The progress and prospect of the solar-driven photoelectrochemical desalination

Typical desalination techniques, such as reverse osmosis, distillation, capacitive deionization, and battery desalination, require lots of electrical or thermal energy consumption. As a new emerging desalination technique, the solar-driven photoelectrochemical desalination (SD-PED) technology by using sustainable solar energy to remove salt ions without any external bias has been developed and caused much attention. The SD-PED technique with dual functions of desalination and photoelectric conversion driven by sunlight has demonstrated that a high initial photocurrent up to 9.5 mA can be obtained in the existing work with 99.95% salt removal rate. However, some limitations are remained such as the fast decline of photocurrent, difficulty in the seawater desalination, the long-term stability of system etc. To better understand this new desalination technique, herein, we comprehensively review and discuss the status of SD-PED system for the first time, including the device configuration, influencing factors and the active involved materials of solar absorbers and redox electrolyte species. Further, the strategies to improve the performance of long-term stability desalination are summarized, such as the configuration connection in series or parallel, the combination of photoanode and photocathode, the photosensitive material with wide solar absorption. At last, the challenge and prospect are further guided for the future development of SD-PED technology, which are expected to realize the commercialization.