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Operando XAS and NAP-XPS investigation of CO oxidation on meso- and nanoscale CoO catalysts
摘要： In contrast to Co3O4, CoO has been much less studied for CO oxidation. Herein, the phase changes of commercial mesoscopic CoO (particle size ?1 μm) and nanosized CoO (20–50 nm particle size), the latter prepared by vacuum reduction of commercial Co3O4, were examined by operando X-ray absorption (XAS) and near-ambient pressure X-ray photoemission (NAP-XPS) spectroscopy during CO oxidation, as well as ex situ by transmission electron microscopy and di?raction (TEM/SAED). Commercial mesoscopic CoO exhibited CO oxidation activity at ?200 °C, but even up to 530 °C in pure O2 no substantial (bulk) oxidation was observed by operando XAS, likely due to the large grains and bulk nature of CoO. After pre-oxidation at 400 C, electron di?raction detected thin surface layers of Co3O4. This increased activity but the activity of nanosized Co3O4 of equal surface area was still not reached. For nanosized CoO (surface layers on vacuum-reduced Co3O4), operando NAP-XPS/XAS, acquired during CO oxidation, revealed oxidation of CoO to Co3O4 above 150 °C, yielding the activity of nanosized Co3O4. Evidently, the nanoscale CoO shell on a Co3O4 core with small grains more easily and more completely transformed to Co3O4 than mesoscopic (bulk) CoO with large grains. Our study demonstrates how ?exible and dynamic surfaces of cobalt oxide materials adjust to various reaction environments, which also depends on grain size and morphology (bulk vs. thin layers), illustrating the importance of operando techniques to determine active catalyst phases under reaction conditions.
关键词： CO oxidation,CoO,Co3O4,NAP-XPS,XAS,TEM,Operando
更新于2025-09-23 15:23:52
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Constructing 3D sub-micrometer CoO octahedrons packed with layered MoS2 shell for boosting photocatalytic overall water splitting activity
摘要： A 3D architectures of CoO@MoS2 composite photocatalyst was prepared by coating MoS2 onto the (1 1 1) facts of sub-micrometer CoO octahedrons via a facile solvothermal method. The CoO@MoS2 composites show a significantly improved photocatalytic activity for overall water splitting. At an optimal ratio of 3 wt% MoS2, CoO@MoS2-3% composite can split pure water with the stoichiometric ratio production of H2 and O2 under visible light irradiation, meanwhile, presents the highest H2 production evolution (1.07 μmol/h), which is almost four times than that of pure CoO (0.26 μmol/h). Moreover, the CoO@MoS2 composite still remains good stability after three successive cyclings (over 72 h). The enhanced photocatalytic activity and stability can be attributed that the layered MoS2 shell not only promoted the photo-induced charge transfer at the interface of CoO due to the sufficient contact area between CoO and MoS2, but also protected the exposed the (1 1 1) facts of CoO from devastation. Our work offers more insights into the development of a simple synthesis of well-shaped 3D-based composite photocatalysts towards the energy- and environmental-related applications.
关键词： CoO octahedrons,MoS2,Overall water splitting,Core-shell,Visible light
更新于2025-09-23 15:23:52
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LASERAKUPUNKTUR a?? MODERNE LICHTTHERAPIE IN VERBINDUNG MIT JAHRTAUSENDE ALTER CHINESISCHER MEDIZIN; Laser acupuncture a?? modern light therapy in combination with the treasures of ancient chinese medicine;
摘要： The clinical efficacy of LLLT has been scientifically proven in many randomized controlled studies: wound healing disorders, oral mucositis, stroke, traumatic brain injury, nerve regeneration, age-related macular degeneration and much more. Mitochondrial medicine, laser acupuncture and LLLT combine the treasures of modern physical and physiological methods in a unique way for the benefit of our patients. LLLT means targeted mitochondrial medicine.
关键词： laser,auricular medicine,VAS,chinese medicine,resonance therapy,LLLT,cytochrome C oxidase,laser acupuncture,ROS,Weber meridian massage,COO,RAC,PBM,copper,MMW,NIR,mitochondria,coenzyme Q10
更新于2025-09-23 15:21:01
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BCl3-Activated Synthesis of COO-BODIPY Laser Dyes: General Scope and High Yields under Mild Conditions
摘要： A general and straightforward method for the synthesis of COO-BODIPYs from F-BODIPYs and carboxylic acids is established. The method is based on the use of boron trichloride to activate the involved substitution of fluorine, which leads to high yields through rapid reactions under soft conditions. This mild method opens the way to unprecedented laser dyes with outstanding efficiencies and photostabilities, which are difficult to obtain by the current methods.
关键词： COO-BODIPY,Laser Dyes,Mild Conditions,High Yields,BCl3-Activated Synthesis
更新于2025-09-19 17:13:59
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Controlled ultra-thin oxidation of Graphite promoted by cobalt oxides: influence of the initial 2D CoO wetting layer
摘要： The interaction of CoO with highly oriented pyrolytic graphite (HOPG) was studied using a set of complementary techniques. The morphology of the CoO thin film was determined using atomic force microscopy (AFM), whereas the electronic structure was investigated using x-ray absorption (XAS) and photoemission (PES) spectroscopies. The experimental spectra were analyzed using a configuration interaction CoO6 cluster model calculation. The early stages of growth are characterized by the formation of a CoO wetting layer at the CoO/HOPG interface. The electronic structure of the CoO wetting layer presents a clear 2D character, which is closer to the 2D HOPG substrate than to the 3D CoO bulk. This character of the wetting layer explains the posterior formation of CoO islands and excludes the alternative layer by layer growth mode. Further, the interaction between the CoO wetting layer and the outermost graphite layer favors the oxidation of the HOPG substrate which can be controlled by the thickness of the deposited CoO overlayer.
关键词： x-ray absorption spectroscopies,x-ray photoemission spectroscopies,wetting layers,CoO/HOPG interfaces,HOPG oxidation
更新于2025-09-16 10:30:52