Citrate ions-modified NiFe layered double hydroxide for durable alkaline seawater oxidation

Abstract

Seawater electrolysis taking advantage of coastal/offshore areas is acknowledged as a potential way of large-scale producing H₂ to substitute traditional technology. However, anodic catalysts with high overpotentials and limited lifespans (caused by chloride-induced competitive chemical reactions) hinder the system of seawater electrolysis for H₂ production. Herein, we present a citrate anion (CA) modified NiFe layered double hydroxide nanosheet array on nickel foam (NiFe LDH@NiFe-CA/NF), which serves as an efficient and stable electrocatalyst towards long-term alkaline seawater oxidation. It requires only a low overpotential of 387 mV to achieve a current density of 1000 mA cm⁻², outperforming NiFe LDH/NF (414 mV). Moreover, NiFe LDH@NiFe-CA/NF exhibits continuous oxygen evolution testing for 300 h at 1000 mA cm⁻² due to its anti-corrosion characterization. Additionally, the fabricated cell can stably operate at 300 mA cm⁻² (60 °C, 6 M KOH + seawater) and only require 1.69 V, achieving low energy consumption of seawater splitting.