A Modulation QCM Applied to Copper Electrodeposition and Stripping

A fast electrochemical quartz crystal microbalance with dissipation monitoring (EQCM−D) was applied to copper electrodeposition and subsequent stripping. Accumulation brings the frequency noise down to the mHz range, corresponding to 0.1 % of a monolayer. With this precision, the apparent mass transfer rate as determined from the time-derivative of the frequency shift can be directly compared to the current. Small but systematic deviations between the two can be attributed to nanoscale roughness. In the voltage range of underpotential deposition (UPD), the apparent mass transfer rate shows peaks and shoulders. The plating additive benzotriazole (BTA) leaves the magnitude of electrogravimetric signals unchanged, but shifts the UPD onset potential. The additive thiourea (TU) promotes UPD and strongly increases the bandwidth.     

The dilation property of modulation spaces and their inclusion relation with Besov spaces

We consider the dilation property of the modulation spaces Mp,q. Let be the dilation operator, and we consider the behavior of the operator norm ‖Dλ_‖Mp,q→Mp,q with respect to λ. Our result determines the best order for it, and as an application, we establish the optimality of the inclusion relation between the modulation spaces and Besov spaces, which was proved by Toft [J. Toft, Continuity properties for modulation spaces, with applications to pseudo-differential calculus, I, J. Funct. Anal. 207 (2004) 399-429].     

Facile Tuned TSCT-TADF in Donor-Acceptor MOF for Highly Adjustable Photonic Modules based on Heterostructures Crystals

Highly adjustable photonic modules were constructed based on the heterostructures crystals of a new series of donor-acceptor metal–organic framework (D-A MOF) featuring highly tunable thermally activated delayed fluorescence (TADF). By introducing N-phenylcarbazole and derivatives as donor guests into the acceptor host NKU-111, highly tunable through-space charge transfer based TADF could be achieved through the engineering of heavy atom effect, which result in modulatable emission wavelength (540 to 600 nm) and enhanced quantum yield (up to 30.86 %). Furthermore, by rationally integrating the D-A MOFs with distinctive emissions, rod-like heterostructures crystals featuring excitation position dependent tip emissions in wide wavelength range (495 to 598 nm) could be fabricated, which could serve as highly potential photonic modules for photonic circuit applications.     

A Heptacene Analogue Entailing a Quinoidal Benzodi[7]annulene (7/6/7 Ring) Core with a Tunable Configuration and Multiple Redox Properties

Non-benzenoid acenes containing heptagons have received increasing attention. We herein report a heptacene analogue containing a quinoidal benzodi[7]annulene core. Derivatives of this new non-benzenoid acene were obtained through an efficient synthetic strategy involving an Aldol condensation and a Diels–Alder reaction as key steps. The configuration of this heptacene analogue can be modulated from a wavy to a curved one by just varying the substituents from a (triisopropylsilyl)ethynyl group to a 2,4,6-triisopropylphenyl (Trip) group. When mesityl (Mes) groups are linked to the heptagons, the resulting non-benzenoid acene displays polymorphism with a tunable configuration from a curved to a wavy one upon varying the crystallization conditions. In addition, this new non-benzenoid acene can be oxidized or reduced by NOSbF₆ or KC₈ to the respective radical cation or radical anion. Compared with the neutral acene, the radical anion shows a wavy configuration and the central hexagon becomes aromatic.     

Coordination-Modulated Metal Tetrathiafulvalene Octacarboxylate Frameworks for High-Performance Lithium-Ion Battery Anodes

Modulation of the ligands and coordination environment of metal–organic frameworks (MOFs) has been an effective and relatively unexplored avenue for improving the anode performance of lithium-ion batteries (LIBs). In this study, three MOFs are synthesized, namely, M₄(o-TTFOB)(bpm)₂(H₂O)₂ (where M is Mn, Zn, and Cd; o-H₈TTFOB is ortho-tetrathiafulvalene octabenzoate; and bpm is 2,2′-bipyrimidine), based on a new ligand o-H₈TTFOB with two adjacent carboxylates on one phenyl, which allows us to establish the impact of metal coordination on the performance of these MOFs as anode materials in LIBs. Mn-o-TTFOB and Zn-o-TTFOB, with two more uncoordinated oxygen atoms from o-TTFOB⁸⁻, show higher reversible specific capacities of 1249 mAh g⁻¹ and 1288 mAh g⁻¹ under 200 mA g⁻¹ after full activation. In contrast, Cd-o-TTFOB shows a reversible capacity of 448 mAh g⁻¹ under the same condition due to the lack of uncoordinated oxygen atoms. Crystal structure analysis, cyclic voltammetry measurements of the half-cell configurations, and density functional theory calculations have been performed to explain the lithium storage mechanism, diffusion kinetics, and structure-function relationship. This study demonstrates the advantages of MOFs with high designability in the fabrication of LIBs.     

Enhanced Metal-Support Interactions Boost the Electrocatalytic Water Splitting of Supported Ruthenium Nanoparticles on a Ni3N/NiO Heterojunction at Industrial Current Density

Developing highly efficient and stable hydrogen production catalysts for electrochemical water splitting (EWS) at industrial current densities remains a great challenge. Herein, we proposed a heterostructure-induced-strategy to optimize the metal-support interaction (MSI) and the EWS activity of Ru-Ni₃N/NiO. Density functional theory (DFT) calculations firstly predicted that the Ni₃N/NiO-heterostructures can improve the structural stability, electronic distributions, and orbital coupling of Ru-Ni₃N/NiO compared to Ru-Ni₃N and Ru-NiO, which accordingly decreases energy barriers and increases the electroactivity for EWS. As a proof-of-concept, the Ru-Ni₃N/NiO catalyst with a 2D Ni₃N/NiO-heterostructures nanosheet array, uniformly dispersed Ru nanoparticles, and strong MSI, was successfully constructed in the experiment, which exhibited excellent HER and OER activity with overpotentials of 190 mV and 385 mV at 1000 mA cm⁻², respectively. Furthermore, the Ru-Ni₃N/NiO-based EWS device can realize an industrial current density (1000 mA cm⁻²) at 1.74 V and 1.80 V under alkaline pure water and seawater conditions, respectively. Additionally, it also achieves a high durability of 1000 h (@ 500 mA cm⁻²) in alkaline pure water.     

Chiral Gold Nanorods with Five-Fold Rotational Symmetry and Orientation-Dependent Chiroptical Properties of Their Monomers and Dimers

Chiral plasmonic nanoparticles have attracted much attention because of their strong chiroptical responses and broad scientific applications. However, the types of chiral plasmonic nanoparticles have remained limited. Herein we report on a new type of chiral nanoparticle, chiral Au nanorod (NR) with five-fold rotational symmetry, which is synthesized using chiral molecules. Three different types of Au seeds (Au elongated nanodecahedrons, nanodecahedrons, and nanobipyramids) are used to study the growth behaviors. Different synthesis parameters, including the chiral molecules, surfactant, reductant, seeds, and Au precursor, are systematically varied to optimize the chiroptical responses of the chiral Au NRs. The chiral scattering measurements on the individual chiral Au NRs and their dimers are performed. Intriguingly, the chiroptical signals of the individual chiral Au NRs and their end-to-end dimers are similar, while those of the side-by-side dimers are largely reduced. Theoretical calculations and numerical simulations reveal that the different chiroptical responses of the chiral NR dimers are originated from the coupling effect between the plasmon resonance modes. Our study enriches chiral plasmonic nanoparticles and provides valuable insight for the design of plasmonic nanostructures with desired chiroptical properties.     

Comprehensive two-dimensional gas chromatography— A discussion on recent innovations

Although comprehensive 2-D GC is an established and often applied analytical method, the field is still highly dynamic thanks to a remarkable number of innovations. In this review, we discuss a number of recent developments in comprehensive 2-D GC technology. A variety of modulation methods are still being actively investigated and many exciting improvements are discussed in this review. We also review interesting developments in detection methods, retention modeling, and data analysis.     

一种重构辐射噪声调制谱的方法

在进行辐射噪声信号的仿真研究中,希望利用经滤波、特征提取等处理所得到的反映目标特性的线谱、连续谱、调制谱来重构辐射噪声,以便于研究辐射噪声在声场中的传播特性。本文提出了利用迭代算法估算调制深度谱的算法,给出了时域辐射噪声的重构模型,以实测数据的调制谱为出发点,来重构其时域信号,并对重构前后的调制谱进行了误差分析,取得了较好的效果。