Ultrathin Two-dimensional Layered Composite Carbosilicates from in situ Unzipped Carbon Nanotubes and Exfoliated Bulk Silica.

A key task in today's inorganic synthetic chemistry is to develop effective reactions, routes, and associated techniques aiming to create new functional materials with specifically desired multilevel structures and properties. Herein, we report an ultrathin two-dimensional layered composite of graphene ribbon and silicate via a simple and scalable one-pot reaction, which leads to the creation of a novel carbon-metal-silicate hybrid family: carbosilicate. The graphene ribbon is in situ formed by unzipping carbon nanotubes, while the ultrathin silicate is in situ obtained from bulk silica or commercial glass; transition metals (Fe or Ni) oxidized by water act as bridging agent, covalently bonding the two structures.

Carbon-Free, Binder-Free MnO@Mn Catalyst for Oxygen Reduction Reaction.

Reasonable design and feasible preparation of low-cost and stable oxygen reduction reaction (ORR) catalysts with excellent performance play a key role in the development of fuel cells and metal-air batteries. A 3D porous superimposed nanosheet catalyst composed of metal manganese covered with MnO nanofilms (P-NS-MnO@Mn) was designed and synthesized by rotating disk electrodes (RDEs) through one-step electrodeposition. The catalyst contains no carbon material.

Active Interphase Enables Stable Performance for an All-Phosphate-Based Composite Cathode in an All-Solid-State Battery.

High interfacial resistance and unstable interphase between cathode active materials (CAMs) and solid-state electrolytes (SSEs) in the composite cathode are two of the main challenges in current all-solid-state batteries (ASSBs). In this work, the all-phosphate-based LiFePO (LFP) and Li Al Ti (PO ) (LATP) composite cathode is obtained by a co-firing technique. Benefiting from the densified structure and the formed redox-active Li Fe Ti Al (PO ) (LFTAP) interphase, the mixed ion- and electron-conductive LFP/LATP composite cathode facilitates the stable operation of bulk-type ASSBs in different voltage ranges with almost no capacity degradation upon cycling.

Single-Ion-Conducting "Polymer-in-Ceramic" Hybrid Electrolyte with an Intertwined NASICON-Type Nanofiber Skeleton.

The fast Li transportation of "polymer-in-ceramic" electrolytes is highly dependent on the long-range Li migration pathways, which are determined by the structure and chemistry of the electrolytes. Besides, Li dendrite growth may be promoted in the soft polymer region due to the inhomogeneous electric field caused by the commonly low Li transference number of the polymer. Herein, a single-ion-conducting polymer electrolyte is infiltrated into intertwined LiAlTi(PO) (LATP) nanofibers to construct free-standing electrolyte membranes.

A new type of noncovalent surface-π stacking interaction occurring on peroxide-modified titania nanosheets driven by vertical π-state polarization.

Noncovalent π stacking of aromatic molecules is a universal form of noncovalent interactions normally occurring on planar structures (such as aromatic molecules and graphene) based on sp-hybridized atoms. Here we reveal a new type of noncovalent surface-π stacking unusually occurring between aromatic groups and peroxide-modified titania (PMT) nanosheets, which can drive versatile aromatic adsorptions. We experimentally explore the underlying electronic-level origin by probing the perturbed changes of unoccupied Ti 3d states with near-edge X-ray absorption fine structures (NEXAFS), and find that aromatic groups can vertically attract π electrons in the surface peroxo-Ti states and increase their delocalization regions.

Ultrathin 2D Fe-Nanosheets Stabilized by 2D Mesoporous Silica: Synthesis and Application in Ammonia Synthesis.

Developing high-performance Fe-based ammonia catalysts through simple and cost-efficient methods has received an increased level of attention. Herein, we report for the first time, the synthesis of two-dimensional (2D) FeOOH nanoflakes encapsulated by mesoporous SiO (mSiO) via a simple solution-based method for ammonia synthesis. Due to the sticking of the mSiO coating layers and the limited spaces in between, the Fe after reduction retains the 2D morphology, showing high resistance against the sintering in the harsh Haber-Bosch process.

Solid-State NMR and MRI Spectroscopy for Li/Na Batteries: Materials, Interface, and In Situ Characterization.

Enhancing the electrochemical performance of batteries, including the lifespan, energy, and power densities, is an everlasting quest for the rechargeable battery community. However, the dynamic and coupled (electro)chemical processes that occur in the electrode materials as well as at the electrode/electrolyte interfaces complicate the investigation of their working and decay mechanisms. Herein, the recent developments and applications of solid-state nuclear magnetic resonance (ssNMR) and magnetic resonance imaging (MRI) techniques in Li/Na batteries are reviewed.

Reconstructing 1D Fe Single-atom Catalytic Structure on 2D Graphene Film for High-Efficiency Oxygen Reduction Reaction.

The ordinary intrinsic activity and disordered distribution of metal sites in zero/one-dimensional (0D/1D) single-atom catalysts (SACs) lead to inferior catalytic efficiency and short-term endurance in the oxygen reduction reaction (ORR), which restricts the large-scale application of hydrogen-oxygen fuel cells and metal-air batteries. To improve the activity of SACs, a mild synthesis method was chosen to conjugate 1D Fe SACs with 2D graphene film (Fe SAC@G) that realized a composite structure with well-ordered atomic-Fe coordination configuration. The product exhibits outstanding ORR electrocatalytic efficiency and stability in 0.

Overall Oxygen Electrocatalysis on Nitrogen-Modified Carbon Catalysts: Identification of Active Sites and In Situ Observation of Reactive Intermediates.

The recent mechanistic understanding of active sites, adsorbed intermediate products, and rate-determining steps (RDS) of nitrogen (N)-modified carbon catalysts in electrocatalytic oxygen reduction (ORR) and oxygen evolution reaction (OER) are still rife with controversy because of the inevitable coexistence of diverse N configurations and the technical limitations for the observation of formed intermediates. Herein, seven kinds of aromatic molecules with designated single N species are used as model structures to investigate the explicit role of each common N group in both ORR and OER. Specifically, dynamic evolution of active sites and key adsorbed intermediate products including O (ads), superoxide anion O *, and OOH* are monitored with in situ spectroscopy.

Highly Efficient Metal-Free Nitrogen-Doped Nanocarbons with Unexpected Active Sites for Aerobic Catalytic Reactions.

Nitrogen (N)-doped nanocarbons (NDN) as metal-free catalysts have elicited considerable attention toward selective oxidation of alcohols with easily oxidizable groups to aldehydes in the past few years. However, finding a new NDN catalytic material that can meet the requirement of the feasibility on the aerobic catalytics for other complicated alcohols is a big challenge. The real active sites and the corresponding mechanisms on NDN are still unambiguous because of inevitable coexistence of diverse edge sites and N species based on recently reported doping methods.

Ultrasensitive ultrasound detection using an intracavity phase-shifted fiber Bragg grating in a self-injection-locked diode laser.

We report a high-sensitivity fiber-optic ultrasonic sensor system using a self-injection-locked distributed-feedback (DFB) diode laser where a π-phase-shifted fiber Bragg grating (πFBG) serves as both the locking resonator and the sensing element in a fiber ring feedback loop. By controlling the delay time of the feedback light through a fiber stretcher, the laser wavelength is locked to an external cavity mode on the spectral slope of the πFBG, and the ultrasound-induced wavelength shifts of the πFBG are converted to laser intensity variation. The ultrasonic sensing scheme simplifies the feedback control because the self-injection locking automatically pulls the laser wavelength to the πFBG resonant wavelength.

Fluorine-free water-in-ionomer electrolytes for sustainable lithium-ion batteries.

The continuously increasing number and size of lithium-based batteries developed for large-scale applications raise serious environmental concerns. Herein, we address the issues related to electrolyte toxicity and safety by proposing a "water-in-ionomer" type of electrolyte which replaces organic solvents by water and expensive and toxic fluorinated lithium salts by a non-fluorinated, inexpensive and non-toxic superabsorbing ionomer, lithium polyacrylate. Interestingly, the electrochemical stability window of this electrolyte is extended greatly, even for high water contents.

Probing Ligand-Induced Cooperative Orbital Redistribution That Dominates Nanoscale Molecule-Surface Interactions with One-Unit-Thin TiO Nanosheets.

Understanding the general electronic principles underlying molecule-surface interactions at the nanoscale is crucial for revealing the processes based on chemisorption, like catalysis, surface ligation, surface fluorescence, etc. However, the electronic mechanisms of how surface states affect and even dominate the properties of nanomaterials have long remained unclear. Here, using one-unit-thin TiO nanosheet as a model surface platform, we find that surface ligands can competitively polarize and confine the valence 3d orbitals of surface Ti atoms from delocalized energy band states to localized chemisorption bonds, through probing the surface chemical interaction at the orbital level with near-edge X-ray absorption fine structure (NEXAFS).

Correction: Synthesis of Ca(PF), formed via nitrosonium oxidation of calcium.

Correction for 'Synthesis of Ca(PF), formed via nitrosonium oxidation of calcium' by Evan N. Keyzer et al., Chem.

The Effect of Water on Quinone Redox Mediators in Nonaqueous Li-O Batteries.

The parasitic reactions associated with reduced oxygen species and the difficulty in achieving the high theoretical capacity have been major issues plaguing development of practical nonaqueous Li-O batteries. We hereby address the above issues by exploring the synergistic effect of 2,5-di-tert-butyl-1,4-benzoquinone and HO on the oxygen chemistry in a nonaqueous Li-O battery. Water stabilizes the quinone monoanion and dianion, shifting the reduction potentials of the quinone and monoanion to more positive values (vs Li/Li).

Understanding LiOH Chemistry in a Ruthenium-Catalyzed Li-O Battery.

Non-aqueous Li-O batteries are promising for next-generation energy storage. New battery chemistries based on LiOH, rather than Li O , have been recently reported in systems with added water, one using a soluble additive LiI and the other using solid Ru catalysts. Here, the focus is on the mechanism of Ru-catalyzed LiOH chemistry.

Fiber-optic anemometer based on single-walled carbon nanotube coated tilted fiber Bragg grating.

In this work, a novel and simple optical fiber hot-wire anemometer based on single-walled carbon nanotubes (SWCNTs) coated tilted fiber Bragg grating (TFBG) is proposed and demonstrated. For the hot-wire wind speed sensor design, TFBG is an ideal in-fiber sensing structure due to its unique features. It is utilized as both light coupling and temperature sensing element without using any geometry-modified or uncommon fiber, which simplifies the sensor structure.

A Novel Low-Power-Consumption All-Fiber-Optic Anemometer with Simple System Design.

A compact and low-power consuming fiber-optic anemometer based on single-walled carbon nanotubes (SWCNTs) coated tilted fiber Bragg grating (TFBG) is presented. TFBG as a near infrared in-fiber sensing element is able to excite a number of cladding modes and radiation modes in the fiber and effectively couple light in the core to interact with the fiber surrounding mediums. It is an ideal in-fiber device used in a fiber hot-wire anemometer (HWA) as both coupling and sensing elements to simplify the sensing head structure.

Simple method for self-referenced and lable-free biosensing by using a capillary sensing element.

We demonstrated a simple method for self-reference and label free biosensing based on a capillary sensing element and common optoelectronic devices. The capillary sensing element is illuminated by a light-emitting diode (LED) light source and detected by a webcam. Part of gold film that deposited on the tubing wall is functionalized to carry on the biological information in the excited SPR modes.

Synthesis of Ca(PF), formed via nitrosonium oxidation of calcium.

The development of rechargeable Ca-ion batteries as an alternative to Li systems has been limited by the availability of suitable electrolyte salts. We present the synthesis of complexes of Ca(PF) (a key potential Ca battery electrolyte salt) via the treatment of Ca metal with NOPF, and explore their conversion to species containing POF under the reaction conditions.

Enhanced efficiency of solid-state NMR investigations of energy materials using an external automatic tuning/matching (eATM) robot.

We have developed and explored an external automatic tuning/matching (eATM) robot that can be attached to commercial and/or home-built magic angle spinning (MAS) or static nuclear magnetic resonance (NMR) probeheads. Complete synchronization and automation with Bruker and Tecmag spectrometers is ensured via transistor-transistor-logic (TTL) signals. The eATM robot enables an automated "on-the-fly" re-calibration of the radio frequency (rf) carrier frequency, which is beneficial whenever tuning/matching of the resonance circuit is required, e.

Insights into the electrochemical performances of Bi anodes for Mg ion batteries using Mg solid state NMR spectroscopy.

Bi nanowires as anode materials for Mg ion batteries exhibit excellent electrochemical behaviour, forming MgBi; this is in part ascribed to the rapid Mg mobility between the two Mg sites of MgBi, as revealed by the Mg NMR spectra of MgBi formed electrochemically and via ball-milling. A mechanism involving hops into vacant Mg sites is proposed.

Micro-capillary-based self-referencing surface plasmon resonance biosensor for determination of transferrin.

A novel self-referencing surface plasmon resonance (SPR) biosensor for detection of transferrin is demonstrated using a micro-capillary as the sensing element. The biosensor employs the SPR mode as a measuring signal and the Fabry-Perot (FP) mode as a referencing signal. The SPR mode is generated in the gold film that is coated on the outside of the capillary; instead, the FP mode is excited in the capillary, which is filled with de-ionized water.