Stabilizer-Free PdCu Nanoparticles Dispersed on Carbon Using Taylor Vortex Flow as Catalysts for Electrochemical Oxidation of Formic Acid

Abstract

Stabilizers play a critical role in synthesizing small and well-dispersed nanoparticles with large catalytic surface areas. Simultaneously, they strongly bind to the surface of the nanoparticles and interfere with the catalytic reaction. In this study, we report that the effects of stabilizers can be replaced by the periodic and uniform fluid shear of Taylor vortex flow (TVF). Small PdCu alloy nanoparticles well-dispersed on carbon were synthesized in the Couette–Taylor reactor using TVF without the stabilizer. TVF could provide effective micromixing for a fast reaction and uniform fluid shear to prevent aggregation in nanoparticle synthesis, thus forming small and well-dispersed nanoparticles. In contrast, turbulent eddy flow generated by impeller agitation in a mixing tank reactor could only synthesize aggregates of nanoparticles seriously, indicating the importance of the periodic uniform flow. The synthesized stabilizer-free PdCu nanoparticles (Pd41Cu59/C) showed 1.4 times and 3 times higher mass activity than PdCu/C covered with a stabilizer (polyvinylpyrrolidone) and commercial Pd/C toward electrochemical formic acid oxidation, respectively.