Boosted thermal redox desalination of seawater driven by gradient of redox electrolyte

Electrolyte-based thermal redox desalination (ETRD) offers an alternative approach to freshwater production in regions with limited electricity. However, maintaining the redox electrolyte gradient between the two electrodes has limited its practical application. To address this challenge, we introduce a reactivation ETRD system that employs Fe(CN) 6 4− /Fe(CN) 6 3− electrolytes flowing separately through hot and cold chambers. Electrolyte gradient is sustained through an external reactivation loop utilizing LiFePO 4 and Prussian blue (PB). With the maintained gradient of redox electrolyte, the coupled thermocell achieves a remarkable Seebeck coefficient ( S e ) of 1.88 mV K −1 , an open-circuit voltage of 311 mV at a temperature difference (Δ T ) of 50 K—1.67 times higher than the highest reported value for thermoelectric systems using aqueous Fe(CN) 6 4− /Fe(CN) 6 3− , and a temperature-insensitive maximum power density of 0.635 mW m −2 K −2 . Accordingly, the ETRD device, operating under the maintained electrolyte gradient, exhibits competitive salt removal performance, and can produce freshwater while simultaneously generating electricity, rather than consuming it. Scalability was demonstrated by connecting 10 units in series. This work presents a novel approach to designing high-performance ETRD for efficient low-grade heat harvesting and seawater desalination.