Latest ArticlesThe high specific capacitance along with good cycling stability are crucial for practical applications of supercapacitors, which always demands high-performance and stable electrode materials. In this work, we report a series of ternary composites of CoO-ZnO with different fractions of reduced graphene oxide (rGO) synthesized by in-situ growth on nickel foam, named as CZG-1, 2 and 3, respectively. This sort of binder-free electrodes presents excellent electrochemical properties as well as large capacitance due to their low electrical resistance and high oxygen vacancies. Particularly, the sample of CZG-2 (CoO-ZnO/rGO 20 mg) in a nanoreticular structure shows the best electrochemical performance with a maximum specific capacitance of 1951.8 F/g (216.9 mAh/g) at a current intensity of 1 A/g. The CZG-2-based hybrid supercapacitor delivers a high energy density up to 45.9 Wh/kg at a high power density of 800 W/kg, and kept the capacitance retention of 90.1% over 5000 charge-discharge cycles.
The methanol oxidation reaction (MOR) is the limiting half-reaction in direct methanol fuel cell (DMFC). Although Pt is the most active single-metal electrocatalyst for MOR, it is hampered by high cost and CO poisoning. Constructing a Pt or Ru monolayer on a second metal substrate by means of galvanic replacement of underpotentially deposited (UPD) Cu monolayer has been shown as an efficient catalyst design strategy for the electrocatalysis of MOR because of the presumed 100% utilization of atoms and resistance to CO poisoning. Herein, we prepared one-dimensional surface-alloyed electrocatalyst from predominantly (111) faceted Au nanowires with high aspect ratio as the substrate of under-potential deposition. The electrocatalyst comprises a core of the Au nanowire and a shell of catalytically active Pt coated by Ru. Coverage-dependent electro-catalytic activity and stability is demonstrated on the Pt/Ru submonolayers on Au wires for MOR. Among all these catalysts, Au@PtML@RuML exhibits the best electrocatalytic activity and poisoning tolerance to CO. This presents a viable method for the rational catalyst design for achieving high noble-metal utilization efficiency and high catalytic performance.
Surface oxygen vacancy defects and metal deposition on semiconductor photocatalysts play a critical role in photocatalytic reactions. In this work, oxygen-deficient Bi2WO6 microspheres have been prepared by a facile ethylene glycol-assisted solvothermal method. Bi0 nanoparticles were reduced by in situ thermal-treatment on Bi2WO6 microspheres to obtain Bi0@Bi2WO6-x as well as maintaining the oxygen vacancies (OVs) under N2 atmosphere. Afterwards, photocatalytic NO oxidation removal activities of these photocatalysts were investigated under visible light irradiation and Bi0@Bi2WO6-x shows the best NO removal activity than other samples. The photogenerated charge separation and transfer are promoted by Bi0 nanoparticles deposited on the surface of semiconductor catalysts. OVs defects promote the activation of reactants (H2O and O2), thereby enhancing the formation of the active substance. Moreover, both OVs defects and Bi0 metal have the characteristics of extending light absorption and enhancing the efficient utilization of solar energy. Besides, the photocatalytic NO oxidation mechanism of Bi0@Bi2WO6-x was investigated by in situ FTIR spectroscopy for reaction intermediates and final products. This work furnishes insight into the synthesis strategy and the underlying photocatalytic mechanism of the surface-modified Bi0@Bi2WO6-x composite for pollutants removal.
This work reports the investigation of a new triptycene-derived oxacalixarene (TDOC) as the stationary phase for gas chromatography (GC) with high-resolution performance for a wide range of analytes and isomers. The TDOC scaffold is composed of triptycene and 1, 8-naphthyridine moieties, inherently differing from the conventional calixarenes in structures and properties. As a result, the TDOC column exhibited outstanding column efficiency of 5679 plates/m by n-dodecane at 120 ℃. It showed advantageous performance for separations of the mixtures with various analytes and achieved high resolution of diverse isomers (skeletal, positional and cis-/trans-isomers) from apolar to polar nature. Moreover, the TDOC column exhibited high thermal stability up to 310 ℃. To date, the TDOC-based materials have not been reported in chromatography. This work demonstrates the good potential of the triptycene-derived heterocalixarenes as a new class of stationary phases for chromatographic analyses.
A novel photoenzyme-coupled artificial catalytic system is fabricated by immobilizing horseradish peroxidase (HRP) on the Bi2WO6 hollow nanospheres via a facile electrostatic self-assembly process. The obtained Bi2WO6/HRP sample not only improves the visible light harvest ability but also promotes the high-efficiency separation of charge carriers. More importantly, the photogenerated electrons and produced H2O2 on Bi2WO6 directly take part in redox cycle reactions of HRP to induce photoenzyme synergic catalytic effect. In consequence, the degradation activity of Bi2WO6/HRP is significantly improved relative to Bi2WO6 and HRP for removing bisphenol A (BPA) under the visible light irradiation. This work launches a feasible design strategy for exploiting photoenzyme-coupled artificial catalytic system with special structure to degrade organic pollutants in water efficiently.
The rapid recombination of charge carriers in piezoelectric materials has always been the problem that limits their piezoelectric performance for removal of organic pollutants in water. Herein, we construct a piezoelectric BaTiO3/MoS2 (BTO/MS) that follows a type Ⅱ heterojunction charge transfer system to inhibit the recombination of electron-hole (e‒-h+) pairs, which is beneficial to the activation of peroxymonosulfate (PMS) for the removal of antibiotic ornidazole (ORZ) pollutants. The optimal ratio of BTO/MS for ORZ degradation under the piezo/PMS process is 13.9, 3.6, 62.1 and 2.0 times higher than that of the BTO/piezo, MS/piezo, (BTO/MS)/PMS and (BTO/MS)/piezo processes, respectively. The high efficiency charge separation in the piezoelectric heterojunction of BTO/MS promotes the activation of PMS, resulting in the synergy of pizeocatalysis and PMS oxidation during the process of ORZ degradation. This study provides an idea for enhancing piezo-activation of PMS by constructing heterojunctions in piezoelectric materials.
Herein, a facile glycol reduction route is successful employed to synthesize bimetallic PtAg alloys with homogeneous distribution of sizes and elements. Experimental studies reveal that the ultrafine PtAg alloys with well-defined sizes from around 3.3 nm to 5.8 nm are immobilized onto MnO2 microsphere, which remarkably enhances the catalytic performances for CO oxidation. Importantly, quasi in-situ X-ray photoelectron spectroscopy (XPS) result reveals that both Mn and Pt ions on the surface of catalysts would realize alternating reduction-oxidation by CO and O2 molecules, and the oxygen vacancy sites could be replenished and excited by gas-phase O2.
Two-dimensional covalent organic framework (COF) has distinctive properties that offer potential opportunities for developing advanced electrode materials. In this work, a core-shell material composed of TAPB-DMTP-COF (TAPB, 1, 3, 5-tris(4-aminophenyl)benzene; DMTP, 2, 5-dimethoxyterephaldehyde) core and conducting polymer shell, TAPB-DMTP-COF@PANI, was synthesized solvothermally using a polymerization method. The structural characteristics of the prepared composite were revealed by X-ray diffraction patterns (XRD), fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM). The electrochemical analyses were verified by subsequent monitoring of trace levels of acetaminophen. This resultant composite not only facilitated acetaminophen to interact with absorption sites by π-π stacking effect and hydrogen bonding but also overcame the poor conductivity of COF. Under the optimal conditions, a low limit of detection of 0.032 μmol/L and wide linear range of 0.10-500 μmol/L were obtained. The electrochemical platform was almost unaffected by other interfering substances, and successfully applied for the practical detection of acetaminophen in commercial tablet, human blood serum and urine. The enhanced performance makes this COF based core-shell composite a promising material in electrochemical sensor.
It is well known that zero-valent iron (ZVI) could catalyze the oxidation of various oxidants to realize the rapid oxidation removal of pollutants. However, in this study, we found that the addition of different oxidants could regulate the redox function of ZVI system. In three different co-treatment systems, the effects of different oxidizers (peroxymonosulfate (PMS), persulfate (PDS), hydrogen peroxide (H2O2)) dosages on the ratios of oxidative degradation rate and reductive degradation rate of p-nitrophenol (PNP) were studied. The effect of the H+ released from oxidizers and the generated reactive oxygen species (ROS) in ZVI/PMS, ZVI/PDS, ZVI/H2O2 systems were detailed discussed. Especially, the contribution of generated ROS for reductive degradation of PNP was quantified in the ZVI/H2O2 system. Based on the results of TOC removal, UV–vis absorption spectra, and intermediates concentration curves, it was found that the degradation of PNP changed from reduction to oxidation with the increase of oxidant proportion. When the molar ratio of ZVI to oxidizer equal to 100, PNP was mainly degraded by reduction accompanied by slight oxidation. Combined with the results of SEM-EDS and XPS, it was confirmed that the enhanced degradation of PNP under the addition of oxidant was mainly related to the generated ROS, the additional H+, and the corrosion products of ZVI.
The electrocatalysis of nitrate reduction reaction (NRR) has been considered to be a promising nitrate removal technology. Developing a highly effective iron-based electrocatalyst is an essential challenge for NRR. Herein, boron-iron nanochains (B-Fe NCs) as efficient NRR catalysts were prepared via a facile low-cost and scalable method. The Fe/B ratio of the B-Fe NCs-x can be elaborately adjusted to optimize the NRR catalytic performance. Due to the electron transfer from boron to metal, the metal-metal bonds are weakened and the electron density near the metal atom centers are rearranged, which are favor of the conversion from NO3- into N2. Moreover, the well-crosslinked chain-like architectures benefit the mass/electron transport to boost the exposure of abundant catalytic active sites. Laboratory experiments demonstrated that the optimized B-Fe NCs catalyst exhibits superior intrinsic electrocatalytic NRR activity of high nitrate conversion (~80%), ultrahigh nitrogen selectivity (~99%) and excellent long-term reactivity in the mixed electrolyte system (0.02 mol/L NaCl and 0.02 mol/L Na2SO4 mixed electrolyte), and the electrocatalytic activity of the material shows poor performance at low chloride ion concentration (Nitrate conversion of ~61% and nitrogen selectivity of ~57% in 0.005 mol/L NaCl and 0.035 mol/L Na2SO4 mixed electrolyte). This study provides a broad application prospect for further exploring the high-efficiency and low-cost iron-based functional nanostructures for electrocatalytic nitrate reduction.
No. 86 Xueyuan South Road, Haidian District, Beijing
010-62662699(Operation and Technical Support)
qkjq@cast.org.cn
Copyright © 2025 China Association for Science and Technology. All rights reserved. For all open access content, the relevant licensing terms apply.
Sponsored by the Office of the Leading Group for Cybersecurity and Informatization of CAST, and supported by Science and Technology Review Publishing House
