Latest ArticlesExploring 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.
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.
Solid 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.
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.
Developing a new type of deep eutectic solvents (DESs) is indispensable for expanding their application in various fields. Here, we report a series of new highly basic DESs. FT-IR, quantitative 1H NMR, MD simulation and physical properties show that these basic liquids are made up of hydroxide acceptor of alkali metal hydroxides in which the hydrogen bonding interactions coordinate the donor. These DESs can be played three roles as new solvents, template and reactant for facile and ultra-fast preparation of transition metal oxide nanomaterials such as NiCo2O4, MnCo2O4, NiMn2O4, CoCu2O4 and Co3O4 under mild condition. This work shows one of the low energy-intensive methods for nanomaterial preparation. These initial findings of basic deep eutectic solvents provide a potential applicability around the systematic development of transition metal oxide nanosheets.
Bladder cancer is the most common malignant tumor in the urinary system, with high morbidity, mortality and recurrence after surgery. However, current bladder cancer urine diagnosis methods are limited by the low accuracy and specificity due to the low abundance of bladder cancer biomarkers in the urine with complex biological environments. Herein, we present a high stability indium gallium zinc oxide field effect transistor (IGZO-FET) biosensor for efficient identification of bladder cancer biomarkers from human urine samples. The recognition molecular functionalized IGZO-FET biosensor exhibits stable electronic and sensing performance due to the large-area fabrication of IGZO thin-film FET. Owing to the excellent electrical performance of IGZO-FET, the IGZO-FET biosensor exhibits high sensitivity and extremely low detection limit (2.7 amol/L) towards bladder cancer biomarkers. The IGZO-FET biosensor is also able to directly detect bladder tumor biomarker in human urine with high sensitivity and specificity, and could differentiate bladder cancer patients' urine samples from healthy donors effectively. These results indicate that our designed high-performance biosensor shows great potential in the application of portable digital bladder cancer diagnosis devices.
The trans-hydroboration of alkyne represents a challenging task in organic synthesis. Reported herein is an Et2Zn promoted β-trans hydroboration of ynamides by using N-heterocyclic carbene (NHC)-ligated borane as boryl source. The reaction leads to a stereoselective construction of enamides bearing a valuable boryl substituent. Both aromatic and aliphatic ynamides were applicable to the reaction. Synthetic transformation of the C—B bond in the product via Suzuki-Miyaura coupling provides a simple and stereospecific route to multi-substituted enamides. Mechanistic studies were conducted and the possible mechanism was discussed
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.
Electrocatalytic CO2 reduction (CO2ER) into formate is a desirable route to achieve efficient transformation of CO2 to value-added chemicals, however, it still suffers from limited catalytic activity and poor selectivity. Herein, we develop a hybrid electrocatalyst composed of bismuth and bismuth oxide nanoparticles (NPs) supported on nitrogen-doped reduced graphene oxide (Bi/Bi2O3/NrGO) nanosheets prepared by a combined hydrothermal with calcination treatment. Thanks to the combination of undercoordinated sites and strong synergistic effect between Bi and Bi2O3, Bi/Bi2O3/NrGO-700 hybrid displays a promoted CO2ER catalytic performance and selectivity for formate production, as featured by a small onset potential of -0.5 V, a high current density of -18 mA/cm2, the maximum Faradaic efficiency of 85% at -0.9 V, and a low Tafel slope of 166 mV/dec. Experimental results reveal that the higher CO2ER performance of Bi/Bi2O3/NrGO-700 than that of Bi NPs supported on NrGO (Bi/NrGO) can be due to the partial reduction of Bi2O3 NPs into Bi, which significantly increases undercoordinated active sites on Bi NPs surface, thus boosting its CO2ER performance. Furthermore, a two-electrode device with Ir/C anode and Bi/Bi2O3/NrGO-700 cathode could be integrated with two alkaline batteries or a planar solar cell to achieve highly active water splitting and CO2ER.
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.
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