The Preparation Of Ag-M Nanocatalyst-based Systems And Application In Electrocatalysis For Benzyl Chloride

Organic chlorinated pollutants, as a kind of important and hardly decomposedcompounds, are widely applied, but they are very harmful to the organism andenvironments. Most of chlorinated organics are synthetic products with stable chemicalproperties and toxicity owing to the existence of chlorine atoms in the molecules, sothey often degrade slowly and cause long-term harm to nature. Thus, the research onquick and efficient dechlorination becomes important and urgent from both theoreticaland industrial points of view. As a new and very promising class of catalytic materials,the nanocatalysts fabricated from Ag-based nanoparticles （NPs） show their potentialapplication prospects in many increasing fields, especially in electrochemicalreduction of dechlorination. However, one of the most significant barriers for thewidespread application of electroreduction of dechlorination is the high cost, limitedresources and easy aggregation of nano-sized particles. To reduce the cost and furtherimprove their electrocatalytic dechlorination performances of noble metal Ag-Mnanocatalysts, this paper focuses on developing new type electrocatalysts based onAg-M nanohybrids and improving catalytic activity of catalysts as cathode materials.And taking the reduced graphene oxide and carbon nanotubes as support, noble metalNPs with high dispersion and small particle size have been supported on the selectednanohybrid surfaces. Additionally, the electrocatalytic properties of the as-preparednoble metal Ag-M nanohybrids towards the electroreduction of benzyl chloride havebeen researched in detail. The main points of this thesis are as follows:（1） Taking the polyglycol octylphenyl ether （Triton X-100） as both reducing agent andprotective agent, bimetallic Ag-Pd NPs with various molar ratios weresuccessfully prepared by co-reduction. The as-prepared Ag-Pd NPs werecharacterized by Ultraviolet-Visible absorption spectroscopy（UV-vis）, powderX-ray diffraction（XRD）, energy dispersive X-ray spectroscopy （EDS）,transmission electronic microscopy（TEM） and selected-area electrondiffraction（SAED）. Their electrocatalytic reduction activities toward benzylchloride were investigated by electrochemical technology. The results show thatthe bimetallic Ag-Pd NPs not only possess alloying structures, but also presentmuch higher electrocatalytic activity and better long-term performance than AgNPs, which was perhaps closely related to synergistic effect between Ag and Pd of bimetal catalysts during the catalytic reduction of benzyl chloride.（2） Using reduced graphene oxide-multi walled carbon nanotubes with differentweight ratios （RGO-MWCNTs（w/w）） as composite supporting materials,nanostructured AgPd particles were dispersed successfully on reduced grapheneoxide-multi walled carbon nanotubes hybrids surface by chemical co-reductionmethod The element composition and morphology of the as-preparednanocomposites were characterized by UV-vis and EDS, SEM and TEM. Theirelectrocatalytic performance as cathode materials for electrochemical reduction ofbenzyl chloride was investigated by cyclic voltammetry and chronoamperometrictechnique in CH3CN solution. The results reveal that AgPd nanoparticles with anaverage diameter of5nm are well-dispersed on the RGO-MWCNTs hybridmaterials, which is helpful for metal nanoparticles to distribute uniformly on thesurface of RGO-MWCNTs. Furthermore, these AgPd/RGO-MWCNTs（w/w）hybrid catalysts have higher catalytic activity and better long-term stability thaneither AgPd/RGO or AgPd/MWCNTs catalyst.（3） Based on self-regulated reduction by sodium dodecyl sulfate （SDS） and takingreduced graphene oxide-multi walled carbon nanotubes （RGO-MWCNTs（7:3,w/w））as supporting material, bimetal Ag-Pt with various molar ratios and trimetalPd-Ag-Pt（1:10:1,n/n/n） were successfully prepared without additional reductionagent and dispersed on RGO-MWCNTs hybrids. The as-prepared nanohybridswere characterized by UV-vis, SEM and EDS. Their electrocatalytic reductionactivities toward benzyl chloride were investigated by cyclic voltammetry andchronoamperometric technique. The results show that the bimetallicAg-Pt/RGO-MWCNTs nanocomposites with various molar ratios of Ag to Pt,present greatly excellent electrocatalytic activities for benzyl chloride reduction.Especially, comparing with Ag/RGO-MWCNTs, Ag₁₀Pd₁/RGO-MWCNTs andAg₁₀Pt₁/RGO-MWCNTs nanohybrids, trimeal Pd₁Ag₁₀Pt₁/RGO-MWCNTs alloynanosponges with network nanowires possess much higher electrocatalytic activityand better long-term performance toward the electroreduction of benzyl chloride.