Metal Nanoparticle-Catalyzed Reduction Using Borohydride in Aqueous Media: A Kinetic Analysis of the Surface Reaction by Microfluidic SERS.
Hydrides are widely used in reduction reactions. In protic solvents, their hydrolysis generates molecular hydrogen as a second reducing agent. The competition between these two parallel reduction pathways has been overlooked so far since both typically yield the same product. We investigated the platinum-catalyzed reduction of 4-nitrothiophenol to 4-aminothiophenol in aqueous sodium borohydride solution as a prominent model reaction, by using label-free SERS monitoring in a microfluidic reactor. Kinetic analysis revealed a strong pH dependence. Surprisingly, only at pH>13 the reduction is driven exclusively by sodium borohydride. This study demonstrates the potential of microfluidics-based kinetic SERS monitoring of heterogeneous catalysis in colloidal suspension.
Department of Chemistry and Center for Nanointegration Duisburg-Essen, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany. wei.xie@uni-due.de.
Wei
W
Xie
Department of Chemistry and Center for Nanointegration Duisburg-Essen, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany.
Roland
R
Grzeschik
Department of Chemistry and Center for Nanointegration Duisburg-Essen, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany. sebastian.schluecker@uni-due.de.
Sebastian
0000-0003-4790-4616
S
Schlücker
Raman spectroscopy; heterogeneous catalysis; microreactors; pH dependence; reduction