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Editorial Issue
Female scientists in nano research
Nano Research 2023, 16 (3): 3605-3606
Published: 10 March 2023
Downloads:69
Research Article Issue
La ions-enhanced NH3-SCR performance over Cu-SSZ-13 catalysts
Nano Research 2023, 16 (10): 12126-12133
Published: 27 February 2023
Downloads:129

Lanthanum (La) ions are generally recognized to cause a decline of the catalytic performance for Cu-SSZ-13 zeolite in the selective catalytic reduction of NOx with NH3 (NH3-SCR). Herein, we demonstrate that the NH3-SCR performance and hydrothermal stability of Cu-La-SSZ-13 zeolites can be enhanced with the incorporation of a small amount of La ions. The incorporation of La ions into SSZ-13 favors more Z2Cu2+ ions at six-membered rings (6MRs), which results in higher hydrothermal stability of Cu-La-SSZ-13 than that of Cu-SSZ-13. The NO conversion of Cu-La-SSZ-13 achieves 5%–10% higher than that of Cu-SSZ-13 at the temperature range of 400–550 °C after hydrothermal ageing. While introducing excess amount of La ions in SSZ-13 may cause the formation of inactive CuOx, leading to the decrease of catalytic activity and hydrothermal stability. Notably, the low-temperature activity of Cu-SSZ-13 with a low Cu content (≤ 2 wt.%) can be boosted by the introduction of La ions, which is largely due to the improved redox ability of Cu active sites modified by La ions. Density functional theory (DFT) calculations indicate that La ions prefer to locate at eight-membered rings (8MRs) and thus promoting the formation of more Z2Cu2+ ions. Meanwhile, the existence of La ions in SSZ-13 inhibits the dealumination process and the transformation from Z2Cu2+ to CuOx, resulting in its enhanced hydrothermal stability. The present work sheds a new insight into the regulation of secondary metal cations for promoting high NH3-SCR performance over Cu-SSZ-13 zeolite catalysts.

Research Article Issue
Confining carbon dots in amino-functionalized mesoporous silica: n→π* interaction triggered deep-red solid-state fluorescence
Nano Research 2023, 16 (3): 4170-4177
Published: 22 August 2022
Downloads:92

Deep-red and near-infrared emissive carbon dots (CDs) are highly desired for bioimaging, especially in deep tissue imaging, but they are extremely rare and the known ones usually suffer from low-efficient fluorescence in water and aggregation-induced fluorescence quenching in solid state. In this work, CDs with intriguing solvent-dependent and two-photon fluorescence emissions have been prepared by a facile solvothermal method. Detailed characterizations reveal that there is an n→π* interaction between the carboxyl functional groups on CDs and the electron donor groups in solvent, which leads to the increase of energy density of CDs and the decrease of energy level, resulting in the red shift of luminescence with enhanced electron donating ability of solvent. Inspired by this finding, mesoporous silica nanoparticles (MSNs) with suitable pore size and low biological toxicity are modified by amino groups to confine CDs, thus the deep-red fluorescence emission is achieved both in solid state and in water facilitated by the n→π* interaction of host–guest. The as-prepared CDs@EDA-MSN composite exhibits high-efficient fluorescence with 650 nm wavelength, low toxicity, and good biocompatibility, which endow them a promising application in bio-imaging.

Research Article Issue
Entropy-driven self-assembly of chiral nematic liquid crystalline phases of AgNR@Cu2O hyper branched coaxial nanorods and thickness-dependent handedness transition
Nano Research 2018, 11 (2): 1018-1028
Published: 15 August 2017
Downloads:11

The chiral nematic liquid crystalline phase (CNLCP) of noble metal nanorods induces a strong chiroptical response due to their intrinsic physical and chemical properties. Here, we demonstrate that the formation of CNLCP of Ag nanorods (AgNRs) originates from their bent-shape and is the result of purely entropic effects. The chirality of the liquid crystalline phase of AgNR@Cu2O hyper branched coaxial nanorods (HBCNRs) can be switched from left-handed to right-handed by increasing Cu2O thickness. It is proposed that the increase of coating thickness decreases the curvature of nanorods, which induces variation of the twist constant (K2) and bend elastic constant (K3). The increased thickness also changes the direction of director with respect to the helical axis. In addition, hydrogen bonds can break the CNLCP, which can be attributed to their stronger effection compared to van der Waals forces and electrostatic interactions. In contrast to the variation of coating thickness, the surface morphology, constituents of the hybrid building blocks and polarity of the solvents do not play important roles in the handedness transition of the liquid crystalline phase. Furthermore, the results presented here give insight into the structure–property relationship and our strategy provides guidance for the synthesis of other inorganic chiral suprastructures driven by entropic effects.

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