MOF-derived ZnO nanocages with enhanced UV absorption and photocarrier dynamics for high-performance underwater photodetection and optical imaging

Self-powered photoelectrochemical (PEC) photodetectors hold great promise for underwater optical applications, yet suffer from sluggish carrier dynamics and limited stability. Herein, high-performance, self-powered, and stable PEC ultraviolet (UV) photodetectors were fabricated using metal-organic-framework derived ZnO nanocages (NCs). These topography-engineered ZnO NCs synchronously enhance UV absorption, facilitate photogeneration carrier separation, and promote charge transfer at the ZnO/electrolyte interface, thus optimizing the overall photoresponse performance. The ZnO NCs-based PEC device achieves an ultrahigh responsivity of 300.6 mA/W under 365 nm UV light irradiation, a fast response time of 10/20 ms, outstanding spectra selectivity (UV/visible rejection ratio of 2000), and excellent cycling stability (10,000 cycles), which is one of the best reported PEC UV photodetectors. Furthermore, the self-powered ZnO-based PEC PDs have good underwater optical imaging capability. This work provides a new idea for designing high-performance UV photodetectors for application in underwater environments.