Membraneless unbuffered seawater electrolysis for pure hydrogen production using PtRuTiOx anode and MnOx cathode pairs

Seawater electrolysis is promising as an in situ H2 production method, allowing immediate overseas transport of the produced H2. In this study, membraneless electrolysis of undisturbed, unbuffered seawater (pH 8.2) is proposed to produce high-purity H2. A ternary Pt, Ru, and Ti (PRT) catalyst with a minimized Pt level (Pt0.06Ru0.24Ti0.7Ox) drives chloride oxidation reaction (ClOR) at a Faradaic efficiency (FE) of ∼100% in saline water at current density (J) of 800 mA cm−2 over 500 h. Chlorine reduction reaction (ClRR) is also inhibited on MnOx electrodes, leading to hydrogen evolution reaction (HER) at an FE of ∼100% even in the presence of chlorine species (HClO/ClO−). Finally, the PRT anode/MnOx cathode pair is demonstrated to drives ClOR and HER at FEs of ∼100% at J = 80 mA cm−2 over 100 h in a single-compartment cell containing seawater. Oxygen evolution reaction and ClRR are completely inhibited during seawater electrolysis.