Latest ArticlesSolid photocatalysts with high specific surface area, superior photoactivity and ease of recycling are highly desired in chemical process, water treatment and so on. In this study, a facile stepwise sol-gel coating approach was utilized to synthesize Pt decorated oxygen-deficient mesoporous titania microspheres with core-shell structure and convenient magnetic separability (denoted as Fe3O4@SiO2@Pt/mTiO2-x). These photocatalysts consist of magnetic Fe3O4 cores, nonporous insulating SiO2 middle layer and mesoporous anatase TiO2-x shell decorated by Pt nanoparticles (~3.5 nm) through wet impregnation and H2 reduction. As a result of high activity of oxygen-deficiency of black TiO2-x by H2 reduction and efficient inhibition of electron-hole recombination by Pt nanoparticles, the rationally designed core-shell Fe3O4@SiO2@Pt/mTiO2-x photocatalysts exhibit superior photocatalytic performance in rhodamine B (RhB) degradation under visible light irradiation, with more than 98% of RhB degraded within 50 min. These core-shell structured photocatalysts show excellent recyclability under the assistance of magnetic separation with well-retained photocatalytic performance even after running five cycles. This stepwise synthesis method paves the way for the rational design of a high-efficiency recyclable heterogeneous catalyst, including photocatalysts, for various applications.
CuWO4, as an n-type oxide semiconductor with a bandgap of 2.2 eV, has stimulated enormous interest as a potential broad-spectrum-active photocatalyst for environmental pollution remediations. However, rapid charge recombination greatly hinders its practical applications. Herein, we present a cascaded electron transition pathway in a ternary heterostructure consisting of CdS quantum dots, carbon dots (CDs) and CuWO4 hollow spheres, which proves to greatly facilitate the photogenerated electron-hole separation, and eventually boosts the degradation efficiency of phenol and congo red by 100% and 46% compared to bare CuWO4. The enhanced performance of the CuWO4/CdS/CDs heterostructure mainly originates from the unidirectional electron migration from CdS to CuWO4 and then to the organics through CDs. This work elucidates the electron transfer kinetics in multi-phase system and provides a new design paradigm for optimizing the properties of CuWO4 based photocatalysts.
Reported herein is the first example of electrochemical selenocyanation of imidazo[1, 5-a]quinolines with KSeCN under metal catalyst- and chemical oxidant-free conditions. This sustainable strategy shows a broad scope and great compatibility with functional groups, and affords synthetically and biologically important selenocyanated imidazo[1, 5-a]quinolines in good to excellent yields with cheap graphite and Ni plates as the electrodes. The gram-scale synthesis was also successfully conducted, which might demonstrate the potential value of this electrochemical protocol.
Cancer is one of the diseases that have the highest mortality, which threatens the human health. Chemotherapy functions as the most widely used strategy in clinic to treat cancer, still exists urgent problems, like lacking selectivity and causing severe side effects. According to detailed researches on the metabolism, functions and histology of cancer tissues, many different features of cancer are uncovered, like lower pH in microenvironment, abnormal redox level in intracellular compartments and elevated expression level of several enzymes and receptors. Recently, the development of smart nanoparticles that response to tumor specific microenvironment has lighted up hope for selective cancer therapy. Herein, this review mainly focuses on pH-sensitive nanoscale materials for anti-cancer drug delivery. We summarized the formation progress of acidic tumor microenvironment, the mechanism of pH-responsive drug delivery system and nanomaterials that responsive to acidic pH in tumor microenvironment.
The effects of bisulfite-activated permanganate technology (PM/BS) as a pre-oxidation process on enhancing Microcystis aeruginosa (M. aeruginosa) removal by post coagulation were investigated. The results demonstrated that pretreatment with PM/BS process effectively promoted the algae removal by coagulation with Al2(SO4)3 as the coagulant and this phenomenon was more obvious with the increase of water hardness. Compared to the sole coagulation, PM/BS pre-oxidation combing with coagulation could neutralize the zeta potential of algal cells effectively, decrease the algal cell size, and lead to the formation of more compact flocs due to the in-situ generated MnO2. The effect of oxidant dosages on algal organic matter (AOM) was also studied and no obvious release of macromolecular substances was observed with the dosage of KMnO4 increasing from 3.0 mg/L to 7.0 mg/L, suggesting the integrity of algal cells at a high KMnO4 dosage. Moreover, PM/BS pre-oxidation could lead to the decrease of most analyzed disinfection by-products (DBPs) at a Al2(SO4)3 dosage of 40.0 mg/L. The algae removal efficiency was also significantly enhanced by PM/BS pre-oxidation in the test using real algae-laden water. This study indicated that PM/BS process might be a potential assistant technology for algae removal by subsequent coagulation.
Exploring 3D hybrid nanocarbons encapsulated with metal nanoparticles (NPs) are recently considered as emerging catalysts for boosting CO2 electroreduction reaction (CRR) under practical and economic limits. Herein, we report a one-step pyrolysis strategy for fabricating N-doped carbon nanotube (CNT)-encapsulated Ni NPs assembled on the surface of graphene (N/NiNPs@CNT/G) to efficiently convert CO2 into CO. In such 3D hybrid, the particle size of Ni NPs that coated by five graphitic carbon layers is less than 100 nm, and the amount of N dopants introduced into graphene with countable CNTs is determined to 7.27 at%. Thanks to unique CNT-encapsulated Ni NPs structure and N dopants, the achieved N/NiNPs@CNT/G hybrid displays an exceptional CRR activity with a high Faradaic efficiency of 97.7% and large CO partial current density of 7.9 mA/cm2 at -0.7 V, which outperforms those reported metallic NPs loaded carbon based CRR electrocatalysts. Further, a low Tafel slope of 134 mV/dec, a turnover frequency of 387.3 CO/h at -0.9 V, and tiny performance losses during long-term CRR operation are observed on N/NiNPs@CNT/G. Experimental observations illustrate that the Ni NPs encapsulated by carbon layers along with N dopants are of great importance in the conversion of CO2 into CO with high current density.
Commercial carbon clothes have the potential to be utilized as supercapacitor electrodes due to their low cost and high conductivity. However, the negligible surface area of the carbon clothes serves as a serious impediment to their utilization. Herein, we report a facile calcination activation method for carbon cloths to realize remarkable comprehensive electrochemical performance. The activated carbon cloths deliver a high areal capacitance (1700 mF/cm2), good rate capability, and stable cycling performance up to 20, 000 cycles. Owing to the stability in the wide potential window, a designed symmetric capacitor can function in a cell voltage of 2.0 V and delivers high volumetric and gravimetric energy densities of 7.62 mWh/cm3 and 18.2 Wh/kg, respectively. The remarkable electrochemical performance is attributed to rich microporosity with high surface area, superior electrolyte wettability, and stability in wide potential window.
The removal of ciprofloxacin (CIP) in sulfur-mediated bioprocesses, e.g., sulfate-reducing bacteria (SRB)-mediated process and sulfur-oxidizing bacteria (SOB)-mediated process, was examined for the first time. The results showed that the SRB-mediated process had more efficient CIP removal than that in SOB-mediated process. Adsorption was the primary removal pathway of CIP in SRB-mediated process and SOB-mediated process with the specific adsorption removal rate of 131.4±1.1 μg/g-SS/d and 30.1±1.4 μg/g-SS/d, respectively, at influent CIP concentration of 500 μg/L. In addition, extracellular polymeric substances (EPS) also played an important role on CIP migration and removal in both types of sludge. Further study was conducted to specify the different adsorption of CIP in these two sludge systems from the perspective of sludge properties. The results indicated that there are more potential adsorption sites exist on the SRB-mediated sludge for CIP adsorption than SOB-mediated sludge since the higher protein (PN) content and more kinds of aromatic amino acid substances in EPS, more negative zeta-potential and stronger and more numbers of functional groups in SRB-mediated sludge compared to SOB-mediated sludge. The findings of this study provide insights into the sludge properties affecting CIP removal in sulfur-mediated bioprocesses, and are of guiding significance to employ sulfur-mediated biological systems for treating CIP-containing wastewaters.
A Lewis base catalyzed ring expansion of isatin with 2, 2, 2-trifluorodiazoethane (CF3CHN2) is developed. It is characterized that the merge of tetramethylethylenediamine and CF3CHN2 generates reactive triazene intermediates, which construct substituted 3-hydroxy-4-(trifluoromethyl)quinolinones with high efficiency. Synthetic application of the procedure is broadened by 3-trifluormethylpyrazole fused 3-hydroxy-4-(trifluoromethyl)quinolinone synthesis.
Four pillar[5]arene based [3]rotaxanes (1-4) involving two 1,4-diethoxypillar[5]arene (DEP5) rings and a dumbbell-shaped component were successfully synthesized. The dumbbell-shape molecules contain one longer bridge, two triazole sites and two multicomponent stoppers. After threading DEP5 rings with linear guests (G1-G4) which contain two benzaldehyde units, the base catalyzed three-component reaction of dimedone, malononitrile and benzaldehyde was performed to construct the stoppers and connected the pseudorotaxanes with stoppers to generate 1–4. The structures of [3]rotaxanes and their self-assembly behaviors were characterized by 1H NMR, 13C NMR, NOESY, HR-ESI-MS, DLS and TEM technologies. We hope that pillar[5]arene based [3]rotaxanes may have potential applications in drug delivery systems and molecular devices.
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