Selectivity of Electrochemical Reactions Based on Adsorption at Nanoporous Electrodes.

Abstract

Enhancing selectivity is a pivotal area of research when electrodes are utilized as catalysts or sensors. Nanoporous electrodes are representative electrode materials for diverse applications, such as catalysts and sensors. Selectivity arising from nanoporous structures has been applied to systems involving nonfaradaic reactions such as capacitive deionization, electrochemical supercapacitors, and conductometry. Since selectivity in faradaic reactions has primarily been explored based on reactivity and molecular charge and size, we propose that the surface adsorption of reactant molecules can be considered as another crucial factor in achieving selectivity. Our observations reveal that the nonadsorptive reaction of 2-propanol and 2-butanol experienced a more pronounced enhancement compared to the adsorptive reaction of 1-propanol and 1-butanol at nanoporous Pt electrodes, owing to the nanoconfinement effect. Even within the same molecule with a mixture of adsorptive and nonadsorptive reactions, the degree of influence of the nanostructure depends on the adsorptive capacity of the reaction, which affects the overall selectivity. Moreover, the size effect of the reactants in the nanoporous electrode is also dependent on the degree of adsorption. These findings provide valuable insights into the effective utilization of nanoporous materials as catalysts or sensors.