Preparation of Novel Layered High Entropy Bismuth-Based Materials and their Photocatalytic Degradation Mechanism.

We prepared BiOCl, BiO(ClBr), BiO(ClBrI), and BiO[ClBrI(CO3)0.5] materials using a simple coprecipitation method. It was found that adjusting the number of anions in the anion layer was conducive to adjusting the band structure of BiOX and could effectively promote the migration and separation of photogenerated carriers, thus improving the photocatalytic activity. We first selected methyl orange (MO) as the study pollutant and compared it with BiOCl, BiO(ClBr), and BiO(ClBrI). The first-order kinetic constants of MO degradation by BiO[ClBrI(CO3)0.5] increased by 90.3, 33.9, and 3.1 times, respectively. The photocatalytic degradation rate of methylene blue by BiO[ClBrI(CO3)0.5] was 89.5%, indicating the excellent photocatalytic performance of BiO[ClBrI(CO3)0.5]. The stability of BiO[ClBrI(CO3)0.5] was demonstrated through cyclic experiments and XRD analysis before and after the reaction. The photocatalytic degradation of MO by BiO[ClBrI(CO3)0.5] showed that h+ and 1O2 were the main active oxidizing species and •O2- was the secondary active substance. Overall, our work provides new ideas for the synthesis and degradation of organic pollutants by using two-dimensional anionic high-entropy materials.

Mesoporous carbon nanoenzyme as nano-booster for photothermal-enhanced photodynamic therapy compared with graphene oxide.

The over-expressed GSH in tumor microenvironment significantly weakens the lethal reactive oxygen species (ROS) generated by photodynamic therapy (PDT) and catalysis of nanoenzyme. Hence, it is necessary to excavate a versatile and effective vehicle with oxidative stress-enhancement and GSH-depletion capacity to break the redox homeostasis in tumor microenvironment. GO has been reported to possess GSH-depletion and peroxidase (POD)-like capacity. Based on this, PEGylated mesoporous carbon (MC-PEG) was prepared as ICG vehicle to compare with PEGylated graphene oxide (GO-PEG). Excitingly, MC-PEG was found to exhibit three times higher oxidative capacity by POD-like process than GO-PEG, and owned more effective and continuous GSH-depletion capacity to further amplify the oxidative stress. Meanwhile, MC-PEG exhibited better protective effect on the loaded ICG against unwanted light excitation than GO-PEG. Together with the higher photothermal conversion effect, under the NIR light irradiation, MC-PEG could markedly improve the temperature of tumor cells and produce more hydroxyl radical, continuously consume GSH and provide more better protection for ICG compared with GO-PEG, thus further boosting the combination of photothermal and photodynamic effects. The anti-tumor experiment in cell and in-vivo level both validated that ICG/MC-PEG showed better synergistic effect with lower IC50 value and higher tumor suppression rate than ICG/GO-PEG.

Biosafe Bi2O2Se ultrathin nanosheet for water disinfection via solar-induced photothermal synergistic effect.

Solar-induced sterilization via photothermal synergy has attracted enormous attention due to its zero-energy consumption and the elimination of hazardous chemical disinfectant. Herein, we successfully synthesized a super biosafety Bi2O2Se with crossed nanosheet structure (Bi2O2Se-CN) for the sterilization of Escherichia coli (E. coli) via solar-induced photothermal synergistic effect. In comparison to bulk Bi2O2Se, the lower light reflection and more efficient photogenerated charge carrier separation under visible-infrared light irradiation resulted in the excellent sterilization effect of Bi2O2Se-CN, with a sterilization efficiency of 99.9% under the synergistic effect of light and heat. The crossed ultrathin nanosheet structure and suitable band gap width of Bi2O2Se-CN are fundamental reasons for its enhanced light absorption and charge carrier separation efficiency. Mechanistic studies showed that Bi2O2Se-CN can completely inactivate bacteria via generating a large amount of reactive oxygen species (•O2-, •OH, and 1O2) to attack the cell membrane, which further resulted in the reduced activity of intracellular enzymes and the leakage of intracellular contents. The biosafety property of Bi2O2Se-CN was confirmed by in vivo toxicological evaluation on the mice model. This work provided new ideas for the design of more efficient, energy-saving, biocompatible and environmental friendly solar water purification projects.

Hard carbon micro-nano tubes derived from kapok fiber as anode materials for sodium-ion batteries and the sodium-ion storage mechanism.

Hard carbon materials are considered as the most promising anode for sodium-ion batteries (SIBs). However, the high cost and poor rate performance hinder their application in SIBs. Moreover, the controversial mechanism of Na-ion storage restricts the improvement of hard carbon anodes. Herein, hard carbon micro-nano tubes (HCMNTs) from low-cost biomass kapok fibers are prepared as a promising anode for SIBs. Benefitting from the micro-nano structure, which offers low surface area and short Na+ diffusion path, 1400HCMNT possesses a good initial Coulombic efficiency of 80%, a high reversible capacity of 290 mA h g-1, and an excellent rate capacity. Furthermore, electron paramagnetic resonance and thermogravimetric analysis were applied to investigate the Na-ion storage mechanism in the HCMNTs. Sodium is stored in the hard carbon in an ionic state in the slope region and as quasi-liquid metallic sodium clusters in the low-voltage plateau.

Observation of a Helical Luttinger Liquid in InAs/GaSb Quantum Spin Hall Edges.

We report on the observation of a helical Luttinger liquid in the edge of an InAs/GaSb quantum spin Hall insulator, which shows characteristic suppression of conductance at low temperature and low bias voltage. Moreover, the conductance shows power-law behavior as a function of temperature and bias voltage. The results underscore the strong electron-electron interaction effect in transport of InAs/GaSb edge states. Because of the fact that the Fermi velocity of the edge modes is controlled by gates, the Luttinger parameter can be fine tuned. Realization of a tunable Luttinger liquid offers a one-dimensional model system for future studies of predicted correlation effects.