Signal amplified self-powered cathodic photoelectrochemical sensor based on elevating potential strategy and prolonging electron lifetime

The self-powered cathodic photoelectrochemical (PEC) sensor has attracted widespread attention in recent years due to its excellent anti-interference performance, but its weak sensitivity has limited further application. Herein, a dual-photoelectrode self-powered sensing platform was constructed for high-sensitive detection of oxytetracycline (OTC). To amplify the response signal for the sensor, a two-step approach has been tailored: (i) The selfpowered potential was significantly elevated by introducing the CoTiO3/g-C3N4 photoanode to form the dualphotoelectrode system. (ii) Photoelectrode materials were further designed as Z-scheme heterojunctions to prolong the electron lifetime. Compared with the individual g-C3N4 semiconductor, the maximum self-powered potential and the average electron lifetime for the Z-scheme heterojunction-based sensing platform enhanced 2.13 times and 2.01 times, respectively, thus significantly amplifying the photocurrent signal. To achieve the selective detection of OTC, a molecularly imprinted polymer film was anchored on the photocathode. The prepared self-powered PEC sensor exhibited good sensitivity, with a detection limit of 0.08 pM. The elevating potential strategy and prolonging electron lifetime offer a new method to amplify the signal for sensitive PEC detection.