Paper
Paper
Abstract The field of photoelectrochemical‐type (PEC) ultraviolet (UV) photodetectors has witnessed swift progression due to their facile fabrication processes and self‐powered function. The realization of high‐performance and self‐powered PEC UV photodetectors is attractive and challenging. In this study, the application of ZnAl mixed metal oxide (MMO) heterojunctions in self‐powered PEC UV photodetectors is introduced for the first time. The MMO heterojunctions are composed of ZnO and ZnAl 2 O 4 , which provide a suitable band structure for accelerating the photogenerated carrier separation and transport, boosting UV photodetection. Irradiation of the self‐powered MMO PEC UV photodetectors with UV light (365 nm) results in a high responsivity of 46.82 mA W −1 and a fast response time of 18/35 ms. An impressive UV/visible rejection ratio of 1088.8 and excellent multi‐cycle stability are demonstrated, exceeding the most recently reported PEC UV photodetectors. Moreover, the MMO PEC UV photodetectors possess underwater optical communication capability, confirming promising potential for underwater optoelectronic devices. This study provides a new perspective on the development of high‐performance PEC UV photodetectors.