In this study, an InP-cored quantum dot (InP-QD) material was prepared and physically immobilized on TiO 2 particles functionalized with an archetypical reduction catalyst, (4,4-Y 2bpy)Re I (CO) 3 Cl (ReP, Y = CH 2 PO(OH) 2 ), to form a new type of InP quantum dot-sensitized hybrid photocatalyst (InP-QD/TiO 2 / ReP) and evaluated as a lower-energy photosensitizer in this hybrid system. It was found that the TiO 2 heterogenization of the InP-QD material promotes the photoexcited electron transfer process from the photoexcited InP-QD* to the inorganic TiO 2 solid with rapid electron injection (by ∼25 ps) through oxidative quenching, resulting in efficient charge separation at the InP-QD/TiO 2 interface. With such an effective photosensitization, the stabilization of the structurally vulnerable InP-cored QDs by TiO 2 heterogenization resulted in highly efficient and durable photochemical CO 2 -to-CO conversion of the InP-QD/TiO 2 /ReP hybrid in a 10 times-repeated photolysis, giving a turnover number of ∼51,000 over a 420 h period without any damage to the InP-QD photosensitizer. The stability of TiO 2 -bound InP-QDs was confirmed by the comparative analysis of their photophysical and chemical structures before and after long-term photoreaction. This catalytic performance is the highest reported for QD-sensitized photocatalytic CO 2 conversion systems using sacrificial organic electron donors. This study provides useful design guidelines for photocatalysts using QD materials as photosensitizing components.

While the incorporation of pendant Brønsted acid/base sites in the secondary coordination sphere is a promising and effective strategy to increase the catalytic performance and product selectivity in organometallic catalysis for CO 2 reduction, the control of product selectivity still faces a great challenge. Herein, we report two new trans(Cl)-[Ru(6-X-bpy)(CO) 2 Cl 2 ] complexes functionalized with a saturated ethylene-linked functional group (bpy = 2,2′-bipyridine; X = −(CH 2 ) 2 −OH or −(CH 2 ) 2 −N(CH 3 ) 2 ) at the ortho(6)-position of bpy ligand, which are named Ru-bpy OH and Ru-bpy diMeN , respectively. In the series of photolysis experiments, compared to nontethered case, the asymmetric attachment of tethering ligand to the bpy ligand led to less efficient but more selective formate production with inactivation of CO 2 -to-CO conversion route during photoreaction. From a series of in situ FTIR analyses, it was found that the Ru−formate intermediates are stabilized by a highly probable hydrogen bonding between pendent proton donors (−diMeN + H or −OH) and the oxygen atom of metal-bound formate (Ru I −OCHO•••H−E−(CH 2 ) 2 −, E = O or diMeN + ). Under such conformation, the liberation of formate from the stabilized Ru I −formate becomes less efficient compared to the nontethered case, consequently lowering the CO 2 -to-formate conversion activities during photoreaction. At the same time, such stabilization of Ru−formate species prevents the dehydration reaction route (η 1 -OCHO → η 1 -COOH on Ru metal) which leads toward the generation of Ru−CO species (key intermediate for CO production), eventually leading to the reduction of CO 2to-CO conversion activity.