Regulation spin state in CuCo₂O₄ nanozyme by heterojunction construction with polyoxometalate for detoxification of...

As one of the most lethal chemical warfare agents (CWAs), mustard gas causes irreversible damage to human health. Selective oxidation of mustard gas into non-toxic sulfoxide using reactive oxygen species (ROS) generated from H₂O₂ represents an effective detoxification strategy. In this context, nanozymes with peroxidase-like (POD-like) activity have attracted increasing attention because of their ability to activate H₂O₂ to produce ·OH or ·O₂^-. Among spinel oxides, CuCo₂O₄ exhibits intrinsic POD-like activity; however, its catalytic efficiency for mustard gas detoxification remains limited. To improve the POD-like activity of p-type CuCo₂O₄, a p-n heterojunction was constructed by coupling it with n-type H₃PW₁₂O₄₀ (PW₁₂), a polyoxometalate (POM). Theoretical analysis demonstrates that a built-in electric field is formed at the CuCo₂O₄/PW₁₂ interface, leading to charge redistribution and modulation of the electron spin state at Co³⁺ active sites. As a consequence, *OH desorption is facilitated and ·OH generation is significantly accelerated. Benefiting from these effects, CuCo₂O₄/PW₁₂ exhibits enhanced POD-like activity and efficient selective oxidation performance toward 2-chloroethyl ethyl sulfide (CEES), a mustard gas stimulant. These results indicate that nanozymes are effective candidates for mustard gas detoxification, and that heterojunction construction combined with electron spin state regulation is an effective strategy for performance enhancement.