Operando Mössbauer Spectroscopic Tracking the Metastable State of Atomically Dispersed Tin in Copper Oxide for Selective CO2 Electroreduction.

Metastable state is the most active catalyst state that dictates the overall catalytic performance and rules of catalytic behaviors; however, identification and stabilization of the metastable state of catalyst are still highly challenging due to the continuous evolution of catalytic sites during the reaction process. In this work, operando 119Sn Mössbauer measurements and theoretical simulations were performed to track and identify the metastable state of single-atom Sn in copper oxide (Sn1-CuO) for highly selective CO2 electroreduction to CO. A maximum CO Faradaic efficiency of around 98% at -0.8 V (vs. RHE) over Sn1-CuO was achieved at an optimized Sn loading of 5.25 wt. %. Operando Mössbauer spectroscopy clearly identified the dynamic evolution of atomically dispersed Sn4+ sites in the CuO matrix that enabled the in situ transformation of Sn4+-O4-Cu2+ to a metastable state Sn4+-O3-Cu+ under CO2RR conditions. In combination with quasi in situ X-ray photoelectron spectroscopy, operando Raman and attenuated total reflectance surface enhanced infrared absorption spectroscopies, the promoted desorption of *CO over the Sn4+-O3 stabilized adjacent Cu+ site was evidenced. In addition, density functional theory calculations further verified that the in situ construction of Sn4+-O3-Cu+ as the true catalytic site altered the reaction path via modifying the adsorption configuration of the *COOH intermediate, which effectively reduced the reaction free energy required for the hydrogenation of CO2 and the desorption of the *CO, thereby greatly facilitating the CO2-to-CO conversion. This work provides a fundamental insight into the role of single Sn atoms on in situ tuning the electronic structure of Cu-based catalysts, which may pave the way for the development of efficient catalysts for high-selectivity CO2 electroreduction.

A novel Zn-Al spinel-alumina composite supported gold catalyst for efficient CO oxidation.

A spinel-alumina inert oxide supported gold catalyst with high Au dispersion and excellent CO oxidation activity was developed by a deposition-precipitation method. The activation atmosphere could tune the reaction pathway by adjusting the amount of surface adsorbed water species, thus transforming the reaction intermediates from HCO3- or CO32- to COOH.

Efficient Ce-Co composite oxide decorated Au nanoparticles for catalytic oxidation of CO in the simulated atmosphere of a CO2 laser.

Gold nanoparticles have a high activity for CO oxidation, making them suitable to be used in a CO2 laser which maintains its efficiency and stability via the recombination of CO and O2 produced by the CO2 decomposition. However, the high concentration of CO2 in the working environment greatly reduces the activity of the catalyst and makes the already unstable gold nanoparticles even more so. A novel Au/Ce-Co-O x /Al2O3 gold catalyst, prepared by a deposition precipitation method in this study, displays high activity and good stability for CO oxidation in a simulated atmosphere of a CO2 laser with the feed gases containing a high concentration of CO2 up to 60 vol% but a low concentration of O2 for the stoichiometric reaction with CO. An excellent performance for CO oxidation under CO2-rich conditions could be achieved by decorating the surface of the Al2O3 support with Ce-Co composite oxides. The strong interaction between gold and the composite support, accompanied by the increase of labile lattice oxygen species and the decrease of surface basicity, led to a high CO oxidation rate and resistance towards CO2 poisoning.

[Effects of serum of rats with ventilator-induced lung injury on endothelial cell permeability and its mechanism].

OBJECTIVE: To investigate the effects of inflammatory mediators in the serum of rats with ventilator-induced lung injury (VILI) on endothelial cellular cytoskeleton and monolayer cellular permeability and explore the molecular mechanism of VILI-induced lung edema. METHODS: Thirty healthy male SD rats were divided into 3 groups, namely group A with normal tidal volume ventilation, group B with high tidal volume ventilation and group C with high tidal volume ventilation plus ulinastatin treatment. The serum was collected from each rat after ventilation and added into endothelial cell line ECV-304 culture medium, and 2 h later the changes of F-actin and cell permeability were observed. RESULTS: Compared to sera from rats with normal tidal volume ventilation, the sera of rats with high tidal volume ventilation caused obvious reorganization of actin cytoskeleton with weakened fluorescent intensity at the peripheral filament bands and formation of long and thick stress fibers in the center, which resulted in endothelial contraction and increased cell permeability. Pretreatment with ulinastatin could lessen these changes significantly. The percentage in change of permeability coefficient (Ppa%) after stimulation with the sera of rats in groups A, B and C was (6.95+/-1.66)%, (27.50+/-7.77)%, and (17.71+/-4.66)%, respectively, showing statistically significant differences (P<0.05). CONCLUSION: The pro-inflammatory mediators in the serum of rats with high tidal volume ventilation increases endothelial cell permeability by reorganizing actin cytoskeleton, and pretreatment with ulinastatin can lessen the hyperpermeability by inhibiting multiple pro-inflammatory mediators.

Effects of serum of the rats ventilated with high tidal volume on endothelial cell permeability and therapeutic effects of ulinastatin.

BACKGROUND: With the widespread use of ventilators in treating critically ill patients, the morbidity of ventilator-induced lung injury (VILI) is increasing accordingly. VILI is characterized by a considerable increase in microvascular leakiness and activation of inflammatory processes. In this study we investigated the effects of inflammatory mediators in VILI rat serum on endothelial cytoskeleton and monolayer cellular permeability, as well as the therapeutic effect of ulinastatin, to explore the pathogenesis and the relationship between biotrauma and lung oedema induced by VILI. METHODS: Thirty healthy male Sprague-Dawley rats were randomly divided into three groups: group A (normal tidal volume ventilation), group B (high tidal volume ventilation) and group C (high tidal volume ventilation plus ulinastatin). The serum of each rat after ventilation was added to endothelial cell line ECV-304 medium for two hours to observe the effects of serum and/or ulinastatin on endothelial fibrous actin and permeability. RESULTS: Compared to rats ventilated with normal tidal volume, serum of rats ventilated with high tidal volume caused a striking reorganization of actin cytoskeleton with a weakening of fluorescent intensity at the peripheral filament bands and formation of the long and thick stress fibres in the centre resulting in endothelial contraction and higher permeability. Prior treatment with ulinastatin lessened the above changes significantly. The changes of permeability coefficient of endothelial permeability after group A, B or C rats serum stimulation were (6.95 +/- 1.66)%, (27.50 +/- 7.77)% and (17.71 +/- 4.66)% respectively with statistically significant differences (P < 0.05) among the three groups. CONCLUSIONS: The proinflammatory mediators in the serum of the rats given high tidal volume ventilation increases endothelial permeability by reorganizing actin cytoskeleton, and pretreatment with ulinastatin lessens the permeability by inhibiting of proinflammatory mediators.