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•A new strategy was proposed to obtain a large amount of new Dirac materials.•16 new hydrogenated group IV-V monolayer are dynamically stable and possess Dirac cones.•The effect of ...spin-orbit coupling could remarkably open a band gap in the systems with heavy elements.
The Dirac materials possess characters of massless fermions, ultrahigh carrier mobility, and many other novel features, which make them have significant applications in the massless and dissipationless quantum devices. Here we found that the hydrogenation of semi-conducting PC6 (HPC6) monolayer could produce a new Dirac material. The fully optimized HPC6 monolayer presents a two-dimensional puckered pristine honeycomb structure. The ab initio molecular dynamics simulations and phonon spectra calculations confirm that HPC6 monolayer can maintain good structural integrity at temperatures up to 400 K. The calculation results reveal that the H atoms form strong covalent bond with P atoms and present −1 valence state, the electronic structure calculations show that HPC6 monolayer possess Dirac cone at K point, and the Fermi velocity is up to 106 m/s, which is the same order of magnitude as graphene. The origin of Dirac point could be explained by isoelectronic rule. Based on this, a series of structures of hydrogenated Group IV-V monolayer HAB6 (A = N, P, As, Sb, Bi; B = C, Si, Ge, Sn) were proposed. Further electronic structure calculations reveal that 16 of them are dynamically stable and belong to Dirac materials.
Well-defined Cu catalysts containing different amounts of zirconia were synthesized by controlled surface reactions (CSRs) and atomic layer deposition methods and studied for the selective conversion ...of ethanol to ethyl acetate and for methanol synthesis. Selective deposition of ZrO2 on undercoordinated Cu sites or near Cu nanoparticles via the CSR method was evidenced by UV–vis absorption spectroscopy, scanning transmission electron microscopy, and inductively coupled plasma absorption emission spectroscopy. The concentrations of Cu and Cu-ZrO2 interfacial sites were quantified using a combination of subambient CO Fourier transform infrared spectroscopy and reactive N2O chemisorption measurements. The oxidation states of the Cu and ZrO2 species for these catalysts were determined using X-ray absorption near edge structure measurements, showing that these species were present primarily as Cu0 and Zr4+, respectively. It was found that the formation of Cu-ZrO2 interfacial sites increased the turnover frequency by an order of magnitude in both the conversion of ethanol to ethyl acetate and the synthesis of methanol from CO2 and H2.
An asymmetric hydrogenation of 3‐benzoylaminocoumarins was achieved for the first time using our BridgePhos‐Rh catalytic system, providing chiral 3‐amino dihydrocoumarins in high yields (up to 98 %) ...and with excellent enantioselectivities (up to 99.7 % ee). The relationship between the enantioselectivities of the hydrogenations and the dihedral angles and the resulting π‐π stacking effects of the BridgePhos‐Rh complexes, which were determined by X‐ray diffraction analysis, are discussed. The corresponding hydrogenated products allow for many transformations, providing several chiral skeletons with important physiological and pharmacological activities.
An asymmetric hydrogenation of 3‐benzoylaminocoumarins was achieved for the first time using a BridgePhos‐Rh catalytic system. Chiral 3‐amino dihydrocoumarins were obtained in high yields (up to 98 %) and with excellent enantioselectivities (up to 99.7 % ee).
The efficiency of heterogeneous photocatalysis for converting solar to chemical energy is low on a per photon basis mainly because of the difficulty of capturing and utilizing light across the entire ...solar spectral wavelength range. This challenge is addressed herein with a plasmonic superstructure, fashioned as an array of nanoscale needles comprising cobalt nanocrystals assembled within a sheath of porous silica grown on a fluorine tin oxide substrate. This plasmonic superstructure can strongly absorb sunlight through different mechanisms including enhanced plasmonic excitation by the hybridization of Co nanoparticles in close proximity, as well as inter‐ and intra‐band transitions. With nearly 100% sunlight harvesting ability, it drives the photothermal hydrogenation of carbon dioxide with a 20‐fold rate increase from the silica‐supported cobalt catalyst. The present work bridges the gap between strong light‐absorbing plasmonic superstructures with photothermal CO2 catalysis toward the complete utilization of the solar energy.
A cobalt plasmonic superstructure is developed to enable almost 100% broadband photon efficient CO2 photocatalysis through enhanced plasmonic excitation by the hybridization of Co nanoparticles in close proximity, as well as inter‐ and intra‐band transitions. This work will bridge the gap between plasmonic absorbers with photothermal catalysis, toward the complete utilization of the solar energy.
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•Yttrium loading in In-based catalysts reduce surface reducibility.•Y and La promoters increase number of CO2 adsorption sites.•Y and La promoters promoted catalysts have 40–60% ...higher methanol selectivity than conventional Cu-based catalyst.•The formate pathway is, most likely, the dominant reaction channel for methanol synthesis on Y-promoted supported In-catalyst.
Supported indium oxide catalysts are investigated for the CO2 hydrogenation to methanol at a total pressure of 40 bar (528–573 K) using a laboratory flow reactor. Surface reducibility, optical spectral characteristics, and catalytic rates and selectivity were correlated to catalyst composition. Promoted catalysts, especially Yttrium or Lanthanum-promoted indium oxide, require higher temperatures (H2-TPR) for surface reduction and display higher CO2 desorption temperatures (CO2-TPD). The promoted samples also have ˜20% higher methanol selectivity compared to the non-promoted catalyst, while having similar methanol formation rates (0.330–0.420 gMeOH gcat.−1 h−1 at 573 K). From 528 K to 558 K, methanol selectivity was over 80%, over all the promoted catalysts, and nearly 100% selectivity was observed at the low temperature range (˜528 K) investigated. The reaction kinetics of Y-promoted catalyst and the results of CO co-feeding experiments suggest that formate pathway is the likely reaction mechanism for methanol formation.
•MIL-68(In)-derived In2O3 with different morphologies and sizes was applied to CO2 hydrogenation to methanol.•Self-assembled MIL-68(In)-derived perfect In2O3 hollow tubes were successfully ...synthesized by appropriate 0.5 M NaOAc.•The perfect In2O3 hollow tube composed of ordered arranged nanoparticles was most beneficial to generate of oxygen vacancies.•The more perfect and regular the structure of In2O3 hollow tubes, the higher the methanol formation activity.
MIL-68(In)-derived In2O3 hollow tubes with different morphology and size using MIL-68(In) as a template were prepared at different NaOAc concentrations and applied to CO2 hydrogenation to methanol. The size of a series of MIL-68(In) gradually decreased with increasing NaOAc concentration. Too large or small diameter of MIL-68(In) (NaOAc at 0.2 M or 1 M) led to the collapse of corresponding derivative In2O3 tubular structure and only haphazardly accumulated In2O3 nanoparticles were retained. However, the In2O3 hollow tubular-like structure could be obtained when NaOAc concentrations were in the range of 0.4 M to 0.65 M. Interestingly, the self-assembly MIL-68(In)-0.5 M-derived In2O3 with the most regular and perfect hollow tube structure was composed of ordered arrangement of In2O3 nanoparticles at 0.5 M NaOAc, which exhibited much higher methanol synthesis performance than that of other In2O3 catalysts. The lowest surface reduction temperature led to oxygen vacancies easily exposed on In2O3-0.5 M hollow tube surface. The space confinement effect further enhanced the reaction efficiency of oxygen vacancies, and adsorption capacity of CO2 was enhanced to improve the methanol yield. It achieved a CO2 conversion of 14.0%, while methanol selectivity remained at 65%. The space-time yield was up to 1.07 gMeOHh-1gcat-1, showing excellent methanol activity.
In this work, a novel idea for obtaining in processes performed in real-world processes (here, the illustrative example is the gas phase hydrogenation of propene) a precise kinetic equation that ...corresponds to the experimental results was examined. The considerations are based on quasi-steady-state hypothesis and using elements of graph theory. The mathematical basis of the method used was developed by Lazman and Yablonsky
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, further considerations are presented in Yablonski et al.
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, Marin et al.
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. The exemplary derivations of kinetic equations without simplifications are presented in the aforementioned works. The lack of assumptions allows consideration of all possible interactions between the reagents and the surface species, which is a pro of the method. However, the equation obtained usually has a complex form. Some of the parameters that result from theoretical considerations are simply insignificant for the real-world process. To eliminate this problem, the original procedure, based on statistical and process analysis, was employed. The previously determined kinetic equation, which does not have additional assumptions, was simplified. Statistical analysis helps to find and justify possible simplifications of the kinetic equation by eliminating insignificant parameters present in the kinetic equation and provides strong evidence for the correctness of the approach. The resulting kinetic equation indicates that the new proposed mechanism for the propene hydrogenation process that accepts reactions between adsorbed propene and gaseous hydrogen corresponds to the experiment. The residual sum of squares is significantly lower than those for the equations presented in the literature. The statistical test (the Akaike criterion) also indicates that the new model is better than the others. The results obtained indicate that the commonly applied approach based on the rate-determining step concept has become obsolete, apart from obvious cases. The application of the more advanced mathematical approach gives better results, as was presented.
With his hand holding the sail and his feet on the sailboard, the position of the windsurfer mimics the key strategy of this work: the activation of hydrogenated substrates by chelating coordination ...with cobalt. The surfer is the cobalt catalyst holding the sail to coordinate parazole, and with his foot on the hydrogenated substrate board to coordinate the vinyl group. Bubbles in the seawater represent the main reagent of the reaction, hydrogen, the dolphin represents the hydrogenated product of this reaction, and the wind represents the bisphosphine ligand that promotes the catalytic activity. Overall, the picture shows that the reaction we developed is powerful like the sport of surfing. More information can be found in the Research Article by Z. Zhang, W. Zhang, and co‐workers (DOI: 10.1002/chem.202201517).
Selective electrochemical hydrogenation of alkynes to alkenes under ambient conditions is a promising alternative to the traditional energy‐intensive and high‐cost thermocatalytic hydrogenation. ...However, the systematic summary on the electrocatalysts and electrolyzers remains lacked. Herein, we demonstrate a comprehensive review about recent achievements in the electrocatalysts including noble metal and non‐noble‐metal materials. Several effective strategies of catalyst design were developed to improve alkyne conversion, and alkene selectivity, for example, accelerating the formation of active hydrogen species, enhancing alkyne adsorption and suppressing the side reactions. Furthermore, the advantages and disadvantages of various electrolyzers are systematically discussed. Accordingly, major challenges and future trends in this field are proposed.
Electrochemical hydrogenation of alkynes to alkenes is a potential candidate to traditional thermocatalytic process. Alkynes adsorption, hydrogenation and alkenes desorption intrinsically determine the activity and alkene selectivity. In this review, the advances in electrocatalysts and electrolyzers for selective hydrogenation of alkynes are focused.
Nickel phosphide is a promising catalyst for hydrogenation of nitroarenes but suffers from sluggish H desorption and low chemoselectivity. Herein, we overcome these problems through reducing the Ni2P ...into subnanosized clusters, tailoring the d-band center of Ni, and coupling them with P-doped carbon. Using density functional theory (DFT) calculations, we predicted that electron transfer from P-doped carbon to Ni2P cluster results in downshift of d-band center of Ni that promotes H desorption on highly charged antibonding orbital of Ni–H, and reactant is preferentially adsorbed on P-doped carbon surface through nitro group due to the geometrical hindrance on Ni2P clusters that leads to good selectivity. Then we developed a chemical anchoring method to fabricate Ni2P supported on P-doped carbon with high dispersion of 81.3%. The synthesized catalyst delivers high activity and selectivity chemoselective hydrogenation of nitroarenes, and outperforms various noble- and transition-metal catalysts. Moreover, we revealed the origins of the superior performance of catalyst by characterizations, and confirmed the conclusion of DFT calculation. Such concept of tailoring d-band center and improving dispersion of active phase can provide insight for design of catalysts for hydrogenation and beyond.
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