Preparation And Performance Of Mesoporous And Branched Palladium Based Nanoelectrocatalysts

Electrocatalysis is crucial for the development of clean and renewable energy technologies,which may reduce our reliance on fossil fuels.Noble metal nanomaterials serve as state-of-the-art electrocatalysts as a result of their unique physicochemical properties,especially play an important role in the fields of fuel cells and electrochemical synthesis of ammonia.The performance of electrocatalysts can be improved by adjusting the size,morphology and composition of noble metal nanomaterials.The main research contents and results of this paper are as follows:?1?Tri-metallic Pd@PtPdNi core-shell mesoporous truncated octahedrons are prepared by a one-pot co-reduction strategy using hydrochloric acid,sodium tetrachloropalladate and nickel chloride as precursors,L-ascorbic acid as reducing agent,Pluronic F127 as surfactant and structure-directing agent.After etching with concentrated nitric acid at room temperature,PtPdNi truncated octahedral nanocage with mesoporous surface was obtained for electrocatalytic oxygen reduction.The rational combinations of polyhedral shape,mesoporous surface,and hollow structure provide sufficiently exposed active sites and efficient reactant permeability.With these unique properties,the mass activity of the mesoporous PtPdNi truncated octahedron nanocage(1.14 A mg_Pt^-1)is higher than those of the mesoporous Pd@PtPdNi truncated octahedron(0.38 A mg_Pt^-1)and Pt/C catalyst(0.17 A mg_Pt^-1).The synthesized mesoporous PtPdNi truncated octahedron nanocage has larger electrochemical activity area and better stability.?2?Hyperbranched PdRu nanospine assemblies used for formic acid oxidation were synthesized by a simple and rapid one-step co-reduction method using sodium tetrachloropalladate and ruthenium trichloride as precursors,L-ascorbic acid as reducing agent,Pluronic F127 as surfactant,KBr as structure-directing agent.The effects of reaction time,proportion of precursors,addition of hydrochloric acid and potassium bromide on the formation of PdRu nanospine assemblies were investigated.Because of its unique dendritic structure and bimetallic composition,the mass activity of the PdRu nanospine assemblies(1.10 A mg_Pd^-1)is 2.4 times and 3.3 times those of the Pd nanoparticles(0.46 A mg_Pd^-1)and PdB(0.33 A mg_Pd^-1),respectively.Moreover,the PdRu nanospine assemblies have better stability than palladium nanoparticles and commercial palladium black.?3?A simple and efficient method was proposed for the preparation of PdRu nanorod assemblies with F127 as surfactant,KBr as structure-directing agent and ascorbic acid as reducing agent.In addition,their composition and morphology can be regulated by changing the proportion of the precursor and the formation process of PdRu nanorod assemblies was explored.Due to their unique structure and bimetallic composition,the NH₃ producing yield of the PdRu nanorod assemblies(34.2?g h^-1mg^-1_cat.)is 1.3 and 2.0 times higher than those of the PdRu nanoparticles(26.3?g h^-1mg^-1_cat.)and PdRu nanodendrites(17.1?g h^-1 mg^-1_cat.)in the electrocatalytic nitrogen reduction reaction.Moreover,PdRu nanorod assemblies has excellent stability and selectivity.