CuO Nanosheets for Use in Photoelectrochemical Photodetectors

Metal oxide semiconductors have attracted growing attention due to their excellent electrical and optical properties, low-cost fabrication, and good stability, which grant them great application potential in photodetectors (PDs). However, broadband photoelectrochemical (PEC)-type PDs based on metal oxide semiconductors are deficient. In this work, we synthesized two-dimensional (2D) CuO nanosheets (NSs) by annealing Cu-based metal–organic frameworks (Cu-MOFs) and first demonstrated broadband PEC PDs based on 2D CuO NSs. The thicknesses of 2D CuO NSs are 2–6 nm. 2D CuO PEC PDs show a broadband photoresponse from 365 to 850 nm with a responsivity of 2.7 mA/W and a response time of 60/400 ms, which surpass most 2D material-based PEC PDs. Moreover, CuO NSs PEC PDs exhibit outstanding multicycle stability and long-term stability for 1-month storage with negligible decay, exceeding all recently reported 2D material-based PEC PDs. These results endow 2D CuO NSs with great potential in underwater photodetection.