Hollow Multivoid Nanocuboids Derived from Ternary Ni–Co–Fe Prussian Blue Analog for Dual-Electrocatalysis of Oxygen and Hydrogen Evolution Reactions

Hydrogen generation from electrochemical water-splitting is an attractive technology for clean and efficient energy conversion and storage, but it requires efficient and robust non-noble electrocatalysts for hydrogen and oxygen evolution reactions (HER and OER). Nonprecious transition metal–organic frameworks (MOFs) are one of the most promising precursors for developing advanced functional catalysts with high porosity and structural rigidity. Herein, a new transition metal-based hollow multivoid nanocuboidal catalyst synthesized from a ternary Ni–Co–Fe (NCF)-MOF precursor is rationally designed to produce dual-functionality toward OER and HER. Differing ion exchanging rates of the ternary transition metals within the prussian blue analog MOF precursor are exploited to produce interconnected internal voids, heteroatom doping, and a favorably tuned electronic structure. This design strategy significantly increases active surface area and pathways for mass transport, resulting in excellent electroactivities toward OER and HER, which are competitive with recently reported single-function nonprecious catalysts. Moreover, outstanding electrochemical durability is realized due to the unique rigid and interconnected porous structure which considerably retains initial rapid charge transfer and mass transport of active species. The MOF-based material design strategy demonstrated here exemplifies a novel and versatile approach to developing non-noble electrocatalysts with high activity and durability for advanced electrochemical water-splitting systems.