An Electrochemical Neutralization Cell for Spontaneous Water Desalination

We show that conversion of acid-base neutralization energy into electrical energy via reversible H₂ redox can be used to spontaneously desalinate saline water while generating electric power and consuming ∼13.6 kJ for the removal of 1 mol of NaCl. This electrochemically driven neutralization pathway exhibits a positive temperature coefficient for the open circuit voltage (1.63 ± 0.11 mV/K), which, in turn, means it can harvest ∼24 kJ/mol of entropic heat, at room temperature, from the surroundings as electrical driving force. Our demonstration of desalination without the aid of an external power supply by performing reversible redox reactions and involving only gases, water, H⁺, and OH⁻, such that the products and the reactants of the reaction do not contaminate the desalinated water, opens up an unprecedented pathway for addressing the potable water crises looming over the 21^st century.