Manganese Dioxide Nanosheets‐Induced Oxidation of Dopamine for Colorimetric Sensing of Hydrogen Sulfide

Abstract Here we report a selective and highly sensitive colorimetric sensing system based on MnO 2 nanosheets and dopamine for the detection of hydrogen sulfide (H 2 S). MnO 2 nanosheets show a capability for direct oxidation of dopamine to aminochrome, producing a strong UV‐vis absorption at 470 nm and accompanying a distinct color change from colorless to orange. When H 2 S is present in the sensing system, it can effectively inhibit the redox reaction between MnO 2 nanosheets and dopamine. In this case, the concentration of the aminochrome in the reaction solution significantly decreases, and the color of the solution gradually fades with the increasing of the concentration of H 2 S. The solution turns colorless when the concentration of H 2 S exceeds 75 μM. The dynamic range of the calibration curve is 0.2‐125 μM, and the limit of detection is estimated to be 0.08 μM at a signal‐to‐noise ratio of 3:1.