Controllable Synthesis And Electrochemical Antibacterial Application Of Metal Nanocluster Composites

The problem of shortage of safe drinking water is currently affecting over 650million people worldwide.This is an urgent issue that needs to be addressed for the health and sustainable development of society.Water-borne infectious diseases such as cholera,dysentery,and typhoid are caused by the presence of microorganisms such as bacteria,viruses,and fungi in natural water bodies.Therefore,it is essential to ensure that drinking water is sterilized to eliminate these harmful pathogens.However,existing traditional sterilization methods are not without their drawbacks.In light of these issues,it is imperative that new water sterilization technologies be developed urgently to ensure the safety of drinking water while promoting sustainable development.The new sterilization methods should be efficient,eco-friendly,energy-efficient,and cost-effective.The current ROS-based water sterilization technologies,such as photocatalysis and electrocatalysis,have attracted widespread attention due to their safety,environmental friendliness,and lack of toxic by-products.ROS,a class of substances containing oxygen atoms and free radicals,has a strong oxidation capacity and can be quickly decomposed into oxygen and water after sterilization.This characteristic makes ROS an efficient,broad-spectrum,and green sterilization agent.However,the challenge remains in achieving contact between high concentrations of ROS and bacteria in existing ROS-based water sterilization technologies.Capacitive deionization technology（CDID）is a newly emerging water sterilization technology in recent years.Similar to capacitive deionization technology（CDI）,a small voltage（usually lower than 2 V）is applied to two parallel electrode plates to force charged bacteria and other microorganisms in the water to move to the electrode surface.When the number of bacteria adsorbed on the electrode surface reaches saturation,the regeneration of the sterilization system can be realized by simply short-circuiting and cleaning the circuit.Electrode sterilization material kills bacteria by physically damaging their cell membranes when the material comes into contact with bacteria.Combining CDID with ROS may become a new way to achieve high efficiency,low energy consumption,and green water antibacterial activity,taking advantage of ROS with high-efficiency and broad-spectrum antibacterial activity,and CDID with high-efficiency bacterial adsorption and enrichment.However,the realization of this technology requires new requirements for its electrode materials.Good catalytic activity is needed for ROS generation,high specific surface area is necessary to ensure the availability of sufficient bacterial adsorption sites,and uniform distribution of electrode surface is essential for stable ROS output.Therefore,the achievement of the above requirements poses a new material science challenge.It is not difficult to find that if ROS and CDID can be combined,the advantages of ROS with high efficiency and broad-spectrum antibacterial and the advantages of CDID with high-efficiency bacterial adsorption and enrichment,it may become a new way to achieve high efficiency,low energy consumption and green water antibacterial.However,the above assumptions put forward new requirements for its electrode materials:1)good catalytic activity（ROS generation）;2)High specific surface area（to ensure sufficient bacterial adsorption sites）;3)Uniform distribution of electrode surface（ROS stable output）.Therefore,how to achieve the above requirements has become a new material science challenge.Metal nanoclusters（MNCs,core size<2 nm）are widely considered to be an important component of the next generation of nanomaterials,which are Bridges between atoms and nanoparticles.They are composed of a few or several hundred atoms,and they have many interesting properties such as atomic precision structure,ultra-high surface-to-volume ratio,ultra-small size,adjustable surface chemistry,And molecular properties（such as strong luminescence,and chirality）,in the field of catalysis and luminescence has shown a high value of the application.It is worth mentioning that MNCs not only have HOMO-LUMO transition to ensure good catalytic activity but also have an ultra-small size,which makes it easy to compound and disperse with porous carriers,to ensure good adsorption and uniform dispersion of bacteria.To sum up,aiming at the deficiencies of ROS and CDID water sterilization technologies,this paper tries to combine their technical advantages,selects Au NCs,Ag NCs,and Cu NCs as core materials,and further uses metal-organic framework（MOF）to limit and protect them.The advantages of the high catalytic activity of MNCs and the structural stability of MOF are respectively utilized to realize efficient,continuous,green,low energy consumption and broad-spectrum water sterilization.The specific contents are as follows:1)Using Au NCs with high electrocatalytic activity as electrode material,a novel capacitance-charging induction electrochemical sterilization strategy（CEWD）was designed.Based on the principle that all bacteria carry negative charges on their surfaces,and with the advantage of the architecture of the CEWD system,the electrode material can effectively enrich bacteria from the water body through electrostatic interaction to produce a"bacterial-rich area",thus avoiding the defect of low sterilization efficiency caused by the blind diffusion of ROS in the water body.Au NCs are a functional nanomaterial with excellent electrocatalytic performance.By catalyzing the water oxidation reaction on the anode surface,two kinds of ROS（H₂O₂and·OH）are generated,thus forming a locally high concentration"ROS diffusion zone"on the electrode material surface,which greatly improves the bactericidal efficiency of traditional CDID.In order to facilitate the in-situ electrocatalysis of reactive oxygen species（ROS）generation,we wrapped Au NCs with ZIF-67 to meet the conductivity and stability requirements of CEWD electrode materials.This approach improved both the stability of Au NCs and their electroadsorption area.2)The sterilization rate of the CEWD electrochemical sterilization system based on Au NCs constructed in Topic 1 is heavily dependent on the ROS concentration level catalyzed by Au NCs.Once the concentration level generated by ROS is lower than the concentration threshold,the sterilization rate will be significantly reduced.We synthesized Ag₂₈（GSH）₂₀NCs（Ag NCs）with high atomic precision to solve the problem of sterilization.We also designed and constructed a CEWD sterilization system based on Ag NCs@ZIF-67.The system produced a locally high concentration of"ROS-layer"through the water oxidation reaction catalyzed by Ag NCs on the anode surface.Furthermore,the high specific surface area of ZIF-67 and the external electric field were used to induce bacteria in water to migrate and adsorb on the anode surface.Ag NCs can produce ROS through in-situ electrocatalysis and have their own genetic antibacterial activity,which enhances the sterilization process.By inducing contact sterilization through the antibacterial electrode in addition to maintaining the ROS production concentration level,the sterilization efficiency was greatly improved.3)In order to achieve the goal of further reducing cost while maintaining ultra-high sterilization rates,we designed and constructed the CEWD sterilization system based on Cu NCs@ZIF-67.The previous project greatly improved sterilization efficiency,thus solving the problem of low sterilization rates caused by relying only on single ROS in project 1.However,the first two projects utilized noble metal nanoclusters as electrode materials,which increased its overall cost and limited practical application prospects.The CEWD sterilization system is capable of efficient bacteria inactivation as well as reducing costs and improving practical application value.