Latest ArticlesLithium-sulfur batteries are considered to be a new generation of high energy density batteries due to their non-toxicity, low cost and high theoretical specific capacity. However, the development of practical lithium-sulfur batteries is seriously impeded by the sluggish multi-electron redox reaction of sulfur species and obstinate shuttle effect of polysulfides. In this study, a porous lanthanum oxychloride (LaOCl) nanofiber is designed as adsorbent and electrocatalyst of polysulfides to regulate the redox kinetics and suppress shuttling of sulfur species. Benefiting from the porous architecture and luxuriant active site of LaOCl nanofibers, the meliorative polarization effect and sulfur expansion can be accomplished. The LaOCl/S electrode exhibits an initial discharge specific capacity of 1112.3 mAh/g at 0.1 C and maintains a superior cycling performance with a slight decay of 0.02% per cycle over 1000 cycles at 1.0 C. Furthermore, even under a high sulfur loading of 4.6 mg/cm2, the S cathode with LaOCl nanofibers still retains a high reversible areal capacity of 4.2 mAh/cm2 at 0.2 C and a stable cycling performance. Such a porous host expands the application of rare earth based catalysts in lithium-sulfur batteries and provides an alternative approach to facilitate the polysulfides conversion kinetics.
It has been challenging for Fe(Ⅲ) regeneration in Fe-based photocatalysts for continuous peroxydisulfate (PDS) activation due to the lower ability to reduce Fe(Ⅲ). In this work, Fe-doped ultrathin VO2 (Fe-VO2) nanobelts were synthesized for purifying metronidazole (MNZ) via PDS activation. As an efficient Fenton-like catalyst for PDS activation, 2 wt% Fe-doped VO2 can remove 98% of MNZ within 40 min and exhibits impressive recyclability. The synergistic effect of Fe-VO2 and Fe(Ⅲ) activated PDS boosted the photocatalytic performance. Moreover, SO4•−, h+, O2•−, 1O2, and •OH were the main reactive radicals. The effects of initial MNZ concentration, Fe-VO2, PDS dosage, and various anions/cations on MNZ removal by the Fe-VO2/PDS/Vis system were studied. The intermediates of MNZ degradation and possible pathways were determined by density function theory (DFT) calculations and HPLC-MS. This study provided a sustainable technology using Fe-doped ultrathin VO2 nanobelts for photocatalytic PDS activation and decontamination of pharmaceutical wastewater.
Hymoins A–C (1–3), three unusual polycyclic polyprenylated acylphloroglucinols (PPAPs) were isolated from the flowers of Hypericum monogynum. Hymoin A features the first intriguing 6/5/5/5/7 pentacyclic caged PPAP. Hymoin B is characterized by an unprecedented rearranged 5/6/8 tricyclic ring system, while hymoin C represents the first rearranged PPAP with a fantastic spirocyclic 5/6/7 ring system. Their structures were established by extensive spectroscopic analysis, X-ray crystallography, and computational methods. The plausible biosynthetic routes for the compounds were also proposed. In oleic acid (OA)-induced HepG2 cells, all compounds exhibited significant lipid-lowering activity at the concentrations of 2–8 µmol/L. Further mechanistic study implied that compound 1 exhibited excellent lipid-lowering activity in OA-induced HepG2 cells through inhibiting the proteins of free fatty acids synthesis and improving lipidolysis.
Ultrafast reaction kinetics is essential for rapid detection, synthesis, and process monitoring, but the intrinsic energy barrier as a basic material property is challenging to tailor. With the involvement of nanointerfacial chemistry, we propose a carbonization-based strategy for achieving ultrafast chemical reaction. In a case study, ultrafast Griess reaction within 1 min through the carbonization of N-(1-naphthalene)ethylenediamine (NETH) was realized. The carbonization-mediated ultrafast reaction is attributed to the synergic action of reduced electrostatic repulsion, enriched reactant concentration, and boosted NETH nucleophilicity. The enhanced reaction kinetics in o-phenylenediamine-Cu2+ and o-phenylenediamine-ascorbic acid systems validate the universality of carbonization-engineered ultrafast chemical reaction strategy. The finding of this work offers a novel and simple tactic for the fabrication of multifunctional nanoparticles as ultrafast and effective nanoreactants and/or reporters in analytical, biological, and material aspects.
Introducing ligand into the surface of gold (Au)-based catalyst has been recognized as an efficient strategy to enhance the performance of catalyst in acetylene hydrochlorination reaction. However, due to the multifactorial deactivation, the usage of single type of ligand has limitations on the performance improvement. In this work, two types of ligands including a molecular 2-methylimidazole and an ionic cetrimonium are selected to protect Aun+ species. After kinetics analysis, advanced characterization, and density functional theory simulation, we demonstrate the optimal interaction model between two ligands and Au species: Two 2-methylimidazole molecules are coordinated with high-valent Au species while cetrimonium is interacted via electrostatic interaction. Except the synergistic effect in the decrease of Au species reduction and agglomeration, the existence of molecular ligand greatly increases the adsorption of hydrogen chloride while the ionic ligand significantly inhibits the deposition of coke. Due to the positive effect of dual-ligands, we achieved 97.1% of acetylene conversion and 0.29 h−1 of deactivation rate under high gas hourly space velocity of acetylene. This work establishes a foundation to explore the property-activity relationships in Au-based catalyst via ligand engineering.
The large current density of electrochemical CO2 reduction towards industrial application is challenging. Herein, without strong acid and reductant, the synthesized BiVO4 with abundant oxygen vacancies (Ovs) exhibited a high formate Faradaic efficiency (FE) of 97.45% (-0.9 V) and a large partial current density of -45.82 mA/cm2 (-1.2 V). The good performance benefits from the reconstruction of BiVO4 to generate active metal Bi sites, which results in the electron redistribution to boost the OCHO* formation. In flow cells, near industrial current density of 183.94 mA/cm2 was achieved, with the FE of formate above 95% from 20 mA/cm2 to 180 mA/cm2. Our work provides a facily synthesized BiVO4 precatalyst for CO2 electroreduction.
Improper abuse of roxarsone (ROX) in industrial production leads to harmful effects on water, soil, food, and living creatures. It is significant to detect its concentration in the environment and biosystem. Herein, two aggregation-induced emission (AIE)-active fluorescence probes, TPE-TPE and TPE-TPE-CN, are successfully synthesized via a sulfur(Ⅵ) fluoride exchange (SuFEx) click reaction and first employed to detect ROX in the environment and living 3T3 cells. These two probes can selectively detect ROX in water due to the synergistic effect of photoinduced electron transfer (PET) and fluorescence resonance energy transfer (FRET) between the probes and ROX. The detection limit of TPE-TPE and TPE-TPE-CN is 0.154 and 0.385 µmol/L, respectively, much lower than the safety concentration stipulated by the World Health Organization (WHO). In addition, with the aid of a color discrimination application in a smartphone, these two probes can also detect ROX in real samples (such as water, soil, and cabbage), demonstrating their excellent potential for monitoring ROX in a practical environment.
Butyrylcholinesterase (BChE) is a key enzyme in the metabolism of cholinergic compounds. It has been recognized as a key biomarker for many diseases, including liver diseases and Alzheimer’s disease. However, classical methods for detecting BChE activity suffer from low sensitivity, cumbersome pre-treatment, and poor stability. Chemiluminescence is a promising new method for detecting and imaging the activity of BChE. It has several advantages over traditional methods, including low background interference, high sensitivity, and the absence of external illumination. In this study, we developed a novel BChE-activatable chemiluminescent probe (CL-BChE). It exhibited a significant chemiluminescence enhancement at 525 nm upon incubation with BChE. It had a low limit of detection (6.25 × 10−3 U/mL) and was highly selective for BChE. CL-BChE was used to image BChE activity in living cells and tumor-bearing animal models. It was also successfully applied to detect pesticide residue, even under the interference of representative phytochromes and real vegetable samples. Given its high sensitivity, selectivity, and versatility, we believe that CL-BChE will be a promising tool for investigating BChE’s activity in biomedical research as well as other BChE-related scenarios.
Anode active materials involving transition metal oxides and sulfides are of great significance for high energy density lithium-ion batteries (LIBs), but the huge volume expansion and inferior electronic conductivity upon cycling critically constrain their further application. Herein, from a new perspective, a highly conductive and stable 3D flexible composite current collector is rationally designed by facilely electrodepositing metallic Ni thin layer onto the carbon cloth (CC/Ni), which endows the supported active materials with exceptional electronic conductivity and structural stability. In addition, the homogeneously distributed metallic Ni protrusions external CC can strongly bond with the active components, ensuring the structural integrity of electrodes upon cycling. More importantly, the 3D network structure with large specific surface area provides abundant space to alleviate the volume expansion and more active sites for electrochemical reactions. Therefore, taking Ni3S2 nanosheet (Ni3S2 NS) anode as an example, the prepared Ni3S2 NS@CC/Ni electrode shows a high specific capacity of 2.32 mAh/cm2 at 1 mA/cm2 and high capacity retention of 1.68 mAh/cm2 at a high rate of 8 mA/cm2. This study provides a universal approach to obtain highly conductive and stable 3D flexible current collectors towards high performance metal-ion batteries beyond LIBs.
Van der Waals (vdW) ferroelectric-semiconductor heterojunction provides reconfigurable band alignment based on optical/electrical-assisted polarization switching, which shows great potential to construct artificial visual neural systems. However, the mechanical exfoliation fabrication scheme for proof-of-concept demonstrations and fundamental studies is cumbersome and not scalable for practical application. Here, we present a synthetic strategy for the large-scale and high crystallinity growth of planar/vertical α-In2Se3/MoS2 heterojunctions by dynamically tuning the growth temperature. Furthermore, based on the α-In2Se3/MoS2 heterostructures, photo-synapse devices are designed and fabricated to simulate visual neural systems functions, including multistate storage, optical logic operation, potentiation and depression, paired-pulse facilitation (PPF), short-term memory (STM), long-term memory (LTM), and Learning-Forgetting-Relearning. By coupling the spatiotemporally relevant optical and electric information, the device can mimic the superior biological visual system's light adaptation and Pavlovian conditioning. This work provides a strategy for dynamically tuning the orientation of ferroelectric-semiconductor heterojunction stacks and will give impetus to applying all-in-one sensing and memory-computing artificial vision systems.
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