Fe Single-Atom Electrochemical Sensors for H₂O₂ Produced by Living Cells

Reasonable sensor construction for precisely real-time detecting H2O2 produced from living cells has always been of great significance and challenges. Due to the excellent catalytic efficiency and unparalleled peroxidase-like activity, single-atomic catalysts with Fe-Nx active sites show great potential in H2O2 detection. These special atomic active sites make it easier for the Fenton reaction to occur, which provides basic support for H2O2 sensors. Their application in the in situ real-time detection of H2O2 has important market prospects. Herein, single-atomic Fe catalysts with distorted graphitic carbon are obtained through a simpler preparation method. A precursor hemin@zeolitic imidazolate framework-8 (hemin@ZIF-8) is calcined at a high temperature and carbonized to get the nitrogen-carbon codoped Fe single atoms (Fe SAs-N/C) and then successfully prepare a H2O2 electrochemical sensor by modifying it on a glassy carbon electrode (GCE). Its peroxidase activity is calculated by enzymatic kinetics, which shows a better peroxidase activity compared with horseradish peroxidase and other reported single-atom (SA) materials. Moreover, the electrocatalytic kinetics is explained by Laviron calculation, which more directly confirms that it has a faster electron transfer rate. Importantly, Fe SAs-N/C@GCE has a wider linear range than sensors combined with other SA materials and a low detection limit of 0.34 μM. It is an attractive design of H2O2 sensors and single-atomic catalysts with superior substrate affinity that are novel alternatives to natural enzymes.