CuO Nanobelt Array-Based Omnidirectional UV–Visible–NIR Photoelectrochemical Photodetectors

Photoelectrochemical photodetectors (PEC PDs) are promising in underwater optoelectronic devices because of their low cost, good sensitivity, and self-powered characteristics. However, achieving high-performance omnidirectional visible PEC PDs using seawater as the electrolyte is still challenging, hindering their practical application. This work successfully synthesized CuO nanobelt arrays (NAs) on a linear copper wire via a low-temperature solution method with an annealing process. The self-powered CuO NA PEC PDs exhibit good UV–vis–NIR photoresponse ranging from 365 to 850 nm with a high responsivity of −83.18 mA/W (455 nm irradiation), a fast response time of 28/140 ms, and good stability in simulated seawater. The high responsivity surpasses all of the reported PEC PDs when seawater or simulated seawater is used as the electrolyte. In addition, the CuO NA PEC PDs show good 360° omnidirectional photodetection and underwater wireless optical communication capabilities. This work provides new insights into achieving omnidirectional visible PEC PDs and demonstrates the potential application of CuO NAs in underwater optoelectronic devices.