Synthesis Of Hollow Submicrospheres Of Cu₂O And Ni By Soft Template And Application Performance

Hollow nanostructures are widely used due to their excellent properties such as low density,high specific surface area,high porosity,and high permeability.At present,the template method has become the main method to prepare hollow nanomaterials.The hard template method in the preparation of hollow nanomaterials has disadvantages such as complicated procedures and high energy consumption etc.The soft template method often needs to react for a long time under hydrothermal and solvothermal conditions with high temperature.Therefore,the preparation of hollow nanomaterials by a green,low-energy and simple method is of great significance.According to the literature and the previous research of our group,when the polymer polyvinylpyrrolidone(PVP)and the anionic surfactant sodium dodecyl sulfate(SDS)reach a certain concentration value in the aqueous solution,the SDS clusters on the PVP chain in the form of bound micelles through counter-ion bridging to form an association of pseudo-polyanionic structure,and the microstructure model of necklace-like ordered aggregates is established.It is inferred that it has the possibility of forming hollow structure induced by secondary template according to the hierarchical and ordered structure of pseudo-polyanion aggregates and the substitutability of bridging ions.Our group previously prepared Cu₂O hollow submicrospheres in the SDS-PVP pseudo-polyanion system,which initially verified this conjecture,and the reaction conditions in line with the concept of green chemistry are mild and environmentally friendly.However,there are few studies on the synthesis of hollow structures under this template system,and the controllability is not yet clear.Therefore,this paper will further explore the formation of Cu₂O hollow submicrospheres to clarify its mechanism and perfect application based on our previous results.Since nickel also shows a microsphere structure in the template system,it is speculated and verified that the template has the possibility of inducing nickel to form hollow submicrospheres.Furthermore,it is inferred that the possibility of the pseudo-polyanion template inducing other metals to form a hollow structure is to achieve a balance among the crystal growth law,template orientation and reduction conditions.The main research contents and results of this paper are as follows:(1)Hollow Cu₂O submicrospheres with an average particle size of 400 nm were prepared at 40?,using SDS-PVP pseudo-polyanion as the soft template and hydrazine hydrate as the reducing agent.This method is simple,gentle,green and low energy consumption,effectively improving the shortage of hard templates.Because of the secondary structure of SDS-PVP pseudopolyanion,obviously it can play a more regulatory role than a single soft template.It's found that the formation of Cu₂O hollow submicrospheres is the result of Ostwald ripening assisted by the SDS-PVP pseudo-polyanion soft template with multi-level regulation.(2)The hollow Cu₂O submicrospheres are used as photocatalysts to degrade the toxic dye methyl orange in sewage.The results showed that the degradation rate of methyl orange(10mg·L^-1)by hollow Cu₂O submicrospheres catalyst could reach 92%when the reaction time was1 h,and the degradation rate was as high as 96.4%after 5 h.In addition,hollow Cu₂O submicrospheres exhibited excellent reusability,because the degradation rate is still more than90%after being reused five times.On the other hand,the release of Cu²⁺in the coating sample plate in artificial seawater within 45 days was explored,when hollow Cu₂O submicrospheres are used in marine antifouling coatings.The results demonstrated that the exudation rate of copper ions became stable after 21 days.When the content of the antifouling agent was greater than 10%,the steady exudation rate of the sample can reach the minimum exudation rate(10mg·cm^-2·d^-1)of the antifouling agent.As an antifouling agent,the exudation rate of Cu²⁺of Cu₂O hollow submicrospheres is much higher than industrial-grade Cu₂O purchased from the market.In addition,in the sterilization experiments of Escherichia coli and Staphylococcus aureus,the Cu₂O hollow submicrospheres showed better sterilization performance than industrial-grade Cu₂O,and a low addition amount could achieve a high sterilization rate.(3)Mesoporous hollow nickel submicrospheres with a particle size distribution of300?700 nm showing a pine needle-like superimposed morphology were prepared using SDS-PVP pseudopolyanion as a soft template at 65?.Studies have shown that this template can indeed induce nickel to form a hollow structure and has the same growth mechanism as Cu₂O hollow submicrospheres.The selective hydrogenation reaction of phenol was catalyzed by the hollow nickel submicrospheres at 150?for 4 h.The phenol conversion and cyclohexanol selectivity selectivity were up to 100%and 90%,respectively.In addition,the catalytic performance of the hollow nickel submicrospheres nearly did not decrease and the surface of the catalyst was not oxidized after the catalyst was recycled 20 times and exposed in the air,showing excellent catalytic activity and cycle stability and possessing the potential as a good candidate catalyst for packed bed or fluidized bed for the selective hydrogenation of phenol.