Sub-2 nm Ir Nanoclusters Immobilized on Mesoporous Nitrogen-Doped Carbons as Efficient Catalysts for Selective Hydrogenation

The development of high-performance heterogeneous catalysts for chemoselective hydrogenation reactions is particularly important for the industrial production of fine-chemical intermediates and biologicals. Downsizing the active component (usually metals) in heterogeneous catalysts to the nanocluster scale and even atomic dispersion is highly desirable for maximizing their efficiency and regulating their selectivity by optimizing their electronic properties. Herein, we report a nitrogen-tethering strategy for the synthesis of sub-2 nm Ir nanoclusters supported on mesoporous nitrogen-doped carbons with high Ir loading up to 10 wt %. The as-prepared Ir nanocluster catalysts exhibit outstanding activity, selectivity, and reusability in diverse vital hydrogenation reactions, including the hydrogenation of nitroarenes, quinoline compounds, and acetophenone for the synthesis of the corresponding amines, 1,2,3,4-tetrahydroquinolines, and aromatic alcohols, respectively. The superior performance of the catalyst is associated with the efficient exposure of the active Ir surface and the optimal electronic properties of Ir nanoclusters based on the strong metal–support interaction.