Latest ArticlesPhotoelectrochemical (PEC) sensor is an emerging technology in analysis as the advantage of fast response, high sensitivity and uncomplicated operation. In this study, an effective label-free PEC sensor for bisphenol A (BPA) detecting is constructed, in which ZnIn2S4/g-C3N4 heterojunction is prepared via a simple hydrothermal method. The characterization outcomes display that the formation of p-n heterojunction helps for promoting the separation efficiency of photo-generated carrier. Under visible light irradiation, the ZnIn2S4/g-C3N4 modified electrode exhibits broader liner range from 0.05 mmol/L to 30 mmol/L and lower detection limit of 0.016 µmol/L (S/N = 3) with remarkable stability and reproducibility of detection BPA under visible light irradiation. Furthermore, the constructed PEC sensor displays favorable potential for detection of BPA in practical applications.
CO2 is a representative prototype model in energy and environmental fields. Many factors for CO2 capture and activation have been investigated extensively but the research on the influence of thermal conductivity is still absence. We herein have calculated many properties, including dipole moment, electric structure, and adsorption energies, on Pt doped graphene and 2D BC3N2 substrates and served the thermal conductivity as the bridge. Our results have demonstrated that the lower (higher) thermal conductivity for 2D BC3N2 (graphene) corresponds to larger (lower) dipole moment, which is beneficial for CO2 activation (capture) process. Our research have not only revealed the dominant role of heat conductivity for CO2 capture and activation, but also paved the way for further catalyst design of various areas.
Exploring highly efficient electrocatalysts and understanding the reaction mechanisms for hydrogen electrocatalysis, including hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) in alkaline media are conducive to the conversion of hydrogen energy. Herein, we reported a new strategy to boost the HER/HOR performances of ruthenium (Ru) nanoparticles through nitrogen (N) modification. The obtained N-Ru/C exhibit remarkable catalytic performance, with normalized HOR exchange current density and mass activity of 0.56 mA/cm2 and 0.54 mA/µg, respectively, about 4 and 4.5 times higher than those of Ru/C, and even twofold enhancement compared to commercial Pt/C. Moreover, at the overpotential of 50 mV, the normalized HER current density of N-Ru/C is 5.5 times higher than that of Ru/C. Experimental and density functional theory (DFT) results verify the electronic regulation of Ru after N incorporation, resulting in the optimized hydrogen adsorption Gibbs free energy (ΔGH*) and hence enhancing the HOR/HER performance.
We have prepared well-resolved Nbn+ (n = 1–10) clusters and report here an in-depth study on the essentially different reactivity with N2 and O2, by utilizing a multiple-ion laminar flow tube reactor in tandem with a customized triple quadrupole mass spectrometer (MIFT-TQMS). As results, the Nbn+ clusters are found to readily react with N2 and form adsorption products NbnN2m+; in contrast, the reactions with O2 give rise to NbnO1−4+Oproducts, and the odd-oxygen products indicate O-O bond dissociation, as well as increased mass abundance of NbO+ pertaining to oxygen-etching reactions. We illustrate how N2 prefers a physical adsorption on Nbn+ clusters with an end-on orientation for all the products, and allow for size-selective Nbn+ clusters to act as electron donor or acceptor in forming NbnN2m+. In contrast to these nitrides, the dioxides NbnO2+ display much larger binding energies, with O2 always as an electron acceptor, corresponding to superoxide or peroxide states in the initial reactions. Density-of-states and orbital analyses show that the interactions between Nbn+ and O2 are dominated by strong π-backdonation indicative of incidental electron transfer; whereas weak π-backdonation and simultaneous σ donation interactions exist in NbnN2+. Further, reaction dynamics analysis illustrates the different interactions for N2 and O2 in approaching the Nbn+ clusters, showing the energy diagrams for N2 adsorption and O-O bond dissociation in producing odd-oxygen products. Fragment analyses with orbital correlation and donor-acceptor charge transfer are also performed, giving rise to full insights into the reactivities and interactions of such transition metal clusters with typical diatomic molecules.
A novel copper-based MOFs adsorbent (Cu-BTC-Th) was prepared using an one-step method by introducing a new organic ligand of 4-thioureidobenzoicacid (Th) with active groups for selectively adsorbing Pb(Ⅱ) from aqueous solutions. The chemical composition and structure of the prepared MOFs materials were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Brunner−Emmet−Teller (BET) analysis, and zeta potential measurements. The adsorption capability of the prepared Cu-MOFs was significantly enhanced by introducing the new organic ligand of Th in the materials. The maximum adsorption capacity of the Cu-BTC-Th for Pb(Ⅱ) attains 732.86 mg/g under the optimal conditions. In addition, the adsorption kinetics and adsorption isotherm analysis showed that the adsorption process followed the pseudo-second-order kinetic model and Langmuir adsorption model, indicating that the adsorption of Pb(Ⅱ) by Cu-BTC-Th was a monolayer chemisorption. The adsorption mechanism of Cu-BTC-Th for Pb(Ⅱ) was discussed and revealed. On one hand, the adsorption of Pb(Ⅱ) is mainly through ion exchange with the Cu(Ⅱ). On the other hand, the −NH2 and −C=S functional groups introduced in the Cu-BTC-Th materials have stronger coordination ability with the Pb(Ⅱ) ions to enhance the adsorption capability.
The development of effective and low-energy-consumption catalysts for CO2 conversion into high-value-added products by constructing versatile active sites on the surface of heterogeneous compounds is an urgent and challenging task. In this study, a stable and well-defined heterogeneous cobalt hexacyanocobaltate (Co3[Co(CN)6]2), typical cobalt Prussian blue analogue (CoCo-PBA) modified with tetrabutylammonium bromide (TBAB), is proven to be the superior catalyst for CO2 and epoxide coupling to produce cyclic carbonates with > 99% yield under mild reaction conditions (1.0 MPa, 65 ℃). Based on a series of characterizations, it is revealed that the CoCo-PBA structure can maintain relatively high thermal and chemical stability. Recycling experiments exhibited that the CoCo-PBA system could retain 98% of the original activity after six reaction rounds. The CoCo-PBA/TBAB catalytic system was also highly active for coupling CO2 with other industrial-grade epoxides. These results show the CoCo-PBA catalytic system potential flexibility and the generality of the catalyst preparation strategy.
Despite the continuously increased requirement on automated synthesis of medicines for distributed manufacturing and personal care, it remains a challenge to realize automated synthesis which requires solid-liquid phase reactions. In this work, we demonstrated an automated solid-liquid synthesis for gadopentetate dimeglumine, the most widely used magnetic resonance imaging (MRI) contrast agent. The high-efficiency reaction was performed in a 3D microfluidic chip which was fabricated by femtosecond laser micromachining. The structure of the chip realized 3D shear flow which was essential for highly efficient mixing and movement of the solid-liquid mixtures. Ultraviolet visible (UV-vis) spectrometer was employed for in-line analysis to help automation of this system. Comparing with the round-bottom flask system, this synthetic system showed significantly higher reaction rate, indicating the advantage of the 3D microfluidic technology in micro chemical engineering.
The electrocatalytic methanol conversion is of importance in direct methanol fuel cell, biomass reforming, and hydrogen generation. To achieve a "carbon-neutral" target, CO2 byproducts derived from biofuels should be mitigated. In contrast to the complete oxidation of methanol to CO2, the selective oxidation of methanol to formate is a CO2-emission-free route without the generation of toxic CO intermediates. Herein, we present a highly active catalyst based on transition-metal disulfide nanosheet arrays supported on Ni foam for methanol conversion. Through composition screening, we find that the FeCoNi disulfide nanosheet exhibits a highly efficient and selective methanol-to-formate conversion. The surface reconstruction of this catalyst allows us to produce 0.66 mmol cm−2 h−1 of formate at low potential (1.40 V) with high faradaic efficiency of > 98%. This work offers a substantial composition tuning strategy to construct noble-metal-free active multi-metal sites for CO2-emission-free conversion of methanol to value-added formate.
Various advanced microwave absorbing materials have been developed for reducing/avoiding the harm of microwave radiation. Among them, core-shell structural nanomaterials have been widely fabricated for microwave absorption. However, the "structure-performance" relationship between shell thickness and microwave absorption performance is rarely reported. In this paper, we first explored the "structure-performance" relationship between shell thickness and microwave absorption performance, based on the core-shell α-Fe2O3@SiO2 nanoparticles with a constant α-Fe2O3-core size and changeable SiO2-shell thickness. With increasing the SiO2-shell thickness, the microwave absorption ability first increased, then decreased. Under a proper SiO2-shell thickness of 35 nm, α-Fe2O3@SiO2 sample achieved the strongest microwave absorbing ability with a reflection loss minimum value of –4.3 dB, better than that of pure α-Fe2O3 (–3.8 dB). This enhanced microwave absorption performance was mainly derived from the dielectric loss. Although the absolute value of the reflection loss was relatively low (–4.3 dB), this study shed an important reference on designing next-generation advanced iron oxide-based materials for microwave absorption.
Nature consists of various soft tissues with well-ordered hierarchical anisotropic structures, which play essential roles in biological systems to exhibit particular functions. Mimicking bio-tissues, synthetic hydrogels with anisotropic structures have received considerable attention in recent years. However, existing approaches to fabricate anisotropic hydrogels often require complicated procedures, which are time-consuming and labor-demanding. Inspired by the dry-induced crystallization phenomenon, we report a simple yet effective prestretching-drying-swelling method to afford anisotropic crystalline polyvinyl alcohol hydrogels. Owing to the distinct anisotropic microstructure, the hydrogels demonstrate excellent mechanical properties with noticeable directional distinction. It is revealed that both the enhancing of pre-orientation strain and the extending of heating time make the hydrogels with better mechanical properties and more remarkable anisotropicity. Owing to the anisotropically aligned structure, the hydrogels exhibit remarkably differential ionic conductivity: the difference between the parallel and vertical conductivity of the same sample can reach as high as 6.6 times, making the materials possible candidates as nano-conductive materials. We anticipate that this simple yet effective approach may become highly useful for fabricating oriented hydrogels and endow the materials with more promising application prospects in the future.
No. 86 Xueyuan South Road, Haidian District, Beijing
010-62199257
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
