Nanoporous Cobalt Hexacyanoferrate Nanospheres for Screen-Printed H2O2 Sensors

The development of highly sensitive hydrogen peroxide (H 2 O 2 ) sensors of low cost with high stability is essential because of the significance of H 2 O 2 in biological systems and its practical applications in different fields. The present work concerns the development of a highly sensitive flexible screen-printed amperometric H 2 O 2 sensor. Hexacyanoferrates are known to be excellent sensing materials for nonenzymatic electrochemical sensing of hydrogen peroxide (H 2 O 2 ), but they have certain limitations such as instability and low sensitivity. We have developed a method for the synthesis of porous cobalt hexacyanoferrate nanospheres (CoHCF-NSp’s) (<50 nm size) by using EDTA as a chelating agent. Increasing the EDTA concentration and heating the EDTA complex at 60 °C turned the microspheres of CoHCF into porous nanospheres due to the rapid nucleation of CoHCF. The synthesized porous nanospheres with high specific surface area and pore volume led to much improved electrochemical properties. The porous CoHCF-NSp’s were used for the fabrication of a highly sensitive H 2 O 2 sensor. Amperometric characterization of screen-printed sensors prepared using the CoHCF nanospheres showed a linear response in the detection range of 0.002–1.13 mM with a detection limit of 2.1 μM. The sensitivity of the sensor was found to be 329 μA·mM –1 ·cm –2, which is much better than the sensitivities of most of the previously reported H 2 O 2 sensors. The fabricated sensors were found to be stable at ambient temperature. The sensors were found to be effective in the testing of real samples (lake water and flavored drink).