Study On The Construction Of Copper Based Catalyst Supported By ZIF-8 And Its Catalytic Performance

Due to Cu's various oxidation states(Cu0,Cu?,Cu?,and Cu?),Cu-based materials can promote and react a plenty of reactions via one-and two-electron pathway,including catalytic organic transformations,electrocatalysis,and photocatalysis.In the field of catalysis,the scarcity and expensive cost of noble-metals(e.g.,Pt,Pd,Au)and their metal alloy greatly restrict their commercial applications,so earth-abundant and affordable copper materials attract much attention.Despite the strong background on the applications of Cu in wide range of fields(e.g.,optics,electronics,etc.),the use of Cu-based materials is limited by Cu's inherent instability that atmospheric conditions make it prone to oxidation.Many efforts to increase the stability of Cu-based materials by develop the methods and supporting materials to reduce their sensitivity to oxygen,water,and other chemical entities.Therefore,it is particularly important to develop a new type of carrier and alloy system to change the physical and chemical properties of copper.The catalytic activity of Cu-based catalyst is closely related to its particle size.So it is critical to prepare Cu-based catalyst with lower load,higher activity and more stable structure.In this paper,we designed,synthesized and screened nanocopper based catalysts with excellent catalytic performance by using ZIF-8's unique channel effect.The main contents of this paper are summarized as follows:1.Slected zeolitic imidazolate framework-8(ZIF-8)as catalyst supporter and NaBH4 as reducing agent to quickly and simply synthesized Cu/ZIF-8 by ultrasonic impregnation method.The prepared catalysts were characterized by X-ray Diffraction,transmission electron microscope,fourier infrared,X-ray photoelectron,et al.The p-nitrophenol catalytic reduction reaction was choosen as a model reaction to investigate the catalytic activity of Cu/ZIF-8 with different amount of metal loadings.Under the same conditions,the time consumption of Cu/ZIF-8 catalysts with 6%metal loading(6%Cu/ZIF-8)catalyzed reduction of p-nitrophenol was shortest and the rate constant k of 6%Cu/ZIF-8 is the largest(2.39 min-1),which showed the maximum catalytic activity among Cu/ZIF catalysts.In addition,the conversion rate of 6%Cu/ZIF-8 was significantly highest among other catalysts at room temperature,the catalytic activity of 6%Cu/ZIF-8 was almost unchanged after circular reaction,which provided a potential application prospects for large-scale industrial wastewater treatment.2.On the basis of the previous research work,Cu-Ag/ZIF-8 alloy catalysts were successfully synthesized through one-step reduction process by slecting ZIF-8 as catalyst supporter,fixing the amount of metal loadings to 6%and altering Cu/Ag ratio.The prepared catalysts were characterized by X-ray Diffraction,transmission electron microscope,fourier infrared,X-ray photoelectron,et al.The catalytic reduction reaction model of p-nitrophenol was still used to study the catalytic activity of the alloy catalysts with different ratios of copper and silver.Under the same conditions,the maximum activity of Cu Ag alloy catalysts was 4%Cu-2%Ag/ZIF,which coud catalyze the reduction of the same amount of p-nitrophenol within 60 s.Compared to Cu/ZIF-8,the catalytic efficiency of 4%Cu-2%Ag/ZIF doubled due to the synergistic effects.Based on Arrhenius equation,we invesgated the kinetic study of 4%Cu-2%Ag/ZIF to obtain the apparent activation energy as low as 28 kJ mol-1,much smaller than other catalysts.Besides,4%Cu-2%Ag/ZIF could remain active after long storage.This provides a good direction for the development of the alloy catalyst.3.ZIF-8 as catalyst supporter,novel three-element composite Cu-Ag/g-C3N4/ZIF catalyst was synthesized by one-step reduction method.The prepared catalysts were characterized by X-ray Diffraction,transmission electron microscope,fourier infrared,X-ray photoelectron,et al.The feasibility of Cu-Ag/g-C3N4/ZIF for detecting H2O2 and glucose was investigated by choosing tetramethylbenzidine(TMB)as substrate.It was found that the catalytic activity of Cu-Ag/g-C3N4/ZIF was more effective than g-C3N4 pure material and Cu-Ag/ZIF alloy catalyst.At the same time,the catalytic reaction mechanism of Cu-Ag/g-C3N4/ZIF was explored,the affinity of Cu-Ag/g-C3N4/ZIF for substrate was higher than other nanozymes.In addition,we investigated the effects of temperature,pH and substrate concentration on the activity of the catalyst.In optimum conditions,the linear range of detection of H2O2 and glucose was 0.05 mM-1 mM and 5 ?M-1000 ?M,respectively.From the results,we could see this method was simple,non-toxic and environmental protection.