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11. Synthesis, characterization, and hydrazine sensing property of two covalent organic frameworks.

Author

Liu, Leijing, Wang, Canran, Wang, Jiangpeng, Jiang, Shan, Ma, Wenyue, Zou, Yongcun, and Tian, Wenjing

Subjects
HYDRAZINES, ORGANIC synthesis, ESTERIFICATION, FLUORESCENCE, THERMAL stability
Abstract

Sensitive and efficient detection of hydrazine is of great significance because hydrazine is a highly toxic organic molecule, which can pose great threats to human health. Herein, two covalent organic frameworks (COFs) modified with ester groups in the pores, TAPB‐DHE and TAPT‐DHE, have been successfully synthesized via esterification reaction. Both of the two COFs have good crystallinity, thermal stability, and fluorescence properties. TAPB‐DHE can be used as a turn‐on fluorescence sensor for the sensitive detection of trace hydrazine in aqueous solution with a detection limit of 0.40 μM and a wide linear range of 0–100 μM due to the fluorescence enhancement of TAPB‐DHE caused by the chemical reaction between hydrazine and TAPB‐DHE, in which the ester group of the COF is converted into hydroxyl group, leading to the restriction of the intramolecular charge transfer (ICT) effect. This work provides a reference for the design of COFs with hydrazine recognition function and a helpful expansion for the practical application of COFs. [ABSTRACT FROM AUTHOR]

Published
2024
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22. Nano-metal diborides-supported anode catalyst with strongly coupled TaOx/IrO2 catalytic layer for low-iridium-loading proton exchange membrane electrolyzer.

Author

Wang, Yuannan, Zhang, Mingcheng, Kang, Zhenye, Shi, Lei, Shen, Yucheng, Tian, Boyuan, Zou, Yongcun, Chen, Hui, and Zou, Xiaoxin

Subjects
IRIDIUM catalysts, DIRECT methanol fuel cells, GIBBS' free energy, PROTONS, COMPOSITE materials, ELECTRIC conductivity, OXYGEN evolution reactions, ALLYLIC amination
Abstract

The sluggish kinetics of oxygen evolution reaction (OER) and high iridium loading in catalyst coated membrane (CCM) are the key challenges for practical proton exchange membrane water electrolyzer (PEMWE). Herein, we demonstrate high-surface-area nano-metal diborides as promising supports of iridium-based OER nanocatalysts for realizing efficient, low-iridium-loading PEMWE. Nano-metal diborides are prepared by a novel disulphide-to-diboride transition route, in which the entropy contribution to the Gibbs free energy by generation of gaseous sulfur-containing products plays a crucial role. The nano-metal diborides, TaB2 in particular, are investigated as the support of IrO2 nanocatalysts, which finally forms a TaOx/IrO2 heterojunction catalytic layer on TaB2 surface. Multiple advantageous properties are achieved simultaneously by the resulting composite material (denoted as IrO2@TaB2), including high electrical conductivity, improved iridium mass activity and enhanced corrosion resistance. As a consequence, the IrO2@TaB2 can be used to fabricate the membrane electrode with a low iridium loading of 0.15 mg cm−2, and to give an excellent catalytic performance (3.06 A cm−2@2.0 V@80 oC) in PEMWE―the one that is usually inaccessible by unsupported Ir-based nanocatalysts and the vast majority of existing supported Ir-based catalysts at such a low iridium loading. The extreme scarcity of Ir largely limits the wide application of proton exchange membrane water electrolyzer (PEMWE) for hydrogen production. Here, the authors report high-surface area nano-metal diboride as promising support of anode nanocatalyst IrO2 for realizing efficient, low Ir loading PEMWE. [ABSTRACT FROM AUTHOR]

Published
2023
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42. Hierarchical SAPO-34 preparation based on the crystal metastability in mother liquor solution

Author

Han, Ji, Yang, Guoju, Zou, Yongcun, Chen, Xiaoxin, Valtchev, Valentin, Laboratoire catalyse et spectrochimie (LCS), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), and Valtchev, Valentin

Subjects
metastability, in situ etching, mother liquor, hierarchical zeolite, [CHIM] Chemical Sciences, [CHIM]Chemical Sciences, MTO, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2021

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