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The Promise and Challenge of Phosphorus-Based Composites as Anode Materials for Potassium-Ion Batteries
No full textPotassium-ion batteries (KIBs) are a core energy storage device that can meet the need for scalable and affordable stationary applications because they use low-cost and earth-abundant potassium. In addition, KIB shares a similar storage mechanism with current Li-ion batteries. As the key to optimizing a battery's performance, the development of high-performance electrode materials helps to increase the feasibility of KIB technology. In this sense, phosphorus-based materials (i.e., phosphorus and metal phosphide) with high theoretical capacity and low redox potential tick all the right boxes as a material of choice. A rapid glimpse at recent studies on phosphorus-based anode materials for advanced KIBs is provided, covering the synthetic methods, reaction mechanisms, electrochemical properties, and performances. In addition, several promising strategies are highlighted to address the imminent challenges faced by phosphorus-based anode materials, hoping to cast an insightful outlook for possible future direction in this field
Large-Scale Ligand-Free Synthesis of Homogeneous Core-Shell Quantum-Dot-Modified Cs4PbBr6 Microcrystals
No full textAn organic ligand-free solution method is developed for preparing homogeneous core shell quantum-dot (QD)-modified pure Cs4PbBr6 microcrystals on a large scale (similar to 12 g) at room temperature. The ligand-free Cs4PbBr6 microcrystals show a high green photoluminescence quantum yield of 76% with 360 nm of excitation light, which is attributed to their unique microarchitecture, with several features including quantum confinement of the outer QDs, stability of the inner Cs4PbBr6 microcrystals, improved light trapping, and interfacial recombination. UV-vis-near-IR and photoluminescence analyses provide valued evidence to support the ligand-free Cs4PbBr6 with synergy between the QDs and microcrystals
Facile preparation of porefilled membranes based on poly(ionic liquid) with quaternary ammonium and tertiary amine head groups for AEMFCs
No full textIonic liquid with quaternary ammonium and tertiary amine head groups is obtained by adding 4-vinylbenzylchloride (VBC) into tetramethylethylenediamine (TMEDA) drop by drop in the ice water bath. The ionic liquid is polymerized at 100 degrees C with porous polyethylene (PE) membrane as the substrate, resulting in a porefilled anion exchange membrane. After soaking in 1 M KOH solution for 48 h, an alkaline anion exchange membrane is obtained. The conductivity of the membrane is 32.8 mS/cm at 60 degrees C and is stable in 1 M KOH for > 350 h. And the tensile strength at break is > 80 MPa with a swelling rate of about 26.7%. The water permeability is also improved, mostly because the tertiary amine head groups afford extra water transport channels. The half-cell tests show that the ionic liquid monomer ruins the activity of Pt/C catalyst, while after polymerizing the ionic liquid and washing the resulted AEM for several times, the AEM do not poison the catalyst any more. The peak power density of the single cell using this membrane reaches 545 mW/cm(2) at 1000 mA/cm(2)
An rGQD/chitosan nanocomposite-based pH-sensitive probe: application to sensing in urease activity assays
No full textHerein, we developed a pH sensing platform based on reduced graphene quantum dots (rGQDs) and chitosan (CS). CS was used as the recognition element in the self-assembly of the rGQD/CS nanocomposite because of its fascinating pH-sensitivity, induced by the protonation and deprotonation of the -NH2 group on its edge. The -NH2 was easily protonated under acidic conditions, making CS positively charged. The negatively-charged rGQDs under weak acidic conditions thus could couple with CS through electrostatic attraction, leading to fluorescence quenching. When the pH was changed to basic, the CS became negatively charged, resulting in the disassembly of the rGQD/CS system and causing the system to exhibit a turn-on fluorescence signal. The proposed pH-sensing nanocomposite was successfully applied for sensitive and reliable pH measurements from 5.0 to 9.0. This nanocomposite system was further utilized for the sensitive detection of pH changes caused by the enzymatic activity of urease, thereby proving its utility as a fluorescence turn-on sensor for urease in the field of biochemical and environmental analysis. The photoluminescence (PL) intensity of the rGQD/CS system increased as the pH increased. The increased intensity is directly related to the urease activity in the assay system. Thus, a novel fluorescence turn-on biosensor for urease based on the disassembly of the rGQD/CS composite is proposed. The system response exhibited a nearly linear relationship with urease concentration in the range of 0.05-0.75 U mL(-1). The detection limit for urease was 0.036 U mL(-1). This is the first report of this type of sensor for urease detection. When applied to real sample analysis, the present strategy exhibited satisfactory results
Cooperative Pollutant Adsorption and Persulfate-Driven Oxidation on Hierarchically Ordered Porous Carbon
No full textThis study presents a 3D hierarchically ordered porous carbon material (HOPC) that simultaneously achieves efficient adsorption of a range of water pollutants as well as catalytic oxidation of adsorbed pollutants. High adsorption capacity and rapid adsorption kinetics are attributed to the hydrophobic nature of the carbon substrate, the large surface area due to high porosity, and the relatively uniform size of pores that comprise the structure. The oxidative degradation is achieved by efficient mediation of electron transfer from pollutants to persulfate through the sp(2)-hybridized carbon and nitrogen network. As the persulfate activation and pollutant oxidation do not involve reactive radicals, oxidative degradation of the adsorbent is prevented, which has been a primary concern when adsorption and oxidation are combined either to regenerate adsorbate or to enhance oxidation performance. Batch tests showed that near complete removal of various recalcitrant micropollutants can be achieved within a short time (less than 1 min) even when treating a complex water matrix, as pollutants are concentrated on the surface of HOPC, where their oxidation is catalyzed