TY - JOUR
T1 - A Dual Catalyst with SERS Activity for Probing Stepwise Reduction and Oxidation Reactions
AU - Li, Jumei
AU - Wu, Yiren
AU - Sun, Xiaojun
AU - Liu, Jingyue
AU - Winget, Sarah A.
AU - Qin, Dong
N1 - Funding Information:
This work was supported in part by the National Science Foundation (CHE-1412006), start-up funds from the Georgia Institute of Technology, and 3M non-tenured faculty award. We thank Ming Luo for performing the ICP-MS analysis. J.L. was supported by the start-up funds from Arizona State University (ASU). We acknowledge the use of facilities in the John M. Cowley Center for High Resolution Electron Microscopy at ASU.
Publisher Copyright:
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2016/8
Y1 - 2016/8
N2 - Aromatic azo compounds are high-value chemicals extensively used as pigments, drugs, and food additives, but their production typically requires stoichiometric amounts of environmentally unfriendly metals or nitrites. There is an urgent need to develop a dual catalytic system capable of reducing nitroaromatics to aromatic amines, followed by their oxidation to azo compounds. Here we report such a dual catalyst based on Ag@Pd-Ag core-frame nanocubes for the stepwise conversion of 4-nitrothiophenol to trans-4,4′-dimercaptoazobenzene under ambient conditions. Our in situ surface-enhanced Raman spectroscopy study reveals three sequential processes that include the Pd-catalyzed reduction of 4-nitrothiophenol to 4-aminothiophenol by hydrogen, a period during which the 4-aminothiophenol remain unchanged until all hydrogen has depleted, and the Ag-catalyzed oxidation of 4-aminothiophenol to trans-4,4′-dimercaptoazobenzene by the O2 from air. This work will lead to an environmentally friendly and sustainable approach to the production of aromatic azo compounds.
AB - Aromatic azo compounds are high-value chemicals extensively used as pigments, drugs, and food additives, but their production typically requires stoichiometric amounts of environmentally unfriendly metals or nitrites. There is an urgent need to develop a dual catalytic system capable of reducing nitroaromatics to aromatic amines, followed by their oxidation to azo compounds. Here we report such a dual catalyst based on Ag@Pd-Ag core-frame nanocubes for the stepwise conversion of 4-nitrothiophenol to trans-4,4′-dimercaptoazobenzene under ambient conditions. Our in situ surface-enhanced Raman spectroscopy study reveals three sequential processes that include the Pd-catalyzed reduction of 4-nitrothiophenol to 4-aminothiophenol by hydrogen, a period during which the 4-aminothiophenol remain unchanged until all hydrogen has depleted, and the Ag-catalyzed oxidation of 4-aminothiophenol to trans-4,4′-dimercaptoazobenzene by the O2 from air. This work will lead to an environmentally friendly and sustainable approach to the production of aromatic azo compounds.
KW - Ag-catalyzed oxidation
KW - Pd-catalyzed reduction
KW - bimetallic nanocrystals
KW - catalysis
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U2 - 10.1002/cnma.201600153
DO - 10.1002/cnma.201600153
M3 - Article
AN - SCOPUS:84992200717
VL - 2
SP - 786
EP - 790
JO - ChemNanoMat
JF - ChemNanoMat
SN - 2199-692X
IS - 8
ER -
