NIR‐Excitable POM‐Encapsulated Yb‐Bi₂S₃ Decorated Graphene for Wearable Photoelectrochemical Sensing

Abstract Transition metal sulfides have garnered significant interest in the realm of photoelectrochemical (PEC) sensors due to their remarkable optical and electrical properties. However, their intrinsic UV–vis adsorption and electron‐donor consumption severely hinder their nonirritating and in situ epidermal PEC applications. Herein, a NIR‐808 nm light‐excited heterojunction, phosphomolybdic acid‐encapsulated ytterbium‐doped bismuth sulfide (Yb‐Bi₂S₃/PMA), is synthesized by hydrothermal method for self‐sufficient electron donor‐based PEC sensing. Further, the Yb‐Bi₂S₃/PMA heterojunction is decorated on flexible and integrated laser‐induced graphene electrode arrays, providing ultrafast charge carrier transfer capacity and robust mechanical durability (300 bending cycles) for subsequent wearable PEC sensing. As a showcase, the aptamer molecular recognition‐based wearable PEC sensor for sweat trace Neuropeptide Y (NPY, a stress or depression biomarker) presents an ultra‐low detection limit (0.39 fM) and good anti‐interference ability. Moreover, the integration of wearable PEC aptasensor with signal processing and wireless communication facilitates nonirritating and in situ analysis of sweat trace NPY dynamics in various real scenarios (feeding behaviors, physiological stress, and circadian rhythm). More broadly, this research establishes the foundation for NIR‐excitable semiconductors equipped with self‐sufficient electron donor capabilities, unlocking the potential for ultrasensitive wearable PEC sensing applications.