Redox-mediated decoupled seawater direct splitting for H<sub>2</sub> production.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39402055.
- Also identified by DOI 10.1038/s41467-024-53335-w and PMC identifier 11473778.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Seawater direct electrolysis (SDE) using renewable energy provides a sustainable pathway to harness abundant oceanic hydrogen resources. However, the side-reaction of the chlorine electro-oxidation reaction (ClOR) severely decreased direct electrolysis efficiency of seawater and gradually corrodes the anode. In this study, a redox-mediated strategy is introduced to suppress the ClOR, and a decoupled seawater direct electrolysis (DSDE) system incorporating a separate O<sub>2</sub> evolution reactor is established. Ferricyanide/ferrocyanide ([Fe(CN)<sub>6</sub>]<sup>3-/4-</sup>) serves as an electron-mediator between the cell and the reactor, thereby enabling a more dynamically favorable half-reaction to supplant the traditional oxygen evolution reaction (OER). This alteration involves a straightforward, single-electron-transfer anodic reaction without gas precipitation and effectively eliminates the generation of chlorine-containing byproducts. By operating at low voltages (~1.37 V at 10 mA cm<sup>-2</sup> and ~1.57 V at 100 mA cm<sup>-2</sup>) and maintaining stability even in a Cl<sup>-</sup>-saturated seawater electrolyte, this system has the potential of undergoing decoupled seawater electrolysis with zero chlorine emissions. Further improvements in the high-performance redox-mediators and catalysts can provide enhanced cost-effectiveness and sustainability of the DSDE system.