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Metal-Organic Frameworks Mediate Cu Coordination for Selective CO<sub>2</sub> Electroreduction
Nam, Dae-Hyun,Bushuyev, Oleksandr S.,Li, Jun,De Luna, Phil,Seifitokaldani, Ali,Dinh, Cao-Thang,Garcí,a de Arquer, F. Pelayo,Wang, Yuhang,Liang, Zhiqin,Proppe, Andrew H.,Tan, Chih Shan,Todorovic& American Chemical Society 2018 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.140 No.36
<P>The electrochemical carbon dioxide reduction reaction (CO<SUB>2</SUB>RR) produces diverse chemical species. Cu clusters with a judiciously controlled surface coordination number (CN) provide active sites that simultaneously optimize selectivity, activity, and efficiency for CO<SUB>2</SUB>RR. Here we report a strategy involving metal-organic framework (MOF)-regulated Cu cluster formation that shifts CO<SUB>2</SUB> electroreduction toward multiple-carbon product generation. Specifically, we promoted undercoordinated sites during the formation of Cu clusters by controlling the structure of the Cu dimer, the precursor for Cu clusters. We distorted the symmetric paddle-wheel Cu dimer secondary building block of HKUST-1 to an asymmetric motif by separating adjacent benzene tricarboxylate moieties using thermal treatment. By varying materials processing conditions, we modulated the asymmetric local atomic structure, oxidation state and bonding strain of Cu dimers. Using electron paramagnetic resonance (EPR) and in situ X-ray absorption spectroscopy (XAS) experiments, we observed the formation of Cu clusters with low CN from distorted Cu dimers in HKUST-1 during CO<SUB>2</SUB> electroreduction. These exhibited 45% C<SUB>2</SUB>H<SUB>4</SUB> faradaic efficiency (FE), a record for MOF-derived Cu cluster catalysts. A structure-activity relationship was established wherein the tuning of the Cu-Cu CN in Cu clusters determines the CO<SUB>2</SUB>RR selectivity.</P> [FIG OMISSION]</BR>
Zhikun Zhang,Ying Zhou,Jing-Kui Yang,Peilong Wang,Xiaoou Su,Hong Zhao,Yujian He,Zhiqin Cao,Maoqiang Luo 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.7
A new method has been proposed to realize the visual detection of Cr3+ using 4-nitrobenzenethiol (4-NBT) and 4-mercaptobenzoic acid (4-MBA) modified silver nanoparticles (AgNPs). The presence of Cr3+ induces the aggregation of AgNPs through cooperative metal–ligand interaction, resulting in a color change from bright yellow to purple. Consequently, Cr3+ could be monitored by colorimetric response of AgNPs by a UV-Vis spectrophotometer or even naked eyes. We firstly used ethylene diamine tetraacetic acid (EDTA) as a masking agent to selectively detect Cr3+, and other metal ions have little influence on the Cr3+–AgNPs system. The cofunctionalized AgNPs exhibited a highly sensitive detection limit of Cr3+, which is as low as 5 x 10-9 mol L-1, and the absorbance ratio (A600nm /A387nm) is linear with the concentration of Cr3+ ranging from 5 x 10-9 mol L-1 to 2 x 10-6 mol L-1 with a coefficient of 0.993. Particularly, the sensor has been further evaluated to monitor the concentration of Cr3+ in drinking water, the recovery was in good agreement with those obtained by ICP-MS, indicating that this proposed method is successfully applied in real samples.