Latest ArticlesThe utilization of an efficient photocatalyst is crucial for the photocatalytic degradation of antibiotics in water through visible light, which is an imperative requirement for the remediation of water environments. In this study, a novel Cu-CeO2/BiOBr Z-type heterojunction was synthesized by calcination and hydrothermal methods, and the degradation rate of sulfathiazole (STZ) antibiotic solution was studied using simulated illumination (300 W xenon lamp). The results indicated that 3% Cu-CeO2/BiOBr achieved a degradation rate of 92.3% within 90 min when treating 20 mg/L STZ solution, demonstrating its potential for practical water treatment applications. Characterization using various chemical instruments revealed that 3% Cu-CeO2/BiOBr exhibited the lowest electron-hole recombination rate and electron transfer resistance. Furthermore, the utilization of ESR data and quenching experiments has substantiated the involvement of hydroxyl radicals (•OH) and superoxide radicals (•O2−) as the primary active species. Consequently, a plausible degradation mechanism has been inferred. These findings offer a prospective approach for the development of heterojunction materials with appropriate band matching.
Formic acid (FA), which is obtainable through CO2 hydrogenation with green hydrogen or biomass conversion, has been used as a prospective liquid organic hydrogen carrier (LOHC) because of the abundant advantages of renewability, wide availability, stability, and high volumetric capacity (53 g H2/L). The development of highly efficient catalytic systems to achieve enhanced catalytic activity is attractive but still challenging. Herein, ultrafine and highly dispersed PdAu nanoclusters (NCs) anchored on amino-modified reduced graphene oxide (ArGO) were successfully synthesized via a facile impregnation-reduction method and applied as a catalyst toward formic acid dehydrogenation (FAD). Benefiting from the promoting effect of amino groups, the strain and ligand effect in the alloy, and the Mott–Schottky effect between PdAu NCs and ArGO, the resultant PdAu/ArGO affords an ultrahigh activity under visible light irradiation with an exceptional turnover frequency value of 10, 699.5 h−1 at 298 K without any additives, more than 2.6 times improvement than that under dark, which is the highest among all reported catalysts under the same conditions. This study provides a green and convenient strategy for developing more efficient and sustainable FAD catalysts and promotes the effective utilization of FA as a prospective renewable LOHC.
Effective adjustment and control of the oxidation state of plutonium (Pu) and neptunium (Np) is an indispensable component of Np/Pu separation in spent nuclear fuel reprocessing. Some hydrazine derivatives including methylhydrazine (CH3N2H3) effectively achieves the reduction of Np(Ⅵ) to Np(Ⅴ) without reducing Pu(Ⅳ). Herein, we explored the reduction mechanisms of Pu(Ⅳ) and Np(Ⅵ) by CH3N2H3 in HNO3 solution using scalar-relativistic density functional theory. We elucidated the difference in the reduction mechanism between Np(Ⅵ) and Pu(Ⅳ) ions by CH3N2H3. The energy barrier for the reduction of [NpⅥO2(H2O)5]2+ and [NpⅥO2(NO3)(H2O)3]+ by CH3N2H3 is largely different due to the coordination of nitrate ion. Moreover, the energy barrier of the reduction of [NpⅥO2(H2O)5]2+ is apparently lower than that of [PuⅣ(NO3)2(H2O)7]2+, which is in line with the experimental observations. The results of Mayer bond order and localized molecular orbitals clarify the structural evolution of the reaction pathways. Analysis of the spin density demonstrates that the first Np(Ⅵ) and Pu(Ⅳ) reduction belongs to the outer-sphere electron transfer and the second Np(Ⅵ) and Pu(Ⅳ) reduction is the hydrogen transfer. This study explains theoretically why CH3N2H3 reduces Np(Ⅵ) but not Pu(Ⅳ), and helps to design promising reductants for the Np/Pu separation in spent nuclear fuel reprocessing.
Transition-metal-catalyzed cross-electrophile coupling has emerged as a reliable method for constructing carbon–carbon bonds. Herein, we report a general method, cobalt-catalyzed reductive alkynylation, to construct C(sp)-C(sp3) and C(sp)-C(sp2) bonds. This presented reaction has a broad substrate scope, enabling the efficient cross-electrophile coupling between alkynyl bromides with alkyl halides and aryl or alkenyl (pseudo)halides. This presented reaction is conducted under mild conditions, tolerating many functional groups, thus suitable for the modification and synthesis of biologically active molecules.
Improving the highly selective and sensitive binding of chemosensor to target guest is always very challenging. In order to solve this issue, herein, the enrichment effect was introduced into the design of chemosensor molecule. A novel bi-fused-macrocyclic host molecule BPN1 was synthesized by bridging a pillar[5]arene and a naphthalene diimide (NDI) group through hydrogen-bond-rich chain. In the BPN1, the naphthalimide side ring is outside the cavity of the pillar[5]arene. In addition, Cr(Ⅵ) greatly threat human health and the environment due to its severe toxicity, and it is very important to develop effective chemosensor for sensitive and selective detection of Cr2O72− or its ion pairs. In this paper, the novel bi-fused-macrocyclic host molecule BPN1 can recognize Cr2O72− with high selectivity and sensitivity. The mechanism of BPN1 recognition of Cr2O72− was studied through experiments and density functional theory (DFT), the results show that BPN1 could supply enrichment effect to bind Cr2O72− through multiple weak interactions such as hydrogen bonds and anion-π, and achieve highly sensitive and selective detection of Cr2O72−. It is a significant and feasible strategy for improve high selectivity and sensitivity of host to specific objects by using the enrichment effect of fused bi-macrocyclic.
Herein, we report the NHC-Ru catalyst system that realizes the chemo-selective transformation of ketones with methanol. By simply changing the base, a broad range of structurally diverse ketones, could be selectively and efficiently converted to the corresponding β-methylated secondary alcohols or secondary alcohols. Remarkably, this catalytic system was very effective for the synthesis of bio-related molecules and deuterated alcohols, as well as the three-component coupling between methyl ketones, primary alcohols, and methanol. The reaction mechanism was further revealed by experiment and DFT mechanistic investigations.
Cobalt-based phosphides show excellent hydrogen evolution reaction (HER) performance, however, improving the intrinsic activity and stability of it in alkaline electrolyte still remains a challenge. Herein, CoRuOH/Co2P/CF with heterojunction structure was developed by means of molten salt and rapid hydrolysis (30 s). The OH− from rapid surface hydrolysis of Co2P as a hydrogen adsorption site can facilitate the formation of thin CoRuOH layer as a water dissociation site, which may bring out better synergistic effect for alkaline HER. Moreover, the covering of CoRuOH can improve the stability of Co2P for HER. When drives at 100 mA/cm2, it only requires overpotential of 81 mV in 1.0 mol/L KOH (25 ℃). Even at higher current density (1000 mA/cm2), CoRuOH/Co2P/CF can also operate stability for at least 100 h. When coupling with NiFe-LDH/IF in a two-electrode system, the voltage of NiFe-LDH/IF(+) || CoRuOH/Co2P/CF(−) at 1000 mA/cm2 is merely 1.77 V with 100 h, demonstrating great potential for water splitting. The implementation of this work provides a new strategy and reference for the further improvement of transition metal phosphides as HER electrocatalysts.
Here, we designed asymmetric (mDS) and symmetrical (dDS) chiral V-shaped molecules by linking one or two dansyl groups to trans-1,2-cyclohexane diamine and investigated the solvent-regulated structural transformation and inversed circularly polarized luminescence (CPL) in the self-assemblies. Upon increasing water volume fraction (fw) in the mixed solvent of water/acetonitrile, asymmetric mDS selfassembled into hollow nanospheres and microtubes, while solid nanospheres and solid microplates were corresponding to symmetric dDS. During this transformation process, the emission of mDS and dDS was changed from yellow-green to blue and cyan color, which was ascribed to twisted intramolecular charge transfer (TICT) and locally excited (LE) fluorescence of V-shaped DS molecules. The conformation of N,N-dimethyl groups with respect to naphthalene ring also led to the transformation of structures. These tubular and platelike structures had stronger and reversed CPL signals in comparison with spheroidal structures. The chiral information of DS assembly could be effective transferred to achiral Nile red via co-assembly strategy, which endowed Nile red exhibiting inversed induced CPL signal regulated by water fraction. This work provides a method for achieving a variety of self-assembled structures with adjustable chiroptical properties.
Dynamic DNA nanotechnology plays a significant role in nanomedicine and information science due to its high programmability based on Watson-Crick base pairing and nanoscale dimensions. Intelligent DNA machines and networks have been widely used in various fields, including molecular imaging, biosensors, drug delivery, information processing, and logic operations. Encoders serve as crucial components for information compilation and transfer, allowing the conversion of information from diverse application scenarios into a format recognized and applied by DNA circuits. However, there are only a few encoder designs with DNA outputs. Moreover, the molecular priority encoder is hardly designed. In this study, we introduce allosteric DNAzyme-based encoders for information transfer. The design of the allosteric domain and the recognition arm allows the input and output to be independent of each other and freely programmable. The pre-packaged mode design achieves uniformity of baseline dynamics and dynamics controllability. We also integrated non-nucleic acid molecules into the encoder through the aptamer design of the allosteric domain. Furthermore, we developed the 2-n encoder and the Endo Ⅳ-assisted priority encoder inspired by immunoglobulin's molecular structure and effector patterns. To our knowledge, the proposed encoder is the first enzyme-free DNA encoder with DNA output, and the priority encoder is the first molecular priority encoder in the DNA reaction network. Our encoders avoid complex operations on a single molecule, and their simple structure facilitates their application in complex DNA circuits and biological scenarios.
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