Emergence of Visible‐Light Water Oxidation Upon Hexaniobate‐Ligand Entrapment of Quantum‐Confined Copper‐Oxide Cores

The formation of small 1 to 3 nm organic-ligand free metal-oxide nanocrystals (NCs) is essential utilization their attractive size-dependent properties in electronic devices and catalysis. We now report that hexaniobate cluster-anions, [Nb6O19]8−, can arrest the growth NCs stabilize them as water-soluble complexes. This exemplified by hexaniobate-complexed 2.4-nm monoclinic-phase CuO (1), whose ca. 350 Cu-atom cores feature quantum-confinement effects impart an unprecedented ability catalyze visible-light water oxidation with no added photosensitizers or applied potentials, at rates exceeding those hematite NCs. findings point polyoxoniobate-ligand entrapment a potentially general method for harnessing very semiconductor versatile, entirely-inorganic