A self-powered photoelectrochemical sensor based on an In₂O₃/Ag₂S heterojunction for tetracycline detection and...

A self-powered photoelectrochemical (PEC) sensor based on an In₂O₃/Ag₂S heterojunction was successfully developed for the highly sensitive monitoring of tetracycline (TC) traces in water matrices. Benefiting from superior intrinsic optoelectronic properties, hexagonal tubular In₂O₃ was initially synthesized via a solvothermal reflux-heating route followed by thermal calcination. Subsequently, the In₂O₃/Ag₂S heterojunction was fabricated through an in situ growth strategy, yielding a remarkably amplified photoelectric response and a robust, stable initial photocurrent driven entirely by internal potential. Under optimized operational parameters, the developed sensor delivered a wide linear detection range spanning from 1 nM to 1 mM, coupled with an ultra-low detection limit of 0.87 nM. Moreover, the sensing platform demonstrated outstanding long-term stability, rapid transient response, robust anti-interference selectivity, and satisfactory reproducibility. Crucially, by integrating a dedicated microcontroller-based hardware module, device portability was successfully realized, offering a viable blueprint for the decentralization of PEC instrumentation. Although the current hardware prototype remains at a preliminary stage, this work establishes a rigorous and practical fundamental framework for low-cost, on-site antibiotic field screening.