Photoenhanced Oxidase–Peroxidase-like NiCo2O4@MnO2 Nanozymes for Colorimetric Detection of Hydroquinone

Artificial oxidase and peroxidase mimics that are based on nanomaterials have drawn enormous attention due to their high stability, high efficiency, and low cost as compared with natural enzymes. Achieving multifunction and further boosting catalytic efficiency are two key directions of future nanozyme development. In this work, NiCo2O4@MnO2 microcubes with p–n junctions were constructed, exhibiting both oxidase- and peroxidase-like activities, capable of catalyzing the oxidation of tetramethylbenzidine (TMB) in the presence of O2 or H2O2. More importantly, such catalytic activity can be dramatically enhanced through illumination due to the in-build p–n junctions and the consequent photoelectric effect. As a prototype, NiCo2O4@MnO2 was utilized in a colorimetric assay to detect trace hydroquinone. An outstanding lowest detection limit of 0.042 μM is achieved, and the recovery in real water samples ranges from 99.87 to 101.10%. The dual enzyme-mimetic and photoenhanced catalytic activities render the nanozyme promising for various applications in sensors and catalysts.