Architecture engineering of Fe/Fe2O3@MoS2 enables highly efficient tetracycline remediation via peroxymonosulfate activation: Critical roles of adsorption capacity and redox cycle regulation.

Design and synthesis of high-efficiency multicomponent nanostructure for activating peroxymonosulfate (PMS) to destruct emerging antibiotics remains a daunting challenge. We report herein the simplest one-step hydrothermal construction of hierarchical Fe/Fe2O3@MoS2 architecture composed of MoS2 nanosheets integrated commercial Fe2O3 nanoparticles. The fabricated Fe/Fe2O3@MoS2 architecture can be utilized as an efficient PMS activator to destruct tetracycline hydrochloride (TCH) with a removal efficiency of 90.3 % within 40 min, outperforming Fe2O3 nanoparticles, MoS2 nanosheets analogues and many MoS2-based materials. The Fe/Fe2O3@MoS2/PMS works well under various reaction conditions, and SO4•- and 1O2 are identified as major reactive oxygen species. Thirteen intermediates towards TCH destruction are detected via four pathways, and their acute/chronic toxicity and phytotoxicity are assessed. The origins of Fe/Fe2O3@MoS2/PMS system for efficient degrading TCH are ascribed to the synergy catalysis between Fe2O3 and MoS2, which originate from: (a) the exposed Mo4+ sites on catalyst surface facilitating high-speed electron transfer from MoS2 to Fe3+ and accelerating the Fe2+ regeneration; (b) the generated Fe0 serving as an excellent electron donor to jointly promote Fe3+/Fe2+ redox cycle. This study provides a simple way to establish architecture for synergistically promoting PMS-mediated degradation.

Rational design on high-performance triboelectric nanogenerator consisting of silicon carbide@silicon dioxide nanowhiskers/polydimethylsiloxane (SiC@SiO2/PDMS) nanocomposite films.

The relatively low output performance of triboelectric nanogenerator (TENG), which faces a challenge in performance improvement, limits its practical applications. Here, a high-performance TENG consisting of a silicon carbide@silicon dioxide nanowhiskers/polydimethylsiloxane (SiC@SiO2/PDMS) nanocomposite film and a superhydrophobic aluminum (Al) plate as triboelectric layers is demonstrated. The 7 wt% SiC@SiO2/PDMS TENG presents a peak voltage of 200 V and a peak current of 30 µA, which are ~ 300 and ~ 500% over that of the PDMS TENG, owing to an increase in dielectric constant and a decrease in dielectric loss of the PDMS film because of electric insulated SiC@SiO2 nanowhiskers. Furthermore, a 10 µF capacitor can be charged up to 3 V within ~ 87 s, which can be continuously operated on the electronic watch for 14 s. The work provides an effective strategy for improving output performance of TENG by adding core-shell nanowhiskers to modulate the dielectric properties of organic materials.

Hierarchical porous Fe-N/C@surfactant composites synthesized by a surfactant-assisted strategy as high-performance bifunctional oxygen electrodes for rechargeable zinc-air batteries.

Herein, a soft-template strategy involving the cationic surfactants has been successfully applied to size-controlled synthesis of hierarchical porous Fe-N/C for the first time. Specifically, a small amount of Fe and cationic surfactants can be uniformly doped into the zinc-based zeolite imidazole framework (ZIF-8) crystal particles and the cationic surfactants play a critical role in the formation of hierarchically porous Fe-ZIF-8@surfactant precursors. When the Fe-ZIF-8@surfactant is subsequently pyrolyzed, atomically dispersed Fe-Nx coordination structures can be in-situ converted to Fe-N/C, while the cationic surfactants decompose to form a carbon matrix to encapsulate the active sites, thereby preventing the aggregation of nanoparticles to a certain extent. As a result, the combined Fe nanocrystals and atomically dispersed Fe-Nx in the graphitic carbon matrix generate a synergistic effect to boost the electrocatalytic behaviors with a more positive half-wave potential (0.92 V) for oxygen reduction reaction (ORR) and a lower overpotential (420 mV at 10 mA cm-2) for oxygen evolution reaction (OER). As a proof of concept, the Fe-N/C@TTAB based zinc-air batteries (ZABs) present an outstanding peak power density (107.9 mW cm-2) and a superior specific capacity (706.3 mAh g-1) with robust cycling stability over 900 cycles for 150 h, which are better than the commercial Pt/C + IrO2 based ZABs.

Design of a Self-Powered System by Wind-Driven Triboelectric Nanogenerator Based on 0.94(Bi0.5 Na0.5 )TiO3 -0.06Ba(Zr0.25 Ti0.75 )O3 /Polyvinylidene Fluoride (BNT-BZT/PVDF) Composites.

The portable power bank as an energy storage device has received tremendous attention while the limited capacity and periodical charging are critical issues. Here, a self-charging power system (SCPS) consisting of a 0.94(Bi0.5 Na0.5 )TiO3 -0.06Ba(Zr0.25 Ti0.75 )O3 /polyvinylidenefluoride (BNT-BZT/PVDF) composite film-based triboelectric nanogenerator (TENG) is designed as a wind energy harvester and an all-solid-state lithium-ion battery (ASSLIB) as the energy storage device. The optimized TENG can provide an output voltage of ≈400 V, a current of ≈45 µA, and a maximum power of ≈10.65 mW, respectively. The ASSLIB assembled by LiNiCoMnO2 as the cathode, NiCo2 S4 as the anode, and Li7 La3 Zr2 O12 as the solid electrolyte can maintain a discharge capacity of 51.3 µAh after 200 cycles with a Coulombic efficiency of 98.5%. Particularly, an ASSLIB can be easily charged up to 3.8 V in 58 min using the wind-driven TENG, which can continuously drive 12 parallel-connected white light-emitting diodes (LEDs) or a pH meter. This work demonstrates the development of low-cost, high-performance and high-safety SCPSs and their large-scale practical application in self-powered microelectronic devices.

Rational Design on Chemical Regulation of Interfacial Microstress Engineering by Matching Young's Modulus in a CsPbBr3 Perovskite Film with Mechanical Compatibility toward Enhanced Photoelectric Conversion Efficiency.

Thermodynamically induced tensile stress in the perovskite film will lead to the formation of atomic vacancies, seriously destroying the photovoltaic efficiency stability of the perovskite solar cells (PSCs). Among them, cations and halide anions vacancies are unavoidable; these point vacancies are considered to be a major source of the ionic migration and perovskite degradation at the crystal boundary and surface of the perovskite films. Here, we use choline bromide to modify the perovskite film by occupying the atomic defects in the CsPbBr3 perovskite film. The results show that the zwitterion quaternary ammonium ions and bromide ions in choline bromide can simultaneously occupy the Cs+ cation and Br- anions vacancies in the perovskite film by the ionic bonding effect, for which the defect-state density on the surface of the perovskite film can be significantly reduced, leading to the effective enhancement of carrier lifetime. In addition, the residual stress at the crystal boundary can be effectively reduced by lowering the Young's modulus in the CsPbBr3 perovskite film. As a result, the optimized device achieves a photoelectric conversion efficiency (PCE) of 9.06% with an increase of 41.1% compared to the control device with a PCE of 6.42%. Most importantly, the newborn thermal stress due to thermal expansion during heat working conditions can be transferred from the polycrystalline perovskite to the carbon layer by the matched Young's modulus, thus resulting in improved stability perovskite film under environmental conditions. The work provides new insights for preparing high-quality perovskite films with low defect-state density and residual stress.

Hierarchically Hybrid Porous Co3O4@NiMoO4/CoMoO4 Heterostructures for High-Performance Electrochemical Energy Storage.

Hierarchical, ultrathin, and porous NiMoO4@CoMoO4 on Co3O4 hollow bones were successfully designed and synthesized by a hydrothermal route from the Co-precursor, followed by a KOH (potassium hydroxide) activation process. The hydrothermally synthesized Co3O4 nanowires act as the scaffold for anchoring the NiMoO4@CoMoO4 units but also show more compatibility with NiMoO4, leading to high conductivity in the heterojunction. The intriguing morphological features endow the hierarchical Co3O4@NiMoO4@CoMoO4 better electrochemical performance where the capacity of the Co3O4@NiMoO4@CoMoO4 heterojunction being 272 mA·h·g-1 at 1 A·g-1 can be achieved with a superior retention of 84.5% over 1000 cycles. The enhanced utilization of single/few NiMoO4@CoMoO4 shell layers on the Co3O4 core make it easy to accept extra electrons, enhancing the adsorption of OH- at the shell surface, which contribute to the high capacity. In our work, an asymmetric supercapacitor utilizing the optimized Co3O4@NiMoO4@CoMoO4 activated carbon (AC) as electrode materials was assembled, namely, Co3O4@NiMoO4@CoMoO4//AC device, yielding a maximum high energy density of 53.9 W·h·kg-1 at 1000 W·kg-1. It can retain 25.92 W·h·kg-1 even at 8100 W·kg-1, revealing its potential and viability for applications. The good power densities are ascribed to the porous feature from the robust architecture with recreated abundant mesopores on the composite, which assure improved conductivity and enhanced diffusion of OH- and also the electron transport. The work demonstrated here holds great promise for synthesizing other heterojunction materials M3O4@MMoO4@MMoO4 (M = Fe, Ni, Sn, etc).

Glancing angle deposition of large-scale helical Si@Cu3Si nanorod arrays for high-performance anodes in rechargeable Li-ion batteries.

Silicon (Si) anode materials have attracted substantial interest due to their high theoretical capacity. Here, the growth of helical Si@Cu3Si nanorod arrays via glancing angle deposition (GLAD) followed by an annealing process is reported. Pre-deposited Cu atoms were driven into Si-nanorods and successfully reacted with Si to form a Si-Cu alloy at a high temperature. By varying the rotation rate and annealing temperature, the resultant Si@Cu3Si nanorod arrays showed a reasonably accessible surface area with precise control spacing behavior in favor of accommodating Si volume expansion. Meanwhile, the Si@Cu3Si anode materials showed higher electrical conductivity, facilitating Li+ ion diffusion and electron transfer. The Si@Cu3Si nanorod arrays in half cells exhibited a volumetric capacity as high as 3350.1 mA h cm-3 at a rate of 0.25 C and could maintain 1706.7 mA h cm-3 after 100 cycles, which are superior to those of pristine Si materials. This facile and innovative technology provided new insights into the development of Si-based electrode materials.

In situ synthesis of Fe2O3 nanosphere/Co3O4 nanowire-connected reduced graphene oxide hybrid networks for high-performance supercapacitors.

Three-dimensional (3D) hybrid networks consisting of reduced graphene oxide (rGO) sheets interconnected by Co3O4 nanowires (rGO/Co3O4), followed by the decoration of Fe2O3 nanospheres (NSs) (rGO/Co3O4@Fe2O3), were demonstrated by a facile hydrothermal method, with which the rGO/Co3O4 networks acted as nucleation sites for the in situ synthesis of Fe2O3 NSs. The intimate contacts between rGO, Co3O4 NWs and Fe2O3 NSs, which result in an excellent conductive behavior, provide a unique structure with huge potential for electrochemical property promoted electrochemical supercapacitors. The rGO/Co3O4@Fe2O3 hybrid networks as electrodes exhibit a high capacitance of 784 F g-1 at 1 A g-1 with 83% retention of the initial capacitance as the current density increases from 1 to 10 A g-1, which is explained by the graphene-based interconnected structure owing to the advantages of accommodating the volume expansion between Co3O4 NWs and Fe2O3 NSs. The supercapacitor was assembled by applying a nickel aluminum layered double hydroxide (NiAl-LDH) structure and rGO/Co3O4@Fe2O3 as the electrode materials and yields an energy density of 70.78 W h kg-1 at a power density of 0.29 kW kg-1. The energy density can maintain 24.24 W h kg-1 with 9.94 kW kg-1.

Strong Lewis Acid-Base and Weak Hydrogen Bond Synergistically Enhancing Ionic Conductivity of Poly(ethylene oxide)@SiO2 Electrolytes for a High Rate Capability Li-Metal Battery.

Solid-state composite polymer electrolytes (CPEs) usually suffer from intrinsic low ionic conductivity and a solid-solid interface, badly inhibiting their widespread commercial application in all-solid-state Li-metal battery (ASSLMB) energy storage. Herein, a synergetic strategy using strong Lewis acid-base and weak hydrogen bonds was employed for self-assembly in situ construction of three-dimensional (3D) network-structured poly(ethylene oxide) (PEO) and SiO2 CPEs (PEO@SiO2). Ascribed to this synergistically rigid-flexible coupling dynamic strategy, a harmonious incorporation of monodispersed SiO2 nanoparticles into PEO could remarkably reduce crystallinity of PEO, significantly enhancing the ionic conductivity (∼1.1 × 10-4 S cm-1 at 30 °C) and dramatically facilitating solid electrolyte interface stabilization (electrochemical stability window > 4.8 V at 90 °C). Moreover, the PEO@SiO2-based ASSLMBs possess excellent rate capability over a wide temperature range (∼105 mA h g-1 under 2 C at 90 °C), high temperature cycling capacity (retaining 90 mA h g-1 after 100 cycles at 90 °C), and high specific capacity (146 mA h g-1 under 0.3 C at 90 °C). Unambiguously, these high ionic conductivity CPEs along with excellent flexibility and safety can be one of the most promising candidates for high-performance ASSLMBs, evidently revealing that this synergistically rigid-flexible coupling dynamic strategy will open up a way to exploit the novel high ionic conductivity solid-state electrolytes.

Understanding the Ion-Sorption Dynamics in Functionalized Porous Carbons for Enhanced Capacitive Energy Storage.

Heteroatom-functionalized porous carbon has long been regarded as a promising electrode material to construct high-performance capacitive energy storage devices. However, the development of this field is seriously limited due to the lack of an in-depth understanding of the ion-sorption dynamics. Herein, the component and structure controllable N, O, and Cl codoped bimodal (micro-to-meso) porous carbons were prepared and further used as the investigated object for exploring the intrinsic ion-sorption dynamics, which is the root of the enhanced electrochemical response in capacitive energy storage devices. Voltammetry response analysis is employed to quantify the charge storage contributions from both electrostatic adsorption effect (electrical double-layer capacitance) and highly reversible redox process (pseudocapacitance). The existence of electronic capacitance enables a positive correlation between surface capacitance and the ratio of micropores. Besides, an electron-dependent correlation between the electroactive functional groups and redox reaction induced capacitance is also explored. This work will advance the capacitive energy storage field by presenting a clear understanding of the ion-sorption dynamics in the functionalized porous carbons.

Synthetic Biopigment Supercapacitors.

Biomass-based energy storage devices have drawn increasing attention owing to their renewability and sustainability, particularly that the heteroatom-doped carbons derived from natural polymers are regarded as the promising candidates in discovering advanced electrode materials for supercapacitors. This work has developed a facile one-pot fabrication strategy toward synthetic pheomelanin nanoparticles with controllable size and chemical composition (i.e., sulfur content) via the copolymerization of dopamine and cysteine. The resulting synthetic pigment materials possess outstanding thermal stability and are able to directly transform into monodispersed S,N-codoped carbon spheres with unaltered morphology. Compared with conventional polydopamine-based carbon spheres, the present carbonized pheomelanin nanoparticles with electroactive sulfur atoms could possess lower charge-transfer resistance and consequently higher specific capacitance (e.g., 243 F g-1 at 1 A g-1). This research continues to inspire researchers to develop new kinds of energy storage materials based on synthetic biopigment materials.

Self-Powered Acceleration Sensor Based on Liquid Metal Triboelectric Nanogenerator for Vibration Monitoring.

An acceleration sensor is an essential component of the vibration measurement, while the passivity and sensitivity are the pivotal features for its application. Here, we report a self-powered and highly sensitive acceleration sensor based on a triboelectric nanogenerator composed of a liquid metal mercury droplet (LMMD) and nanofiber-networked polyvinylidene fluoride (nn-PVDF) film. Due to the ultrahigh surface-to-volume ratio of nn-PVDF film and high surface tension, high mass density, high elastic as well as mechanical robustness of LMMD, the open-circuit voltage and short-circuit current reach up to 15.5 V and 300 nA at the acceleration of 60 m/s2, respectively. The acceleration sensor has a wide detection range from 0 to 60 m/s2 with a high sensitivity of 0.26 V·s/m2. Also, the output voltage and current show a negligible decrease over 200,000 cycles, evidently presenting excellent stability. Moreover, a high-speed camera was employed to dynamically capture the motion state of the acceleration sensor for insight into the corresponding work mechanism. Finally, the acceleration sensor was demonstrated to measure the vibration of mechanical equipment and human motion in real time, which has potential applications in equipment vibration monitoring and troubleshooting.