2D/3D-Shaped Fe0.8Ni0.2S2/ZIF-67 as a Nanozyme for Rapid Measurement of H2O2 and Ascorbic Acid with a Low Limit of Detection

Metal–organic frameworks (MOFs) can be used as ideal artificial nanozymes for an open structure to transfer substances and products. The nanozymic mechanism of MOFs needs further investigation for wide application. In this manuscript, no peroxidase-like activity was found for ZIF-67 (a kind of MOF), however, it enhanced the peroxidase-like activity of the Fe0.8Ni0.2S2/ZIF-67 composite, in which Fe0.8Ni0.2S2 was the active composition. The catalytic constant (Kcat) is higher at 1.98 (for TMB) and 2.08 (for H2O2) times and the catalytic efficiency (Kcat/Km) is higher at 3.13 (for TMB) and 2.67 (for H2O2) times, than those of Fe0.8Ni0.2S2. The Km value decreased about 85 times (for H2O2) for Fe0.8Ni0.2S2/ZIF-67 than that of horseradish peroxidase (natural enzyme). The mechanism was proposed. The limit of detection of H2O2 for Fe0.8Ni0.2S2/ZIF-67 is 0.039 μM, which is lower by about 18.2 times than that of Fe0.8Ni0.2S2. Simultaneously, Fe0.8Ni0.2S2/ZIF-67 was used to rapidly detect ascorbic acid for only 1.0 min in food monitoring. This study may be important to design a new kind of nanozyme.