Design strategy of cathodic electrocatalysts to effectively suppress inorganic fouling for long-term stability of reverse electrodialysis

Abstract

In seawater based-electrochemical devices including reverse electrodialysis (RED) and electrolysis devices, inorganic fouling occurs from the cathodic reaction owing to the precipitation of hydroxides and/or carbonates. Inorganic fouling decreases electrocatalytic activity and disrupts the charge transport, thus reducing power density. In this study, we investigated inorganic fouling over various cathodic electrocatalysts prepared for large-scale RED. Notably, nano-Pt/C which has four times higher scaling control than bulk Pt, exhibited a formation of thin and porous foam-like Mg(OH)2, whereas bulk Pt was coated by a thick and dense film-like precipitate. Surface-modified carbon nanostructures showed a stronger anti-fouling behavior than Pt catalysts at high voltages (≥300-cell-paired RED stacks). In particular, acid–air plasma-treated O-rich functionalized C catalysts produced one-dimensional nanostructures, exhibited excellent electrocatalytic activity and allowed rapid charge transport, resulting in a stable RED performance at a power density of 545 ± 1 W m−2 (current density of 35.17 ± 0.02 A/m−2 over 12-h of operation. This study will promote the upscaling of RED systems toward industrial applications that use natural seawater.