Electronic Structure Modulation in a Co-Ni Dual-Metal Decorated Titanium-Oxo Cluster for Enhanced Photocatalytic CO2 to CO Reduction

Abstract Atomically dispersed metal catalysts demonstrate significant catalytic potential, though achieving precise structural elucidation and electronic modulation remains a key challenge. Herein, we report the synthesis and characterization of three isostructural, semiconducting heterometallic titanium-oxo clusters, Ti14M2(μ3-O)13(μ2-O)8(H2O)(C6H5CO2)18(Nfm)3 (designated as Ti14M2, where M2 = CoNi, Co2, or Ni2), serving as molecularly precise model systems for dual single-atom catalysts. Distinct electronic interaction between the heterometallic Co and Ni sites in Ti14CoNi modulates the local charge distribution, lowering the charge density at Ni while elevating it at Co. In photocatalytic CO2 reduction reaction (CO2RR), Ti14CoNi exhibits high performance, ranking among the best catalysts, surpassing Ti14Co2 and Ti14Ni2, as well as many state-of-the-art solid-state Ni, Fe, Cu, and Co single atom catalysts. Notably, Ti14CoNi retains activity even when using simulated flue gas as the CO2 source. Experimental and DFT studies reveal that Ni acts as the primary catalytic site for CO2RR in Ti14CoNi, with *COOH formation as the rate-determining step, while the lowered Ni valence state enhances CO2 activation and suppresses H2 evolution. The dual-metal strategy improves CO2RR efficiency and provides a thermodynamically favorable pathway for CO production. Our findings establish molecular metal-oxo clusters as atomically precise dual single atom catalysts and offer valuable insights for developing efficient CO2RR catalysts of the next generation.