Engineering Ni-O-Ir interfacial coupling on MOF-74 through controlled iridium incorporation for efficient overall water splitting

The development of bifunctional electrocatalysts with outstanding catalytic activity and long-term stability for overall water splitting is urgently needed. Herein, two distinct strategies, namely in situ synthesis and post-synthesis modification, were employed to introduce iridium (Ir) into Ni-MOF-74, and the effect of the Ir incorporation pathway on electrocatalytic performance was systematically compared. Structural characterizations reveal that the post-synthetic modification strategy anchors highly dispersed Ir nanoparticles onto the MOF surface and establishes Ni-O-Ir interfacial bonds, thereby significantly enhancing surface exposure of Ir species. In 1.0 M KOH, Ir@Ni-MOF-74/NF-P shows superior activity for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), achieving current densities of 10 mA cm −2 at overpotentials of merely 26 mV and 210 mV. Moreover, a symmetric two-electrode overall water splitting electrolyzer assembled using Ir@Ni-MOF-74/NF-P requires a cell voltage of just 1.54 V to deliver 50 mA cm −2 , and operates continuously for 200 h with negligible performance degradation.