Self-protecting interlocked electrodes for highly efficient and stable alkaline seawater electrolyzers

Abstract

Seawater electrolysis holds immense potential for sustainable hydrogen production, primarily due to its utilization of an effectively inexhaustible water source. However, the high salt concentrations in seawater, especially chloride, calcium and magnesium ions, result in electrode corrosion and induce Ca²⁺/Mg²⁺ precipitation, thereby reducing the stability of seawater electrolyzers. To address these issues, we develop self-protecting interlocked electrodes, which simultaneously inhibit the side reactions and side product precipitations. The anode, featuring a dual-layer configuration with a graphene oxide layer as a chloride-resistant protective sieve, ensures both enhanced catalytic activity and stability in seawater. Meanwhile, the cathode is formed by interconnected nanorod arrays that promote the agglomeration of tiny bubbles and expose more active sites, thereby enhancing stability and activity. Experimental results demonstrate that the electrolyzer with self-protecting electrodes is able to maintain a voltage of as low as 1.79 V at an industrial-level current density of 1 A cm⁻² at 60 °C. Remarkably, with a decay rate of only 0.1 mV h⁻¹, the alkaline seawater electrolyzer operates stably for 1000 hours and ClO⁻ is seldom observed in the o-tolidine test after long-term electrolysis. This work lays the foundation for innovative electrode design, enabling efficient and stable alkaline seawater electrolysis.