Latest ArticlesMetal-nanocluster materials have gradually become a promising electrode candidate for supercapacitor application. The high-efficient and rational architecture of these metal-nanocluster electrode materials with satisfied supercapacitive performance are full of challenges. Herein, Fe-nanocluster anchored porous carbon (FAPC) nanosheets were constructed through a facile and low-cost impregnation-activation strategy. Various characterization methods documented that FAPC nanosheets possessed a mesopore-dominated structure with large surface area and abundant Fe-N4 active sites, which are crucial for supercapacitive energy storage. The optimal FAPC electrode exhibited a high specific capacitance of 378 F/g at a specific current of 1 A/g and an excellent rate capability (271 F/g at 10 A/g), which are comparable or even superior to that of most reported carbon candidates. Furthermore, the FAPC-based device achieved a desired specific energy of 14.8 Wh/kg at a specific power of 700 W/kg. This work opens a new avenue to design metal-nanocluster materials for high-performance biomass waste-based supercapacitors.
Flow-electrode capacitive deionization (FCDI) represents a promising approach for ion separation from aqueous solutions. However, the optimization of spacer, particularly for nitrate-contaminated groundwater systems, has often been overlooked. This research comprehensively investigates the influence of using a conductive (carbon cloth, CC) spacer on nitrate removal performance within FCDI system, comparing it to a non-conductive (nylon net, NN) spacer. In both CC and NN FCDI systems, it is unsurprisingly that nitrate removal efficiency improved notably with the increasing current density and hydraulic retention time (HRT). Interestingly, the specific energy consumption (SEC) for nitrate removal did not show obvious fluctuations when the current density and HRT varied in both systems. Under the auspiciously optimized process parameters, CC-FCDI attained a 20% superior nitrate removal efficiency relative to NN-FCDI, accompanied by a notably diminished SEC for CC-FCDI, registering at a mere 28% of NN-FCDI. This great improvement can be primarily attributed to the decrement in FCDI internal resistance after using conductive spacer, which further confirmed by electrochemical tests such as linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Upon prolonged continuous nitrate removal at the optimized conditions, the CC-FCDI system achieved a consistent 90% nitrate removal efficiency with a low SEC of 2.7–7.8 kWh/kg NO3-N, underscoring its steady performance. Overall, this study highlights the pivotal importance of careful spacer design and optimization in realizing energy-efficient groundwater treatment via FCDI.
Electrochemical-nitrate-reduction-reaction (eNitRR) synthesis of ammonia is an effective way to treat nitrate wastewater and alleviate the pressure of the Haber-Bosch ammonia production industry. How to develop effective catalysts to electrochemically reduce nitrate to ammonia and purify sewage under complex environmental conditions is the focus of current research. Herein, the dopamine polymerization process and the [(C12H8N2)2Cu]2+ complex embedding process were run simultaneously in time and space, and ultrafine Cu nanoparticles (Cu/CN) were effectively loaded on nitrogen-doped carbon after heat treatment. Using Cu/CN as the catalyst, the ammonia yield rate and Faradaic efficiency of the electrochemical conversion of to NH3 are highly 8984.0 µg h−1 mgcat.−1 and 95.6%, respectively. Even in the face of complex water environments, such as neutral media, acidic media, coexisting ions, and actual nitrate wastewater, nitrate wastewater can be effectively purified to form high value-added ammonia. The strategy of simultaneous embedding increases the exposure rate of Cu sites, and the support of CN is also beneficial to reduce the energy barrier of *NO3 activation. This study rationally designed catalysts that are beneficial to eNitRR, and considered the situation faced by practical applications during the research stage, reducing the performance gap between laboratory exploration and industrial applications.
Hydrogen (H2) is a promising renewable energy which finds wide applications as the world gears toward low-carbon economy. However, current H2 production via steam methane reforming of natural gas or gasification of coal are laden with high CO2 footprints. Recently, methane (CH4) pyrolysis has emerged as a potential technology to generate low-carbon H2 and solid carbon. In this review, the current state-of-art and recent progress of H2 production from CH4 pyrolysis are reviewed in detail. Aspects such as fundamental mechanism and chemistry involved, effect of process parameters on the conversion efficiency and reaction kinetics for various reaction media and catalysts are elucidated and critically discussed. Temperature, among other factors, plays the most critical influence on the methane pyrolysis reaction. Molten metal/salt could lower the operating temperature of methane pyrolysis to < 1000 ℃, whereas plasma technology usually operates in the regime of > 1000 ℃. Based on the reaction kinetics, metal-based catalysts were more efficient in lowering the activation energy of the reaction to 29.5–88 kJ/mol from that of uncatalyzed reaction (147–420.7 kJ/mol). Besides, the current techno-economic performance of the process reveals that the levelized cost of H2 is directly influenced by the sales price of carbon (by-product) generated, which could offset the overall cost. Lastly, the main challenges of reactor design for efficient product separation and retrieval, as well as catalyst deactivation/poisoning need to be debottlenecked.
In Fenton-like oxidation, the catalyst directly influences the reaction mechanism for the degradation of pollutants from water. Here, a α-MnO2 catalyst (OAm-1) was synthesized via a self-assembly method with the assistance of a surfactant. OAm-1 possessed a large specific surface area of 221 m2/g, abundant mesoporous structures and a large proportion of Mn(Ⅲ). Further characterization exhibited that OAm-1 had abundant oxygen vacancies and excellent reducibility and conductivity. The adsorption and catalytic ability of OAm-1 were studied in the degradation of oxytetracycline (OTC) via the activation of hydrogen peroxide (H2O2). Through the radical quenching experiments, electron resonance spectroscopy (EPR), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR) analysis, Mn(Ⅲ) of OAm-1 was proved to be the active sites for the chemisorption of OTC. Systematic electrochemical experiments and analysis have shown that a process of electron transfer mediated by OAm-1 occurred between the pollutant and H2O2 during a Fenton-like reaction. This work experimentally verifies the electron transfer process dominated nonradical mechanism over α-MnO2, which is helpful for understanding the catalytic mechanism of the Fenton-like oxidation.
Herein, a modified metal-free acetylene black (MMF-AB) catalyst was synthesized by a simple solvothermal-calcination method and designed successfully to activate peroxodisulfate (PDS) for the degradation of sulfisoxazole (SIZ). Due to the doping of N, S and O metal-free elements, the modified catalyst showed excellent catalytic performance with 100% SIZ removal within 30 min. Pseudo first-order reaction rate constants (evaluating catalytic efficiencies and activity) of MMF-AB (kobs = 0.105 min−1) was 3 times higher than pure-AB (kobs = 0.029 min−1). Interestingly, it was demonstrated that the reaction system is based on the transfer of electrons from SIZ to PDS to realize an electron-transfer-based mechanism by the evidence of premixing, electron paramagnetic resonance (EPR) spectroscopy, salt-bridge experiments and electrochemical analyses. The introduction of recyclable filtration device solved the secondary pollution caused by the dispersion of the powdered catalyst in the treated water, which further proved the practicality and superiority of the MMF-AB catalyst.
In this study, three-dimensional microspherical CQDs/Bi2MoO6 heterostructures were synthesized using a simple alcohol-thermal method. It was found that the CQDs/Bi2MoO6 had a large specific surface area of 56.0 m2/g, and the introduction of CQDs extended the light absorption spectrum from 480 nm to 496 nm. When utilizing the synthesized CQDs/Bi2MoO6 composite for photocatalytic degradation of antibiotic norfloxacin in a water environment, complete decay of norfloxacin and effective removal of total organic carbon (TOC) were achieved within 30 min. Through the optimization of material synthesis and experimental conditions, the optimal CQDs loading amount was determined as 200 µL, the optimal CQDs/Bi2MoO6 dosage was 0.8 g/L. Moreover, the CQDs/Bi2MoO6 worked well under a wide pH range of 4.4–10.8. The coexistence of HCO3− enhanced the norfloxacin decay, while the presence of Cl−, NO3−, and SO42− slightly retarded it. The synthesized CQDs/Bi2MoO6 had the great potential in removing and mineralizing norfloxacin in real aquatic environments.
Owing to the serious potential side-effects on the environment and human health, the rapid detection and removal of antibiotics have become an important research focus. In this work, four zinc-based metal-organic frameworks (MOFs) with different functional groups, i.e., Zn-MOF, Zn-MOF-CH3, Zn-MOF-NO2, Zn-MOF-COOH, were utilized for the construction of LDO/MOF composite materials with a nickel-iron-cobalt-based layered double oxide, NiFeCo-LDO. The results showed that the LDO/MOF composites not only had high sensitivity in detecting sulfonamide and quinolone antibiotics, but also had an appreciable ability to adsorb them from wastewater. The maximum adsorption capacities of all the four types of LDO@Zn-MOFs to all antibiotics can at least reach 150 mg/g, and the limits of detection in relation to all four antibiotics were at least as low as 100 µg/L. Our work suggested the dual-function extraction performance can be attributed to the synergistic effects between the LDO and the MOFs. Moreover, the strong ferromagnetism derived from the LDO provided great convenience for the separation and regeneration of the LDO/MOF composites.
As a powerful noninvasive imaging technology, positron emission tomography (PET) has been playing an important role in disease theranostics and drug discovery. The successful application of PET relies on not only the biological properties of PET tracers but also the availability of facile and efficient radiochemical reactions to enable practical production and widespread use of PET tracers. Most recently, photochemistry is emerging as a novel, mild and efficient approach to generating PET agents. In this review, we focus on the recent advances in newly developed photocatalytic radiochemical reactions, innovation on automated photochemical radiosynthesis modules, as well as implementation in late-stage radiolabeling and radiopharmaceutical synthesis for PET imaging. We believe that this review will inspire the development of more promising radiolabeling protocols for the preparation of clinically useful PET agents.
Transition-metal-catalyzed remote sp2C—H functionalization of aryl sulfonic acids was hardly ever realized owing to competitive ortho-C—H functionalization of aryl sulfonates and electron-deficient nature of phenyl ring. Herein, with the assistance of a practical biaryl indolyl directing template, palladium-catalyzed remote sp2C—H alkylation of aryl sulfonic acids have been achieved in moderate to good yields with exclusive meta selectivity. Moreover, remote meta-selective C—H alkynylation of aryl sulfonic acids was also accomplished with a rhodium catalyst. These meta-C—H functionalized products proved to be the superior synthetic precursors, which are difficult to access using the conventional strategy.
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