Potassium (K) ion-exchanged ZSM-5 zeolites were investigated for catalytic soot combustion. X-ray absorption fine-structure (XAFS), Raman, in situ IR and NH3-temperature programmed desorption (NH3-TPD) confirmed the location of K+ at the ion-exchanged sites. Temperature-programmed oxidation (TPO) reactions showed that K-ZSM-5 decreased ignition tempeatures of soot combustion and increased selectivity to CO2. The improved activity for soot combustion by increasing K+-exchanged amounts via decreasing the Si/Al ratio reinforced the K+ ions participating in soot combustion. 18O2 isotopic isothermal reactions suggested the activation of gaseous oxygen by the K+ ions. This demonstrated a new appliction of alkali metal exchanged zeolites and the strategy for enhancement of catalytic soot combustion activity.
The development of single-atom catalysts (SACs) has become a rapidly growing research field. It is a critical challenge to understand the interactions between the single-atom metal active sites and the support materials. Recently, original research reports of SACs in biomedical applications have emerged in the literature, yet this topic has seldom been reviewed. Here, this review focuses on the latest advances in single-atom catalysis for biomedical applications and highlights the keys for the design of SACs, such as understanding the interactions between metals and supports and classifying various enzyme-like activities. This review helps bridge the knowledge of multiple disciplines and provides prospects regarding the development of SACs for biomedicine.
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