Multi-metallic Metal–Organic Framework Nanosheets with 3D Flower-like Nanostructure-Based Natural Seawater Splitting toward Stable Industrial-Scale Current Density

Rational modification of the chemical components of the metal–organic framework (MOF) is one of the most promising and challenging strategies to alternate noble metals in the electrochemical water-splitting field. Multimetallic MOFs have emerged as excellent materials for several applications; however, it remains a significant challenge to synthesize and characterize these materials. In this work, we report a facile approach to synthesizing a series of multimetallic MOF nanosheet-assembled hierarchical flower-like morphologies as highly active and durable electrocatalysts for natural seawater electrolysis. Simultaneously, their three-dimensional hierarchical nanostructures and multimetallic components can provide abundant active sites, improve intrinsic catalytic activity, and facilitate electron transfer. Consequently, the obtained RhCoNi-MOF exhibits overpotentials as low as 40, 48, and 50 mV at 10 mA cm–2 in alkaline freshwater, alkaline simulated seawater, and alkaline natural seawater. In natural seawater, the RhCoNi-MOF also offers an outstanding performance comparable to Pt/C. Impressively, a two-electrode overall seawater electrolysis device using RhCoNi-MOF as a bifunctional catalyst requires a voltage of 1.52 V at 10 mA cm–2 and can stably maintain over 80 h. The density functional theory calculation reveals that the superior electrocatalytic activity of the RhCoNi-MOF can be attributed to the synergistic effects of introducing Co and Rh metal ions.