Cadmium Sulfide-Based Semiconductor Materials For Photocatalytic Regeneration Of Coenzyme NADH

In order to meet the challenges of global energy and environmental security in the future,the demand for enzymatic transformations with both economic and environmental benefits is ever-growing.Enzymatic reactions complete catalytic biotransformation with superior catalytic efficiency and remarkable substrate specificity.In the field of environmental engineering,enzymatic transformation also has broad application prospects in the degradation of Volatile Organic Compounds(VOCs),Advanced Oxidation Processes(AOPs),and the development of biodegradable materials.More than a quarter of all enzymes are oxidoreductases that cooperate with coenzymes,and the commonly used coenzyme is nicotinamide adenine dinucleotide(NADH).Enzyme catalysis relies on coenzymes to supply electrons,protons and energy,and the reaction require the consumption of chemical equivalents of coenzymes.But the high cost of NADH limits the large-scale development of the enzyme industry.Therefore,it is necessary to establish an efficient and economical NADH regeneration system and expand its recycling capacity,which is crucial to meet the commercial production of enzyme catalysis.Photocatalytic NADH regeneration utilizing clean and renewable solar energy is considered to be an environmentally friendly and sustainable method.In this paper,CdS semiconductor is used as the substrate material,and it is modified and optimized through noble metal loading,construction of binary heterojunctions,and ternary hybrid photocatalysts to improve the NADH regeneration performance and further achieve the absence of electron mediators in the system.This provides a new strategy for the photo-mediated NADH regeneration and the subsequent application of photo-enzyme synergistic catalysis.The specific research work is summarized as follows:(1)Through simple hydrothermal and photo-deposition methods,Pt/CdS composite materials were prepared by uniformly loading Pt nanoparticles onto CdS nanorods(CdS NRs)and were used for photocatalytic NADH regeneration.After reaction for 40 minutes,the modified Pt/CdS stably maintained an 81%NADH regeneration yield.Pt as an electron acceptor can quickly and effectively extract photo-generated electrons from CdS NRs.The Schottky junction formed at the interface between Pt and CdS NRs further promoted the separation of photo-generated carriers.In addition,Pt/CdS reduced the generation of ·O2-in the NADH regeneration system,slowing down its oxidation of regenerated NADH.This study proved that Pt loading can effectively improve the photocatalytic NADH regeneration performance of CdS NRs.(2)Based on electrostatic interaction,CdS/ZIS binary heterostructures were obtained by anchoring CdS nanoparticles(CdS NPs)onto Znln2S4(ZIS)nanosheets and used for photocatalytic NADH regeneration.CdS/ZIS exhibited highly efficient and stable photocatalytic activity,achieving a 97%NADH regeneration yield after reaction for 1 hour.Thanks to the formation of type Ⅱ heterojunctions,CdS/ZIS can achieve efficient charge separation and transfer,thereby enhancing photocatalytic activity.This study provides a new idea for the design of effective heterojunction photocatalysts for photocatalytic NADH regeneration.(3)The Rh/Rh2S3 structure was simultaneously loaded onto CdS NRs by the one-step photo-deposition method to synthesize the Rh/Rh2S3-CdS ternary hybird photocatalyst.And the composite photocatalyst was applied to the photocatalytic NADH regeneration system without adding electron mediators.Rh/Rh2S3-CdS materials achieved a maximum NADH regeneration yield of 67%after illumination for 30 minutes,and can still maintain a 52%regeneration yield after 1 hour.This study proved that the synergy of Rh/Rh2S3 structure enhanced the photogenerated carrier transfer in ternary heterojunctions.The photogenerated electrons in Rh2S3 can be transferred to CdS,making more electrons available for NADH regeneration,and Rh2S3 promoted the separation of photogenerated holes from CdS.At the same time,the introduction of Rh can make electrons quickly transfer through Schottky junctions and combine with NAD+to regenerate NADH,improving regeneration efficiency and selectivity.