The unique carrier mobility of Janus MoSSe/GaN heterostructures

Heterostructure is an effective approach in modulating the physical and chemical behavior of materials. Here, the first-principles calculations were carried out to explore the structural, electronic, and carrier mobility properties of Janus MoSSe/GaN heterostructures. This heterostructure exhibits a superior high carrier mobility of 281.28 cm²·V⁻¹·s⁻¹ for electron carrier and 3951.2 cm²·V⁻¹·s⁻¹ for hole carrier. Particularly, the magnitude of the carrier mobility can be further tuned by Janus structure and stacking modes of the heterostructure. It is revealed that the equivalent mass and elastic moduli strongly affect the carrier mobility of the heterostructure, while the deformation potential contributes to the different carrier mobility for electron and hole of the heterostructure. These results suggest that the Janus MoSSe/GaN heterostructures have many potential applications for the unique carrier mobility.     

Emissions of PM10 from the co-combustion of high-Ca pyrolyzed biochar and high-Si coal under air and oxyfuel atmosphere

The single or co-combustion experiments of high-Ca pyrolyzed biochar and high-Si coal were carried out on a drop tube furnace (DTF) at 1300 °C under air and oxyfuel (CO₂:O₂=50:50, oxy50) conditions. The produced PM₁₀ (of an aerodynamic diameter of 10 µm or less) was analyzed to investigate the interactions during co-combustion. Due to the characteristics of the selected samples (low S and Cl), the PM₁ emissions including PM_0.1 and PM_0.1–1 are very low during single combustion, except for the PM_0.1–1 emission during the combustion of biochar under oxy50 condition because of the massive partitioning of Mg, Ca and Fe. The interaction during co-combustion was observed to mainly occur in the generation of PM_1–10, and also slightly occur in the formation of PM_0.1–1 under oxy50 condition. The capture of Mg, Ca, and Fe from biochar by the Si-containing minerals in coal under the oxy50 condition results in a slight decrease in PM_0.1–1 during co-combustion. The higher the proportion of coal blended, the more obvious the reduction of elements. As for the formation of PM_1–10 during co-combustion, high-melting minerals of biochar would weaken the coalescence of minerals in coal to cause more PM₁₀, while the large mineral grains of coal would capture the minerals in biochar to generate more PM₁₀₊. Under the competition of the above two types of interactions, the experimental value of PM_1–10 yields was almost consistent with the theoretically calculated value, except for blended ratio of 80:20 (coal: biochar, air) or 50:50 (oxy50) with prior interaction predominating.     

Effect of cellulose–lignin interactions on char structural changes during fast pyrolysis at 100–350 °C

This study investigates the cellulose–lignin interactions during fast pyrolysis at 100–350 °C for better understanding fundamental pyrolysis mechanism of lignocellulosic biomass. The results show that co-pyrolysis of cellulose and lignin (with a mass ratio of 1:1) at temperatures < 300 °C leads to a char yield lower than the calculated char yield based on the addition of individual cellulose and lignin pyrolysis. The difference between the experimental and calculated char yields increases with temperature, from ～2% 150 °C to ～6% at 250 °C. Such differences in char yields provide direct evidences on the existence of cellulose–lignin interactions during co-pyrolysis of cellulose and lignin. At temperatures below 300 °C, the reductions in both lignin functional groups and sugar structures within the char indicate that co-pyrolysis of cellulose and lignin enhances the release of volatiles from both cellulose and lignin. Such an observation could be attributed to two possible reasons: (1) the stabilization of lignin-derived reactive species by cellulose-derived reaction intermediates as hydrogen donors, and (2) the thermal ejection of cellulose-derived species due to micro-explosion of liquid intermediates from lignin. In contrast, at temperatures ≥ 300 °C, co-pyrolysis of cellulose and lignin increases char yields, i.e., with the difference between the experimental and calculated char yields increasing from ～1% at 300 °C to ～8% at 350 °C. The results indicate that the cellulose-derived volatiles are difficult to diffuse through the lignin-derived liquid intermediates into the vapor phase, leading to increased char formation from co-pyrolysis of cellulose and lignin as temperature increases. Such an observation is further supported by the increased retention of cellulose functional groups in the char from co-pyrolysis of cellulose and lignin.     

Synthesis and characterization of tetraoctyloxy substituted naphthalenophanedienes

Tetraoctyloxy-substituted naphthalenophanedienes were synthesized from tetraoctyloxy-substituted dithia[3.3]naphthalenophanes via sequential benzyne Stevens rearrangement, oxidation, and pyrolysis reactions. Surprisingly, only the pseudo-geminal isomer of tetraoctyloxy-substituted dithia[3.3]naphthalenophane was obtained after cyclization of the corresponding starting materials. The structures of the pseudo-geminal isomers of tetraoctyloxy-substituted dithia[3.3]naphthalenophane and tetraoctyloxy-substituted naphthalenophanediene were fully determined by nuclear magnetic resonance spectroscopy, high resolution mass spectrometry, and X-ray crystallography. The pseudo-geminal and pseudo-meta diastereomers of tetraoctyloxy-substituted naphthalenophanedienes were isolated by multiple fractional recrystallization from hexane at 5 °C. The solid state structure of the pseudo-geminal isomer of tetraoctyloxy-substituted naphthalenophanediene revealed strongly distorted naphthyl rings with high levels of ring strain.     

NMR and theoretical study on the linking properties of peroxovanadium(V) complexes with the 3-aminomethyl-pyridine derivatives

To understand the substitution effects of 3-aminomethyl-pyridine on the reaction equilibrium, the interactions between a series of 3-aminomethyl-pyridine derivatives and peroxovanadium(V) complex [OV(O₂)₂(D₂O)]^?/[OV(O₂)₂(HOD)]^? in solution were explored by the combined use of multinuclear (¹H, ¹³C, and ⁵¹V) magnetic resonance spectroscopy together with HSQC in 0.15 M NaCl ionic medium for mimicking the physiological conditions. Some direct NMR data are given for the first time. The relative reactivity among the 3-aminomethyl-pyridine derivative ligands are N-(pyridin-3-ylmethyl)acetamide (1) ≈ N-(pyridin-3-ylmethyl)propionamide (2) > N-(pyridin-3-ylmethyl)pivalamide (3) > t-butyl(pyridin-3-ylmethyl)carbamate (4). The competitive coordination results in the formation of a series of new six-coordinate peroxovanadium species [OV(O₂)₂L]^? (L = 1–4). The results of density functional calculations indicated that the solvation effects play an important role in these reactions, providing a reasonable explanation on the relative reactivity of the 3-aminomethyl-pyridine derivatives.     

A Practical High-Energy Cathode for Sodium-Ion Batteries Based on Uniform P2-Na0.7CoO2 Microspheres

Layered metal oxides have attracted increasing attention as cathode materials for sodium-ion batteries (SIBs). However, the application of such cathode materials is still hindered by their poor rate capability and cycling stability. Here, a facile self-templated strategy is developed to synthesize uniform P2-Na_0.7CoO₂ microspheres. Due to the unique microsphere structure, the contact area of the active material with electrolyte is minimized. As expected, the P2-Na_0.7CoO₂ microspheres exhibit enhanced electrochemical performance for sodium storage in terms of high reversible capacity (125 mAh g⁻¹ at 5 mA g⁻¹), superior rate capability and long cycle life (86 % capacity retention over 300 cycles). Importantly, the synthesis method can be easily extended to synthesize other layered metal oxide (P2-Na_0.7MnO₂ and O3-NaFeO₂) microspheres.     

Quantum reaction dynamics of C(1D) + HD → CH(CD) + D(H) on the ground state potential energy surface

We present accurate quantum dynamic calculations of the reaction C(¹D) + HD on the latest version of the potential energy surface [Zhang et al., J. Chem. Phys. 140, 234301 (2014)]. Using a Chebyshev real wave packet method with full Coriolis coupling, we obtain the initial state‐specified ( ) reaction probabilities, integral cross sections, and rate constants. The resulting probabilities display oscillatory structures due to numerous long‐lived resonances supported by the deep potential well. The calculated rate constants and CD/CH product branching ratio at room temperature are in reasonably good agreement with the experimental measurements.     

高效固体酸SBA-15-Zr(OTf)3催化胺或醇开环环氧化合物

通过简单的一锅两步法制备了三氟金属(铝,钛,锆)接枝介孔SBA-15 (AlTf/S,TiTf/S,ZrTf/S)固体酸材料,并通过XRD,N2吸附,TGA,FTIR,原位吡啶FTIR和元素分析对这些材料进行了详细的表征.其中,ZrTf/S能够高效催化环氧化物温和条件下被胺或醇开环生成对应β-氨基醇或β-烷氧基醇,并且催化剂能循环利用.ZrTf/S相较于AlTf/S和TiTf/S酸性最强,因而催化活性也最高.