Synthesis Of Pd, Sn-based Alloy Nanomaterials And Their Electrochemical Performances

Nanomaterials have been gained more attention in optics, electricity, magnetics, catalysis, energy storage and conversion due to their unique optical, electrical, magnetic, mechanical properties, which is dramatically different from that of their bulk materials. As one kind of the nanometeials, Pd-and Sn-based alloy nanomaterials have been investigated intensively because of their outstanding electrochemical properties.The electrochemical properties of Pd-and Sn-based alloy can be modified by tunning their compostion, morphology, and structures, since these paprameters have a great influence on their properties. We have developed servral facile approaches to the synthesis of Pd-and Sn-based nanomaterials with excellent electrochemical properties. The main innovative results are listed as follows:(1) We developed a facile polyol approach to synthesis Pd-Pt alloy concave cube nanocrystals with different compositions via a combination of bromide-induced galvanic replacement between Pd and Pt4+ions and co-redution of Pd2+and Pt4+ions. The composition of Pd-Pt nanocrystals can controlle by the varation of the mole ratios of the Pd and Pt salt precursors supplied in the synthesis. The eletrocatalytic performance of the Pd-Pt alloy concave nanocubes for methanol oxidation was enhanced due to the presence of large density of atomic steps, ledges and kinks on the high-index facets, as well as the strong coupling between these two metals. Among these concave nanocubes, Pd40Pt6o alloy concave nanocubes showed the highest specific activity towards methanol oxidation, and were4.6times more active than the commercial Pt/C catalyst(2) We developed a facile polyol approach to synthesis Rh-Pd alloy cubes and octahedral nanocrystals with different compositions in presence of one capping agent by extremely slowing down the injection rate of the precursors to manipulate the growth kinects. The shape control was achieved by varying the molar ratios of the Rh to Pd precursors and the reaction temperature. The incorporation of Rh into Pd-based nanocrystals can substantially enhanced the mass activity and durability towards ORR relative to commercial Pt/C, with the RhgPd92alloy octahedra being the best catalysts due to the possible synergistic effects between facet and composition.(3) We reported a two-step electrodeposition method for the synthesis of Cu/SnCo core-shell rod-shaped arrays as anodes of lithium-ion batteries. These hybrid electrodes delivered the enhanced cyclic performance and high rate capability serving as the anode materials for lithium-ion batteries, showing the high capacity of about660mAh/g at a current rate of0.25C after80charge/discharge cycles and being capable of rendering70%of its initial capacity even at a high current rate of4C. The improved electrochemical performance might be attributed to the large surface-to-volume area, sufficient buffering space, and high electronic conductivity associated with these3-dimensional (3D) nanostructures.