TiO<SUB>2</SUB> Immobilization of Molecular Ru(II) Catalyst Promotes its Monomeric Catalytic Route and Secures the Efficient and Steady Photocatalytic CO<SUB>2</SUB> to CO/Formate Conversion
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초록
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Herein, we employed the TiO2 immobilization of molecular Ru(II) catalyst, (4,4′-Y2-bpy)RuII(CO)2Cl2 (RuP; Y = CH2PO(OH)2), as a method to secure the efficient and steady catalytic activity of molecular bipyridyl Ru(II) complex-based photocatalytic system for CO2 reduction. From series of operando FTIR spectrochemical analysis, it was found that TiO2-fixation of molecular Ru(II) complex leads to the efficient stabilization of monomeric key intermediate, Ru–hydride (LRuII(H)(CO)2Cl), and suppresses the formation of polymeric Ru(II) complex (–(L(CO)2Ru‒Ru(CO)2L)n–), a major deactivation pathway, during photoreaction, unlike solution mechanism of Ru(II) catalyst involving the considerable Ru–Ru dimeric route. The active promotion of hetero-binary system (IrPS + TiO2/RuP) that uses TiO2-bound Ru(II) complex as reduction catalyst led to the highly increased activity and durability of photocatalytic behavior giving the maximal TON of ＞4816 and ＞2228 for CO and HCOO‒ production.