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High-performance and low-cost catalysts are particularly desirable for the exploitation of practical low-overpotential Na–CO2 batteries with protracted cyclability. Herein, a well-defined morphology of nitrogen-rich graphitic carbon frameworks with dense bimetallic active sites (Fe–Cu–N–C) was facilely prepared by introducing Fe3+ and Cu2+ to regulate in situ grown carbon nanotubes as an advanced catalyst toward hybrid Na–CO2 batteries. Through metal content tuning and carbon architecture altering, Fe–Cu–N–C proved to be dramatically more effective than Cu–N–C and Fe–N–C. As the cathodic catalyst of a hybrid Na–CO2 battery, Fe–Cu–N–C can facilitate the fast evolution and degradation of flocculent discharge products and achieve an excellent long-term cyclability with up to 1550 cycles (over 600 h), which makes it one of the greatest catalysts for hybrid Na–CO2/air batteries that have been reported to date. The observed outstanding battery performance is attributable to the cross-linked conductive framework affording a "highway" for accelerated electron transport and Na+/CO2 diffusion. Besides, the synergistic effects among defect-rich interfaces, Fe/Fe3C nanocrystals, and Fe–Nx and Cu–Nx sites derived from nitrogen atom doping enhance the catalytic activity. In addition, the possible growth and decomposition mechanisms of NaHCO3 products with different morphologies on Fe–N–C, Cu–N–C, and Fe–Cu–N–C electrodes were presented and discussed. [ABSTRACT FROM AUTHOR]

1T-MoS2 is the metallic phase of molybdenum disulfide (MoS2), and has obvious advantages in energy storage applications compared with the 2H phase. However, the 1T phase is inherently unstable and can be easily converted to the 2H phase, specifically under thermal annealing. So, the 1T phase can hardly be further modified after synthesis, and there is a hidden danger that high boiling point organic solvents or moisture cannot be removed, which will inevitably affect the performance of the material. In this paper, we described a 3-dimensional fishnet-like 1T-MoS2 heterostructure (3D@1T-MoS2), and revealed that the 1T phase MoS2 in the as-synthesized 3D@1T-MoS2 nanostructure is thermally-stable (even at high-temperature: ∼700 °C). Aided by theoretical calculations and XPS deconvolution spectrum analysis, the phase stability mechanism is revealed to be closely related to the presence of carbon nanotubes and graphite carbon in this structure. Remarkably, after high temperature treatment, this 3D@1T-MoS2-700 electrode delivers a large reversible capacity of 5.25 mA h cm−2 (∼1800 mA h g−1) at 0.1 mA cm−2. [ABSTRACT FROM AUTHOR]

With the increasing concerns about energy and environments, there are growing demands for efficient metal removal/recovery strategies for environmental protection and sustainable development. Here, a novel reductive ion exchange (RIE) strategy is proposed to use faradaic electrode materials, such as NaTi2(PO4)3 (NTP), for metal removal/recovery from wastewater. For a pre-charged Na3Ti2(PO4)3 in metal-bearing water, the potential differences between the NTP film and the reducible metal ions (such as Pb, Cu, Ag and Au) drive a rapid metal reduction process, which produces metallic nanoparticles, while the NTP film is discharged by the release of Na ions. Compared to the common adsorption-based methods, the NTP film provides a large electrical force to capture and reduce the specific metal ions, which highly increases its efficiency in removing trace amounts of metal ions from water. We show that by using an as-assembled NTP-based device the reducible metal concentrations all drop by two orders of magnitude at both the ppm and ppb levels. More interestingly, the reduced nanoparticles are loosely attached on the surface of the NTP films and can be facilely separated and recycled, converting metal pollutants into valuable materials without utilizing reductive agents or high temperature thermal treatments. Also, the charging of NTP is in Na-bearing water instead of wastewater; therefore, the film contamination by the organic matter and other unreducible cations in wastewater can be avoided, and the NTP film can be recharged and reused for hundreds of times. Our research brings a new strategy for recycling trace amounts of valuable noble metal ions from wastewater. It may also bring new insights in the application of the traditional faradaic electrode materials. [ABSTRACT FROM AUTHOR]

Electrochromic energy storage (EES) devices with high capacity, long-term stability and multicolor display are highly desired for practical applications. Here, we propose a new three-electrode design of an EES device. Two kinds of electrochromic materials (WO3 and Ti-V2O5 respectively) deposited on ITO glass work as electrochromic active layers. Al metal is used as the anodic frame of the device and helps to seal the mixed Li/Al-ion electrolyte. For electrochromic applications, the device shows rapid, self-powered color switching with multicolor display (light yellow, transparent, light red, dark green, dark blue and black). As an energy storage device, the as-assembled device provides open-circuit voltages up to 3.5 V (Al anode/Ti-V2O5 cathode) with an areal capacity of up to 933 mA h m−2 (Al/Ti-V2O5 and Al/WO3), which are the best among those of all reported EES devices. Meanwhile, the utilization of the mixed Li/Al-ion electrolyte and the addition of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) into the films greatly promote the robustness and the cycle stability of the electrochromic layers. Such a new design of the EES device with multicolor display, large charge capacity and high cycle stability can be promising for future color switching/energy storage applications, which may also provide new insights into the design of multifunctional devices. [ABSTRACT FROM AUTHOR]

Nowadays, a variety of multifunctional electrocatalysts are being developed while there is still a lack of suitable design to fully realize their multifunctionalities. Here, we propose a general, simple, two-component design of an electrolyser to replace the traditional three-component design for decoupled water splitting. Trifunctional (OER, HER and ORR) electrocatalysts (such as nickel sulfide foams with surface grown N-doped carbon nanotube arrays) are used as the gas evolution electrode to replace both the cathode and the anode, while materials with suitable redox activities (NaTi2(PO4)3 or commercial Ni(OH)2) are used as the relay electrode. In such a design, the H2/O2 evolution can be switched by reversing the current polarity, and the ORR before the HER consumes the residual O2 left in the electrolyser, guaranteeing the high purity (∼99.9%) of the as-obtained H2. With NaTi2(PO4)3 as the relay electrode and the nickel sulfide foam as the gas evolution electrode, owing to the high decoupling efficiency of the NaTi2(PO4)3 relay (97%) and the low HER/OER overpotentials of the trifunctional nickel sulfide foam, an energy conversion efficiency of up to 94.3% can be obtained for the as-assembled electrolyser at a current density of 10 mA cm−2. When combined with a commercial Si PV module with an efficiency of 14.4%, the as-designed PV-electrolysis system showed a solar-to-hydrogen conversion efficiency of up to 10.4%. Utilization of trifunctional electrocatalysts greatly reduces the complexity of the electrolyser and the overall cost for electrochemical H2 production, and these electrolysers may potentially be used to construct highly competitive water splitting systems for continuous H2 production and green energy harvesting. Our research may also bring new insights into the utilization of multifunctional electrocatalysts in other devices, such as metal–air batteries and fuel cells. [ABSTRACT FROM AUTHOR]

A new luminescent composite material GQD@ZIF-8 was obtained by incorporating edge-sulfonated graphene quantum dots (GQDs) as an active fluorescent species into nanocrystals of the zeolitic imidazolate framework (ZIF-8) as both a stabilizer and a carrier by a simple, rapid, and eco-friendly approach. The as-synthesized GQD@ZIF-8 composite not only exhibits excellent fluorescence properties in aqueous solutions but can also emit bright fluorescence in the solid state due to the effective encapsulation by ZIF-8. The GQD@ZIF-8 nanocomposite was used as a novel yellow phosphor in the fabrication of white light-emitting diodes (WLEDs) based on a blue-light LED chip with a proximate CIE coordinate (0.33, 0.33) of highly pure white light and a relatively high color-rendering index. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs) are considered ideal fluorescent probes owing to their excellent optical properties and low cytotoxicity. We report a low-cost solvothermal method to synthesize orange fluorescent CQDs from coal tar. The as-fabricated CQDs exhibit bright and stable photoluminescence with long wavelength emission at 605 nm. To improve the biocompatibility of the oil-soluble CQDs, we chose liposomes as a carrier. After being encapsulated by liposomes, the CQDs become water-soluble and show a redshift of fluorescence to 640 nm. The in vitro and in vivo imaging application of the liposome-CQDs is demonstrated. Our work has provided a way for the conversion of low-value coal tar into high-value fluorescent carbon materials. [ABSTRACT FROM AUTHOR]

Enhancement of electroless deposition using reduced-graphene-oxide (rGO) coating for a conductive surface on the non-conductive substrate is proposed and demonstrated. We confirmed that the rGO treatment enhanced the Pd catalytic activity and achieved a sufficient rate in electroless deposition with extremely low Pd loading (3.94 × 10−2μg cm−2). [ABSTRACT FROM AUTHOR]

We have developed a controllable solvothermal method to grow intrinsically conductive MoS2 nanosheet arrays in a metastable 1T phase on carbon fiber cloth (CFC) as binder-free, high-activity Li-ion battery (LIB) anodes. By introducing surface hydroxyl groups on the CFC and tuning the DMF content in the mixed solvent, MoS2 nanosheet arrays were perpendicularly grown to the surface of the carbon fibers with a high coverage. Electrochemical measurements reveal that the 1T phase nanosheet arrays have excellent Li-ion storage performances, including high specific capacity, high rate capability and good cycling stability, outperforming 2H phase arrays. Because of the metallic 1T phase and the highly oriented array architecture, after subtracting the total capacity of CFC, the 1T arrays also deliver a high reversible specific capacity of 1789 mA h g−1 at 0.1 A g−1 and a retained capacity of 853 mA h g−1 after 140 cycles at 1 A g−1. [ABSTRACT FROM AUTHOR]

The wide use of functionalized graphene quantum dots (GQDs) in stable dispersions is currently hampered by the lack of industrially scalable, low-cost, and eco-friendly methods. Herein we report the first realization of the industrial-scale (20 L) production of high-quality fluorescent GQDs via a molecular fusion route from a low-cost, active derivative of pyrene. By a wholly “green”, conventional sulfonation reaction at low hydrothermal temperature, the molecular precursor is wholly converted into highly water-soluble, sulfonated GQDs without byproducts such as insoluble carbon. The GQDs show superior optical properties including strong excitonic absorption bands extended to ∼530 nm, bright photoluminescence (PL) at 510 nm with a quantum yield of up to 42%, and a wide PLE spectrum. The edge-site sulfonic functionalization enables the GQDs to stably re-disperse in water and maintains high fluorescence activities even after annealing up to 250 °C, whereas amino GQDs and graphene oxide sheets markedly aggregate after drying at low temperature. The GQDs are applied as biological fluorescent probes for visualizing and targeting Golgi apparatus in Hela and MCF7 live cells. The low-cost mass production, excellent biocompatibility, and superior optical properties make the GQDs an attractive alternative probe for efficient Golgi targeted imaging in biomedical applications. [ABSTRACT FROM AUTHOR]

A magneto-elastic resonant ‘micro-diver’ system (MER-μDS) is proposed and developed for rapid liquid-phase detection of pathogens in a wireless way. The magneto-elastic micro-resonator (i.e., the μ-diver) is placed in the micro-chamber of the MER-μDS that is connected to the inlet/outlet for flow of the liquid analyte and a closed-loop micro-channel. After specific attachment of the analyte onto the μ-diver, the μ-diver is conveyed by the flow into the detection segment of the channel, around which a metal micro-coil is wound for both excitation resonance of the μ-diver and reading of its resonance frequency signal. After the pre-functionalized μ-diver captures the analyte and, then, is driven into the detection channel segment, the added mass induced resonant frequency shift can be wirelessly sensed by the coil. The micro-system features rapid and repeatable liquid-phase bio-sensing and the wireless signal readout scheme is favorable to real-time pathogen detection in liquid food, e.g., milk or juice, for food safety applications. An equivalent circuit model is established for design of the magneto-elastic μ-diver. After a bar-shaped μ-diver with length-extensional bulk-resonance mode is optimally designed and micro-fabricated, the MER-μDS is formed by micro-machining/assembling techniques. By placing a biotin-immobilized μ-diver into the wireless micro-sensing system, avidin-attached magnetic beads are detected to calibrate the mass sensitivity as 0.061 Hz pg−1, which well confirms the modeling result. By using the antibody-immobilized μ-diver, PBS solution with an E. coli concentration of 102–108 CFU mL−1 is detected, resulting in a corresponding wireless f0-shift sensing signal of about 300–2300 Hz and a limit of detection of 102 CFU mL−1. Food safety application potential of the MER-μDS technique is proven by detection of E. coli added to orange and apple juices (E. coli concentration: 104–108 CFU mL−1). [ABSTRACT FROM AUTHOR]