situ, а также сканирующей и просвечивающей электронной микроскопии, показано образование наносплава Pt0.49Pd0.38Cr0.13, включенного в виде блоков (~1 мкм) и более мелких (от 2 нм) шаровых образований в матрицу Cr2O3.

Уважаемые коллеги!Благодарим Вас за проявленный интерес к Четвертой российской конференции «Графен: молекула и 2D кристалл» и желание принять участие в её работе.Конференция проходит в научно-образовательном центре города Новосибирска -Академгородке.Мероприятие посвящено актуальным направлениям исследований и разработок в области углеродных и низкоразмерных материалов.Проведение конференции поможет координации усилий ученых в решении современных проблем материаловедения и привлечению молодых исследователей для решения актуальных научных задач.Оргкомитет выражает особую благодарность НГУ, Центру компетенций НТИ «Моделирование и разработка новых функциональных материалов с заданными свойствами», компаниям «Диаэм», «НТ-МДТ Спектрум Инструментс» и корпорации "Графеновая Долина" за финансовую поддержку и журналам Аналитика, Наноиндустрия и РЭНСИТ за информационную поддержку.Искренне надеемся, что пребывание в Новосибирском Академгородке и в стенах Новосибирского государственного университета оставит множество положительных эмоций и

Министерство науки и высшего образования Российской Федерации Российская академия наук Научный совет по неорганической химии РАН Научный совет по аналитической химии РАН Научный совет по химической технологии РАН Российское химическое общество имени Д.И