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By using melamine as a precursor for the copolymerization process, g-C3N4 and g-C3N4/TCNQ/Eu complexes with various amounts of doping were created. These complexes were then examined using XRD, FT-IR, SEM, TEM, XPS, PL, UV-vis, and I-T. The degradation rates of pefloxacin (PEF), enrofloxacin (ENR), and ciprofloxacin (CIP) were 91.1%, 90.8%, and 93.2% under visible light (λ > 550 nm). The photocatalytic performance of the composite was analyzed, and the best effect was obtained for CIP photocatalysis when Eu doping was 3 mg at 20 °C and pH 7. Kinetic analysis showed that there was a linear relationship between the sample and the photocatalytic time, and the degradation rate was about 5 times that of g-C3N4. The cyclic stability of the g-C3N4/TCNQ/Eu composite sample was found to be good through repeated experiments. UPLC-MS visualizes the degradation process of CIP. The extremely low stability of piperazine ring induced subsequent degradation, followed by the fracture of quinolone ring promoting the complete decomposition of CIP. [ABSTRACT FROM AUTHOR]

The widespread use of lithium–sulfur (Li–S) batteries is hindered by slow cathode kinetics, the shuttle effect, and dendrite growth on the anode. We show that these challenges can be overcome by replacing a linear ether (i.e., 1,2-dimethoxyethane) in commonly used electrolytes with a macrocyclic amine, 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane (TMTAC). Theoretical studies and experimental data indicate that the cavity of TMTAC matches a Li ion to form a robust solvation structure. Such a solvation structure not only leads to 3D deposition of Li2S on the cathode, which is responsible to the reduced overpotentials of Li2S nucleation and decomposition, but also suppresses Li dendrite growth on the anode. Moreover, the shuttle effect of polysulfides is effectively suppressed as the quantity of free TMTAC in the TMTAC-based electrolyte is substantially reduced. As a result, coin-type cells prepared with TMTAC-based electrolytes exhibit outstanding performance metrics for all key device parameters. Furthermore, pouch-type cells can be prepared with high sulfur loadings (e.g., 3.43 mg cm−2) and a low electrolyte to sulfur ratio (e.g., 6.16 μl mg−1) while maintaining a high areal specific capacity (3.38 mA h cm−2). This work demonstrates that the effective solvation of critical ions in energy storage devices is paramount to achieving peak performance. [ABSTRACT FROM AUTHOR]

Using an ultrasound-assisted chemical technique, ZnO quantum dot and ZnO composites were created. The optical characteristics and structural details of these composites were examined using TEM, XRD, XPS, FT-IR, UV-vis, and BET. The results revealed that both the ZnO quantum dot composite and ZnO composite exhibited outstanding optical properties, making them suitable for photocatalytic reactions. In order to analyze the photocatalytic performance, a degradation experiment was conducted using Rhodamine B solution as the simulation dye wastewater. The experiment demonstrated that the degradation of Rhodamine B followed the first-order reaction kinetics equation when combined with the photocatalytic reaction kinetics. Moreover, through cyclic stability testing, it was determined that the ZnO QDs-GO-g-C3N4 composite sample showed good stability and could be reused. The degradation rates of Rhodamine B solution using ZnO-GO-g-C3N4 and ZnO QDs-GO-g-C3N4 reached 95.25% and 97.16%, respectively. Furthermore, free-radical-trapping experiments confirmed that ·O2− was the main active species in the catalytic system and its photocatalytic mechanism was elucidated. The photocatalytic oxidation of ZnO quantum dots in this study has important reference value and provides a new idea for the subsequent research. [ABSTRACT FROM AUTHOR]

Despite significant progress in the preparation and characterization of two‐dimensional (2D) materials, the synthesis of 2D organic materials remains challenging. Here, we report a novel space‐confined polymerization method that enables the large‐scale synthesis of 2D sheets of a functional conjugated polymer, namely, poly(3,4‐ethylenedioxythiophene) (PEDOT). A key step in this method is the confinement of monomer to the boundaries of ice crystals using micelles. This spatial confinement directs the polymerization to form 2D PEDOT sheets with high crystallinity and controlled morphology. Supercapacitors prepared from the 2D PEDOT sheets exhibit outstanding performance metrics. In aqueous electrolyte, a high areal specific capacitance of 898 mF cm−2 at 0.2 mA cm−2 along with an excellent rate capability is achieved (e.g. capacitance retention of 67.6 % at a 50‐fold higher current). Moreover, the 2D PEDOT‐based supercapacitors exhibit outstanding cycling stability (capacitance retention of 98.5 % after 30,000 cycles). Device performance is further improved when an organic electrolyte is used. [ABSTRACT FROM AUTHOR]

Lithium (Li) metal has attracted significant attention in areas that range from basic research to various commercial applications due to its high theoretical specific capacity (3860 mA h g−1) and low electrochemical potential (−3.04 vs. standard hydrogen electrode). However, dendrites often form on the surfaces of Li metal anodes during cycling and thus lead to battery failure and, in some cases, raise safety concerns. To overcome this problem, a variety of approaches that vary the electrolyte, membrane, and/or anode have been proposed. Among these efforts, the use of three‐dimensional frameworks as Li hosts, which can homogenize and minimize the current density at the anode surface, is an effective approach to suppress the formation of Li dendrites. Herein, we describe the development of using carbon‐based materials as Li hosts. While these materials can be fabricated into a variety of porous structures, they have a number of intrinsic advantages including low costs, high specific surface areas, high electrical conductivities, and wide electrochemical stabilities. After briefly summarizing the formation mechanisms of Li dendrites, various methods for controlling structural and surface chemistry will be described for different types of carbon‐based materials from the viewpoint of improving their performance as Li hosts. Finally, we provide perspective on the future development of Li host materials needed to meet the requirements for their use in flexible and wearable devices and other contemporary energy storage techniques. [ABSTRACT FROM AUTHOR]

Logarithmic-conversion data processing used in wavelength modulation spectroscopy (WMS) with a current-modulated diode laser as its source is analyzed and compared with second-to-first ratio detection. Analytic Fourier coefficients of logarithmic-converted residual amplitude modulation (RAM) of a light source are given. An experimental setup for methane absorption detection at 1650 nm is described. It is shown theoretically and experimentally that logarithmic-converted WMS cannot only eliminate the fluctuation of received light power, but also improve the signal-to-noise ratio significantly. OCIS codes: 060.2370, 300.1030, 300.6260, 300.6300, 300.6320, 300.6380.

Graphene has demonstrated broad applications due to its prominent properties. Its molecular structure makes graphene achiral. Here, we propose a direct way to prepare chiral graphene by transferring chiral structural conformation from chiral conjugated amino acids onto graphene basal plane through π–π interaction followed by thermal fusion. Using atomic resolution transmission electron microscopy, we estimated an areal coverage of the molecular imprints (chiral regions) up to 64 % on the basal plane of graphene (grown by chemical vapor deposition). The high concentration of molecular imprints in their single layer points to a close packing of the deposited amino acid molecules prior to "thermal fusion". Such "molecular chirality‐encoded graphene" was tested as an electrode in electrochemical enantioselective recognition. The chirality‐encoded graphene might find use for other chirality‐related studies and the encoding procedure might be extended to other two‐dimensional materials. [ABSTRACT FROM AUTHOR]

Electrocatalysis is critical to the performance displayed by sulfur cathodes. However, the constituent electrocatalysts and the sulfur reactants have vastly different molecular sizes, which ultimately restrict electrocatalysis efficiency and hamper device performance. Herein, the authors report that aggregates of cobalt single‐atom catalysts (SACs) attached to graphene via porphyrins can overcome the challenges associated with the catalyst/reactant size mismatch. Atomic‐resolution transmission electron microscopy and X‐ray absorption spectroscopy measurements show that the Co atoms present in the SAC aggregates exist as single atoms with spatially resolved dimensions that are commensurate the sulfur species found in sulfur cathodes and thus fully accessible to enable 100% atomic utilization efficiency in electrocatalysis. Density functional theory calculations demonstrate that the Co SAC aggregates can interact with the sulfur species in a synergistic manner that enhances the electrocatalytic effect and promote the performance of sulfur cathodes. For example, Li–S cells prepared from the Co SAC aggregates exhibit outstanding capacity retention (i.e., 505 mA h g–1 at 0.5 C after 600 cycles) and excellent rate capability (i.e., 648 mA h g−1 at 6 C). An ultrahigh area specific capacity of 12.52 mA h cm−2 is achieved at a high sulfur loading of 11.8 mg cm–2. [ABSTRACT FROM AUTHOR]

Lithium (Li) metal is regarded as the ultimate anode material for use in Li batteries due to its high theoretical capacity (3860 mA h g−1). However, the Li dendrites that are generated during iterative Li plating/stripping cycles cause poor cycling stability and even present safety risks, and thus severely handicap the commercial utility of Li metal anodes. Herein, we describe a graphene and carbon nanotube (CNT)‐based Li host material that features vertically aligned channels with attached ZnO particles (designated ZnO@G‐CNT‐C) and show that the material effectively regulates Li plating and stripping. ZnO@G‐CNT‐C is prepared from an aqueous suspension of Zn(OAc)2, CNTs, and graphene oxide by using ice to template channel growth. ZnO@G‐CNT‐C was found to be mechanically robust and capable of guiding Li deposition on the inner walls of the channels without the formation of Li dendrites. When used as an electrode, the material exhibits relatively low polarization for Li plating, fast Li‐ion diffusion, and high Coulombic efficiency, even over hundreds of Li plating/stripping cycles. Moreover, full cells prepared with ZnO@G‐CNT‐C as Li host and LiFePO4 as cathode exhibit outstanding performance in terms of specific capacity (155.9 mA h g−1 at 0.5 C), rate performance (91.8 mA h g−1 at 4 C), cycling stability (109.4 mA h g−1 at 0.5 C after 800 cycles). The methodology described can be readily adapted to enable the use of carbon‐based electrodes with well‐defined channels in a wide range of contemporary applications that pertain to energy storage and delivery. [ABSTRACT FROM AUTHOR]

Sulfur covalently bonded to porous graphitic carbon (CB–S@PGC) as an anode for lithium-ion capacitors is shown to offer an ultrawide operating potential window of 4 V. When coupled with activated carbon as a cathode, the CB–S@PGC electrode exhibits a markedly high specific capacitance (412 F g−1 at 0.2 A g−1) and superiorly high capacity retention. And CB–S@PGC//lithium cobalt oxide cells exhibit high power and energy densities (e.g., a power density of 1665 W kg−1 is obtained at an energy density of 411 W h kg−1). [ABSTRACT FROM AUTHOR]