Recent advances on hydrogen production through seawater electrolysis

Electrolysis of mostly abundant seawater rather than scarce fresh water is not only a promising way to generate clean hydrogen energy, which also alleviates the use of highly demanding fresh water. At first, this review discusses about the challenging issues for seawater electrolysis including competition of chlorine evolution reaction (ClER) with oxygen evolution reaction (OER) on the anode, need for the robust and efficient electrocatalysts to sustain against chloride corrosion, and the formation of precipitates on the electrode surface. Then, the present review provides the recent advancement in terms of synthetic methodologies, chemical properties, density functional theory (DFT) calculations, and catalytic performances of several nanostructured earth-abundant/precious-metal-containing electrocatalysts for hydrogen evolution reaction (HER) and OER in seawater electrolyte, where the discussion includes highly OER selective robust electrocatalysts such as transition-metal-hexacyanometallates based electrocatalyst, transition metal nitride, and layered double hydroxide (LDH) integrated with transition metal sulfide. Finally, this review summarizes the several promising strategies to enhance the HER and OER performance of electrocatalysts in seawater (including η of ≤ −200 mV at −10 mA cm−2 for HER; η of ≤300 mV at ≥100 mA cm−2 for OER; high long term stability for ≥600 h for overall water splitting).