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The effect of La‐deficiency and Ce/Sr‐substitution in the benchmark LaCo0.8Fe0.2O3 has been investigated for the decomposition of N2O between 500 and 900 °C. Real inlet gas composition and space velocity reveal that La‐deficiency and Ce/Sr‐substitution can improve the thermal stability of catalyst, while La1‐xSrxCo0.8Fe0.2O3 with x≥0.1 was highlighted as a promising formula due to the strongest resistance to deactivation and suppressed undesired NOx decomposition at high space velocity. This phenomenon is mainly ascribed to the incorporation of Sr2+ into the perovskite lattice during the reaction consequently stabilizing the Co3+ species and creating the oxygen vacancies in La1‐xSrxCoO3‐δ. On the contrary, the loss of activity on Ce‐substituted LaCo0.8Fe0.2O3 has been preferentially related to the cobalt exsolution to extra framework of perovskite making the catalytic cycle with Co3+ unfavorable. All these bulk and surface changes are accompanied with opposite evolution of apparent activation energy and pre‐exponential factor which can be discussed based on a redox mechanism. [ABSTRACT FROM AUTHOR]

Substitutional lanthanide doping of 2D transition metal dichalcogenides (TMDs) is expected to be a promising strategy to engineer optical, electronic, and optoelectronic properties of TMDs. Understanding the interactions between lanthanide dopants and 2D TMDs host is one of the key problems to be resolved for their profound research studies. Herein, the interactions between Ce dopants and monolayer WS2 in a physical vapor deposition grown Ce‐doped WS2 monolayer are studied by combining scanning tunneling microscopy with optical characterizations with high spatial and temporal resolution. It is found that the highly anisotropic crystal field can effectively split the energy levels of the Ce dopants' f orbital. The electrons in the split energy levels can bind the holes in the valence band maximum of the Ce‐doped WS2, forming optical bright excitons. These excitons collide with the free A excitons when increasing the pump fluences, reducing the A exciton's lifetime. This study may be beneficial for the design and fabrication of optical, electronic, and optoelectronic devices based on lanthanide‐doped TMDs. [ABSTRACT FROM AUTHOR]

Upconversion materials have attracted much attention because of their broad application prospects in biomedicine and energy. Although various methods have been tried in nanoparticles and nanocrystals, it is still a challenge to realize monochromatic upconversion luminescence (UCL) in traditional lanthanide-doped materials. Two-dimensional transition metal chalcogenides (2D-TMDs) are a class of excellent luminescent semiconductors, offering a promising platform due to their chemical accessibility and physical sensitivity. However, multi-lanthanide doping, typically boosting the upconversion efficiency, has not been accomplished in monolayer TMD nanosheets. In this work, an optimized liquid precursor-assisted technique is designed to synthesize monolayer MoS2 nanosheets embedded with Er/Yb and Er/Ho by surmounting the precipitation of Ln3+-doped precursors, which is confirmed by structural characterization. The monolayer MoS2 can split the 4f configuration remarkably to produce diverse energy levels due to its strong Coulomb binding and spin–orbit coupling, as well as the unique asymmetric crystal field along the [001] direction. Hence, multiband monochromatic UCL from violet to near-infrared ranges was obtained on these codoped MoS2 nanosheets. This work provides an effective way to tune the luminescence performance and wavelength of 2D-TMD nanosheets as well as a strategy for the design of UCL nanomaterials for light applications as nanophotonic devices. [ABSTRACT FROM AUTHOR]

1T-TaS2 has attracted much attention recently due to its abundant charge density wave phases. In this work, high-quality two-dimensional 1T-TaS2 crystals were successfully synthesized by a chemical vapor deposition method with controllable layer numbers, confirmed by the structural characterization. Based on the as-grown samples, their thickness-dependency nearly commensurate charge density wave/commensurate charge density wave phase transitions was revealed by the combination of the temperature-dependent resistance measurements and Raman spectra. The phase transition temperature increased with increasing thickness, but no apparent phase transition was found on the 2~3 nm thick crystals from temperature-dependent Raman spectra. The transition hysteresis loops due to temperature-dependent resistance changes of 1T-TaS2 can be used for memory devices and oscillators, making 1T-TaS2 a promising material for various electronic applications. [ABSTRACT FROM AUTHOR]

The bimetallic Pt–Ni nano-catalysts with different platinum to nickel mass ratios supported on the carbon nanotubes (PtNi(x : y)/FCNTs-D) were successfully synthesized by the polyol method and applied to the H2 generation from ammonia borane (AB) hydrolysis. Several state-of-the-art characterization methods were performed to explore the correlation between catalytic performance and the physicochemical characterizations of the catalysts. The results show that the optimum Pt : Ni ratio is critical to enhance the H2 generation from AB hydrolysis and in this study, it is 1 : 2. The presence of carbon nanotubes enhanced the dispersion and stability of the Pt–Ni nanoparticles. The availability of more active sites and lowered binding energy of Pt0 in PtNi(1 : 2)/FCNTs-D catalyst, lead to the increased catalytic activity of H2 generation from AB hydrolysis. [ABSTRACT FROM AUTHOR]

Trivalent lanthanoid ions (Ln3+) with substantial inherency have been utilized in luminescent materials and photonic devices for decades. Because the periodic physicochemical properties of lanthanoid compounds have been found to be closely related to the regular f-configuration of the elements, it is essential to study the interaction between the f-electrons and the circumstances for developing new applications. Two-dimensional transition metal dichalcogenides (2D-TMDs) manifest as excellent matrices for tunable electronic structures owing to their chemical accessibility and physical sensitivity. Herein, a novel method is proposed for the fabrication of Ln3+ substitutional doped MoS2 using a Na2MoS4 solution precursor. Monolayers doped with all Ln3+ ions (except Pm3+) are synthesized, which is confirmed by structural characterization. Their shrunk Raman frequency differences and the blue-shifting and intensity boosting of their photoluminescence (PL) peaks are observed. Periodic trends are discovered in the PL spectra, which are sensitive to specific elements. The results reveal the ordered interaction between f-orbitals and the host possessing an appreciable coulombic field, spin–orbital coupling, and a crystal field. This work offers a crucial extension of lanthanoid laws and a new approach to the modulation of the properties of 2D crystals. [ABSTRACT FROM AUTHOR]

Extending the shortest second harmonic generation output wavelength of nonlinear optical crystals into the deep ultraviolet (UV) range is important for their application as frequency conversion devices for an advanced laser. The doping of ions with a large atomic number is believed to be an effective way to realize a shorter SHG output wavelength. In this work, large-sized Sr2+-doped La2CaB10O19 (Sr:LCB) crystals with nominal ratios of 10%, 15% and 30% were grown by the top-seeded solution growth method. The measured lattice parameters of the grown Sr:LCB are nearly the same as that of the LCB crystal, and the rocking curves reveal that the grown Sr:LCB crystals are of high quality. Sr: LCB crystals have a UV cut-off edge of 168 nm. The refractive index of the Sr:LCB crystals was measured, based on which the Sellmeier equations of the Sr:LCB crystals were fitted. The calculated shortest SHG output wavelength for Type I phase matching is 270.5 nm, which is 17.5 nm shorter than that of LCB crystals (288 nm). The characterization results demonstrate that Sr:LCB is a potential nonlinear optical crystal for the deep UV range. [ABSTRACT FROM AUTHOR]

The oxidative dehydrogenation of ethane using CO2 as soft oxidant for the production of ethylene, possesses the features of valorization of light alkane and utilization of greenhouse gas. Although a significant challenge, the control of the reaction extent can provide a potential on‐purpose ethylene technology. In the present paper, CeO2 is proposed to be a promising catalyst, while the deep oxidation process of dry reforming is preferred. The SiO2 coated CeO2 catalyst can render the reaction more selective towards ethylene. Through high sensitivity low energy ion scattering spectroscopy, findings were made that SiO2 only partially covered CeO2 in the Si0.1CeO2 sample, in which the ethylene selectivity was 2.7 times as high as that of the bulk CeO2 based on the same conversion level. Further, density functional theory calculations also demonstrated that the presence of the SiO2 layer was more conducive to the desorption of ethylene. [ABSTRACT FROM AUTHOR]

The various metal‐doped Silicalite‐1 (M−S1, M=Mg, Al, Fe and In) supports were prepared by hydrothermal synthesis method, then were used to disperse the PtSn species through impregnation. The resulting solids were further characterized through XRD, N2 adsorption/desorption isotherms, XPS, H2‐TPR, NH3‐TPD, Raman spectroscopy and TG techniques to investigate the structural property before and after propane dehydrogenation reaction. The results exhibited that the introduction of various metal dopants had profound effects on pore structure, reducibility, acidity and surface content of Pt which was directly related to the activation of propane. And the surface content of Pt acted as the dominant role for converting propane. As a consequence, the maximum initial conversion of propane was obtained over Fe‐modified PtSn/Fe−S1 sample, but it deactivated fast as well because of the coke deposition. [ABSTRACT FROM AUTHOR]

A series of Ce@MOR hybrids based on CeOx nanoparticles (1–2.5 nm) encapsulated in mordenite exhibiting a genuine flower-like morphology were prepared by simple hydrothermal synthesis. The cerium content in the catalysts could be easily tuned by adjusting the Si : Al : Ce composition of the preformed gel, affecting the textural properties and the density of acid sites of the catalysts. The genesis of acid sites with medium strength was directly correlated to the catalytic activity for the vapor-phase dehydration of 1,3-butanediol into butadiene. A Ce@MOR hybrid with a Si/Ce atomic ratio of 50 displayed a superior activity and selectivity compared to the parent MOR at a comparable Si/Al atomic ratio (10), as well as to control Ce-MOR catalysts post-synthesized by incipient wetness impregnation from the parent mordenite. A higher density of Brønsted acid sites with medium strength induced by encapsulated CeOx nanoparticles was argued as the main reason for such an enhanced catalytic performance. [ABSTRACT FROM AUTHOR]

ZnO-Al2O3 derived from layered double hydroxides ( ZnAl-LDH) was successfully applied for dispersion of Pd-Ag bimetallic catalysts for the selective hydrogenation of acetylene to ethylene and the Pd-Ag/ ZnO-Al2O3 catalyst showed the best catalytic performance among the prepared samples. It was found that the catalyst carrier of ZnO-Al2O3 metal-oxides derived form ZnAl-LDH could significantly suppress the over-hydrogenation of acetylene to obtain the relatively higher selectivity of ethylene. The introduction of Ag restricted efficiently the formation of coke because of the oligomerization reaction, which was further evidenced by thermal gravimetric analysis. The selectivity towards ethylene was in the order of Pd-Ag/ ZnO-Al2O3>Pd/ ZnO-Al2O3>Pd-Ag/ Al2O3>Pd/ Al2O3 at a high conversion level. As the thermal gravimetric and differential temperature analysis ( TG-DTA) revealed, Pd-Ag intermetallic catalyst on the ZnO-Al2O3 support showed less coke formation. [ABSTRACT FROM AUTHOR]

SBA-15 catalysts doped with variable aluminum amounts were prepared through a facile evaporation-induced self-assembly process. The textural properties and acidity of the catalysts could be tuned simply by varying the aluminum content. The genesis of acid sites with weak and medium strength during reaction was directly correlated to the catalytic activity for the dehydration of 1,3-butanediol into butadiene (BD). The best performance was achieved over an Al-SBA-15 sample with a silica/alumina ratio of 76, exhibiting a stable BD yield of 59 % at temperatures as low as 200 °C. [ABSTRACT FROM AUTHOR]

Controllable crystallite size of CuO in CuO/ZnO/meso-SiO catalysts was successfully realized by impregnation method using mesoporous silica with different pore diameters as support. Characterization techniques such as N adsorption/desorption, X-ray diffraction, H temperature-programmed reduction, and potentiometric titration were employed to investigate the influences of pore size on textural properties, crystalline phases, reducibility, and acidity. Catalytic evaluation of synthesis of 2-methylpyrazine was carried out at 380 °C under atmospheric conditions. The best catalytic performance was achieved over catalyst CZ/S1 supported on the carrier with smallest pore size. [ABSTRACT FROM AUTHOR]

Single crystalline BaZnF4 is grown by the Czochralski technique. Optical measurements indicate a wide transparency from the vacuum ultraviolet to the far infrared (0.145–10 μm). The ferroelectric properties are determined for the first time by the polarization hysteresis. The spontaneous polarization Ps is found to be 9 μC/cm2, while the coercive field Ec varies between 9 and 75 kV/cm, depending on the field frequency. The material properties are compared with those of BaMgF4, which is another candidate for the realization of all-solid-state lasers emitting in the ultraviolet wavelength region. [ABSTRACT FROM AUTHOR]