One-pot Wet-chmical Route For Controllable Synthesis Of Gold Based Nanocomposites And Their Electrocatalysis Research

Noble metal nanomaterials,such as Au,Ag,Pt,and Pd,as one of the most important functional materials,have received increasing research interest because of their wide applications in catalysis,sensing,energy storage,biomedical diagnosis and therapy,etc.Interestingly,the properties of a noble metal nanocrystal are determined by a set of parameters,such as composition,size,shape,surface morphology,and structure.By tuning these parameters,the properties of noble metallic materials,in principle,can be tailored to enhance their performance in a specific application.In recent years,scientists from all over the world are devoted to studying shape controlling of noble metallic nanocrystals with excellent properties and have made some headway.In this paper,we proposed four Au-based bimetallic nanomaterials through simple and fast one-pot wet-chemical strategies and profoundly characterized their morphology,composition and structural features.Meanwhile,we further explored their growth mechanism and enhanced electro-catalytic activity and stability.Specific contents are as follows:(1)Facile synthesis of dendritic platinum-gold core-shell alloy nanocrystals with improved electrocatalytic performance for methanol oxidationWell-defined uniform dendritic Pt-Au core-shell alloy nanocrystals(Pt-Au CSANCs)were synthesized on large-scale via a simple and one-pot oligonucleotide-assisted successive coreduction route.The atomic ratios of Pt to Au in the core and shell of Pt-Au CSANCs are 4:1 and 2:3,respectively.Control experiments demonstrate that the dosage of polyinosinic acid and the successive coreduction route are essential to the formation of dendritic Pt-Au CSANCs.The as-synthesized Pt-Au CSANCs show enhanced electrocatalytic activity and improved stability for methanol oxidation in alkaline media by comparison with PtAu nanocrystals(PtAu NCs)and commercial Pt black catalyst.(2)Simple synthesis of bimetallic AuPd dendritic alloyed nanocrystals with enhanced electrocatalytic performance for hydrazine oxidation reactionA simple one-pot successive co-reduction method was developed for synthesis of bimetallic AuPd dendritic alloyed nanocrystals(AuPd DANCs),in which 3-aminopyrazine-2-carboxylic acid acted as a capping agent.The electrocatalytic activity and stability of AuPd DANCs toward hydrazine oxidation reaction(HOR)were evaluated by cyclic voltammetry and chronoamperometry.AuPd DANCs showed the enhanced catalytic performance as compared with AuPd nanocrystals,Pd nanocrystals and commercial Pd black catalysts.Additionally,the catalytic mechanism and kinetics of HOR were further explored by linear sweep voltammetry,showing the potential applications of AuPd DANCs in fuel cells.(3)One-pot synthesis of bimetallic AuPd nanoclusters supported on graphitic carbon nitride with enhanced electrocatalytic propertiesWe developed a facile one-pot aqueous method to fabricate well-distributed bimetallic AuPd nanoclusters supported on graphitic carbon nitride(AuPd NCs/g-C3N4).The method is simple,rapid,without using any specific additives.The nanocomposites displayed enlarged electrochemically active surface area.The obtained nanocatalyst displayed the more positive onset and half-wave potentials at 1.09 and 0.98 V(vs.NHE)for oxygen reduction reaction,respectively,along with the enhanced kinetic current density of 1.86 mA cm-2.Meanwhile,the catalyst showed the improved catalytic activity for hydrogen evolution reaction with the onset potential of-29 mV(vs.NHE)and small Tafel slope of 47 mV dec-1.These results demonstrated the improved electrocatalytic performance of the catalyst in contrast with commercial Pt/C(50%)and Pd/C(20%)catalysts,indicating its wide application aspects.(4)One-pot ionic liquid-assisted synthesis of bimetallic AuPt alloy nanodendrites assembled on reduced graphene oxide with enhanced electrocatalytic propertiesReduced graphene oxide supported well-dispersed bimetallic AuPt alloy nanodendrites(AuPt ANDs/rG1)were fabricated by a facile one-pot coreduction approach,using Ionic liquid(1-aminopropyl-3-methylimidazolium bromide,[APMIm]Br)as the stabilizer and capping agent.The as-synthesized nanocomposites displayed excellent electrocatalytic activity and durability towards hydrogen evolution reaction and methanol oxidation reaction in contrast with monometallic Pt nanocrystals/rGO and commercial Pt/C(50%),which make it promising candidate for practical catalyst in energy science.