Photoelectrochemical Biosensor Based on the Bimetallic Schottky Junction for Sensitive Analysis of Cd2

In this work, a AuAg-3,4,9,10-perylene tetracarboxylic acid (AuAg-PTCA) bimetallic Schottky junction as the photoactive material with strong stability and high photoelectric conversion efficiency was prepared by decorating PTCA with Au nanoparticles (Au NPs) and Ag NPs through a facile in situ reduction route and exploited to construct a photoelectrochemical (PEC) biosensor for selective and sensitive determination of cadmium ion (Cd2+). Impressively, the photocurrent response of the AuAg-PTCA bimetallic Schottky junction has been improved by 4.8 times compared to that of pristine PTCA for improving the detection sensitivity, which is attributed to the enhanced photon absorption, the accelerated charge separation and transmission, and the increased charge transfer channels caused by the AuAg bimetallic synergistic coupling. Moreover, the Cd2+-aptamer sequence as the specific recognition element was utilized for construction of the PEC biosensor, which could enhance detection selectivity to minimize interference from other ions or molecules in the sample. Thus, the developed PEC biosensor realized the selective and sensitive detection of Cd2+, delivering a limit of detection of 0.33 pM. This work establishes valuable insights for bimetallic Schottky junction development, unlocking new opportunities in environmental sensing, food quality control, and medical diagnosis.