Difference in reaction mechanism between ZnZrOx and InZrOx for CO2 hydrogenation

Oxide solid-solution catalysts, such as Zn-doped ZrO2 (ZnZrOx) and In-doped ZrO2 (InZrOx), exhibit distinctive catalytic capabilities for CH3OH synthesis via CO2 hydrogenation. We investigated the active site structures of these catalysts and their associated reaction mechanisms using both experimental and computational approaches. Electron microscopy and X-ray absorption spectroscopy reveal that the primary active sites are isolated cations, such as Zn2+ and In3+, dissolved in tetragonal ZrO2. Notably, for Zn2+, decomposition of the methoxy group, which is an essential intermediate in CH4 synthesis, is partially suppressed because of the relatively high stability of the methoxy group. Conversely, the methyl group strongly adsorbs on In3+, facilitating the conversion of the methoxy species into methyl groups. The decomposition of CH3OH is also suggested to contribute to CH4 synthesis. These results highlight the generation of CH4 as a byproduct of the InZrOx catalyst. Understanding the active site structure and elucidating the reaction mechanism at the atomic level are anticipated to contribute significantly to the future development of oxide solid-solution catalysts.

Potential-Rate Correlations of Supported Palladium-Based Catalysts for Aqueous Formic Acid Dehydrogenation

Aqueous formic acid dehydrogenation (FAD) is a crucial process for hydrogen production, as hydrogen is a clean energy carrier. During this process, formic acid converts into hydrogen and carbon dioxide over a catalyst. Pd-based catalysts have exhibited significant potential in FAD due to their high activity and selectivity. In this study, we investigated aqueous thermal FAD in a mixture of formic acid and sodium formate using electrochemical open-circuit potential (OCP) measurement by loading the catalysts onto a conductive substrate as a working electrode. By varying the reaction conditions such as the concentration of reactants and modifying Pd with Ag, different FAD rates were obtained. Consequently, we revealed the correlation between the catalyst OCP and FAD rate; superior FAD rates reflected a more negative catalyst OCP. Furthermore, deactivation was observed across all catalysts during FAD, with a concurrent increase in catalyst OCP. Interestingly, we found that the logarithm of the FAD rate showed a linear correlation with the OCP of the catalyst during the decay phase, which we quantitatively explained based on the reaction mechanism. This study presents a new discovery that bridges thermal and electrocatalysis.

Supported Noble Metal Catalysts and Adsorbents with Soft Lewis Acid Functions

Heterogeneous noble metal catalysts exhibit various functions. Although their redox functions have been extensively studied, we focused on their soft Lewis acid functions. Supported Au, Pt, and Pd catalysts electrophilically attack the π-electrons of soft bases such as alkynes, alkenes, and aromatic compounds to perform addition and substitution reactions. Hydroamination, intramolecular cyclization of alkynyl carboxylic acids, isomerization of allylic esters, vinyl exchange reactions, Wacker oxidation, and oxidative homocoupling of aromatics are introduced based on a discussion of the active species and reaction mechanisms. Furthermore, the adsorption of sulfur compounds, which are soft bases, onto the supported AuNPs is discussed. The adsorption and removal of 1,3-dimethyltrisulfane (DMTS), which is the compound responsible for the stale odor of "hine-ka" in alcoholic beverages, particularly Japanese sake, is described.

Low-Temperature Hydrogenation of CO2 to Methanol in Water on ZnO-Supported CuAu Nanoalloys

Optimizing processes and materials for the valorization of CO2 to hydrogen carriers or platform chemicals is a key step for mitigating global warming and for the sustainable use of renewables. We report here on the hydrogenation of CO2 in water on ZnO-supported CuAu nanoalloys, based on ≤7 mol % Au. Cux Auy /ZnO catalysts were characterized using 197 Au Mössbauer, in situ X-ray absorption (Au LIII - and Cu K-edges), and ambient pressure X-ray photoelectron (APXP) spectroscopic methods together with X-ray diffraction and high-resolution electron microscopy. At 200 °C, the conversion of CO2 showed a significant increase by 34 times (from 0.1 to 3.4 %) upon increasing Cu93 Au7 loading from 1 to 10 wt %, while maintaining methanol selectivity at 100 %. Limited CO selectivity (4-6 %) was observed upon increasing temperature up to 240 °C but associated with a ≈3-fold increase in CO2 conversion. Based on APXPS during CO2 hydrogenation in an H2 O-rich mixture, Cu segregates preferentially to the surface in a mainly metallic state, while slightly charged Au submerges deeper into the subsurface region. These results and detailed structural analyses are topics of the present contribution.

Growth mechanisms and anisotropic softness-dependent conductivity of orientation-controllable metal-organic framework nanofilms

Conductive metal-organic frameworks (cMOFs) manifest great potential in modern electrical devices due to their porous nature and the ability to conduct charges in a regular network. cMOFs applied in electrical devices normally hybridize with other materials, especially a substrate. Therefore, the precise control of the interface between cMOF and a substrate is particularly crucial. However, the unexplored interface chemistry of cMOFs makes the controlled synthesis and advanced characterization of high-quality thin films, particularly challenging. Herein, we report the development of a simplified synthesis method to grow "face-on" and "edge-on" cMOF nanofilms on substrates, and the establishment of operando characterization methodology using atomic force microscopy and X-ray, thereby demonstrating the relationship between the soft structure of surface-mounted oriented networks and their characteristic conductive functions. As a result, crystallinity of cMOF nanofilms with a thickness down to a few nanometers is obtained, the possible growth mechanisms are proposed, and the interesting anisotropic softness-dependent conducting properties (over 2 orders of magnitude change) of the cMOF are also illustrated.

Integrated Soft Porosity and Electrical Properties of Conductive-on-Insulating Metal-Organic Framework Nanocrystals

A one-stone, two-bird method to integrate the soft porosity and electrical properties of distinct metal-organic frameworks (MOFs) into a single material involves the design of conductive-on-insulating MOF (cMOF-on-iMOF) heterostructures that allow for direct electrical control. Herein, we report the synthesis of cMOF-on-iMOF heterostructures using a seeded layer-by-layer method, in which the sorptive iMOF core is combined with chemiresistive cMOF shells. The resulting cMOF-on-iMOF heterostructures exhibit enhanced selective sorption of CO2 compared to the pristine iMOF (298 K, 1 bar, SCO 2 / H 2 ${{_{{\rm CO}{_{2}}/{\rm H}{_{2}}}}}$ from 15.4 of ZIF-7 to 43.2-152.8). This enhancement is attributed to the porous interface formed by the hybridization of both frameworks at the molecular level. Furthermore, owing to the flexible structure of the iMOF core, the cMOF-on-iMOF heterostructures with semiconductive soft porous interfaces demonstrated high flexibility in sensing and electrical "shape memory" toward acetone and CO2 . This behavior was observed through the guest-induced structural changes of the iMOF core, as revealed by the operando synchrotron grazing incidence wide-angle X-ray scattering measurements.

Effects of Codoping on Site-Dependent Eu3+ Luminescence in Perovskite-Type Calcium Zirconate and Hafnate

The single doping of Eu³⁺ and codoping with Ga³⁺ or La³⁺ into perovskite (ABO₃)-type CaZrO₃ and CaHfO₃ were carried out to investigate the effect of codoping on the photoluminescence (PL) features of Eu³⁺, attempting the site-selective Eu³⁺ doping at either A or B sites. To comprehend the Eu³⁺ PL features, the accurate locations of Eu³⁺ were examined by X-ray absorption near edge structure (XANES) and the proportions of Eu³⁺ located at A or B sites (Eu³⁺(A) or Eu³⁺(B); Eu_Ca^• or Eu_Zr^'/Eu_Hf^') were analyzed. No considerable differences in the XANES spectra and in the proportions of Eu³⁺(A) and Eu³⁺(B) were observed in the single-doped samples. On the other hand, the shape of the XANES spectra and the Eu³⁺ proportion markedly differed in the codoped samples. Ga³⁺ codoping (Ga_Zr^'/Ga_Hf^') achieved Eu³⁺(A) proportions of more than 90%, and La³⁺ codoping (La_Ca^•) resulted in the largest Eu³⁺(B) proportions of approximately 40%. In both PL and PL excitation spectra, the site-dependent spectral features were changed depending on the proportion of Eu³⁺(A) and Eu³⁺(B), especially the PL peaks at 595 nm were intensified most in the La³⁺ codoped samples. Consequently, the site-dependent Eu³⁺ PL features in CZO and CHO were found to become more conspicuous by the effect of Ga³⁺ or La³⁺ codoping. The results also revealed that the codoped ions work not only to compensate for the charge of aliovalent Eu³⁺ but also to drive Eu³⁺ to the intentional doping sites.

Effects of the Pt Shell Thickness on the Oxygen Reduction Reaction on a Well-Defined Pd@Pt Core-Shell Model Surface

The effect of the Pt shell thickness on the oxygen reduction reaction (ORR) of a Pd@Pt core-shell catalyst was studied using surface science technics and computational approaches. We found Pt shells on Pd rods to be negatively charged because of charge transfer from the Pd substrate when the shell thicknesses were 0.5 or 1 monolayer (ML). The activities of the ORR of the model surface with a Pt shell of 0.5 or 1 ML were similar and more than twice the activities of a Pt/C or Pt rod. The relationship between the ORR activity and the thickness of the Pt shell was the exact opposite of the relationship between the Pt binding energy and the Pt shell thickness. The indication was that more negatively charged Pt had higher ORR activity. Density functional theory calculations confirmed that a single layer of Pt atoms located on Pd was negatively charged compared to pure Pt and resulted in a lower barrier to the rate-limiting step of the ORR.

Catalysis of surface dispersed Cu2+ species on t-ZrO2: Square-planar Cu catalyzed cross-coupling of arylboronic acid and imidazole

We examined the Chan-Lam cross-coupling of imidazole and arylboronic acids under additive-free and mild conditions using heterogeneous CuO/MOX catalysts such as metal oxide-supported CuO and Cu-doped metal oxides. Among them,...

The Pitfall of VA ECMO management in the Impella era

Introduction

VA ECMO is effective in cardiogenic shock, but complications of cardiogenic pulmonary edema due to increased afterload are problematic. The advent of percutaneous left ventricular assist devices (Impella) has enabled effective reduction of left ventricular intraventricular pressure and has avoided these complications, but differential hypoxia can still occur during VA ECMO + Impella (Ecpella) management, requiring conversion to V-AV ECMO. Cases may be experienced.

Purpose

Elucidate the frequency of differential hypoxia and its pathogenesis, which requires the transition from VA ECMO to V-AV ECMO.

Methods

We retrospectively reviewed 52 consecutive patients who underwent E-CPR from January 2017 through November 2021 in our institute. 8 patients who received ECMO alone were excluded, and 44 patients were recruited. 22 patients underwent VA ECMO with IABP (VA ECMO + IABP group) and 22 patients underwent VA ECMO with Impella (VA ECMO + Impella group). The 30-day survival rate and the rate of transition VA ECMO to VA-V ECMO, The date just before VA ECMO to V-AV ECMO were assessed.

Results

The 30-day all-cause mortality was no significant difference between the two groups. 2 patients (9%) in the VA ECMO + IABP group and 8 patients (36%) in the VA ECMO + Impella group were transferred to V-AV ECMO (P=0.025). At the time of addition of V-AV ECMO, SaO2 (right radial artery) was 87±7.1% and 91.3±1.9% (p=0.112) in the VA ECMO + IABP and VA ECMO + Impella groups, respectively, and the P/F ratio was 86±37.1 and 95±24.6 (p=0.685). Mean pulmonary artery wedge pressure was 23±1.4 mmHg in the VA ECMO + IABP group and 16.3±3 mmHg in the VA ECMO + Impella group (p=0.0193), significantly lower in the Impella group.

Conclusion

The Impella group was more likely to have hypoxia due to factors other than cardiogenic pulmonary edema. In cases of cardiopulmonary arrest requiring V-AV ECMO management, differential hypoxia due to causes other than cardiogenic pulmonary edema may become apparent earlier in the Impella group, suggesting that careful management, including the addition of V-AV ECMO, is required.

Funding Acknowledgement

Type of funding sources: None.

Anchored Palladium Complex-Generated Clusters on Zirconia: Efficiency in Reductive N-Alkylation of Amines with Carbonyl Compounds under Hydrogen Atmosphere

Carbon-nitrogen bond formation is an important method on both laboratory and industrial scales because it realizes the production of valuable pharmaceuticals, agrochemicals, and fine chemicals. Direct reductive N-alkylation of amines with carbonyl compounds via intermediary imine compounds, especially under catalytic hydrogenation conditions, is one of the most convenient, economical, and environmentally friendly methods for this process. Here we report a novel palladium species on zirconia having specific activity towards hydrogenation of imines but other carbonyl groups remaining intact. The present catalytic property offers a practical synthetic method of functionalized secondary amines by reductive N-alkylation under mild conditions with high atom-efficiency. Mechanistic studies revealed that the catalytically active species is the palladium cluster, which is generated in situ from molecular palladium complexes on the support by exposure to atmospheric hydrogen. These fundamental findings are expected to progress in developing novel cluster catalysts for chemical processes directed towards a sustainable society.

Catalytic Selective Hydrogenation of Acetic Acid to Acetaldehyde over the Surface of Iron Shell on the Pd-Fe Alloy Nanoparticle

Since hydrogenation of acetic acid readily leads to ethanol formation, it is challenging to selectively obtain acetaldehyde in a high yield. The present study demonstrates the highly-selective synthesis of acetaldehyde...

Preparation of a platinum nanoparticle catalyst located near photocatalyst titanium oxide and its catalytic activity to convert benzyl alcohols to the corresponding ethers

A novel platinum nanoparticle catalyst closely located near the surface of titanium oxide, PtNP/TiO₂, has been prepared. This catalyst has both the properties of a photocatalyst and a metal nanoparticle catalyst, and acquired environmentally friendly catalytic activity, which cannot be achieved by just one of these catalysts, to afford ethers from benzyl alcohols under the wavelength of 420 nm.

A novel platinum nanoparticle catalyst closely located near the surface of titanium oxide, PtNP/TiO₂, has been prepared. It has catalytic activity to afford ethers from benzyl alcohols under the wavelength of 420 nm.

Crystalline to amorphous transformation in solid-solution alloy nanoparticles induced by boron doping

We synthesized a palladium-ruthenium-boron (Pd-Ru-B) solid-solution ternary alloy. Elemental mappings confirmed successful alloying of B with Pd-Ru body without changing the particle sizes, demonstrating the first discovery of this ternary alloy. Pair distribution function analysis revealed a drastic decrease in atomic correlation in Pd-Ru nanoparticles by B doping. This result gives the first example of structural transformation from crystalline to amorphous in solid-solution alloy nanoparticles induced by the doping of light elements.

Optically Transparent Colloidal Dispersion of Titania Nanoparticles Storable for Longer than One Year Prepared by Sol/Gel Progressive Hydrolysis/Condensation

The molecular catalyst sensitized system (MCSS), where an excited molecular catalyst adsorbed on a semiconductor such as TiO₂ injects electrons to the conduction band of the semiconductor leading to hydrogen evolution/CO₂ reduction coupled with an oxidation of water on the molecular catalyst, has been one of the most probable candidates in the approach to artificial photosynthesis. For a full utilization of visible light, however, a serious light scattering of the aqueous suspension of TiO₂ in the visible region, which is generally experienced, should be avoided. Here, we report a preparation of optically transparent colloidal dispersion of TiO₂ by the sol/gel reaction of TiCl₄ through progressive hydrolysis/condensation under the basic condition without any calcination processes. The TiO₂ nanoparticles (TiO₂(NPs)) obtained were characterized as an amorphous particle (∼10-15 nm) having a microcrystal domain of anatase within several nm by XRD, Raman spectroscopies, XRF, XAFS, TG/DTA, and HRTEM, respectively. The energy-resolved distribution of carrier electron traps in TiO₂(NPs) as a fingerprint of TiO₂ was characterized through reversed double-beam photo-acoustic spectroscopy to have a close similarity to that of TiO₂(ST-01) as well as the observation of carrier traps by transient absorption spectroscopy. Though the powder TiO₂(NP) itself was not dispersed well in aqueous solution, the wet TiO₂(NPs) as prepared before being dried up provided a completely transparent aqueous dispersion under the acidic condition (1 M HCl). Addition of methanol enabled the colloidal dispersion (TiO₂(NPs, MeOH/H₂O, 0.1 M HCl)) to keep the optical transparency for longer than 1 year (550 days), which is the first example of TiO₂ dispersion storable for such a long period. TiO₂(NPs, MeOH/H₂O) exhibited a moderate photocatalytic reactivity of H₂ evolution with a quantum yield of ∼2.6% upon 365 nm light irradiation. An optically transparent thin film of TiO₂(NPs, MeOH/H₂O) was also successfully prepared on a glass plate to exhibit an enhanced hydrophilicity upon UV light irradiation.

Self-Assembled Multilayer Iron(0) Nanoparticle Catalyst for Ligand-Free Carbon-Carbon/Carbon-Nitrogen Bond-Forming Reactions

Self-assembled multilayer iron(0) nanoparticles (NPs, 6-10 nm), namely, sulfur-modified Au-supported Fe(0) [SAFe(0)], were developed for ligand-free one-pot carbon-carbon/carbon-nitrogen bond-forming reactions. SAFe(0) was successfully prepared using a well-established metal-nanoparticle catalyst preparative protocol by simultaneous in situ metal NP and nanospace organization (PSSO) with 1,4-bis(trimethylsilyl)-1,4-dihydropyrazine (Si-DHP) as a strong reducing agent. SAFe(0) was easy to handle in air and could be recycled with a low iron-leaching rate in reaction cycles.

Competing Roles of Two Kinds of Ligand during Nonclassical Crystallization of Pillared-Layer Metal-Organic Frameworks Elucidated Using Microfluidic Systems

To diversify metal-organic frameworks (MOFs), multi-component MOFs constructed from more than two kinds of bridging ligand have been actively investigated due to the high degree of design freedom afforded by the combination of multiple ligands. Predicting the synthesis conditions for such MOFs requires an understanding of the crystallization mechanism, which has so far remained elusive. In this context, microflow systems are efficient tools for capturing non-equilibrium states as they facilitate precise and efficient mixing with reaction times that correspond to the distance from the mixing point, thus enabling reliable control of non-equilibrium crystallization processes. Herein, we prepared coordination polymers with pillared-layer structures and observed the intermediates in the syntheses with an in-situ measurement system that combines microflow reaction with UV/Vis and X-ray absorption fine-structure spectroscopies, thereby enabling their rapid nucleation to be monitored. Based on the results, a three-step nonclassical nucleation mechanism involving two kinds of intermediate is proposed.

Impact of technically qualified surgeons on laparoscopic colorectal resection outcomes: results of a propensity score-matching analysis

Background

The Endoscopic Surgical Skill Qualification System (ESSQS) was introduced in Japan to improve the quality of laparoscopic surgery. This cohort study investigated the short‐ and long‐term postoperative outcomes of colorectal cancer laparoscopic procedures performed by or with qualified surgeons compared with outcomes for unqualified surgeons.

Methods

All laparoscopic colorectal resections performed from 2010 to 2013 in 11 Japanese hospitals were reviewed retrospectively. The procedures were categorized as performed by surgeons with or without the ESSQS qualification and patients' clinical, pathological and surgical features were used to match subgroups using propensity scoring. Outcome measures included postoperative and long‐term results.

Results

Overall, 1428 procedures were analysed; 586 procedures were performed with ESSQS‐qualified surgeons and 842 were done by ESSQS‐unqualified surgeons. Upon matching, two cohorts of 426 patients were selected for comparison of short‐term results. A prevalence of rectal resection (50·3 versus 40·5 per cent; P < 0·001) and shorter duration of surgery (230 versus 238 min; P = 0·045) was reported for the ESSQS group. Intraoperative and postoperative complication and reoperation rates were significantly lower in the ESSQS group than in the non‐ESSQS group (1·2 versus 3·6 per cent, P = 0·014; 4·6 versus 7·5 per cent, P = 0·025; 1·9 versus 3·9 per cent, P = 0·023, respectively). These findings were confirmed after propensity score matching. Cox regression analysis found that non‐attendance of ESSQS‐qualified surgeons (hazard ratio 12·30, 95 per cent c.i. 1·28 to 119·10; P = 0·038) was independently associated with local recurrence in patients with stage II disease.

Conclusion

Laparoscopic colorectal procedures performed with ESSQS‐qualified surgeons showed improved postoperative results. Further studies are needed to investigate the impact of the qualification on long‐term oncological outcomes.

Ru nanoparticles supported on amorphous ZrO2 for CO2 methanation

The influence of support materials and preparation methods on CO₂ methanation activity was investigated using Ru nanoparticles supported on amorphous ZrO₂ (am-ZrO₂), crystalline ZrO₂ (cr-ZrO₂), and SiO₂.

A new and practical Se(IV) removal method using Fe3+ type cation exchange resin

An effective method for removing selenium (Se) from water is required from the viewpoint of environmental preservation. To establish this method, a cation exchange resin that adsorbed ferric ions was applied as an adsorbent. In this study, the adsorption behavior of Se to the adsorbent was examined by both batch and column methods. The batch experiment confirmed that selenite ions (Se(IV)) are effectively adsorbed but selenate ions (Se(VI)) are hardly adsorbed. To elucidate the adsorption mechanism, the Fe in the adsorbent and the Fe in the adsorbent after the adsorption of Se(IV) were characterized by Fe K-edge X-ray absorption spectroscopy and ⁵⁷Fe Mӧssbauer spectroscopy. The analytical result of Se K-edge EXAFS spectra for the Se(IV) adsorbed on the adsorbent suggests that Se(IV) are adsorbed specifically to the adsorbent through the formation of Fe-O-Se bonds. The breakthrough curve obtained by the column experiment showed that Se(IV) in 3 tons of synthetic solution containing 0.1 ppm Se can be efficiently removed using a column in which 12.8 g (10.4 cm³) of the adsorbent was packed.

Site-Selective Doping and Site-Sensitive Photoluminescence of Eu3+ and Tb3+ in Perovskite-Type LaLuO3

Eu³⁺ and Tb³⁺ ions were site-selectively doped into LaLuO₃ with the orthorhombic perovskite-type structure (ABO₃), and their luminescence properties were examined considering the doping sites (A or B sites). The X-ray diffraction analysis revealed the expansion or contraction of the unit cell volumes of the materials depending on the doping sites. The spectra of X-ray absorption near edge structure for the Eu and Tb L_III edge exhibited different shapes for the ions at A and B sites, confirming the site-selective doping of Eu³⁺ and Tb³⁺ in LaLuO₃. The photoluminescence (PL) and PL excitation (PLE) spectra of the materials also showed some differences caused by the doping sites. The intensities of the Eu³⁺ PL peaks derived from the ⁵D₀-⁷F₁ transitions and those from the ⁵D₀-⁷F₂ transitions were markedly different between Eu³⁺ at A sites and those at B sites because of the different site symmetries. The splitting of the intense Tb³⁺ PL peaks originating from the ⁵D₄-⁷F₅ transitions and the absence of PL peaks from ⁵D₃-⁷F_J transitions were found only for Tb³⁺ at B sites because of the strong crystal field at B sites. In addition to the PL spectra, the positions of PLE peaks originating from charge transfer transitions in Eu³⁺ and the 4f-5d transitions in Tb³⁺ depended on the doping sites. The successful site-selective doping enabled us to clarify the site-sensitive luminescence properties of Eu³⁺ and Tb³⁺ doped in the perovskite-type LaLuO₃.

Solid-solution alloy nanoparticles of a combination of immiscible Au and Ru with a large gap of reduction potential and their enhanced oxygen evolution reaction performance

Au and Ru are elements that are immiscible in the bulk state and have the largest gap in reduction potential among noble metals. Here, for the first time, Au x Ru1-x solid-solution alloy nanoparticles (NPs) were successfully synthesized over the whole composition range through a chemical reduction method. Powder X-ray diffraction and scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy showed that Au and Ru atoms are homogeneously mixed at the atomic level. We investigated the catalytic performance of Au x Ru1-x NPs for the oxygen evolution reaction, for which Ru is well known to be one of the best monometallic catalysts, and we found that even alloying with a small amount of Au could significantly enhance the catalytic performance.

Wacker Oxidation of Terminal Alkenes Over ZrO2 -Supported Pd Nanoparticles Under Acid- and Cocatalyst-Free Conditions

Highly efficient Wacker oxidation of aromatic or aliphatic terminal alkenes into methyl ketones and benzofurans is developed by using reusable Pd⁰ nanoparticles (NPs) supported on ZrO₂ under acid- and cocatalyst-free conditions. Molecular oxygen or air can be utilized as the terminal oxidant, which results in the formation of H₂ O as the only theoretical byproduct. The activation of the Pd NPs by O₂ plays an important role in promoting this reaction. Interestingly, PdO supported on ZrO₂ showed no activity. Additionally, the Pd particle size significantly affects the catalytic activity, with an apparent optimal diameter of 4-12 nm. In addition to the heterogeneous catalyst forms, the Pd NPs can be generated from a Pd⁰ complex during the reaction, and these particles are even recyclable.

Transition and post-transition metal ions in borate glasses: Borate ligand speciation, cluster formation, and their effect on glass transition and mechanical properties

A series of transition and post-transition metal ion (Mn, Cu, Zn, Pb, Bi) binary borate glasses was studied with special consideration of the cations impact on the borate structure, the cations cross-linking capacity, and more generally, structure-property correlations. Infrared (IR) and Raman spectroscopies were used for the structural characterization. These complementary techniques are sensitive to the short-range order as in the differentiation of tetrahedral and trigonal borate units or regarding the number of non-bridging oxygen ions per unit. Moreover, vibrational spectroscopy is also sensitive to the intermediate-range order and to the presence of superstructural units, such as rings and chains, or the combination of rings. In order to clarify band assignments for the various borate entities, examples are given from pure vitreous B₂O₃ to meta-, pyro-, ortho-, and even overmodified borate glass compositions. For binary metaborate glasses, the impact of the modifier cation on the borate speciation is shown. High field strength cations such as Zn²⁺ enhance the disproportionation of metaborate to polyborate and pyroborate units. Pb²⁺ and Bi³⁺ induce cluster formation, resulting in PbO_n- and BiO_n-pseudophases. Both lead and bismuth borate glasses show also a tendency to stabilize very large superstructural units in the form of diborate polyanions. Far-IR spectra reflect on the bonding states of modifier cations in glasses. The frequency of the measured cation-site vibration band was used to obtain the average force constant for the metal-oxygen bonding, F_M-O. A linear correlation between glass transition temperature (T_g) and F_M-O was shown for the metaborate glass series. The mechanical properties of the glasses also correlate with the force constant F_M-O, though for cations of similar force constant the fraction of tetrahedral borate units (N₄) strongly affects the thermal and mechanical properties. For paramagnetic Cu- and Mn-borate glasses, N₄ was determined from the IR spectra after deducing the relative absorption coefficient of boron tetrahedral versus boron trigonal units, α = α₄/α₃, using NMR literature data of the diamagnetic glasses.

Remarkable enhancement of Fe–V–Ox composite metal oxide to gold catalyst for CO oxidation in the simulated atmosphere of CO2 laser

A novel Au/Fe–V–Ox/Al₂O₃ displays remarkable activity and good stability for CO oxidation in simulated atmosphere of CO₂ laser. The higher Au dispersion and more labile lattice oxygen after modification contributed to its outstanding performance.

Efficient Decarbonylation of Furfural to Furan Catalyzed by Zirconia-Supported Palladium Clusters with Low Atomicity

Decarbonylation of furfural to furan was efficiently catalyzed by ZrO₂ -supported Pd clusters in the liquid phase under a N₂ atmosphere without additives. Although Pd/C and Pd/Al₂ O₃ have frequently been used for decarbonylation, Pd/ZrO₂ exhibited superior catalytic performance compared with these conventional catalysts. Transmission electron microscopy and X-ray absorption fine structure measurements revealed that the size of the Pd particles decreased with an increase in the specific surface area of ZrO₂ . ZrO₂ with a high surface area immobilized Pd as clusters consisting of several (three to five) Pd atoms, whereas Pd aggregated to form nanoparticles on other supports such as carbon and Al₂ O₃ despite their high surface areas. The catalytic activity of Pd/ZrO₂ was enhanced with a decrease in particle size, and the smallest Pd/ZrO₂ was the most active catalyst for decarbonylation. When CeO₂ was used as the support, a decrease in Pd particle size with an increase in surface area was also observed. Single Pd atoms were deposited on CeO₂ with a high surface area, with a strong interaction through the formation of a Pd-O-Ce bond, which led to a lower catalytic activity than that of Pd/ZrO₂ . This result suggests that zero-valent small Pd clusters consisting of more than one Pd atom are the active species for the decarbonylation reaction. Recycling tests proved that Pd/ZrO₂ maintained its catalytic activity until its sixth use.