Tungstate Intercalated NiFe Layered Double Hydroxide Enables Long-Term Alkaline Seawater Oxidation.

Abstract

Renewable electricity-driven seawater splitting presents a green, effective, and promising strategy for building hydrogen (H2 )-based energy systems (e.g., storing wind power as H2 ), especially in many coastal cities. The abundance of Cl- in seawater, however, will cause severe corrosion of anode catalyst during the seawater electrolysis, and thus affect the long-term stability of the catalyst. Herein, seawater oxidation performances of NiFe layered double hydroxides (LDH), a classic oxygen (O2 ) evolution material, can be boosted by employing tungstate (WO4 2- ) as the intercalated guest. Notably, insertion of WO4 2- to LDH layers upgrades the reaction kinetics and selectivity, attaining higher current densities with ≈100% O2 generation efficiency in alkaline seawater. Moreover, after a 350h test at 1000mAcm-2 , only trace active chlorine can be detected in the electrolyte. Additionally, O2 evolution follows lattice oxygen mechanism on NiFe LDH with intercalated WO4 2- .