Insights into the Potassium Ion Storage Behavior and Phase Evolution of a Tailored Yolk-Shell SnSe@C Anode.

Tin chalcogenides are regarded as promising anode materials for potassium ion batteries (PIBs) due to their considerable specific capacity. However, the severe volume effect, limited electronic conductivity, and the shuttle effect of the potassiation product restrict the application prospect. Herein, based on the metal evaporation reaction, a facile structural engineering strategy for yolk-shell SnSe encapsulated in carbon shell (SnSe@C) is proposed. The internal void can accommodate the volume change of the SnSe core and the carbon shell can enhance the electronic conductivity. Combining qualitative and quantitative electrochemical analyses, the distinguished electrochemical performance of SnSe@C anode is attributed to the contribution of enhanced capacitive behavior. Additionally, first-principles calculations elucidate that the heteroatomic doped carbon exhibits a preferable affinity toward potassium ions and the potassiation product K2 Se, boosting the rate performance and capacity retention consequently. Furthermore, the phase evolution of SnSe@C electrode during the potassiation/depotassiation process is clarified by in situ X-ray diffraction characterization, and the crystal transition from the SnSe Pnma(62) to Cmcm(63) point group is discovered unpredictably. This work demonstrates a pragmatic avenue to tailor the SnSe@C anode via a facile structural engineering strategy and chemical regulation, providing substantial clarification for the phase evolution mechanism of SnSe-based anode for PIBs.

An Exergoeconomic Analysis of a Gas-Type Industrial Drying System of Black Tea.

The performance evaluation and optimization of an energy conversion system design of an energy intensive drying system applied the method of combining exergy and economy is a theme of global concern. In this study, a gas-type industrial drying system of black tea with a capacity of 100 kg/h is used to investigate the exergetic and economic performance through the exergy and exergoeconomic methodology. The result shows that the drying rate of tea varies from the maximum value of 3.48 gwater/gdry matter h to the minimum 0.18 gwater/gdry matter h. The highest exergy destruction rate is found for the drying chamber (74.92 kW), followed by the combustion chamber (20.42 kW) in the initial drying system, and 51.83 kW and 21.15 kW in the redrying system. Similarly, the highest cost of the exergy destruction rate is found for the drying chamber (18.497 USD/h), followed by the combustion chamber (5.041 USD/h) in the initial drying system, and 12.796 USD/h and 5.222 USD/h in the redrying system. Furthermore, we analyzed the unit exergy rate consumed and the unit exergy cost of water removal in different drying sections of the drying system, and determined the optimal ordering of each component. These results mentioned above indicate that, whether from an energy or economic perspective, the component improvements should prioritize the drying chamber. Accordingly, minimizing exergy destruction and the cost of the exergy destruction rate can be considered as a strategy for improving the performance of energy and economy. Overall, the main results provide a more intuitive judgment for system improvement and optimization, and the exergy and exergoeconomic methodology can be commended as a method for agricultural product industrial drying from the perspective of exergoeconomics.

An ultrasensitive electrochemiluminescent sensor based on a pencil graphite electrode modified with CdS nanorods for detection of chlorogenic acid in honeysuckle.

In this paper, a novel and ultrasensitive electrochemiluminescent sensor employing a solvothermal-synthesized CdS nanorod-modified pencil graphite electrode (CdS/PGE) for the determination of chlorogenic acid (CA) is fabricated. In the first step, the PGE surface is modified using CdS nanorods. In the next step, the developed electrode is used to detect CA using a electrochemiluminescent (ECL) technique, in which potassium persulfate (K2 S2 O8 ) served as a co-reactant. The possible ECL mechanism is investigated, and the influences of pH and cyclic voltammetric scanning rate on the signal response are studied. The ECL intensity decreases quantitatively in relation to the concentration of the target molecule. Under optimized conditions, the linear correlation between the quenched ECL intensity and the logarithm of CA concentration is observed in the range from 2 × 10-9 to 8 × 10-7  mol L-1 with a limit of detection of 1 × 10-9  mol L-1 . This proposed method is applied to the analysis of CA in honeysuckle flower, giving recoveries of 99-107%. The experimental results demonstrate that this ECL sensor shows good stability and reproducibility.

Adsorption of perfluorooctane sulfonate on carbonized poly-melamine-formaldehyde sponge.

In this study, we developed a simple carbonized poly-melamine-formaldehyde sponge (CMF) acting as an adsorbent for adsorbing perfluorooctane sulfonate (PFOS) from the waste poly-melamine-formaldehyde (MF) sponge. The PFOS removal by the developed adsorbent was comprehensively investigated using batch adsorption, including kinetics, isotherm, ionic strength and ionic type and pH edge. PFOS adsorption kinetics followed a pseudo-second-order kinetic model, and reached equilibrium within 3 min. The adsorption isotherm was well described by the Freundlich model, as well as by the Langmuir model at a low initial concentration. The adsorption capacity gradually decreased with the increase of pH, and it was up to 216.4 µg/g even at pH 12.1. However, the adsorption capacity increased with the increase in ionic strength. Furthermore, the co-existing ions and small organic acids also promoted the PFOS adsorption on CMF sponge to different extents. Both the hydrophobic interaction and electrostatic attraction played an important role on adsorption, as well as chemical interaction and hydrogen bonding from spectroscopic results.

Structurally diverse halosesquiterpenoids from the red alga Laurencia composita Yamada.

A phytochemical investigation on the MeOH extract of the red alga Laurencia composita Yamada led to the discovery of six new highly halogenated sesquiterpenoids, including two bisabolane-type sesquiterpenoids (1 and 2), one nerolidol derivative (7), and three chamigrane-type sesquiterpenoids (9, 10, and 18), together with 13 known sesquiterpenoids. Their structures, including relative configuration, were elucidated by extensive spectroscopic analysis, and by comparison with data for related known compounds. The absolute configuration at C-10 of laurecomposin A (1) was determined by the modified Mosher's method. Halonerolidol (7) is the first naturally occurring halogenated nerolidol derivative, while compositacin L (9) represents the third example of chamigranes having a C-10 carbonyl group. Antifungal, antibacterial, and receptor tyrosine kinase inhibitory activities of these isolates were evaluated. The results showed that compounds 1-3 and 5 exhibited significant antifungal activity against Microsporum gypseum (Cmccfmza) with MIC values of 4, 8, 8, and 4 µg/mL, respectively. Additionally, compounds 1-3 and 5 also displayed promising antibacterial activity against Gram-positive bacteria Staphylococcus aureus Newman strain with MIC values ranging from 10.9 to 26.8 µg/mL.

The preparation of Ni/Mo-based ternary electrocatalysts by the self-propagating initiated nitridation reaction and their application for efficient hydrogen production.

In the hydrogen evolution reaction (HER), multi-component electrocatalysts with a synergistic effect may possess enhanced catalytic activity and broadened applicability in both acidic and alkaline media. Herein, we developed a novel strategy via the self-propagating initiated nitridation reaction for the synthesis of Mo2C, MoNi4, and Ni2Mo3N nanocrystals as active components assembled in a multiscale porous honeycomb-like carbon (Ni/MoCat@HCC). This strategy can be realized by simply calcining (NH4)6Mo7O24 and Ni(NO3)2 precursor hybrids under a H2/Ar atmosphere at a fairly low temperature of 600 °C. It relies on the in situ thermal decomposition of (NH4)6Mo7O24 and the subsequent nitridation reaction with released NH3, thus avoiding the continuous purging of NH3 in the conventional method. The rich reaction intermediates during the calcination of bimetallic precursors also offer other catalytically active components that are controllable by varying the calcining procedure. Benefiting from the multiscale porous structure, ultrafine size of catalyst particles, and strong synergistic effect of several catalytically active components, the as-prepared Ni/MoCat@HCC exhibits extraordinary HER electrocatalytic activity with low onset overpotentials, small Tafel slopes, and excellent cycling stability in both acidic and alkaline media, outperforming most current noble-metal-free electrocatalysts. This study paves a novel way for synthesizing multi-component electrocatalysts with enhanced catalysis performance.

Fast synthesis of porous copper nanoclusters for fluorescence detection of iron ions in water samples.

Copper nanoclusters (Cu NCs) have attracted great research interest in recent years owing to its unique physical, electrical and optical properties. Macromolecules have been widely used as templates to synthesize fluorescent Cu NCs. In this study, a simple method for synthesis of albumin chicken egg capped porous copper nanoclusters (p-Cu NCs) was developed for the first time. The obtained p-Cu NCs exhibited intense emission and excitation peaks at 280 nm and 340 nm, respectively. Besides, the p-Cu NCs fluorescence probe could be quenched by Fe3+ ions in aqueous solutions. Therefore, the p-Cu NCs can be excellently candidated as fluorescent probe for the detection of Fe3+ ions. Under optimized conditions, this fluorescent probe exhibited a wide linear response concentration range (0.2 to 100 µM) to Fe3+ with a detection limit of 0.0234 µM. In addition, the fluorescent probe has been successfully used for the detection of Fe3+ in natural water samples with satisfactory result.