Rational Design of Fe1–Co1/NC Diatomic Nanozyme-Based Electronic Tongues: Discriminating Active Substances in Licorice

Herein, by the pyrolysis and alkali leaching of zeolitic imidazolate framework-8 (ZIF-8)@SiO 2, followed by Fe and Co doping, a novel Fe 1 Co 1 /NC nanozyme, with adjacent Fe and Co dual-atom pairs decorated on an N-doped carbon support, is exactly built. Due to the synergistic effect of adjacent Fe and Co dual-atom pairs, the peroxidase-like activity of Fe 1 Co 1 /NC is significantly enhanced, far exceeding those of Fe 1 /NC and Co 1 /NC. Based on this, we propose a simple colorimetric electronic tongue consisting of Fe 1 Co 1 /NC, chromogenic substrates (3,3′,5,5′-tetramethylbenzidine) (TMB), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and o -phenylenediamine (OPD) and H 2 O 2 to identify seven active substances in licorice. The mechanism of action of this tongue is that different active substances have differential degrees of inhibition on the three nanozyme-catalyzed reactions (Fe 1 Co 1 /NC-TMB-H 2 O 2, Fe 1 Co 1 /NC-ABTS-H 2 O 2, and Fe 1 Co 1 /NC-OPD-H 2 O 2 ). The collected absorbance variation data, i.e., the colorimetric fingerprint patterns, are analyzed by linear discriminant analysis, realizing the identification of the seven active substances with 100% accuracy. This work provides insights into the rational design of dual-atom catalysts with nanozyme activities for the discrimination of multiple targets.