Layered Double Hydroxides with Carbonate Intercalation as Ultra-Stable Anodes for Seawater Splitting at Ampere-Level Current Density

Owing to the presence of a substantial concentration of chlorine in seawater, the anode still faces severe chlorine corrosion, especially the water splitting operated at high current densities. Herein, the cost-effective and scalable NiFe layered double hydroxides with carbonate intercalation (named as NiFe LDH_CO32-) are synthesized utilizing the etching-hydrolysis and ion exchange strategies under ambient conditions. Experimental findings demonstrate that NiFe LDH_CO32- shows excellent stability at 500 and 1000 mA cm-2 for 1000 h under alkaline simulated seawater. Additionally, a two-electrode system offers great stability at current densities ranging from 100 to 1000 mA cm-2 over a duration of 400 h in alkaline seawater. This remarkably catalytic stability can be ascribed to the etching-hydrolysis and carbonate intercalation strategies. The etching-hydrolysis strategy leads to an integrated electrode for the catalyst-carrier, enhancing the adhesion between them, and retarding hence the divorce of catalysts from the carrier. Theoretical calculations suggest that the carbonate intercalation weakens the adsorbability of chlorine on catalysts and hinders the coupling of metal atoms with chlorine, thereby impeding the anode corrosion caused by chlorine and improving catalytic stability. More importantly, this strategy has been extended to the preparation of other layered double hydroxides with carbonate intercalation. In this work, carbonate intercalation and etching-hydrolysis strategies at room temperature and atmospheric pressure are deployed to synthesize the large-scale and ultra-stable electrodes for seawater splitting. The as obtained material (NiFe LDH_CO32-) exhibits impressive OER activity under alkaline simulated seawater, showing stable operation for 1000 h at 500 and 1000 mA cm-2. image