In addition to the broad environmental implications associated with the removal of toxic nitroaromatics from industrial effluent, their catalytic reduction, and particularly that of paranitrophenol (pNP) has emerged as a benchmark model for quantifying catalytic activity of metal nanoparticles. This process is either the main focus, or a component of hundreds of scientific studies/publications in the field of heterogeneous catalysis every year. Here we present a series of noble metal nanoparticles immobilized on amorphous carbon (Au@C, Ag@C, Pt@C and Pd@C). All materials show competitive catalytic activity over pNP, amino-substituted nitrophenols (ANPs) and azo dyes. However, by testing all materials synthesized over a broader substrate scope (more than just the common pNP) with added functionalities reveals inconsistencies in the prognosticating ability of the ubiquitous pNP model reaction. This begs the question, are we missing out on potentially superior catalysts by relying on this oversimplified protocol? By incorporating variably substituted ANPs into the substrate scope and averaging performance, the resulting rank of catalyst activity more accurately reflects activity trends when applied to other reducible functionalities, such as -N=N- groups in azo dyes.

To pNP or not to pNP? Broader scope study of nitrophenol reduction with noble metal nanoparticles

2019 Fall National Meeting

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