Ambient Electrosynthesis of Ammonia: Electrode Porosity and Composition Engineering

Ammonia, a key precursor for fertilizer production, convenient hydrogen carrier, and emerging clean fuel, plays a pivotal role in sustaining life on Earth. Currently, the main route for NH₃ synthesis is by the heterogeneous catalytic Haber–Bosch process (N₂+3 H₂→2 NH₃), which proceeds under extreme conditions of temperature and pressure with a very large carbon footprint. Herein we report that a pristine nitrogen‐doped nanoporous graphitic carbon membrane (NCM) can electrochemically convert N₂ into NH₃ in an acidic aqueous solution under ambient conditions. The Faradaic efficiency and rate of production of NH₃ on the NCM electrode reach 5.2 % and 0.08 g m^?2 h^?1, respectively. Functionalization of the NCM with Au nanoparticles dramatically enhances these performance metrics to 22 % and 0.36 g m^?2 h^?1, respectively. As this system offers the potential to be scaled to industrial levels it is highly likely that it might displace the century‐old Haber–Bosch process.     

Dynamic Ultralong Organic Phosphorescence by Photoactivation

Smart materials with ultralong phosphorescence are rarely investigated and reported. Herein we report on a series of molecules with unique dynamic ultralong organic phosphorescence (UOP) features, enabled by manipulating intermolecular interactions through UV light irradiation. Our experimental data reveal that prolonged irradiation of single‐component organic phosphors of PCzT, BCzT, and FCzT under ambient conditions can activate UOP with emission lifetimes spanning from 1.8 to 1330 ms. These phosphors can also be deactivated back to their original states with short‐lived phosphorescence by UV irradiation for 3 h at room temperature or through thermal treatment. Additionally, the dynamic UOP was applied successfully for a visual anti‐counterfeiting application. These findings may provide unique insight into dynamic molecular motion for optical processing and expand the scope of smart‐response materials for broader applications.     

基于透明质酸的刺激响应纳米给药系统的研究进展

透明质酸(Hyaluronic acid, HA)是一种天然多糖,具有良好的生物相容性和生物降解性,利用 HA 构建的纳米载体自身就具有肿瘤靶向功能,可以作为抗癌药物载体将药物传递到肿瘤细胞内从而实现精准到达病患处。近年来透明质酸在应用于肿瘤靶向给药系统中的关注越来越多,成为了靶向治疗肿瘤的一大研究热点。基于透明质酸的基本特性和肿瘤靶向的生理学基础,在不同的刺激响应下,透明质酸型纳米给药系统能将药物集中释放于肿瘤的微环境内,更好地杀死肿瘤细胞,同时避免其他正常的组织受到药物损害。本文主要综述了透明质酸型纳米药物输送系统在各种刺激响应下释放药物的最新研究进展。     

钢铁工业CO2捕集技术分析

针对钢铁工业烟气成分复杂、排放量大且处理难的问题,分析各碳捕集技术特点、发展现状以及未来趋势。目前,吸收法是最成熟、最适合的碳捕集方法,在工业上已出现商业化应用。新型碳捕集技术在碳捕集方面有很大潜力,但大多都处于实验室规模的开发,未来这方面是一项巨大挑战。以膜接触器为代表的复合捕集技术破单一捕集技术瓶颈,已出现应用在燃煤工业上。未来在实际过程中,要根据钢铁各工序烟气特点及浓度差异选择不同的捕集方法并对钢铁工业碳捕集技术进行了展望。     

Self-assembly in transition metal complexes: structural characterization of a copper histamine nitrate [Cu(II)(him)2(NO3)2]

A new monomeric copper (II) complex with histamine (him), [Cu(II)(him)₂(No₃)₂], has been prepared by the reaction of Cu(NO₃)₂ with histaminium dichloride and its structure was determined by x-ray crystallography. The complex crystallizes in the triclinic system, space group with a = 5.7238(4), b = 8.7094(7), c = 9.2481(11) Å, = 69.693(8), = 73.242(7), = 71.050(7)°, V = 400.84(6) ų, and Z = 1. The structure consists of discrete [Cu(II)(him)₂(NO₃)₂] molecules in which the metal atom is centrosymmetrically coordinated by two histamine ligands forming an equatorial plane with Cu–N(imidazole ring) being 2.032(2) and Cu–N(NH₂ group) being 2.023(2) Å. Two O atoms from nitrate anions coordinate on the elongated axial positions with Cu–O being 2.549(2) Å. In the crystal structure, the molecules are organized by hydrogen bonds forming a two-dimensional network.     

A six‐connected α‐polonium net based on tetranuclear CdII nodes

The cadmium(II) coordination polymer poly[[(pyrazino[2,3‐f][1,10]phenanthroline‐κ²N⁸,N⁹)cadmium(II)]‐μ₃‐naphthalene‐1,4‐dicarboxylato‐κ⁵O¹:O¹,O^1′:O⁴,O^4′], [Cd(C₁₂H₆O₄)(C₁₄H₈N₄)]_n, contains two Cd^II cations, two pyrazino[2,3‐f][1,10]phenanthroline (L) ligands and two naphthalene‐1,4‐dicarboxylate (1,4‐ndc) anions in the asymmetric unit. Both Cd^II ions are in a distorted CdO₅N₂ monocapped octahedral coordination geometry. Both unique 1,4‐ndc ligands are bonded to three Cd^II ions. In these modes, tetranuclear clusters are formed in which four Cd^II ions are bridged by the carboxylate groups of the 1,4‐ndc ligands to form discrete rods. The tetranuclear cadmium carboxylate clusters act as rod‐shaped secondary building units (SBUs) within the structure. The SBUs are connected together by the aromatic backbone of the dicarboxylate ligands, connecting the clusters into a three‐dimensional α‐polonium net. The title compound represents the first α‐polonium net constructed from rod‐like clusters in coordination polymers. The result indicates that an appropriate combination of dicarboxylate and aromatic chelating ligands is critical to the formation of high‐dimensional structures based on metal clusters in these systems.     

Theoretical investigation of the EPR parameters and local structure for trigonal Yb3+ ion in Bi4Ge3O12 crystal

Bi4Ge3O12 single crystals are of great interest for science research and engineering applications. In this paper, the electron paramagnetic resonance (EPR) g factors g||, gperpendicular of Yb3+ and hyperfine structure constants A||, Aperpendicular of 171Yb3+ and 173Yb3+ isotopes in Bi4Ge3O12 crystal are calculated from the perturbation formulas of these parameters. The crystal-field parameters are obtained from the superposition model and the crystal structure data. The EPR parameters for trigonal Yb3+ centers in Bi4Ge3O12 are reasonably explained by involving the defect structures of impurity Yb3+ centers. Based on the calculations, Yb3+ ion is found not to occupy exactly the host Bi3+ site, but to shift away from the center of oxygen octahedron by a distance DeltaZ approximately 0.317 A along C3 axis. The results are discussed.     

Characterization of aroma active compounds in fruit juice and peel oil of Jinchen sweet orange fruit (Citrus sinensis (L.) Osbeck) by GC-MS and GC-O

Gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) were used to determine the aromatic composition and aroma active compounds of fruit juice and peel oil of Jinchen sweet orange fruit. Totals of 49 and 32 compounds were identified in fruit juice and peel oil, respectively. GC-O was performed to study the aromatic profile of Jinchen fruit juice and peel oil. A total of 41 components appeared to contribute to the aroma of fruit juice and peel oil. Twelve components were the odorants perceived in both samples. The aromatic compositions of fruit juice were more complex than that of peel oil. Ethyl butanoate, beta-myrcene, octanal, linalool, alpha-pinene, and decanal were found to be responsible for the aromatic notes in fruit juice and peel oil. Nineteen components have been perceived only in the juice and ten compounds were described as aromatic components of only the peel oil by the panelists. These differences lead to the different overall aroma between fruit juice and peel oil.     

Ferric hydroxide supported gold subnano clusters or quantum dots: enhanced catalytic performance in chemoselective hydrogenation

An attempt to prepare ferric hydroxide supported Au subnano clusters via modified co-precipitation without any calcination was made. High resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) have been employed to study the structure and chemical states of these catalysts. No Au species could be observed in the HRTEM image nor from the XRD pattern, suggesting that the sizes of the Au species in and on the ferric hydroxide support were less than or around 1 nm. Chemoselective hydrogenation of aromatic nitro compounds and alpha,beta-unsaturated aldehydes was selected as a probe reaction to examine the catalytic properties of this catalyst. Under the same reaction conditions, such as 100 degrees C and 1 MPa H2 in the hydrogenation of aromatic nitro compounds, a 96-99% conversion (except for 4-nitrobenzonitrile) with 99% selectivity was obtained over the ferric hydroxide supported Au catalyst, and the TOF values were 2-6 times higher than that of the corresponding ferric oxide supported catalyst with 3-5 nm size Au particles. For further evaluation of this Au catalyst in the hydrogenation of citral and cinnamaldehyde, selectivity towards unsaturated alcohols was 2-20 times higher than that of the corresponding ferric oxide Au catalyst.     

Local approach to coupled cluster evaluation of polarizabilities for long conjugated molecules

Electron correlation effect in conjugated polymer is a long-standing problem, especially for the nonlinear optical properties. We have implemented a spin-adapted Coupled Cluster with singles and doubles excitation with local molecular orbital approach. As a first application, we evaluate the static polarizability of conjugated polyene chains with finite field approach. It is found that the local molecular orbital approach can tremendously reduce the computational costs at sufficiently high accuracy. It is also found that the electron correlation can largely reduce the molecular polarizability with respect to the Hartree-Fock mean field results.