Nickel Single-Atom Catalyst-Mediated Efficient Redox Cycle Enables Self-Checking Photoelectrochemical Biosensing with Dual Photocurrent Readouts

Developing a self-checking photoelectrochemical biosensor with dual photocurrent signals could efficiently eliminate false-positive or false-negative signals. Herein, a novel biosensor with dual photocurrent responses was established for the detection of acetylcholinesterase activity. To achieve photocurrent polarity-switchable behavior, the iodide/tri-iodide redox couple was innovatively introduced to simultaneously consume the photoexcited electrons and holes, which circumvents the inconvenience caused by the addition of different hole-and electron-trapping agents in the electrolyte. Importantly, benefiting from the high catalytic activity, the enhanced photoelectric responsivity can be realized after decorating the counter electrode with nickel single-atom catalysts, which promotes a more efficient iodide/ tri-iodide redox reaction under low applied voltages. It is envisioned that the proposed photocurrent polarity switching system offers new routes to sensitive and reliable biosensing.

Automated summary

A self-checking photoelectrochemical biosensor with dual photocurrent signals was developed to eliminate false-positive or false-negative signals. By introducing the iodide/tri-iodide redox couple, the photocurrent polarity-switchable behavior was achieved, which circumvented the inconvenience caused by the addition of different hole-and electron-trapping agents in the electrolyte. Moreover, the catalytic activity of nickel single-atom catalysts enhanced the photoelectric responsivity, enabling a more efficient iodide/tri-iodide redox reaction under low applied voltages. This proposed photocurrent polarity switching system offers new routes to sensitive and reliable biosensing.