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An effective and safe route is proposed to prepare supported Mo2C-based catalysts from organic–inorganic hybrids, which exhibit high activity and stability for producing H2from methanol catalytic decomposition. [ABSTRACT FROM AUTHOR]

Abstract: Dehydrogenation of ethane to ethylene in the presence of carbon dioxide was investigated over various gallium-based catalysts. Ga2O3/HZSM-5 catalysts show better stability than β-Ga2O3, and the higher Si/Al ratio HZSM-5 supported gallium oxide catalysts are more resistant to deactivation. The Ga2O3/HZSM-5(97) catalyst exhibits both high activity and stability for dehydrogenation of ethane, with an ethane conversion of 15% and ethylene selectivity of 94% without any observable trend of deactivation in 70h. The results of NH3-TPD and FT-IR spectra of adsorbed pyridine revealed that the enhancement of the catalyst stability with increasing Si/Al ratio of the support is caused by the decrease of the acidity of the catalysts, resulting in the suppression of the side reactions, such as cracking and oligomerization. The promoting effect of CO2 on the dehydrogenation reaction is attributed to the reverse water gas shift reaction. The catalyst stability is also enhanced by the introduction of CO2. [Copyright &y& Elsevier]

Abstract: Series of Rh/SBA-15 catalysts were prepared by impregnation and grafting method applying different Rh precursors. The catalytic behaviors of N2O decomposition over these catalysts were tested in an automated eight flow reactor system. The catalysts were characterized by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), N2 adsorption/desorption, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) techniques. The results showed that the dispersion of Rh species on the catalysts is closely related to the molecular size and the hydrophobic property of the precursors comparing to the hydrophilic support, better dispersion results were found in catalysts by impregnation of smaller precursors, while by grafting better dispersion resulted from big precursor. On the other hand, the activities of the catalysts match well with the Rh dispersion status. Rh/SBA-15-CDCR starting from [(CO)2RhCl]2 showed good dispersion and gave the best N2O decomposition activity. [Copyright &y& Elsevier]

ZrO x /Ni-MnO x /SiO 2 catalyst for CO 2 reforming of methane was prepared using impregnation method, and characterized by in situ DRIFTS, XRD, TEM, XPS and TG. Low-temperature activation of both methane and carbon dioxide was achieved over ZrO x /Ni-MnO x /SiO 2 catalyst, and the catalytic activity was found to be dependent on the reduction temperature. It was found that after being reduced at 550 °C, the ZrO x /Ni-MnO x /SiO 2 catalyst showed relative high content of surface Ni species and small particles of Ni species with a rather narrow particle size distribution. The ZrO x /Ni-MnO x /SiO 2 catalyst reduced at 550 °C showed the highest catalytic activity, with 17.9% and 23.1% initial conversions of CH 4 and CO 2 at the reaction temperature of 500 °C, and the yield of H 2 and CO also reached the maximum value of 9.2% and 14.5%, respectively. In addition to the high catalytic activity, the ZrO x /Ni-MnO x /SiO 2 catalyst also showed a quiet good stability at 500 °C. The initial and stable yields of H 2 and CO were 1.4% and 2.3% at the reaction temperature of 400 °C with the conversion of CH 4 and CO 2 being 2.2% and 4.9%, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mn 1 Zr x O y oxides catalyst with controlled Zr content were prepared. • The reaction rate over Mn 1 Zr 0.10 O y catalyst is 8.3 times over MnO 2. • Propane oxidation on Mn 1 Zr x O y catalyst is revealed to follow the MvK mechanism. Developing efficient non-noble catalysts for low-temperature catalytic oxidation of light alkane is highly desirable and challenging. Herein, we developed a Mn 1 Zr x O y mixed oxide catalyst via a co-precipitation method, finding a significant promotional effect of Zr doping on the catalytic activity of MnO 2 for propane oxidation. It is unraveled that doping Zr into MnO 2 lattice can lead to higher redox ability and oxygen mobility, more oxygen vacancies and enhanced acidity, which are positively responsible for catalytic activity. The kinetic studies and in-situ DRIFTs revealed that the Zr doping does not change the reaction pathway, but facilitates the adsorption and activation of propane and oxygen molecules, thus accelerating the catalytic reaction. In addition, the density functional theory (DFT) calculations further confirmed the contribution of Zr doping in the adsorption of reactant molecules and the formation of oxygen vacancies. Among all, the Mn 1 Zr 0.10 O y catalyst exhibits the highest catalytic activity with the lowest activation energy, and its reaction rate reaches 1.34 μmol g cat. −1 s−1 at 245 °C, 8 times more than that of pure MnO 2 catalyst. Moreover, the catalyst also displays good stability and reusability even under water vapor atmosphere. [ABSTRACT FROM AUTHOR]

Glycerolysis of triglycerides (corn oil) was carried out over CeO promoted CaO catalysts. CeO was introduced into CaO via the sol-gel combustion method with citrate as the precipitator. A strong interaction between CaO and CeO was revealed by XRD, XPS and Raman results, which results in an increased basic strength and amounts of strong basic sites. Moreover, the lixiviation of CaO in the glycerol at high temperature, which is the key problem in the glycerolysis reaction over CaO-based catalysts, was inhibited significantly. XRD, N adsorption-desorption isotherms and SEM results exhibit introducing CeO increases the surface area, pore volume and pore size of CaO catalysts, which are beneficial to the catalytic activity. The 2CaO-1CeO catalyst with strong basicity and large surface area achieved over 90 % conversion after 1 h while the lixiviated Ca decreased dramatically. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Constructing non-noble robust catalysts for deep catalytic oxidation of obstinate light alkanes at low temperature is of great value and significance. Herein, we designed a facile solvent-thermal-reduction strategy to fabricate an O-vacancy-rich porous MnO 2 nanosheet (MnO 2 −PS) catalyst for propane catalytic oxidation. The abundant vacancies in MnO 2 −PS catalysts can significantly promote its redox ability and oxygen activation capacity, and then provide more active oxygen species with enhanced oxygen mobility and reactivity, thus accelerate the cleavage of C-H bond and the decomposition of intermediates. Meanwhile, benefiting from the porous nanosheet structure, MnO 2 −PS catalyst possesses highly accessible surface and high density of exposed active sites, thus facilitating the adsorption and the activation of reactant molecule. At the same time, the catalyst also exhibits good thermal stability and water resistant ability. This robust and efficient catalytic system may provide some enlightenments for designing feasible catalyst with high-performance for deep catalytic destruction of VOCs. [Display omitted] • O-vacancy-rich porous MnO 2 nanosheets (MnO 2 –PS) catalyst were fabricated through a facile method. • High catalytic performance of propane catalytic oxidation on MnO 2 –PS catalyst was achieved. • The MnO 2 –PS with abundant vacancies exhibits higher density of exposed active sites, higher redox ability and oxygen mobility. [ABSTRACT FROM AUTHOR]

Hybrid polyoxometalate-porphyrin copolymeric films were obtained by the electrooxidation of 5, 15-ditolyl porphyrin ( H 2 T 2 P ) and zinc- β -octaethylporphyrin ( ZnOEP ) in the presence of the Lindqvist-type polyoxovanadates TBA 2 [V 6 O 13 {(OCH 2 ) 3 CNHCO(4-C 5 H 4 N)} 2 ] ( Py-POM-Py ). The resulting films have been characterized by UV–visible absorption spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and electrochemistry. Electrochemical quartz crystal microbalance was employed to investigate the copolymer mass. [ABSTRACT FROM AUTHOR]

This paper reports the formation of hybrid polyoxometalate-porphyrin copolymeric films obtained by the electro-oxidation of zinc-β-octaethylporphyrin (ZnOEP) in the presence of a functionalized Dawson-type polyoxometalate bearing two pyridyl groups (POMdb3,3, Py-POM-Py) which will be compared to the copolymer obtained from ZnOEP and a dipyridyl compound without POM (ib3,3). The resulting film has been characterized by UV-visible absorption spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. Electrochemical quartz crystal microbalance was employed to investigate the poly-porphyrin-POMs deposition mass. Graphical Abstract[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Highlights: [•] The Cu-ZSM-11 catalysts are firstly used in direct N2O decomposition. [•] Cu-ZSM-11 is obviously more active than Cu-ZSM-5 with the same Si/Al ratio. [•] Enhanced activity is due to better reducibility and accessibility of Cu+ species. [ABSTRACT FROM AUTHOR]

An impedance-optimized hierarchical TiO 2 @Fe/C@TiO 2 vesicular carbon microtube is constructed for the first time via coaxial electrospinning and solvothermal method. Benefit from the integration of cavities, highly dispersed magnetic nanoparticles, and dielectric coating, the impedance is effectively improved by dielectric-magnetic synergy. The unique structure simultaneously fulfills a dual-network of micron-scale magnetic interaction and charge transfer, embedding the composite with enhanced magnetic and dielectric loss. The interfacial polarization and multiple reflections further promote microwave absorption. [Display omitted] • 1D vesicular structure was successfully constructed via coaxial electrospinning. • Structural and compositional integration progressively improved impedance. • Strong magnetic-dielectric synergy of quaternary components in this absorber. • Electron holography confirmed magnetic coupling and charge transfer dual-network. Impedance matching (Z) is a key issue requested by high-efficient microwave absorption materials, which remains a major challenge. Lacking magnetic loss capacity and electromagnetic impedance balance, the microwave attenuation capacity of carbon-based absorbers urgently needs to be improved. Herein, a TiO 2 @Fe/C@TiO 2 vesicular carbon microtube was reasonably constructed by coaxial electrospinning. The characteristic impedance was gradually improved by introducing cavities, magnetic Fe particles and dielectric TiO 2 coating. The composite achieves an enhanced microwave performance with a maximum reflection loss of as strong as − 60.98 dB and a broad absorption bandwidth of 4.8 GHz at only 2.0 mm thickness. Such a well-integrated hierarchically vesicular carbon microtube with a tubular porous structure endows the assembly with high magnetic anisotropy and multiple interfaces, further offers the composites: i) the dual-networks of micron-scale 1D anisotropic magnetic coupling and charge conduction, ii) dielectric-magnetic synergy of quaternary components, iii) progressively matched impedance, proved by micromagnetic simulation and electron holography. This finding might have great significance in the impedance matching control of high-performance microwave absorbents. [ABSTRACT FROM AUTHOR]

Abstract: Films on ITO of [N(C4H9)4]5H[P2V3W15O59{(OCH2)3CNHCO(ZnTPP)}] (ZnTPP=zinc(II)-tetraphenylporphyrin) were obtained by the Langmuir–Schaefer inverted transfer method. The films were characterized by UV–vis absorption spectroscopy, XPS, AFM, and electrochemistry. In addition, the photovoltaic performances of the Langmuir–Schaefer films were investigated by photocurrent transient measurements, which show significant photocurrent response. [Copyright &y& Elsevier]

Abstract: Films based on electrostatic interactions between tetracationic porphyrin, 5,10,15,20-(4-trimethylammoniophenyl) porphyrin tetra(p-toluenesulfonate), [H2TPhN(Me)3P]4+ and Dawson type polyoxometalate α2-[Fe(P2W17O61)]7− (POM) are formed by the so called layer-by-layer self-assembly method. Successive deposition of layers has been monitored by UV–visible absorption spectroscopy. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) have been used to explore the morphology and composition, respectively. Electrochemistry and permeability studies have been carried out by cyclic voltammetry. The photocatalytic properties of these films have been also studied for the reduction of silver ions. Indeed, in these systems, porphyrins can be excited by visible light which play the role of photosensitizers able to give electrons to POM known to be good catalysts. Giant silver dendrites have been obtained. [Copyright &y& Elsevier]

Abstract: The catalytic N2O decomposition was investigated over a series of Cu x Ce1−x O y mixed oxides with different Cu/Ce molar ratios. Effects of synergy over mixed oxides of CeO2 and CuO were observed significantly, the catalyst of Cu0.67Ce0.33O y exhibited the high activity among the Cu–Ce–O mixed oxides for N2O decomposition. Characterizations of XRD, N2-adsorption, XPS, and H2-TPR were applied to correlate their properties with the corresponding catalytic performance, and reveal the synergetic effect between CuO and CeO2 for N2O decomposition. In situ DRIFTS investigation confirmed the presence of CuI species that was closely related with the activity of Cu x Ce1−x O y catalyst. The synergy of Cu x Ce1−x O y promoted the stability and the ability to regenerate the active CuI site. [Copyright &y& Elsevier]

Abstract: The effect of alkali species on performance of MnO/γ-Al2O3 catalysts for methyl benzoate hydrogenation was investigated in fixed-bed reactor. Doping alkali species on MnO/γ-Al2O3 catalysts enhanced the selectivity of benzaldehyde significantly, toluene and benzyl methyl ether were greatly suppressed. The infrared spectra of adsorbed pyridine adsorption was acquired to study the surface acid properties, the results revealed that doping alkali species weakened the acid strength of MnO/γ-Al2O3 catalysts, which lead to restrain from the formation of toluene and benzyl methyl ether. [Copyright &y& Elsevier]

Abstract: The Cu/ZnO/Al2O3 catalysts were prepared by the coprecipitation method, and were evaluated in the water–gas shift (WGS) reaction. The effects of the calcination temperature on the BET surface area and crystallite size were characterized. In WGS reaction, the Cu/ZnO/Al2O3 catalysts suffered from continuous deactivation in shut-down/start-up operation – the daily requirement for mobile and residential fuel cell systems. Among them, the Cu/ZnO/Al2O3 catalyst prepared at the calcination temperature of 450°C showed the best activity and stability, with the decrement of the CO conversion of only 12.8% after three shut-down/start-up cycles. Deactivation of the Cu/ZnO/Al2O3 catalysts is attributed to the blocking or deterioration of the active sites by Zn6Al2(OH)16CO3·4H2O resulting from the degeneration of the oxides under cyclic operations. Removal of the hydroxycarbonate species by calcination in air followed by re-reduction could restore the steady-state WGS activity; however, the regenerated catalyst underwent much severe deactivation in subsequent shut-down/start-up operation. [Copyright &y& Elsevier]

The Cover Feature b shows the synthesis of a new diarylethene-porphyrin photoswitchable copolymer through the electropolymerization of zinc porphyrin and pyridine substituted diarylethene. Cover Feature: Synthesis and Characterization of Bisthienylethene-Porphyrin Photoswitchable Copolymers (Eur. J. Org. Electropolymerization, Porphyrin, Bisthienylethene, Polymer, Photocyclisation. [Extracted from the article]

Abstract: The selective oxidation of a series of alcohols to their corresponding carbonyl products was carried out over a rationally designed in situ electrolytic nano-silver/zeolite film/copper grid (SZF) catalyst, which was prepared by a combination of the seed-film method for the fabrication of an ultrathin zeolite film and the in situ electrolytic process for the formation of highly dispersed silver nanoparticles. At a relatively low reaction temperature (ca. 320 °C), the SZF catalyst with highly dispersed in situ electrolytic silver nanoparticles exhibited much higher activity for the oxidation of mono-alcohols and higher selectivity for ketonic aldehyde in the oxidation of di-alcohols than the conventional bulk electrolytic silver catalyst. On the basis of the combination of diffuse reflectance ultraviolet visible spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and thermoanalysis, the remarkably high activity and selectivity of the SZF catalyst was attributed to the highly dispersed silver nanoparticles, which were stabilized by the zeolite film against sintering, and, accordingly, a large amount of Ag+ ions and clusters existed in the silver nanoparticles. The improvements of the catalytic performance of the SZF catalyst in a wide application extension will bring new concerns in both theoretical and applied fields. [Copyright &y& Elsevier]

A multifunctional silane-based composite surface coating with self-cleaning, anticorrosive and antimicrobial abilities have been fabricated on metal surface. The surface coating is designed to have a "sandwich" structure that contains a chemically etched surface at the bottom, a SiO 2 -hybridized silane layer in the middle and a Ti 3 C 2 -hybridized silane layer on the top. The chemical etching produces a rough surface that helps to produce superhydrophobicity. The silane molecules are crosslinked to form a film of low surface energy, which not only contributes to surface superhydrophobicity but also plays dominant roles in corrosion resistance. The SiO 2 nanoparticles and Mxene (Ti 3 C 2) nanosheets are hybridized in the film to enhance compactness, mechanical strength and wearing resistance of the film, resulting in a surface coating with excellent anticorrosion efficiency. Mxene can also introduce antimicrobial ability to the surface coating. The study develops an effective strategy to construct multifunctional composite surface coatings, which is not only suitable for modification of clinical and biomedical devices for anticorrosive and antibacterial purposes, but also can be used to modify the surface of daily-use facilities to facilitate their daily maintenance and cleaning. [Display omitted] • Multifunctional silane-based composite coatings have been fabricated on metal surface. • The silane film is fabricated on chemically etched metal surface to produce a superhydrophobic surface. • Nanoparticles are hybridized in the film to enhance its compactness, mechanical strength and wearing resistance. • Hybridization of Mxene in the silane film introduces excellent antimicrobial ability to the surface coating. [ABSTRACT FROM AUTHOR]

• Formation of original and innovative hybrid copolymers obtained by electropolymerization from polyoxometalate and porphyrins. • Good photoelectrocatalytical properties. • Good correlation between impedance and photovoltaic performances under visible illumination. • Best photocurrent generation efficiency for POM photosensitized (with porphyrin) hybrid reported up to now. Four hybrid polyoxometalate–porphyrin copolymer films were obtained by the electrooxidation of zinc- β -octaethylporphyrin (ZnOEP) or 5,15-ditolylporphyrin (H 2 T 2 P) in the presence of organosilyl functionalized Keggin-type POMs TBA 3 [PW 11 Si 2 O 40 C 26 H 16 N 2 ] (abbreviated Py-PW 11 Si 2 -Py) and Dawson-type POMs TBA 6 [P 2 W 17 Si 2 O 62 C 26 H 16 N 2 ] (abbreviated Py-P 2 W 17 Si 2 -Py) bearing two remote pyridyl groups. The electropolymerization process of the four copolymers was monitored by EQCM. The obtained copolymers were characterized by UV/Vis spectroscopy, X-ray photoelectron spectroscopy, electrochemistry, and AFM. Their impedance properties (EIS) were studied and their photovoltaic performances were also investigated by photocurrent transient measurements under visible light irradiation. These studies showed a correlation between impedance and photovoltaic performances, the films based on Dawson type POMs and Zn porphyrins giving the best results. This last system displayed one of the best photocurrent efficiency for a reported POM photosensitized hybrid. Image, graphical abstract [ABSTRACT FROM AUTHOR]

To improve propane combustion activity and illustrate the promotional effects of molybdenum doping, Pt-Mo/ZSM-5 catalysts with different Mo amounts were prepared by the co-impregnation method. XRD, Raman, H2-TPR, NH3-TPD, in situ DRIFTs, XPS and other characterizations were performed. The results indicated that the concentration of Pt0 in Pt/ZSM-5 catalyst increased after the doping of Mo and the content of Pt0 had a positive correlation with the reaction turnover frequency value. The propane combustion activity of Pt/ZSM-5 catalyst was significantly improved after the doping of molybdenum species. Among all the catalysts, Pt-6Mo/ZSM-5 catalyst (Pt/ZSM-5 with 6 wt.% Mo modification) showed the lowest T50 and T90 for propane catalytic combustion. Moreover, the Pt-Mo/ZSM-5 catalyst exhibited outstanding catalytic stability. [ABSTRACT FROM AUTHOR]

• A two-step method for ZnO/ZnFe 2 O 4 /Fe core-shell microrods and microflowers composites. • Modulation of the composition and surface morphology. • Investigating morphology- and composition-dependent electromagnetic properties. • Investigating morphology-and composition-dependent microwave absorbing properties. • Revealing the mechanism of enhanced microwave absorption capacity. To enhance the poor microwave absorption capabilities (MACs) of pure ZnO since its impedance mismatching and lack of magnetic loss ability, ZnO/ZnFe 2 O 4 /Fe core-shell microrods (CSMRs) and microflowers (CSMFs) were respectively fabricated by microwave hydrothermal-chemical vapor deposition and hydrothermal-chemical vapor deposition. The morphology, composition and resulting properties of as-prepared samples were affected by different deposition temperatures (T d) and Fe(CO) 5 volumes. Due to the synergy of Fe(CO) 5 adsorption and decomposition, the Fe/Zn ratio was controlled by varying T d from 300 °C to 500 °C, which conveniently modulated the static magnetic properties and MACs of ZnO/ZnFe 2 O 4 /Fe CSMRs and CSMFs. Results showed that the optimal reflection loss (R L) value was −46.88 dB at 6.88 GHz with absorber thickness as thin as 2.2 mm. When the R L was below −20 dB, 15.15 GHz was covered. The rod shaped heterostructure could be formed due to the presence of magnetic particles with Fe core/ZnFe 2 O 4 shell embedding, promoting the orientation and interfacial polarizations, multiple relaxation and proper impedance matching. Our findings suggest that ZnO/ZnFe 2 O 4 /Fe CSMRs are a type of promising absorber material with high-performance MACs, broad bandwidths and thin thicknesses. [ABSTRACT FROM AUTHOR]

• Cold-start emissions account for a large proportion in the RDE test. • The MAW method used for the RDE cold-start emission data is unreasonable. • Instantaneous emission rates in the RDE cold-start test were investigated. • The RDE cold-start emissions are more affected by driving behavior. • Ambient temperature is a secondary factor for the RDE cold-start emissions. To properly evaluate the cold-start emissions of vehicles, four light-duty vehicles were selected to complete a Real Driving Emissions (RDE) test. The analysis and evaluation of the RDE test results reveal that the cold-start emissions account for a significant proportion of the urban trip emissions, and that the moving average window (MAW) method is not suitable for statistically processing the RDE test data that include the cold-start emission data. Additionally, three on-road emission tests including a cold-start test and two hot-start tests at different vehicle thermal states were designed to evaluate the effect of the initial vehicle thermal state on the vehicle start emissions. The results demonstrate that the thermal state of the TWC converter thermal state has a more direct and important effect on the cold-start emissions in the RDE test. Via a comparative analysis of the instantaneous characteristics of pollutant emission rates, fuel–air equivalent ratios, catalytic converter temperatures, vehicle trip dynamic parameters, etc., it is inferred that driving behavior has a more significant and sensitive impact on the cold-start emissions than on the non-cold-start emissions in the RDE test. Based on the RDE tests performed at different ambient temperatures, it is also indicated that the impact of the ambient temperature on the cold-start emissions is only a secondary factor relative to driving behavior. As a result, the trip dynamic conditions, specifically those for the cold-start period, should be set more reasonably and effectively in future RDE regulations to ensure the consistency of the cold-start emission test results. [ABSTRACT FROM AUTHOR]

Zirconia has recently been used as an efficient catalyst in the conversion of syngas. The crystalline phases of ZrO2 in ZrO2/HZSM-5 bi-functional catalysts have important effects on C–O activation and C–C coupling in converting syngas into aromatics and been investigated in this work. Monoclinic ZrO2 (m-ZrO2) and tetragonal ZrO2 (t-ZrO2) were synthesized by hydrothermal and chemical precipitation methods, respectively. The results of in situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTs) revealed that there were more active hydroxyl groups existing on the surface of m-ZrO2, and CO temperature programmed desorption (CO-TPD) results indicated that the CO adsorption capacity of m-ZrO2 was higher than that of t-ZrO2, which can facilitate the C–O activation of m-ZrO2 for syngas conversion compared to that of t-ZrO2. And the CO conversion on the m-ZrO2 catalyst was about 50% more than that on the t-ZrO2 catalyst. 31P and 13C magic angle spinning nuclear magnetic resonance (MAS NMR) analysis revealed a higher acid and base density of m-ZrO2 than that of t-ZrO2, which enhanced the C–C coupling. The selectivity to CH4 on the m-ZrO2 catalyst was about 1/5 of that on the t-ZrO2 catalyst in syngas conversion. The selectivity to C2+ hydrocarbons over m-ZrO2 or t-ZrO2 as well as the proximity of the ZrO2 sample and HZSM-5 greatly affected the further aromatization in converting syngas into aromatics. [ABSTRACT FROM AUTHOR]

Metal organic frameworks (MOFs) have recently been used as precursors of the catalysts for the combustion of volatile organic compounds (VOCs). In the present work, three kinds of CeO2 catalysts were successfully synthesized from Ce-MOF-808, Ce-BTC, and Ce-UiO-66, with specific topological structures and coordinate environments. Catalysts with small particle size, stacking mode, and structural defects could be created by pyrolysis of Ce-MOFs, which affects the activity in the toluene combustion significantly. Raman spectra, XPS, and OSC studies were performed to reveal the formation of defect sites. The thermal redox properties were determined by H2-TPR. Catalytic activity tests were conducted on the toluene combustion, and CeO2-MOF-808 showed the best catalytic performance (T90 = 278 °C) due to its having the largest specific surface area, abundant active surface oxygen species, and low-temperature reducibility. [ABSTRACT FROM AUTHOR]

Exploring highly efficient and robust non-noble metal catalysts for VOC abatement is crucial but challenging. Mn-based perovskites are a class of redox catalysts with good thermal stability, but their activity in the catalytic combustion of light alkanes is insufficient. In this work, we modulated the Mn-O bond strength in a Mn-based perovskite via defect engineering, over which the catalytic activity of propane combustion was significantly enhanced. It demonstrates that the oxygen vacancy concentration and the Mn-O bond strength can be efficiently modulated by finely tuning the Ni content in SmNi x Mn 1- x O 3 perovskite catalysts (SN x M 1- x ), which in turn can enhance the redox ability and generate more active oxygen species. The SN 0.10 M 0.90 catalyst with the lowest Mn-O bond strength exhibits the lowest apparent activation energy, over which the propane conversion rate increases by 3.6 times compared to that on the SmMnO 3 perovskite catalyst (SM). In addition, a SN 0.10 M 0.90 /cordierite monolithic catalyst can also exhibit a remarkable catalytic performance and deliver excellent long-term durability (1000 h), indicating broad prospects in industrial applications. Moreover, the promotional effect of Ni substitution was further unveiled by density functional theory (DFT) calculations. This work brings a favorable guidance for the exploration of highly efficient perovskite catalysts for light alkane elimination.

Surface property modification of catalyst support is a straightforward approach to optimize the performance of supported noble metal catalysts. In particular, oxygen vacancies and hydroxyl groups play significant roles in promoting noble metal dispersion on catalysts as well as catalytic stability. In this study, we developed a nanoflower-like TiO2-supported Pd catalyst that has a higher concentration of oxygen vacancies and surface hydroxyl groups compared to that of commercial anatase and P25 support. Notably, due to the distinctive structure of the nanoflower-like TiO2, our catalyst exhibited improved dispersion and stabilization of Pd species and the formation of abundant reactive oxygen species, thereby facilitating the activation of CO and O2 molecules. As a result, the catalyst showed remarkable efficiency in catalyzing the low-temperature CO oxidation reaction with a complete CO conversion at 80 °C and stability for over 100 h., (© 2023 Author(s). Published under an exclusive license by AIP Publishing.)

Route topography is an important test boundary of real driving emission (RDE) tests. However, the RDE test boundaries, such as atmospheric environment, driver behavior, route topography, and traffic congestion, are random, uncertain, and completely coupled. It is difficult to know to what extent route topography can determine on-road emissions, especially in a region with hilly topography. In this regard, the neural network predictor importance algorithms were proposed to measure the importance of the route topography test boundary. Based on tens of thousands of data window samples from the RDE tests in Chongqing, factor analysis was performed to reduce the data dimensionality and eliminate information overlap, and neural network models were established to predict pollutant emissions and calculate the relative importance of input variables. The results show that route topography is comparable to trip dynamics for on-road emissions but the importance of the route topography test boundary is not fully appreciated in the existing RDE regulation, making mountain cities suffer from severe vehicle emissions that are not effectively controlled., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Support properties regulation has been a feasible method for the improvement of noble metal catalytic performance. For Pd-based catalysts, TiO 2 -CeO 2 material has been widely used as an important support. However, due to the considerable discrepancy in the solubility product constant between titanium and cerium hydroxides, it is still challenging to synthesize a uniform TiO 2 -CeO 2 solid solution in the catalysts. Herein, an in situ capture strategy was constructed to fabricate a uniform TiO 2 -CeO 2 solid solution as supports for an enhanced Pd-based catalyst. The obtained Pd/TiO 2 -CeO 2 -iC catalyst possessed enriched reactive oxygen species and optimized CO adsorption capability, manifesting a superior CO oxidation activity ( T 100 = 70 °C) and stability (over 170 h). We believe this work provides a viable strategy for precise characteristic modulation of composite oxide supports during the fabrication of advanced noble metal-based catalysts.

With the development of internet of things and artificial intelligence electronics, metal oxide semiconductor (MOS)-based sensing materials have attracted increasing attention from both fundamental research and practical applications. MOS materials possess intrinsic physicochemical properties, tunable compositions, and electronic structure, and are particularly suitable for integration and miniaturization in developing chemiresistive gas sensors. During sensing processes, the dynamic gas-solid interface interactions play crucial roles in improving sensors' performance, and most studies emphasize the gas-MOS chemical reactions. Herein, from a new view angle focusing more on physical gas-solid interactions during gas sensing, basic theory overview and latest progress for the dynamic process of gas molecules including adsorption, desorption, and diffusion, are systematically summarized and elucidated. The unique electronic sensing mechanisms are also discussed from various aspects including molecular interaction models, gas diffusion mechanism, and interfacial reaction behaviors, where structure-activity relationship and diffusion behavior are overviewed in detail. Especially, the surface adsorption-desorption dynamics are discussed and evaluated, and their potential effects on sensing performance are elucidated from the gas-solid interfacial regulation perspective. Finally, the prospect for further research directions in improving gas dynamic processes in MOS gas sensors is discussed, aiming to supplement the approaches for the development of high-performance MOS gas sensors., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

1D structures have been gaining traction in the microwave absorption (MA) field benefiting from their electromagnetic (EM) anisotropy. However, there remain considerable challenges in adjusting EM properties by structural design. Herein, using the coaxial electrospinning and solvothermal method, the EM gradient has been achieved in TiO 2 @Co/C@Co/Ni multilayered microtubes. From the outer layer to the inner one, the impedance matching is gradually worsened, while the EM loss capacity is continuously enhanced, facilitating both the incidence and attenuation of microwave. Besides, 1D structural anisotropy simultaneously realizes multilevel magnetic interaction and 3D conductive double network. Therefore, the 1D EM-gradient hierarchical TiO 2 @Co/C@Co/Ni carbon microtube composite exhibits excellent MA performance. Its maximum reflection loss (RL) value reaches -53.99 dB at 2.0 mm and effective absorption bandwidth (EAB, RL ≤ -10 dB) is as wide as 6.0 GHz, covering most of the Ku band with only 15% filling. The unique design of 1D EM-gradient hierarchical composites promises great potential in the construction of advanced MA materials.

A new metal-organic framework (MOF) with both coordination linkages and covalent linkages is prepared by coordinating Cu I with pyrazolate for an aldehyde-functionalized trinuclear complex, and subsequent imine condensation with p-phenylenediamine, a reaction typical for covalent organic framework (COF) synthesis. This MOF×COF collaboration yields FDM-71 with honeycomb layers stacked in eclipsed fashion. After dissociating the Cu I -pyrazolate coordination in FDM-71, the obtained organic components carry the information of structural defects, and thus vacancy identity (aldehyde-based unit vacancy and amine-based unit vacancy) and concentration are definitely resolved. Further to the redox catalytic activity inherited from the complex, FDM-71 features effective photosensitizing activity. The two functions integrated in one well-defined structure is demonstrated by its high efficiency in decomposing H 2 O 2 and consequent excitation of O 2 to reactive oxygen species., (© 2020 Wiley-VCH GmbH.)

Metal-organic frameworks (MOFs) as solid acid catalysts provide active sites with definite structures. Here, Zr 6 -based MOF-808 and its derivatives were studied as catalysts for glycerol dehydration, the products of which (acrolein vs. acetol) are very sensitive to the nature of the catalytic acid sites. Evolving MOF-808 into MOF-808-S with a 120 % increase in the number of Brønsted OH - /H 2 O coordinated to Zr IV and a vanished Lewis acidity by steam treatment, the post-synthetically modified catalyst presented 100 % conversion of glycerol, 91 % selectivity to acrolein, and 0 % selectivity to acetol within the active window. Real-time analysis of the product composition indicated the in situ MOF structural evolution. Overall, the specific MOF-substrate interaction characterized by the probe reaction provides more understandings on the structural evolution of the MOFs and their impact on the performance as solid acid catalysts., (© 2020 Wiley-VCH GmbH.)

Functionalized mesoporous silicas are an emerging kind of adsorbents for the removal of volatile organic compounds (VOCs). Breaking the limitations of traditional mesoporous silica, in this study, porous silica nanocapsules (PSNs) functionalized with phenyl and n -octyl groups (named as p -PSN and n -PSN, respectively) were developed for the first time. Under dry conditions, the PSNs exhibited highest dynamic adsorption capacity and desorption efficiency among the ever-reported typical adsorbents (i.e., SBA-15, KIT-6, silicalite-1, and activated carbon). Under wet conditions, the functionalized PSNs made up the defects of pure PSNs, displaying excellent hydrophobicity. The Q WET for n -PSN and p -PSN increased by 44 and 76%, respectively, as compared with that of pure PSNs in 50% relative humidity. The Henry constant of static adsorption demonstrated that p -PSN had a better capture ability for toluene, which was owing to the π-interaction between the phenyl groups and the toluene molecules. In addition, p -PSN showed considerable stability after six consecutive dynamic adsorption-desorption cycles in 50% relative humidity., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

We report the fast and efficient conversion of metal-organic frameworks (MOFs) to phase pure transition-metal carbide (TMC) nanoparticles with uniform size using laser as the energy source, consuming only 6 W power. Nanoparticles of HfC, ZrC, TiC, V 8 C 7 , α-MoC, Cr 3 C 2 , and FeC x with homogeneous sizes (varied between 6 and 20 nm) were successfully produced, among which HfC and ZrC nanoparticles were obtained, for the first time, with sizes less than 10 nm and in the pure phase. This method was operated directly in air, in stark contrast to traditional furnace heating and laser spray methods, where a protective atmosphere is required. The use of MOFs allowed us to precisely tune the composition of TMC nanoparticles by dialing in the right type and desirable amounts of organic linkers. FeC x nanoparticles doped with various percentages of nitrogen atoms were synthesized for the Fischer-Tropsch reaction without any pretreatment or activation. Extremely high iron time of yield (FTY) values were observed, 415 and 550 μmol g Fe -1 s -1 (with addition of K), in a 40 h test without any decay in performance. A high olefin to paraffin ratio was achieved for C 2 to C 11 products, where the ratio for C 3 was higher than 10.

We devised iron-based catalysts with honeycomb-structured graphene (HSG) as the support and potassium as the promoter for CO 2 direct hydrogenation to light olefins (CO 2 -FTO). Over the optimal FeK1.5/HSG catalyst, the iron time yield of light olefins amounted to 73 μmol CO2 g Fe -1 s -1 with high selectivity of 59%. No obvious deactivation occurred within 120 h on stream. The excellent catalytic performance is attributed to the confinement effect of the porous HSG on the sintering of the active sites and the promotion effect of potassium on the activation of inert CO 2 and the formation of iron carbide active for CO 2 -FTO.

Films based on electrostatic interactions between tetracationic zinc porphyrins, ZnOEP(py)(4)(4+) or ZnTMePyP(4+), and the tetracobalt Dawson-derived sandwich polyanion αββα-[Co(4)(H(2)O)(2)(P(2)W(15)O(56))(2)](16-) are formed by the so-called layer-by-layer method. These films have been characterized by UV-visible absorption spectroscopy, atomic force microscopy and electrochemistry. The composition of the film was measured by X-ray photoelectron spectrum (XPS). The XPS data confirm the presence of the expected elements. The photocatalytic properties of these films have been also studied for the reduction of silver and gold ions. Indeed, in these systems, porphyrins can be excited by visible light and then play the role of photosensitizers able to give electrons to POM known to be good catalysts. Silver nanowires and gold nanosheets have been obtained.