Atomically Precise Mo 2 Cu 17 Bimetallic Nanocluster: Synergistic Mo 2 O 4 -Coupled Copper Alkynyl Cluster for the Improved Hydrogen Evolution Reaction Performance.

Electrolytic hydrogen production via water splitting holds significant promise for the future of the energy revolution. The design of efficient and abundant catalysts, coupled with a comprehensive understanding of the hydrogen evolution reaction (HER) mechanism, is of paramount importance. In this study, we propose a strategy to craft an atomically precise cluster catalyst with superior HER performance by cocoupling a Mo2 O4 structural unit and a Cu(I) alkynyl cluster into a structured framework. The resulting bimetallic cluster, Mo 2 Cu 17 , encapsulates a distinctive structure [Mo2 O4 Cu17 (TC4A)4 (PhC≡C)6 ], comprising a binuclear Mo2 O4 subunit and a {Cu17 (TC4A)2 (PhC≡C)6 } cluster, both shielded by thiacalix[4]arene (TC4A) and phenylacetylene (PhC≡CH). Expanding our exploration, we synthesized two homoleptic CuI alkynyl clusters coprotected by the TC4A and PhC≡C- ligands: Cu 13 and Cu 22 . Remarkably, Mo 2 Cu 17 demonstrates superior HER efficiency compared to its counterparts, achieving a current density of 10 mA cm-2 in alkaline solution with an overpotential as low as 120 mV, significantly outperforming Cu 13 (178 mV) and Cu 22 (214 mV) nanoclusters. DFT calculations illuminate the catalytic mechanism and indicate that the intrinsically higher activity of Mo 2 Cu 17 may be attributed to the synergistic Mo2 O4 -Cu(I) coupling.