Cobalt Nanoparticles and Atomic Sites in Nitrogen-Doped Carbon Frameworks for Highly Sensitive Sensing of Hydrogen Peroxide.

In situ monitoring of hydrogen peroxide (H2 O2 ) during its production process is needed. Here, an electrochemical H2 O2 sensor with a wide linear current response range (concentration: 5 × 10-8 to 5 × 10-2 m), a low detection limit (32.4 × 10-9 m), and a high sensitivity (568.47 µA mm-1 cm-2 ) is developed. The electrocatalyst of the sensor consists of cobalt nanoparticles and atomic Co-Nx moieties anchored on nitrogen doped carbon nanotube arrays (Co-N/CNT), which is obtained through the pyrolysis of the sandwich-like urea@ZIF-67 complex. More cobalt nanoparticles and atomic Co-Nx as active sites are exposed during pyrolysis, contributing to higher electrocatalytic activity. Moreover, a portable screen-printed electrode sensor is constructed and demonstrated for rapidly detecting (cost ≈40 s) H2 O2 produced in microbial fuel cells with only 50 µL solution. Both the synthesis strategy and sensor design can be applied to other energy and environmental fields.