Crystalline Ru-Decorated MOF-Derived Amorphous CoMo-LDH Nanosheet Arrays as Bifunctional Catalysts for Overall Natural Seawater Electrolysis.

The construction of an amorphous/crystalline heterostructure of MOF-derived electrocatalysts offers an intriguing pathway to improve hydrogen production efficiency, but it has received little attention. Here, we report crystalline Ru-decorated MOF-derived amorphous CoMo-LDH nanosheet arrays as highly active and robust bifunctional electrocatalysts for natural seawater electrolysis. Benefiting from the abundant interfaces, the Ru-CoMo-LDH catalyst exhibits excellent activity toward OER under fresh and natural seawater, in particular; it requires only 257 and 406 mV overpotential at 10 and 500 mA cm^-2 in 1 M KOH + Seawater, outperforming the benchmark RuO₂. In addition, this electrocatalyst is an eminently active and stable HER in various electrolytes, emphasizing its outstanding bifunctional capability. Strikingly, in full-cell overall water splitting in natural seawater test, Ru-CoMo-LDH ∥ Pt/C exhibits superior electrochemical behavior (i.e., overpotential of 1.5545 and 1.731 V to obtain the current density of 10 and 200 mA cm^-2, respectively) and high stability. These excellent electrocatalytic activities highlighted the synergistic effects of intimated amorphous/crystalline junctions, which provide a rich population of exposed active sites and enhance electron transport. This, in turn, lowers the adsorption energy barrier of intermediates, leading to improved performance. Our work proves that designing an amorphous/crystalline heterointerface is a promising platform for further enhancing the hydrogen generation efficiency.