double-layer polymer electrolyte in which one layer contacts the anode and the other polymer layer contacts the cathode.Various types of lithium-conducting polymers have been explored; lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in poly(ethylene oxide) (PEO) composites have been the most extensively studied owing to their relatively high cation conductivity, acceptable anodic stability, and good membrane-forming capability. [4] Despite these advantages, the PEO-based polymer electrolytes are slowly oxidized at voltages over 3.9 V, which has restricted their use to cells with a lower-voltage cathode such as LiFePO 4 . [5] Enlarging the polymer redox voltage window is needed to be compatible with a high-voltage cathode if a polymer solid electrolyte battery is to meet the energy density specification ΔE > 300 Wh kg −1 . Moreover, there has been no suitable single liquid electrolyte having the required redox window. [3] The high oxidation potential solvents that are stable for cathodes show high anodic reactivity at the negative side; the low oxidation potential solvents compatible with a Li-metal anode exhibit a high reactivity on the high-voltage cathode side. The mixture of a high-voltage stable solvent and a low-voltage stable solvent in liquid electrolyte systems might hurt the electrochemical performance owing to the free diffusion of liquid solvent molecules. However, separate polymer interphase layers for lowering the interfacial impedance between a ceramic electrolyte and an electrode have been demonstrated, [6] which has initiated an investigation of a bilayer polymer electrolyte with a high-voltage stable layer contacting cathode and a low-voltage stable layer contacting anode.Poly(N-methyl-malonic amide) (PMA) contains a repeating unit of high dielectric constant dimethylacetamide (DMAc) that is used as an additive to protect electrolyte oxidation by a high-voltage cathode. [7] However, DMAc is easily reduced by a metallic lithium anode, as shown in Figure S1 in the Supporting Information. [8] Therefore, PMA-LiTFSI layer was used to contact only the cathode and PEO-LiTFSI layer to contact only the anode in a double-layer polymer solid electrolyte (DLPSE) having both a wide redox window and the high flexibility and plasticity for retention of electrode/electrolyte interfaces with low interfacial resistance over a long cycle life. In this DLPSE system, the DMAc containing PMA-LiTFSI layer was well isolated from the lithium-metal anode by a PEO-LiTFSI layer and the PEO-LiTFSI layer was protected by a PMA-LiTFSI layer from a high-voltage oxidation.No single polymer or liquid electrolyte has a large enough energy gap between the empty and occupied electronic states for both dendrite-free plating of a lithium-metal anode and a Li + extraction from an oxide host cathode without electrolyte oxidation in a high-voltage cell during the charge process. Therefore, a double-layer polymer electrolyte is investigated, in which one polymer provides dendrite-free plating of a Li-metal anode and the other all...

The development of green synthetic approaches is one of the key materials challenges in moving toward semiconductor quantum dots (QDs) for large-scale production and commercial applications. This article presents a comprehensive overview on the synthesis of colloidal QDs prepared via chemical approaches in solution phase, with emphasis on green routes which possess the advantages of environment-friendly raw materials, simple operation process, and robust mass-scale production. The approaches for the synthesis of QDs in batch reactors are summarized, including hot-injection organometallic synthesis, noninjection organometallic synthesis, aqueous synthesis and biosynthesis approaches, with some of the concerns on their limitations for scale-up, followed by some continuous synthetic methods aiming for reproducible and large-scale production. Current advances in continuous synthesis of QDs by microfluidic devices, high-gravity reactors, and spray-based techniques are briefly introduced. We also provide some insights into challenges and opportunities based on our own understanding of this field.

The development of metal-free catalysts for hydrogenation reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) has been of great increasing scientific and industrial importance. Herein, we reported the preparation of sulfurized graphene (SG) nanomaterials by a well-developed ball-milling method. The as-prepared SG nanomaterials were systematically characterized by scanning electron microscope, transmission electron microscope, Fourier transform infrared, and X-ray photoelectron spectroscopy. The SG exhibited flake-like morphology with average size of 100 nm, and the S doping (3.4 atom %) into the nanocarbon molecules results in asymmetry of electron density distribution, providing high catalytic performance for catalytic reduction of 4-NP to 4-AP by using NaBH4 as the reducer. The related catalytic mechanism and reaction path of the reduction were investigated. The effects of different initial 4-NP concentrations, initial reductant concentrations, catalyst dosages, and reaction temperatures were presented, which have not been reported so far. The thermodynamic parameters including activation enthalpy and entropy were determined.

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