Enhanced electrocatalytic activity and stability of Ce doped NiFe layered double hydroxide for alkaline seawater oxidation

Abstract

Nickel–iron layered double hydroxide (NiFe LDH) is considered as a promising catalyst for the oxygen evolution reaction (OER) during water splitting. However, its application in large-scale seawater electrolysis is limited by poor electrical conductivity, insufficient exposure of active sites, and the competing chlorine evolution reaction in seawater. The multiple limitations are addressed through effective Ce doping in quasi-parallel NiFe LDH (NiFeCe LDH) nanosheet arrays on a Ni foam substrate. The introduction of Ce induces the formation of nanoarrays with open spacing, and the frustrated Lewis pairs (FLPs) induced by the Ce 4f-O 2p interaction lead to the enrichment of high-valence Ni active phases and stabilization of Fe sites, which significantly enhances OER performance. The NiFeCe LDH electrode can achieve a high current density of 500 mA cm⁻² with overpotentials of 262 and 288 mV in 1.0 M KOH and alkaline simulated seawater (1.0 M KOH + 0.5 M NaCl), respectively, and remain stable for 600 h at 500 mA cm⁻² in alkaline seawater without potential decay. This work provides new insights into electronic modulation and activity optimization of nickel-iron-based electrocatalysts.