Hydrothermal synthesis and phase stability of Pb stabilized ZrO2 nanoparticles

The Pb doped metastable tetragonal ZrO₂ (t-ZrO₂:Pb) nanoparticles have been successfully synthesized by hydrothermal method. Pb ion doping has great effects on the phases, crystallite sizes and optical band gaps. Systematic structural characterization revealed that the introduction of Pb ion results in lattice expansion. The as-prepared t-ZrO₂:Pb with ca 4–6 nm in size has high specific surface area (>150 m²/g) and narrow particle size distributions. The diffuse reflectance spectra investigated that the band gap shifts from ultraviolet (E_g = 5.19 eV) for pure ZrO₂ to the visible region for t-ZrO₂:Pb and the gap can be effectively adjusted with the content of Pb in nanocrystals. Through thermal treatment, Pb ion doped in ZrO₂ crystals was excluded with increasing temperature. At 800 °C, the three t-ZrO₂:Pb samples of ZPO-2, ZPO-3 and ZPO-4 still contained the pure tetragonal phase, in which Pb content were not reduced to zero, while the transformation from tetragonal to monoclinic phase occurred due to zero Pb content in ZPO-1. The reason to this transformation and stabilized mechanism of Pb ion in ZrO₂ were discussed.     

Luminescent Mechanochromic Porous Coordination Polymers

Three 2D luminescent isomeric porous coordination polymers are synthesized and characterized. Their luminescence properties can be modified by grinding and they can act as mechanochromic materials and their properties are probably related to the weak interactions of cuprophilicity and π–π interactions.     

Regulating Charge Transfer of Lattice Oxygen in Single-Atom-Doped Titania for Hydrogen Evolution

Single-atom catalysts have attracted much attention. Reported herein is that regulating charge transfer of lattice oxygen atoms in serial single-atom-doped titania enables tunable hydrogen evolution reaction (HER) activity. First-principles calculations disclose that the activity of lattice oxygen for the HER can be regularly promoted by substituting its nearest metal atom, and doping-induced charge transfer plays an essential role. Besides, the realm of the charge transfer of the active site can be enlarged to the second nearest atom by creating oxygen vacancies, resulting in further optimization for the HER. Various single-atom-doped titania nanosheets were fabricated to validate the proposed model. Taking advantage of the localized charge transfer to the lattice atom is demonstrated to be feasible for realizing precise regulation of the electronic structures and thus catalytic activity of the nanosheets.     

A three-layer egg-configurated Bragg microcavity of polyglycerol coated cholesteric-liquid-crystal encapsulated by hollow-glass-microsphere

ABSTRACT

This letter reports the optical pumped lasing behaviours of a three-layer Bragg resonance cavity consisting of dye-doped cholesteric liquid crystal (DDCLC) microdroplet, polyglycerol-2 and hollow glass microsphere. The function of PG2 is to control the parallel anchoring of the liquid crystal (LC) molecules on the surface of the LC microdroplet. The whispering-gallery mode (WGM), radial Bragg (photonic bandgap, PBG) mode and Bragg WGM (BWGM) are observed in DDCLC microspheres with different helical pitches and LC refractive indices. The formation mechanisms of six types of lasing emission conditions are analysed in detail. The study results present the prospect of controlling the output mode of the laser. Furthermore, such solid shell-based DDCLC microspheres have outstanding potential applications in miniaturised 3D Bragg lasers, sensors, and integrated and tunable optical devices.     

Recent Advances in Atomic-scale Storage Mechanism Studies of Two-dimensional Nanomaterials for Rechargeable Batteries Beyond Li-ion

Developing new types of rechargeable batteries with high energy densities and low cost have received increasing attentions, aiming to reduce the dependence on high-priced lithium. Beyond Li-ion batteries, the potential alternatives including Na-ion batteries, Li-S batteries and Li-air batteries have been investigated recently, which are required to be viable for commercial applications. From this point of view, to understand the electrochemical reaction mechanisms and kinetics of these batteries has become the key challenge to make breakthroughs in the field of new energy storage. In this review, we present a critical overview of the two dimensional nanomaterials-based batteries (except Li-ion-based batteries) that could meet such demonds. To develop new energy storage devices with more promising performances, the microstructure evolution and atomic scale storage mechanism of these batteries are comprehensively summarized. In addition, the major challenges and opportunities of advanced characterization techniques are finally discussed. We do hope that this review will give the readers a clear and profound understanding of the electrochemical reaction mechanisms and kinetics of the as-discussed batteries, thus effectively contributing to the smart design of future-generation energy storage devices.     

Covalently Immobilized Battacin Lipopeptide Gels with Activity against Bacterial Biofilms

Novel antibiotic treatments are in increasing demand to tackle life-threatening infections from bacterial pathogens. In this study, we report the use of a potent battacin lipopeptide as an antimicrobial gel to inhibit planktonic and mature biofilms of S. aureus and P. aeruginosa. The antimicrobial gels were made by covalently linking the N-terminal cysteine containing lipopeptide (GZ3.163) onto the polyethylene glycol polymer matrix and initiating gelation using thiol-ene click chemistry. The gels were prepared both in methanol and in water and were characterised using rheology, Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). Antibacterial and antibiofilm analyses revealed that the gels prepared in methanol have better antibacterial and antibiofilm activity. Additionally, a minimum peptide content of 0.5 wt% (relative to polymer content) is required to successfully inhibit the planktonic bacterial growth and disperse mature biofilms of P. aeruginosa and S. aureus. The antibacterial activity of these lipopeptide gels is mediated by a contact kill mechanism of action. The gels are non-haemolytic against mouse red blood cells and are non-cytotoxic against human dermal fibroblasts. Findings from this study show that battacin lipopeptide gels have the potential to be developed as novel topical antibacterial agents to combat skin infections, particularly caused by S. aureus.     

Immobilized complexes of the salen Schiff’s base with metal as oxidation catalysts

The immobilized metal complexes with the Schiff’s base of salen have shown high catalytic activity in oxidation of alkenes, cycloalkenes, and alcohols as compared with their unsupported analogs. Due to the heterogeneous nature of such catalysts, their separation and recycling is rather simple.     

Deep‐Ultraviolet Nonlinear Optics in a Borate Framework with 21‐Ring Channels

A new borate LiBa₃(OH)[B₉O₁₆][B(OH)₄], which combines the uniform porosity of open‐frameworks with the extraordinary NLO properties of borates, has been obtained under hydrothermal conditions by using mixed lithium and barium ions as templates. The framework displays an acs‐type net with large 21‐ring channels. The second harmonic generation (SHG) measurement shows that it is a type I phase‐matchable material with a strong SHG signal intensity about 3.1 times that of KDP (KH₂PO₄). UV/Vis–NIR diffuse reflectance analysis indicates that the compound has a wide transparency range with the short‐wavelength absorption edge below 200 nm. These characteristics reveal that the compound is a promising deep‐UV nonlinear optical material.