| Catalytic oxidation is a broad class of important chemical reactions in the chemical industry,and more than 50% of the chemical is associated with oxidation reactions.The raw materials include some oxygenated and non-oxygenated compounds,which are converted into acids,ketones,epoxides,etc.by a certain temperature,pressure and catalyst.This in turn includes complete and partial oxidation,of which the core is the development of high-performance catalysts.For catalytic oxidation reactions,there are already many guiding principles for the design of catalytic materials,such as regulating the behavior of oxygen by constructing oxygen vacancies,carefully controlling the size of the catalyst to achieve a certain percentage of atoms in the outer,low-matching layers,or adding additional electrical,optical,and force effects to the system to accelerate the movement and utilization of electrons.The progressive optimization and development of characterization methods are essential to provide improved guidance in the design of catalysts.Cataluminescence(CTL)is a catalytic oxidation reflection of reaction molecules on the catalyst surface,accompanied by light emission from the intermediate excited state back to the ground state.CTL has a very sensitive response to the catalyst properties and can be operated easily,and has been utilized in many aspects of catalyst characterization,with great promise for its application in the catalytic oxidation process.The main goal of this thesis is to construct efficient luminescence systems through oxygen vacancy introduction,modification of the coordination environment and recycling of energy,to explore the relationship between catalyst structure and performance in amplified CTL,and to establish a series of new methods for the characterization of CTL.1.Rapid Discrimination of Adsorbed Oxygen and Lattice Oxygen in Catalysts by Cataluminescence Method.Adsorbed oxygen and lattice oxygen are crucial parameters for catalyst characterization and catalytic oxidation mechanism.Therefore,rapid discrimination of adsorbed oxygen and lattice oxygen is highly desired.Herein,a direct correlation between CTL kinetic curve and oxygen species was discovered.The adsorbed oxygen-catalyzed CTL only lasted for a few minutes,while the lattice oxygen-catalyzed CTL could exhibit hours of continuous luminescence.The long-term CTL was attributed to the fact that the slow migration of lattice oxygen in a slow and continuous catalytic oxidation reaction.In addition to the discrimination between adsorbed oxygen and lattice oxygen by CTL kinetic processes,the corresponding CTL intensity was positively proportional to their amounts.Accordingly,the developed catalytic oxidation-related CTL can be used as an indicator for rapid discrimination and determination of adsorbed oxygen and lattice oxygen in catalysts.Oxygen species detected by the proposed CTL method not only matched well with those obtained by conventional X-ray photoelectron spectroscopy and O2-temperature programmed methods,but also appeared some distinguished advantages,such as convenient operation,fast response,and low cost.It can be expected that the established oxygen-responsive CTL probe has a great potential in distinguishing adsorbed oxygen and lattice oxygen in various catalysts.2.Rapid Determination of Coordination Number of Single-Atom Catalysts by Cataluminescence Based on D Band Centers.The coordination number of single atoms is an important indicator of the surrounding environment and plays a key role in catalytic activity and selectivity.However,current methods for the characterization of the coordination of single atoms rely heavily on synchrotron X-ray absorption spectroscopy and M(?)ssbauer spectroscopy(MS)methods.Here,it was found that the CTL signal during the catalytic oxidation of volatile organic compounds(VOCs)by single-atom Pt shows a correlation with the coordination environment around Pt single atoms.Acetone,ethanol and acetonitrile molecules all acted as probe molecules,and the CTL on the surface of Pt single atoms increases with the number of Pt-O coordination.DFT calculations show that the increase in the number of O coordination leads to an enhanced positive charge of Pt,and the adsorption of acetone at Pt sites become easy.The center of the 5d orbital of Pt was calculated and as the number of Pt-O coordination changed from 3 to 5,the center of the d-band gradually shifted downward,reducing the intensity of adsorption on the intermediate,so the proper affinity makes the intermediate easy to resolve and facilitates the catalytic oxidation kinetics.This method has the features of simple operation,low sample requirement,and short cycle time,which can reduce the dependence on existing analytical methods and give a rapid screening method in the synthesis stage of single-atom catalysts.3.Band Gap Matching-Triggered Self-Sustaining Photocatalytic Oxidation.The exploration of novel photocatalytic systems with inner light source and less energy consumption is desirable to further extend the application of photocatalytic oxidation technique.An intelligent route is to achieve energy cycling between light source and photocatalytic oxidation process.However,conventional photocatalytic systems cannot produce light emission,which restricts the energy cycling.In this study,it is found that the involvement of CTL greatly enhances the photocatalytic oxidation efficiency with hetero-structured catalyst comprised from Co(OH)2 and zeolitic imidazolate frameworks-67(ZIF-67),denoted as Co(OH)2@ZIF-67.The mechanism investigation reveals that the band gap matching between CTL emission and absorption of catalyst benefits the energy cycling and facilitates the charge carrier separation/transport,resulting in acceleration of CTL reaction.The universality of this strategy was further verified CTL screening with ZIF-8 and Fe O(OH)catalysts.Our study has opened a new avenue for exploring effective photocatalytic systems through band gap matching-induced energy cycling toward various applications in sensing,organic synthesis,pollutant degradation,and even water-splitting,etc. |
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