Self-powered photoelectrochemical aptasensor based on phosphorus doped porous ultrathin g-C3N4 nanosheets enhanced by surface plasmon resonance effect.

This work reports a facile and sensitive self-powered cathodic photoelectrochemical (PEC) aptasensor for the detection of oxytetracycline (OTC) based on Au nanoparticles-decorated phosphorus-doped porous ultrathin g-C3N4 nanosheets (Au/PCN-S). The prepared PCN-S possesses large specific surface area with abundant in-plane pores on its surface, ideal biocompatibility, and excellent visible light response. The in situ photo-reduced Au nanoparticles further enhanced the PEC performance owing to its unique surface plasmon resonance (SPR) effect. Under visible light irradiation, the photocurrent of Au/PCN-S composites was significantly enhanced, which was about 22 times higher than that of pure g-C3N4. In the self-powered PEC biosensing of OTC, the device exhibited high sensitivity toward the presence of dissolved oxygen in the electrolyte and presented a wide detection range from 0.5 to 200 nM and a detection limit of 0.34 nM, as well as certain selectivity, reproducibility and stability. The proposed Au/PCN-S nanocomposites would be considered as a promising visible light-responsive photoactive material for fabrication of PEC biosensors with high performance.