Bimetallic Ti ₃ C ₂ T _<i>x</i> with three synergistic catalytic pathways and enhanced dual enzyme activities for a visual sensing platform

Nano-enzymes are increasingly used in forensic identification, biochemical testing, food regulation, environmental pollution monitoring and other fields. However, the construction of enzyme cascade catalytic systems based on nano-enzymes with multiple enzyme activities presents both opportunities and challenges. Ti₃AlC₂ is a common MXene with a graphene-like structure, which has the features of a large specific surface area, good electrical conductivity, excellent catalytic properties, and easy functionalization. Moreover, after being functionalized, Ti₃AlC₂ can exhibit excellent peroxidase-like activity. Therefore, in this work, a bimetallic Fe-Ni@Ti₃C₂T _<i>x</i> nano-enzyme with both peroxidase-like and oxidase-like activities was synthesized, and three synergistic catalytic mechanisms of Fe-Ni@Ti₃C₂T _<i>x</i> were verified. A colorimetric sensor was constructed based on Fe-Ni@Ti₃C₂T _<i>x</i> for the detection of H₂O₂ to test its feasibility for practical applications. The prepared colorimetric sensor had a wide linear range (50-6000 µM) and a low detection limit (14.606 µM). In addition, the selectivity, stability and reproducibility of the prepared colorimetric sensor were acceptable. This study laid a foundation for the simple preparation and practical application of a bimetallic nano-enzyme with various enzyme activities.