activation and splitting of carbon dioxide on the surface of an inorganic electride material - carbon dioxide absorbent

by:Demi     2019-09-06
activation and splitting of carbon dioxide on the surface of an inorganic electride material  -  carbon dioxide absorbent
The activation of carbon dioxide is the most important step in its transformation into a valuable chemical.
For this purpose, a stable oxide surface with a low work function may be promising.
Here we report that the surface of the inorganic electron [Ca24Al28O64]4+(e−)
4 activate and decompose carbon dioxide at room temperature.
This behavior is due to the electrons near the highly concentrated places-
The ripple of the surface area and surface can capture oxygen atoms and make carbon monoxide and carbon dioxide molecules tense. The [Ca24Al28O64]4+(e−)
4 Use Temperature-study of surfaces exposed to carbon dioxide
Program analysis and spectral method.
The results of these measurements were confirmed by AB-Ray simulation, indicating that both carbon monoxide and carbon dioxide were adsorbed on [Ca24Al28O64]4+(e−)
4 RT and above the surface, and the unusual structure, will lead to the resolution of molecular carbon monoxide and atomic oxygen during heating.
We have prepared the C12A7: surface sample as follows. A 1-inch [CaAlO](O)(C12A7:O)(refs , , )
Growth ingot with tirafah, along (110)
The plane is single-
Crystal 3 × 13 × 1mm wafers. The extra-
The frame oxygen ion is replaced by a negative electron by heating the wafer 24 km/h at 1,373 k in an evacuated titanium vapor atmosphere (~10u2009Pa)
Silicone glass tube.
Concentration of negative electrons (2 × 10u2009cm)
, By the absorption light intensity at 2.
8 u2009 ev, indicating all additional
In this process, the framework oxygen ion is removed.
Oil mechanical polishing for samples
Diamond powder paste (
Size of particles 9, 3 and 1 μm)
Alumina powder slurry (
50 nm particle size).
Then transfer the surface sample to an ultra-high vacuum (UHV)
Equipment with base pressure below 3 × 10 pa and cleaned using Ar ion sputtering (5u2009keV, 4.
8. Consultation on corruption issues in cucna cuccm
Legal direction)
Then the resistance is heated for 10 min at 1,273 k.
This treatment is necessary in order to obtain a C12A7: surface that retains a large cage structure, has a metal conductivity and a low work function.
After cooling to RT, use XPS (Mg Kα)and UPS (He I).
Samples exposed to CO (99. 999% purity)(CO in the TPDs)
Backfill in UHV equipment by variable leakage valve.
To ensure the sample remains clean, the gas line is evacuated and heated.
The injection port of CO has a 1-
Mm opening size inside the instrument, 5mm apart from the sample.
A four-stage mass spectrometer (ULVAC; MSQ-400)
Used to monitor the split pressure of the injected gas during exposure.
Langmuirs exposure measurement unit (L: 1. 33 × 10u2009Pau2009s. ).
After the sample was received by CO gas, the vacuum chamber was immediately sent to a month before the base pressure of × 10 u2009 Pa, TPD, PES (XPS and UPS)and FTIR-
RAS measurement.
The pd spectrum was taken at a constant heating rate of 0 in the range of 300-1,273 kHz K temperature.
Use SQ-5 k ks400.
Control sample temperature by resistance heating with homemade computer
Control the power supply.
The upper limit of the sample temperature is determined by reference to the melting point of the sample.
Conditions required to achieve CO adsorption saturation on the C12A7: is determined by monitoring the pressure level and pd yield in UHV equipment as a function of CO exposure during pd measurement.
PES measurement using a semi-spherical analyzer (Omicron)
Non-commercial
Single-color ultraviolet light source (He I line: =21. 2u2009eV, Δ=0. 1u2009eV)and an X-ray source (
Mg K α line: = 1,253. 6u2009eV, Δ=1. 0u2009eV).
During UPS measurement, the He I beam strikes the surface of the sample at an angle of 45 ° with the surface normal, illuminating spots of approximately 2mm in diameter. In XPS, X-
Ray photons strike the surface at an angle of 60 ° to the surface normal, illuminating points of several millimeters in diameter.
All PES spectra were taken under RT and displayed as electrons-
The binding energy relative to the fermionic level. FTIR-
RAS spectra were collected by infrared spectrometer at RT (Bruker; Tensor 27).
Place the infrared source and the infrared detector on the outside of the UHV equipment.
The spectrum obtained is as a single-
Beam spectrum with CO adsorption and clean a7 clean surface :.
Full spectrum by 256 times in a month-
Cm spectral resolution.
The infrared beam extracted from the spectrometer impacts the surface of the sample at an angle of 85 ° through the CaF window.
After the light is reflected from the surface of the sample, it passes through the outlet CaF window and is collected and focused on the tellur cadmium mercury infrared detector cooled using liquid nitrogen.
All optical paths are isolated from ambient air and are filled with dry nitrogen.
Unless otherwise stated, computational modeling is performed using density functional theory and the generalized gradient approximation function of PBE and the projected enhanced wave method implemented in the Vienna simulation package. The plane-
The wave base setting deadline is set to 500ev ev.
C12A7: quasi-simulation of surfacetwo-
Size plate, one of the near-
As described in detail elsewhere, the surface cage holds two electrons.
These surfaces have a large number of surface sites with similar but different structures, including LC Ca and Al sites. The super-
The unit parameters in the plane and perpendicular to the direction of the surface are fixed at 12 and 24, respectively. As the near-
The surface area is partially disordered, and only the gamma points in the briyuan area are calculated.
Activation energy of CO-
The decomposition process is calculated with the push belt method and 8 images.
The infrared intensity of a single CO species was calculated.
Scatter correction was calculated using a previously implemented method.
Pre-configuration
The PBE function was optimized to calculate the adsorption energy (
Configuration report for chemical adsorption next to PBE results)
, With mixed density basis theory, CRYSTAL09 package and full electron Gaussian-
Type contract base group of Ca (5,4,1), Al (4,3,1), O (4,3,1)and C (9,3,2).
The reason for using the density function and the correlation of the corresponding adsorption energy are given in this paper.
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