Stable Seawater Oxidation at High-Salinity Conditions Promoted by Low Iron-Doped Non-Noble-Metal Electrocatalysts
Dina Zhang, Hao Cheng, Xiaoyu Hao, Qian Sun, Tianyi Zhang, Xinwu Xu, Zelin Ma, Tong Yang, Jun Ding, Xuqing Liu, Ming Yang, Xiaolei Huang
Abstract
Electrocatalytic seawater splitting offers a promising avenue for cost-effective and environmentally friendly hydrogen production. However, the activity of catalysts has significantly degraded at high-salinity conditions, preventing commercial-scale practical applications. Here, we demonstrate that iron-doped nickel-based electrocatalysts with low doping concentration exhibit an outstanding performance for the oxygen evolution reaction (OER) in seawater, particularly at high-salinity conditions. Notably, the OER catalysts present only a marginal increase in overpotential of ∼5 mV as the sodium chloride concentration in the electrolyte increases from 0 M to saturation. Furthermore, the low iron-doped electrocatalysts sustain consistent oxygen generation over 100 h of operation in a saturated seawater electrolyte. Supported by first-principles calculations, we unravel that low-concentration iron doping in Ni-based catalysts can mitigate chloride ion adsorption, thereby amplifying the OER activity in saturated seawater electrolytes, which is in contrast with high iron-doped electrocatalysts. Our work provides a useful perspective on designing catalysts for electrolytic seawater OER, potentially paving the way for large-scale implementation of seawater splitting technologies.