Design And Application Of Flourescent Precious Metal Nanocluster-based Composites

Metal nanoclusters(MNCs),as an emerging class of functional nanomaterials,have received extensive attention from researchers in recent years.MNCs are ultra-small in size(<3 nm)and their size close to the electronic Fermi wavelength,so MNCs have discrete electronic states and exhibit molecular-like properties,such as tunable light absorption,photoluminescence,highest occupied molecular orbital(HOMO)-lowest unoccupied molecular orbital(LUMO)transition,molecular chirality,etc.(LUMO)transition,molecular chirality,etc.Currently,fluorescence properties are one of the hot topics in the field of MNCs,especially aggregation-induced luminescence(AIE)properties.MNCs with AIE properties show promising applications in photocatalysis and light-emitting devices due to their strong luminescence,high quantum yields,long fluorescence lifetimes,and large Stokes shifts.Bacterial infections have made a serious threat to public health and the environment;therefore,it is urgently needed to develop a rapid and safe antimicrobial strategy.Recent studies have shown that photocatalysis is an ideal antibacterial technique.highly luminescent MNCs have high quantum yields and carrier generation capabilities,making them ideal for photocatalytic antibacterial materials.However,the easy recombination of the photogenerated carrier(i.e.,electron and hole)MNCs results in poor light-driven antimicrobial activity.Additionally,the low visible light utilization greatly limits the application of MNCs in light-driven antimicrobial applications.Therefore,developing a fluorescent MNCs-based composite material with improved visible light absorption and photogenerated carrier separation is expected to effectively solve the above problems.In the field of light-emitting devices,low color rendering index(CRI)and chromaticity parameter drift are factors that limit the wide application of white light-emitting diodes(WLEDs).Due to the strong luminescence,large Stokes shift,and photostability,MNCs show great advantages in developing high-performance WLEDs with high luminous efficiency(LE)and low chromaticity parameters drift.In summary,this paper will focus on the study of fluorescent MNCs-based composites for photocatalytic antibacterial and LED applications.Presented below are the details of this paper:1)To solve the problem of easy recombination of photogenerated charge carriers of Au nanoclusters(AuNCs),we report the design of a long-lasting yet visible-light-driven antibacterial agent based on marrying luminescent Au nanoclusters(AuNCs for short)to TiO₂(TiO₂-NH₂@AuNCs).The designed photocatalyst not only effectively overcomes the problem of easy recombination of photogenerated carriers of AuNCs,but also solves the problem of easy consumption of AuNCs by bacteria,realizing efficient,durable and visible-light-driven antibacterial application.Consequently,the TiO₂-NH₂@AuNCs antibacterial agents display excellent antibacterial activity with good durability against both gram-positive and gram-negative bacteria under visible-light irradiation(??400 nm).This study is interesting because it provides a paradigm for the design of a long-lasting yet visible-light-driven MNC-based antibacterial agent for diversified bactericidal applications.2)In order to further improve the photocatalytic antibacterial activity,we report the design of a visible-light-driven photodynamic antibacterial agent based on conjugating aggregation-induced emission(AIE)-featured AuAgNCs with highly luminescent carbon dots(CDs).The conjugation of CDs with AuAgNCs could not only enhance the visible-light harvest,but also promote charge carrier generation/separation via charge/energy transfer,leading to the photodynamic production of abundant reactive oxygen species(ROS)for bacterial killing under visible-light irradiation.This study is interesting not only because it provides a broad-spectrum yet long-lasting metal NCs-based photodynamic antibacterial agents,but also because it may shed light on the design of other high-performance metal NCs-based photocatalysts for diversified applications.3)To address the challenges of low CRI and chromaticity parameters drift of WLED, we synthesized CDs-AuAgNCs composites by integrating orange-emitting AuAgNCs with green-emitting CDs through a simple amidation reaction.The cleverly ingenious combination of luminescent properties of CDs and AuAgNCs enable CDs-AuAgNCs composite to emit highly stable fluorescence(solid state). Meanwhile,the LE(88.1 lm/W),CRI(82.4)and T_cindex(5604 K)of CDs-AuAgNCs composite meet the requirements of standard WLED.This study not only demonstrates the application of MNCs in WLE D,but also provides a feasible method for the design of high-performance WLED.