Study On The Preparation Of Noble Metal Nanostructures By Cyano-rubber Reduction And Its Electrocatalytic Performance

Cyanogel reduction method is a facial way to synthsize metal nanostructures.Because of the unique three-dimensional network structure,different electrode potential of precursor metal ions,and bimetallic characteristics of cyanogel,monometallic,bimetalic and trimetalic nanostructures with well-defined morphologies can be obtained by using suitable reducing agents and cyanogel precursors.In this thesis,the ultrathin Rh nanosheet nanoassemblies(Rh NNs),cyanide(CN-)functionalized hollow PtNi alloy nanospheres(PtNi@CN ANNSs),and trimetallic PtRhNi alloy nanoassemblies(PtRhNi-ANAs)with tunable Pt/Rh ratio were synthsized by cyanogel reduction method.Meanwhile,the nitrogen electroreduction at Rh NNs,oxygen electroreduction at PtNi@CN ANNSs,and ethanol electrooxidation at PtRhNi-ANAs were also studied systematically.The main results are as follows:1.Surfactant-free atomically ultrathin Rh nanosheets for the nitrogen reduction reaction.The surfactant-free atomically ultrathin Rh nanosheets nanoassemblies(Rh NNs)are synthesized and used for the first time as an effective electrocatalyst in the nitrogen reduction reaction(NRR)at ambient temperature and pressure.The inorganic polymer RhCl3-K3Co(CN)6 cyanogel plays an important role for the generation of ultrathin Rh nanosheets with clean surface.Due to the unique ultrathin two-dimensional nanosheet structure(ca.1 nm)with a high specific surface area and modified electronic structure,the surfactant-free Rh NNs demonstrate an excellent catalytic activity for the NRR with a high production yield(NH3:23.88 ?g h-1 mg-1 cat.)and the favorable selectivity(no N2H4 generation)at low potential(-0.2 V vs RHE),outperforming most of current electrocatalysts reported for the NRR.2.Hollow PtNi alloy nanospheres for the oxygen reduction reaction.In this work,we present an efficient and template-free route for facile synthesis of cyanide(CN-)functionalized hollow PtNi alloy nanospheres(PtNi@CN ANNSs)by using a mild cyanogel-reduction method.The physical and electrocatalytic properties of PtNi@CN ANNSs were investigated by various physical and electrochemical techniques.The PtNi@CN ANNSs exhibit significantly enhanced electrocatalytic activity,durability,and particular methanol tolerance for the oxygen reduction reaction(ORR)compared to the commercial Pt black due to the cyanide(CN-)functionalization and the hollow alloy structure,which are promising cathode electrocatalysts for the direct methanol fuel cells.3.Trimetallic PtRhNi alloy nanoassemblies for ethanol oxidation reaction.The trimetallic PtRhNi alloy nanoassemblies(PtRhNi-ANAs)with tunable Pt/Rh ratio are successfully synthesized by a simple mixed-cyanogel/reduction method.The electrochemical properties of PtRhNi-ANAs are examined by cyclic voltammetry,which exhibit a composition-dependent electrocatalytic performance for the ethanol oxidation reaction(EOR).Compared with commercial Pt black electrocatalyst,the optimal Pt3RhINi2-ANAs display a remarkably enhanced electrocatalytic performance for the EOR in alkaline media.