Ir Nanoparticles Anchored on Metal-Organic Frameworks for Efficient Overall Water Splitting under pH-Universal Conditions.

The construction of high-activity and low-cost electrocatalysts is critical for efficient hydrogen production by water electrolysis. Herein, we developed an advanced electrocatalyst by anchoring well-dispersed Ir nanoparticles on nickel metal-organic framework (MOF) Ni-NDC (NDC: 2,6-naphthalenedicarboxylic) nanosheets. Benefiting from the strong synergy between Ir and MOF through interfacial Ni-O-Ir bonds, the synthesized Ir@Ni-NDC showed exceptional electrocatalytic performance for hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and overall water splitting in a wide pH range, superior to commercial benchmarks and most reported electrocatalysts. Theoretical calculations revealed that the charge redistribution of Ni-O-Ir bridge induced the optimization of H 2 O, OH* and H* adsorption, thus leading to the accelerated electrochemical kinetics for HER and OER. This work provides a new clue to exploit bifunctional electrocatalysts for pH-universal overall water splitting.