Atomically embedded Ag on transition metal hydroxides triggers the lattice oxygen towards sustained seawater electrolysis

Abstract

Exploiting highly robust and active electrocatalysts for large-scale (sea)water electrolysis at industrial-level current densities (> 500 mA cm−2) is an increasingly appealing for developing renewable energy technologies. The current researches are limited by the complex synthetic procedures and poor stability of catalysts in practical application. Transition-metal (oxy)hydroxides are promising candidates for oxygen evolution reaction (OER) yet challenging approach to the clean energy by the low electrical conductivity. In this work, we pioneered an atomical-doping engineering strategy for achieving highly efficient and robust electrocatalyst towards large current density. Ag doped NiFe layered double hydroxide (LDH) was prepared by a one-step redox reaction on Ni foam without complex synthetic approach. Benefiting from the increased intrinsic conductivity, abundant active sites, and improved intrinsic surface area, Ag/NiFe LDH present a superior catalytic activity toward large-scale application, requiring low overpotentials of 240 and 276 mV at 100 and 1000 mA cm−2 in 1 M KOH, respectively. More importantly, a low overpotential of 303 mV at 1000 mA cm−2 in alkaline seawater-based electrolyte was attained, which remained 1000 h with long-term operation. Experimental and theoretical calculations demonstrated that the oxidation of Ag triggers the lattice oxygen redox and stabilizes the lattice oxygen, which does not induce significant material structure change and reconstruction during operation, ensuring the OER stability. This work remarkably advances the development of seawater electrolysis for large-scale clean energy.