Bifunctional tubular step-scheme Co3S4/CdS heterostructure for highly efficient photoelectrochemical detection coupled with the degradation of tetracycline.

A bifunctional tubular step-scheme Co3S4/CdS heterostructure was successfully synthesized for efficient photoelectrochemical (PEC) detection coupled with the degradation of tetracycline (TC). It was found that so-obtained heterostructure could effectively suppress the recombination of photo-generated carriers and display larger PEC responses owing to the internal electrostatic field. Upon adding TC, the photocurrent signal of Co3S4/CdS heterostructure was specifically activated due to the direct consumption of holes in CdS component by TC, resulting in significantly enhanced charge separation. Crucially, the photo-induced holes in CdS and produced •OH radicals can realize catalytic degradation of TC during its detection and the possible intermediates and degradation pathways were speculated. A dual-functional PEC sensing platform has thereby been developed for detection and degradation of TC with ultra-low detection limit and high degradation efficiency. Additionally, the developed sensor displayed excellent selectivity and high stability, demonstrating its potential for TC detection and degradation in tap-water and milk samples.