The smartphone-assisted sensing platform based on manganese dioxide nanozymes for the specific detection and degradation of hydroquinone.

Hydroquinone (HQ) is a prevalent pollutant in aquatic environments, posing significant risks to ecosystems and human health. Practical methods for the simultaneous detection and degradation of HQ are essential. To address this requirement, a dual-mode detection and degradation strategy has been developed utilizing designed nanozymes (DM) consisting of a porous SiO core and MnO shell. Due to the catalytic activity of DM nanozymes, the three types of reactive oxygen species (ROS), singlet oxygen (O), superoxide anion (O), and hydroxyl radical (•OH), were generated to induce the color transferring of 3,3',5,5'-tetramethylbenzidine (TMB) from colorless to blue form (oxTMB). During the reductive HQ-mediated oxTMB fading, the DM has significant selectivity towards HQ from isomers (catechol and resorcinol) due to the differing reductive reaction rates, with an excellent linear range of 0.2-45 μM with a detection limit as low as 0.11 μM. In addition, according to the color parameter changes in the sensing process, colorimeters and smartphones are utilized to achieve on-site and convenient HQ detection. Besides, the DM nanozyme can oxidatively decompose HQ without auxiliary equipment. We believe this research provides a powerful tool for detecting and removing HQ precisely.