In situ self-assembled Ti-MOF@Cu with enzyme activity for colorimetric sensing of sulfur ions

Copper (Cu) nanoparticles have been widely used as catalysts for colorimetric assays. The challenge in developing Cu nanoparticles is to design nanomaterials with high catalytic activity and stability. Herein, a series of NH 2 -MIL-125(Ti)@Cu (Ti-MOF@Cu) composites with enzyme activity were obtained by in situ growth of different proportions of copper on titanium-based metal organic frameworks (Ti-MOFs), among which [email protected] showed the highest enzyme activity. Electron transfer at the interface of Ti-MOF and Cu promoted the decomposition of hydrogen peroxide (H 2 O 2 ) to generate active species under near-neutral conditions, thereby oxidizing colorless TMB to blue oxidized TMB (ox-TMB). On this basis, a sulfide ion (S 2− ) detection method based on a [email protected] colorimetric sensor was constructed, in which the limit of detection (LOD) was 0.16 μM in the linear range of 0.5–30 μM. Furthermore, [email protected] was successfully used for detecting S 2− in water samples. The successful synthesis of Ti-MOF@Cu provides new insights for further study of the enzyme-like activity of copper-based materials, and the constructed facile and sensitive sensor system has broad application prospects.