Exploring thermally robust single atom catalysts (SACs) is of great significance. Here, we develop a universal strategy for stabilizing Pt atoms on the mono-oxygen vacancies of CeO2 with diverse exposed facets. The sta-bilization mechanism was proposed that the formed Pt-O-Ce interface will be taken into distortion spontaneously to keep thermodynamics stable through strong metal-support interactions. The highest degree of Pt-O-Ce dis-tortion is achieved over Pt1-CeO2{100} material, which exhibits exceptional efficiency and thermal stability for oxygenated hydrocarbon removal. The enhanced adsorption capacity of O2 and methanol confirmed in the distortion interface is seen as another crucial reason for improving the stability of SACs. Methanol oxidation on Pt1-CeO2{100} obeys the L-H mechanism under relatively low temperature and then goes through to the MVK mechanism with temperature increasing. We believe that these results would bring new opportunities in the fabrication of SACs and applications of them in thermal reactions.
In the present work, a series of
MOF-74 (Ni) materials with narrow micropore channels and abundant
unsaturated metal sites was respectively prepared via hydrothermal
(HT), condensation reflux (CE), and microwave-assisted (MW) methods.
The physicochemical properties of synthesized materials were characterized
by powder X-ray diffraction, N2-sorption, field-emission
scanning electron microscopy, Fourier-transform infrared (FTIR), thermogravimetric
(TG)/TG-FTIR, X-ray photoelectron spectroscopy, UV–vis–near
infrared, NH3/CO2-temperature programmed desorption,
and in situ diffuse reflectance infrared Fourier
transform spectroscopy. Their CO2/N2 adsorption
performances were evaluated by isotherm adsorption and dynamic adsorption
experiments. We found that the MW is a rapid and facile protocol for
the synthesis of MOF-74 (Ni) materials with highly efficient CO2 capture capacity. The well-shaped MW-140 adsorbent with superior
CO2 adsorption capacity of 5.22 mmol/g at 25 °C can
be obtained within 60 min by the MW process, almost 6 times higher
than that of the commercial activated carbon (0.89 mmol/g). Results
of dynamic adsorption experiments showed that the MW-140 material
possesses the highest CO2 adsorption capacity of 3.37 mmol/g
under humid conditions (RH = 90%). Importantly, MW-140 has excellent
adsorption stability and recyclability, superior CO2 capture
selectivity (CO2/N2 = 31), and appropriate isosteric
heat in CO2 adsorption (21–38 kJ/mol), making it
a promising and potential material for industrial CO2 capture.
Characterization results demonstrated that the high capture capability
of MOF-74 (Ni) materials can be attributed to the synergistic effect
of abundant narrow micropore channels and rich five-coordinated Ni2+ open metal sites which are beneficial for the trapping of
CO2 molecules.
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