Interfacial Engineering in PtNiCo/NiCoS Nanowires for Enhanced Electrocatalysis and Electroanalysis

Searching for new anti-poisoning Pt-based catalysts with enhanced activity for alcohol oxidation is the key in direct alcohol fuel cells (DAFCs). However, in the traditional strategy for designing bimetallic or multimetallic alloy is still difficult to achieve a satisfactory heterogeneous electrocatalyst because the activity often depends on only the surface atoms. Herein, we fabricate the multicomponent active sites by creating a sulfide structure on 1D PtNiCo trimetallic nanowires (NWs), to give a PtNiCo/NiCoS interface NWs (IFNWs). Owing to the presence of sulfide interfaces, the PtNiCo/NiCoS IFNWs enable an impressive methanol/ethanol oxidation reaction (MOR/EOR) performance and excellent anti-CO poisoning tolerance. They have the MOR and EOR mass activities of 2.25 Amg^-1_Pt and 1.62 Amg^-1_Pt, around 1.26, 3.21 and 1.46, 2.96 times higher than those of PtNiCo NWs and commercial Pt/C, respectively. CO-stripping and XPS measurements further demonstrate that the new interfacial structure and optimal bonding of Pt−CO can result in accelerating the removal of surface adsorbed carbonaceous intermediates. Moreover, such a unique structure has also demonstrated a much-improved ability for the electrochemical detection of some important molecules (H₂O₂ and NH₂NH₂).     

Are Hetero-metallapentalenes Aromatic or Not? A DFT Investigation

Aromaticity is one of the most basic concepts in organic chemistry. The planar Möbius aromatic metallapentalynes and metallapentalenes have attracted considerable attention in the past few years. However, the aromaticity of metallapentalenes containing heteroatoms (such as B, N, and O), termed as hetero-metallapentalenes, is rarely studied. Herein, the stability and aromaticity of a series of hetero-metallapentalenes are theoretically investigated. The results reveal lower aromaticity in metallaborapentalene, comparable aromaticity in metallazapentalene, and nonaromaticity in metalloxapentalene relative to that of metallapentalene. Moreover, the effect of Lewis bases on the aromaticity and stability of metallaborapentalene is discussed. These results provide useful information for experimental chemists to realize more hetero-metallapentalenes.     

Toward Understanding the Enhanced Pseudocapacitive Storage in 3D SnS/MXene Architectures Enabled by Engineered Surface Reactions

The optimization of three-dimensional (3D) MXene-based electrodes with desired electrochemical performances is highly demanded. Here, a precursor-guided strategy is reported for fabricating the 3D SnS/MXene architecture with tiny SnS nanocrystals (≈5 nm in size) covalently decorated on the wrinkled Ti₃C₂T_x nanosheets through Ti−S bonds (denoted as SnS/Ti₃C₂T_x-O). The formation of Ti−S bonds between SnS and Ti₃C₂T_x was confirmed by extended X-ray absorption fine structure (EXAFS). Rather than bulky SnS plates decorated on Ti₃C₂T_x (SnS/Ti₃C₂T_x-H) by one-step hydrothermal sulfidation followed by post annealing, this SnS/Ti₃C₂T_x-O presents size-dependent structural and dynamic properties. The as-formed 3D hierarchical structure can provide short ion-diffusion pathways and electron transport distances because of the more accessible surface sites. In addition, benefiting from the tiny SnS nanocrystals that can effectively improve Na⁺ diffusion and suppress structural variation upon charge/discharge processes, the as-obtained SnS/Ti₃C₂T_x-O can generate pseudocapacitance-dominated storage behavior enabled by engineered surface reactions. As predicted, this electrode exhibits an enhanced Na storage capacity of 565 mAh g⁻¹ at 0.1 A g⁻¹ after 75 cycles, outperforming SnS/Ti₃C₂T_x-H (336 mAh g⁻¹), SnS (212 mAh g⁻¹), and Ti₃C₂T_x (104 mAh g⁻¹) electrodes.     

Continuous Electrochemical Synthesis of Iso-Coumarin Derivatives from o-(1-Alkynyl) Benzoates under Metal- and Oxidant-Free

A non-oxidant and metal-free strategy for synthesizing iso-coumarin by using a continuous electrochemical microreactor to initiate an oxidative cyclization reaction of o-(1-alkynyl) benzoate and radicals. This efficient and clean continuous electrosynthesis method not only avoids the complicated gas protection operation and production of by-products in the batch processes, but also help to overcome the difficulty that batch metal catalysis and electrocatalysis are difficult to scale up, and has the potential for pilot-scale experiment.     

Interaction properties of double-hump solitons in the dispersion decreasing fiber

Nonlinear Dynamics - In this paper, the high-order coupled variable coefficient nonlinear Schrödinger equations is studied. The double-hump soliton solutions for the equations are obtained...     

Method validation,residue analysis and dietary risk assessment of trifloxystrobin and trifloxystrobin acid in milk,eggs and pork

Trifloxystrobin (TFS) is a widely used strobilurin fungicide and its residues accumulating in animal-derived food could result in potential harm to consumers. By optimization of extraction solvents and cleanup sorbents, a residue analysis method for TFS and its metabolite trifloxystrobin acid (TFSA) was established in milk, eggs and pork based on QuEChERS sample preparation and LC–MS/MS. The calibration curves exhibited good linearity with determination coefficients (R²) >0.9930 over the range of 0.5–250 ng/ml for both TFS and TFSA. The recoveries of the two analytes were 81–100% with RSD 3–10% and 76–96% with RSD 2–13%, respectively. The limit of quantification (LOQ) was 1 ng/g for both analytes. The milk, egg and pork samples, 30 each, were collected from the 30 main producing regions in China, and residues of TFS and TFSA were analyzed. The concentrations of both analytes were lower than the corresponding LOQs and maximum residue limits. Long-term dietary risk assessment showed that the hazard quotients were 0.001–0.003%, indicating an absence of unacceptable risks in milk, eggs and pork to the health of common consumers in China.     

Chemical Constituents of Corydalis saxicola

Chemistry of Natural Compounds -