Smartphone-Integrated Device Based on d-Band Engineered PtNiFe Nanozymes for on-Site Testing of Perfluorinated Substances

Perfluorinated compounds (PFCs) pose a serious threat to ecological safety and public health due to their environmental persistence and bioaccumulation, underscoring the urgent need to develop efficient and sensitive detection technologies. This work presented a portable colorimetric sensing platform featuring automated sample injection via a miniature peristaltic pump. Leveraging the inhibitory effect of perfluorinated compounds on PtNiFe nanozymes, the platform enables the detection of perfluorinated substances. By optimization of the local electronic states of the platinum active site in PtNiFe nanozymes, the catalytic activity of peroxidase (POD) was significantly enhanced. Through experimental and theoretical approaches, a correlation between POD-like activity and d-band centers was established, revealing that PtFeNi exhibits the highest catalytic activity (212.15 U mg^-1) and the lowest d-band centers (-2.06 eV). The proximity of the d-band centers to the Fermi level indicates greater favorability for the H₂O₂ decomposition process. Based on the inhibitory effect of PFCs on the active sites of PtNiFe nanozymes, a convenient detection system was constructed to achieve quantitative analysis of perfluorooctanoic acid (PFOA) and nonafluorosulfonic acid (NFBSA). This detection method exhibits a satisfactory linear response to PFOA and NFBSA, with the entire analytical process requiring only 45 min. This study provides a new paradigm for the rational design of nanozymes and provides reliable technical support for the rapid on-site detection of perfluorinated compounds in environmental water bodies.