| Atomic oxygen anion (O-) is a monovalent negative ion through the attachment of an electron to atomic oxygen, which is one of the most active oxygen species. As one of the important chemical intermediates, atomic oxygen anion is potentially useful in many fields such as chemical synthesis, air cleaning and surface sterilization. There have been previous studies on C12A7 and its various derivatives. But higher operation temperature remains a main challenge when these materials are used in the anions emission source, catalytic reactions, filming modifications and anionic sterilization processes. It also would cause such problems as high energy cost, experiment equipment damage and high noise influence in anions species identification process. In order to solve these problems, recently, we develop two new methods to low the emission temperature of C12A7. The present studies show that using Cs2O-doped 12CaO·7Al2O3 and CsI-doped 12CaO·7Al2O3 could generate low-temperature atomic oxygen anions (O-) emission. The emission and structure features of the Cs2O-doped 12CaO·7Al2O3 and CsI-doped 12CaO·7Al2O3 have been investigated in detail.The main conclusions have been summarized as follows:(1) Cs2O-doped 12CaO·7Al2O3: The maximal emission intensity of O- from the Cs2O-doped C12A7 at 700℃and 800 V/cm reached about 0.54μA/cm2, which was about two times as strong as that from the un-doped C12A7 (0.23μA/cm2) under the same condition. The initiative temperature of the O- emission from the Cs2O-doped C12A7 was about 500℃, which was also much lower than the initiative temperature from the un-doped C12A7 (570℃) at the given field of 800 V/cm. High pure O- emission close to 100% could be obtained from the Cs2O-doped C12A7 under the lower temperature (< 550℃). The emission features of the Cs2O-doped C12A7, including the emission distribution, temperature effect and emission branching ratio have been investigated in detail and compared with the un-doped C12A7. The structure and storage characteristics of the resulting material were also investigated via X-ray diffraction (XRD) and electron paramagnetic resonance (EPR). It was found that doping Cs2O to C12A7 will lower the initiative emission temperature and enhance the emission intensity.(2) CsI-doped 12CaO·7Al2O3: The maximal emission intensity of O- from the CsI-doped C12A7 at 650℃and 800 V/cm reached about 1.38μA/cm2, which was about one order of magnitude higher than that from the un-doped C12A7 (0.79μA/cm2) under the same condition. The initiative temperature of the O- emission from the CsI-doped C12A7 was about 470℃, which was also much lower than the initiative temperature from the un-doped C12A7 (570℃) at the given field of 800 V/cm. High pure O- emission close to 100% could be obtained from the CsI-doped C12A7 under the lower temperature (< 500℃). The emission features of the CsI-doped C12A7, including the emission distribution, temperature effect, field effect, apparent activation energy and emission stability, have been investigated in detail and compared with the un-doped C12A7. The structure and storage characteristics of the resulting material were also investigated via X-ray diffraction (XRD), electron paramagnetic resonance (EPR) transmission electron microscopeand (TEM), energy dispersive X-Ray spectroscopy (EDS) and field emission scanning electron microscope (FESEM). It was found that adding CsI to C12A7 will reduce the apparent activation energy of the O- emission and the binding energy of the surface.The above results show that adding CsI and Cs2O to C12A7 could significantly promote the emission of O- and lower the initiative emission temperature from the material surface, which was attributed to the reduction of the apparent activation energy of the O- emission and the decrease of binding energy of the surface. Lower operation temperature, potentially, will promote the practical application of the anion storage-emission material in many fields, like the O- source, chemical synthesis, air cleaning, and surface sterilization etc..
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