CdS quantum dots (QDs) are attached onto zirconium-based metal-organic frameworks (Zr-MOFs) with DNA as a bridge to boost the photoelectrochemical (PEC) activity of Zr-MOFs, and the sensitization of Zr-MOFs by using CdS QDs is regulated by the alkaline phosphatase (ALP)-catalyzed hydrolysis of tripolyphosphate, enabling sensitive "signal-on" PEC detection of ALP activity.