CdS QDs@SiO2 immobilized Rh for photo-metal synergistic catalysis of NADH recyclable regeneration.

Using visible light to drive NADH regeneration is an economically viable and environmentally sustainable technique. However, it necessitates a metal hydride (MH, [CpRh(bpy)(H₂O)]²⁺) as a synergist, and the high cost of the Rh noble metal significantly impedes the development and application of in-situ NADH regeneration. Therefore, in this study, single-atom Rh was immobilized onto the CdS QDs@SiO₂ combination via a consecutive ball-milling technique in combination with ionic layer adsorption and substitution. Subsequently, an enhanced photo-metal synergistic catalysis system for the recyclable regeneration of NADH was developed. In this composite, the single-atom Rh serves two main functions: It acts as an electrical medium and a metal catalyst, which regulates the activity and selectivity of the regenerated NADH. This study has successfully addressed the key scientific issues regarding the low electron transport rate and the recycling of the Rh noble metal during catalysis. Results confirm that single-atom Rh is successfully immobilized onto the CdS QDs@SiO₂ combination (Rh-CdS@SiO₂) and exhibits a faster electron transport and enhanced selectivity. Under blue light (LED, 420 nm) irradiation, the Rh-CdS@SiO₂ photo-metal catalyst shows a 25-fold increase in recyclable operability and achieves a 68% regeneration yield of NADH in just 4 min. Moreover, (S)-(+)-4-phenyl-2-butanol can be obtained with the regenerated NADH as the coenzyme of P450 enzyme catalysis.