Layer-by-layer Self-assembly Method To Prepare Pt-based Catalyst And Its Catalytic Performance

Platinum-based nanocatalysts have been widely used in all kinds of industrial fields such as proton exchange membrane fuel cell(PEMFC),dye degradation and so on.Researches suggest that platinum shows catalytic performance in the process of methanol oxidation reaction(MOR),fonnic oxidation reaction(FAOR),leading platinum to be an important component of direct methanol fuel cells(DMFC)and direct formic oxidation fuel cells(DFAFC).Besides,platinum also shows excellent performance in the process of catalytic hydrogenation of dyes.However,the low reservoir abundance and high price of platinum as a nobel metal have been restricting the progress of commercialization.Therefore,researchers at this stage focus on the measure to enhance the performance while reducing the usage of platinum,thus improving atomic utilization.By the way of regulating chemical composition,adjusting morphology and doping with cheaper alternative metals,platinum-based nanocatalysts can maintain its performance while reducing the overall cost.In this thesis,with the help of layer-by-layer self-assembly and hard-template method,we novelly designed and manufactured the following three kinds of platinum-based nanocatalysts,which shows outstanding performance as the catalysts for MOR,FAOR and catalytic hydrogenation of dyes.1.PtFe intermetallic nanotubes:controlled synthesis,crystal structure,and improved electrocatalytic activities.In this work,we synthesized PtFe intermetallic nanotubes through layer-by-layer self?assembly approach,which firstly uses charged polyelectrolyte modified FeOOH nanorods as sacrificial template and PtCl42-to be absorbed and reduced,then requires the high-temperature heat treatment and removal of the sacrificial template.PtFe intermetallic nanotubes have atomically ordered intermetallic structure,while maintaining their tube-like morphology,leading to its promising electrocatalytic oxidation mass activity(533.67 A g-1)and specific activity(61.64 A m-2)for the methanol oxidation reaction.2.Trimetallic PtPdFe alloy nanotubes:controlled synthesis,crystal structure,and improved electrocatalytic activities.This work is to extend the preparation method of the PtFe intermetallic nanotubes.In this work,we synthesized trimetallic PtPdFe alloy nanotubes through layer-by-layer self-assembly approach,with PtCl42-and PdCl42-to be absorbed and reduced simultaneously,and other details of synthesis processes similar to the PtFe intermetallic nanotubes.Trimetallic PtPdFe alloy nanotubes show their electro-oxidation performance for the formic acid oxidation reaction(FAOR)in the dehydrogenation pathway,with its mass activity(77.98 A g-1)and specific activity(4.58 A m-2).3.Carbon hollow nanospheres with Pt nanoparticles embedded:controlled synthesis,and improved activities for catalytic hydrogenation of dyes.In this work,we synthesized carbon hollow nanospheres with Pt nanoparticles embedded,which initially uses charged polyelectrolyte modified SiO2 nanospheres as sacrificial template and PtCl42-to be absorbed and reduced,then requires the uniform dispersion and tight combination between SiO2/Pt nanocomposites and agar,with the high-temperature carbonization and removal of the sacrificial template as final step.Carbon hollow nauaospheres with Pt nanoparticles embedded has excellent catalytic performance for the hydrogenation reaction of rhodamine B,whose reaction rate constant(k)at room temperature is 17 times as higher as the one of commerce Pt/C catalysts,while activation energy(Ea)is 20.62%of the one of commerce Pt/C catalysts,proving its excellent activities for catalytic hydrogenation of dyes.