Sensitive Hydrogen Peroxide Sensor Based on Hexacyanoferrate Nickel–Carbon Nanodots

An electrochemical sensor was developed for the detection of hydrogen peroxide (H2O2) based on the in situ formation of a nickel hexacyanoferrate complex on the electrode surface. Screen-printed carbon electrodes were modified with nickel-doped carbon nanodots (Ni-CNDs), and a nickel hexacyanoferrate complex was electrogenerated over the nickel carbon nanodots. Ni-CNDs were synthetized “a la carte” in one step by including nickel (II) acetate as precursor and characterized using different techniques: transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, atomic force microscopy (AFM), and infrared spectroscopy (FTIR). The electrocatalytic activity toward H2O2 reduction and the oxidation of the resulting modified electrodes was studied. The developed sensor had a strong electrocatalytic effect on the oxidation and reduction of H2O2, yielding detection limits of 3.22 and 0.49 μM, respectively. The H2O2 content of a tap water sample was determined, confirming the viability of the developed electrochemical sensor.