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A Dual Catalyst with SERS Activity for Probing Stepwise Reduction and Oxidation Reactions
Author(s) -
Li Jumei,
Wu Yiren,
Sun Xiaojun,
Liu Jingyue,
Winget Sarah A.,
Qin Dong
Publication year - 2016
Publication title -
chemnanomat
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.947
H-Index - 32
ISSN - 2199-692X
DOI - 10.1002/cnma.201600153
Subject(s) - catalysis , chemistry , environmentally friendly , redox , raman spectroscopy , photochemistry , combinatorial chemistry , organic chemistry , ecology , physics , optics , biology
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 O 2 from air. This work will lead to an environmentally friendly and sustainable approach to the production of aromatic azo compounds.