Au/Pt and Au/Pt(3)Ni nanowires as self-supported electrocatalysts with high activity and durability for oxygen reduction

Novel Au/Pt and Au/Pt(3)Ni nanostructures consisting of Pt and Pt(3)Ni alloy nanodendrites grown on Au nanowires were synthesized, which exhibited high electrocatalytic activity and durability toward oxygen reduction when used as self-supported catalysts.NSFC[21131005, 21021061, 20925103, 20871100]; MOST of China[2011CB932403, 2009CB930703]; NSF of Fujian Province[2009J06005]; Fok Ying Tung Education Foundation[121011]; Key Scientific Project of Fujian Province[2009HZ0002-1]; China Postdoctoral Science Foundation[20100480716

A Mechanistic Study of Asymmetric Transfer Hydrogenation of Imines on a Chiral Phosphoric Acid Derived Indium Metal-Organic Framework

A density functional theory (DFT) study is reported to examine the asymmetric transfer hydrogenation (ATH) of imines catalyzed by an indium metal-organic framework (In-MOF) derived from a chiral phosphoric acid (CPA). It is revealed that the imine and reducing agent (i.e., thiazoline) are simultaneously adsorbed on the CPA through H-bonding to form an intermediate, subsequently, a proton is transferred from thiazoline to imine. The transition state TS-R and TS-S are stabilized on the CPA via H-bonding. Compared to the TS-S, the TS-R has shorter H-bonding distances and longer C-H···π distances, it is more stable and experiences less steric hindrance. Consequently, the TS-R exhibits a lower activation barrier affording to the (R)-enantiomer within 68.1% ee in toluene. Imines with substituted groups such as −NO2, −F, and −OCH3 are used to investigate the substitution effects on the ATH. In the presence of an electron-withdrawing group like −NO2, the electrophilicity of imine is enhanced and the activation barrier is decreased. The non-covalent interactions and activation-strain model (ASM) analysis reveal that the structural distortions and the differential noncovalent interactions of TSs in a rigid In-MOF provide the inherent driving force for enantioselectivity. For −OCH3 substituted imine, the TS-S has the strongest steric hindrance, leading to the highest enantioselectivity. When the solvent is changed from toluene to dichloromethane, acetonitrile, and dimethylsulfoxide with increasing polarity, the activation energies of transition state increase whereas their difference decreases. This implies the reaction is slowed down and the enantioselectivity becomes lower in a solvent of smaller polarity. Among the four solvents, toluene turns out to be the best for the ATH. The calculated results in this study are in fairly good agreement with experimental observations. This study provides a mechanistic understanding of the reaction mechanism, as well as substitution and solvent effects on the activity and enantioselectivity of the ATH. The microscopic insights are useful for the development of new chiral MOFs toward important asymmetric reactions

Temporal Landmarks and Nostalgic Consumption: The Role of the Need to Belong

This study investigates the influence of temporal landmarks on nostalgic consumption through the mediating role of the need to belong. In particular, the study identifies end landmarks as one of the triggers of landmarks, a phenomenon that has not been studied in the existing nostalgic consumption literature. The research is composed of one pilot study and three experiments to test our research hypotheses. The results show that end temporal landmarks trigger feelings of nostalgia, which leads to nostalgic consumption through the need to belong. This study underscores the mediating role of the need to belong, which plays an important role in leading to nostalgic consumption. Building upon theoretical perspectives on the need to belong, our study enriches the research literature by linking extreme consumer emotional statuses, such as social anxiety, to the consumer need to belong, showing that consumer nostalgic consumption can become a coping strategy that counteracts these negative feelings and helps in regaining connection and supporting social relationship networks. Marketers may use the signs of end temporal landmarks to increase consumers’ nostalgia, which, in turn, will enhance consumers’ need to belong and thus lead to the purchasing and consumption of nostalgic products

Role of Chiral Skeleton in Chiral Phosphoric Acids Catalyzed Asymmetric Transfer Hydrogenation: A DFT Study

Chiral phosphoric acids (CPAs) have received considerable attention due to their high activity for enantioselective transformations. However, the role of various chiral skeletons of CPAs in regulating the mechanism and enantioselectivity of asymmetric transfer hydrogenation has remained unclear. Density functional theory (DFT) calculations are performed to elucidate the role of chiral skeletons on the acidity, mechanism, enantioselectivity, and kinetic stabilities of transition states (TSs) in Asymmetric Transfer Hydrogen (ATH) reaction catalyzed by five CPAs. We found that the acidity of CPAs is strongly dependent on the chiral skeleton. The origin of enantioselectivity of ATH reaction arises from the differential noncovalent interactions between TSs and CPAs. Moreover, the shape and size of the catalyst pocket depending on chiral skeletons play key roles in the stability of TSs and the enantioselectivity of ATH. This study might facilitate to design and computationally screening of CPAs and guide the strategic choice of CPA skeletons to reduce the experimental workload

Pretreatment of Lithium Surface by Using Iodic Acid (HIO₃) To Improve Its Anode Performance in Lithium Batteries

Iodic acid (HIO₃) was exploited as the effective source to build an artificial solid-electrolyte interphase (SEI) on the surface of Li anode. On one hand, HIO₃ is a weak solid-state acid and can be easily handled to remove most ion-insulating residues like Li₂CO₃ and/or LiOH from the pristine Li surface; on the other hand, both the products of LiI and LiIO₃ resulted from the chemical reactions between Li metal and HIO₃ are reported to be the ion-conductive components. As a result, the lower voltage polarization and impedance, longer cycling lifetime and higher Coulombic efficiency have been successfully achieved in the HIO₃-treated Li–Li and Li–Cu cells. By further using the HIO₃-treated Li anode into practical Li–S batteries, the impressive results also have been obtained, with average discharge capacities of 719 mAh g^–1 for 200 cycles (0.2 C) and 506 mAh g^–1 for 500 cycles (0.5 C), which were better than the Li–S batteries using the pristine Li anode (552 and 401 mAh g^–1, respectively) under the same conditions

Supplementary document for Cross-connection of multiplexed cylindrical vector beams using off-axis spin-decoupled metasurfaces - 6948891.pdf

Supplement