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 Fe 0.8 Ni 0.2 S 2 /ZIF-67 composite, in which Fe 0.8 Ni 0.2 S 2 was the active composition. The catalytic constant ( K cat ) is higher at 1.98 (for TMB) and 2.08 (for H 2 O 2 ) times and the catalytic efficiency ( K cat / K m ) is higher at 3.13 (for TMB) and 2.67 (for H 2 O 2 ) times, than those of Fe 0.8 Ni 0.2 S 2 . The K m value decreased about 85 times (for H 2 O 2 ) for Fe 0.8 Ni 0.2 S 2 /ZIF-67 than that of horseradish peroxidase (natural enzyme). The mechanism was proposed. The limit of detection of H 2 O 2 for Fe 0.8 Ni 0.2 S 2 /ZIF-67 is 0.039 μM, which is lower by about 18.2 times than that of Fe 0.8 Ni 0.2 S 2 . Simultaneously, Fe 0.8 Ni 0.2 S 2 /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.