Divalent anion intercalation and etching-hydrolysis strategies to construct ultra-stable electrodes for seawater splitting

• Published in: Science China. Chemistry Vol. 67; no. 2; pp. 687 - 695
• Main Authors: Lu, Jiajia, Liu, Yang, Liang, Han-Pu
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01.02.2024; Springer Nature B.V
• Subjects: Anions; Catalysts; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Chlorine; Corrosion rate; Current density; Electrodes; Etching; Ferric hydroxide; Hydrolysis; Intercalation; Nickel; Seawater; Splitting; Stability; divalent anion intercalation; etching-hydrolysis; seawater splitting; stability
• ISSN: 1674-7291; 1869-1870
• DOI: 10.1007/s11426-023-1761-8

Developing stable electrodes for seawater splitting remains a great challenge due to the detachment of catalysts at a large operating current and severe anode corrosion caused by chlorine. Herein, divalent anion intercalation and etching-hydrolysis strategies are deployed to synthesize the ultra-stable anode, dendritic Fe(OH) 3 grown on Ni(SO 4 ) 0.3 (OH) 1.4 -Ni(OH) 2 . Experimental results reveal that the anode exhibits good activity and excellent stability in alkaline simulated seawater. After 500 h, the current density operated at 1.72 V remains 99.5%, about 210 mA cm −2 . The outstanding stability originates from the etching-hydrolysis strategy, which strengthens the interaction between the catalyst and the carrier and retards thus the detachment of catalysts at a large current density. Besides, theoretical simulations confirm that the intercalated divalent anions, such as SO 4 2− and CO 3 2− , can weaken the adsorption strength of chlorine on the surface of catalysts and hinder the coupling and hybridization between chlorine and nickel, which slows down the anode corrosion and improves catalytic stability. Furthermore, the two-electrode system shows the remarkable 95.1% energy efficiency at 2,000 A m −2 and outstanding stability in 6 mol L −1 KOH + seawater at 80 °C.