A Vanadium-Based Polyoxometalate Nanozyme for 2-Mercaptobenzothiazole Colorimetric Detection and Visible-Light-Driven Degradation in Water

As a notorious pollutant in water, 2-mercaptobenzothiazole (MBTZ) severely endangers environmental safety and human survival. In this respect, MBTZ detection and removal are urgently required. For MBTZ detection, colorimetry based on a nanozyme with oxidase-mimic activity is an efficient method. Herein, a vanadium-based polyoxometalate (POM), [V₄O₁₀(bpy)₃]₂·bpy (V₄O₁₀, bpy = bipyridine), is synthesized. As a stable and nonexpensive nanozyme, it shows promising oxidase-mimic activity, which accelerates 3,3',5,5'-tetramethylbenzidine (TMB) oxidation and generates blue ox-TMB. Once it encounters MBTZ, the blue color will fade obviously. This feature qualifies V₄O₁₀ as a prospective choice for point-of-care MBTZ detection with colorimetry. Theoretical calculations illustrate that the good oxidase-mimic activity is rooted in appropriate interactions between V₄O₁₀ and substrates in the reaction. In addition, V₄O₁₀ exhibits intensive absorption in both ultraviolet and visible light regions with a narrow band gap (E_g). Under visible light irradiation, the MBTZ degradation efficiency in the presence of V₄O₁₀ reaches 96.6% in 60 min. Besides MBTZ, it also takes effect on other organic pollutants, such as sulfamethoxazole, 2,6-dichloro-4-nitroaniline, methotrexate hydrate, p-nitrophenol, and tetracycline. We expect that this research on the MBTZ detection and degradation properties of V₄O₁₀ will provide a valuable reference for practical MBTZ control in an aquatic environment.