Mn-Ce-Ti mixed-oxide catalyst prepared by the hydrothermal method was investigated for the selective catalytic reduction (SCR) of NOx with NH3 in the presence of oxygen. It was found that the environmentally benign Mn-Ce-Ti catalyst exhibited excellent NH3-SCR activity and strong resistance against H2O and SO2 with a broad operation temperature window, which is very competitive for the practical application in controlling the NOx emission from diesel engines. On the basis of the catalyst characterization, the dual redox cycles (Mn(4+) + Ce(3+) ↔ Mn(3+) + Ce(4+), Mn(4+) + Ti(3+) ↔ Mn(3+) + Ti(4+)) and the amorphous structure play key roles for the high catalytic deNOx performance. Diffuse reflectance infrared Fourier transform spectroscopy studies showed that the synergetic effect between Mn and Ce contributes to the formation of reactive intermediate species, thus promoting the NH3-SCR to proceed.
Magnetism in the two-dimensional
limit has become an intriguing
topic for exploring new physical phenomena and potential applications.
Especially, the two-dimensional magnetism is often associated with
novel intrinsic spin fluctuations and versatile electronic structures,
which provides vast opportunities in 2D material research. However,
it is still challenging to verify candidate materials hosting two-dimensional
magnetism, since the prototype systems have to be realized by using
mechanical exfoliation or atomic layer deposition. Here, an alternative
manipulation of two-dimensional magnetic properties via electrochemical
intercalation of organic molecules is reported. Using tetrabutyl ammonium
(TBA+), we synthesized a (TBA)Cr2Ge2Te6 hybrid superlattice with metallic behavior, and the
Curie temperature is significantly increased from 67 K in pristine
Cr2Ge2Te6 to 208 K in (TBA)Cr2Ge2Te6. Moreover, the magnetic easy
axis changes from the ⟨001⟩ direction in Cr2Ge2Te6 to the ab-plane in
(TBA)Cr2Ge2Te6. Theoretical calculations
indicate that the drastic increase of the Curie temperature can be
attributed to the change of magnetic coupling from a weak superexchange
interaction in pristine Cr2Ge2Te6 to a strong double-exchange interaction in (TBA)Cr2Ge2Te6. These findings are the first demonstration
of manipulation of magnetism in magnetic van der Waals materials by
means of intercalating organic ions, which can serve as a convenient
and efficient approach to explore versatile magnetic and electronic
properties in van der Waals crystals.
An environmentally benign Fe-Ce-Ti mixed oxide catalyst, which was prepared via the hydrothermal method, has been investigated for the selective catalytic reduction of NO x with NH 3 (NH 3 -SCR). It was found that the Fe-Ce-Ti catalyst exhibited excellent NH 3 -SCR activity, high N 2 selectivity and strong resistance against H 2 O and SO 2 with a wide operation temperature window. XRD and Raman spectra suggest that the Fe-Ce-Ti catalyst has an amorphous structure. The co-presence of Fe and Ce induced the formation of a redox cycle (Ce 4+ + Fe 2+ ↔ Ce 3+ + Fe 3+ ), which promotes the activation of NO and NH 3 . In situ DRIFTS studies demonstrate that the synergetic effect between Fe and Ce contributes to the formation of reactive intermediate species, thus leading to the high catalytic deNO x performance of the Fe-Ce-Ti mixed oxide catalyst.Catal. Sci. Technol. This journal is
Thermoelectric materials can be used to convert heat to electric power through the Seebeck effect. We study magneto-thermoelectric figure of merit (ZT) in three-dimensional Dirac semimetal Cd 3 As 2 crystal. It is found that enhancement of power factor and reduction of thermal conductivity can be realized at the same time through magnetic field although magnetoresistivity is greatly increased. ZT can be highly enhanced from 0.17 to 1.1 by more than six times around 350 K under a perpendicular magnetic field of 7 Tesla. The huge enhancement of ZT by magnetic field arises from the linear Dirac band with large Fermi velocity and the large electric thermal conductivity in Cd 3 As 2 . Our work paves a new way to greatly enhance the thermoelectric performance in the quantum topological materials.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.