Small Molecules-Assisted Synthesis And Control Of Bimetal Nanomaterials With Improved Electrocatalysis Performance

Direct methanol fuel cells (DMFC) with its abundant raw materials, convenient operation, environment-friendly has been received widespread concern in the field of energy device.Noble nanmaterials, platinum/palladium catalysts serve as a class of electrocatalysts can effectively improve the efficiency of methanol oxidation on anodic and the kinetic rate of oxygen reduction on cathode, which are the important materials in DMFC. However, it is restricted to use them due to the high cost and easy to poisoning in the catalytic process etc. In view of this, based on the use of small molecules, this paper has fabricated six kinds of precious metal-based nanomaterials with relatively larger special electrochemical active area. By adjusting the concentration of small molecules, the morphology, structure and component of the catalyst are improved. The synthesized electro-catalytic materials are economical andexhibitsuperiorcatalytic activity and stability. These researches are as follows:(1) A simple one-pot solvothermal coreduction approach was developed for facile preparation of inter-connected monodisperse bimetallic PtAu nanocrystals superlattice arrays (PtAu SLAs) in oleylamine with assistance of urea via hydrogen bonding induced self-assembly. The as-synthesized hybrid nanocrystals exhibited enhanced electrocatalytic performances for oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) in alkaline media.(2) A surfactants or templates free strategy was designed for facile synthesis of AuM (M= Pt or Pd) alloyed flowerlike-assembly nanochains (FANs), with the assistance of diprophylline as structure directing agent and stabilizing agent. The growth mechanism was discussed in some details by varying the concentration of diprophylline. The as-prepared AuPt and AuPd FANs displayed improved catalytic ability and better stability towards ORR.(3) A facile one-pot wet-chemical method was developed for preparation of bimetallic platinum-gold string-bead nanochain networks (PtAu SCNs), using allantoin as a structure-directing agent, without any template, surfactant, or seed. The as-prepared Pt-Au nanocrystals showed enhanced electrocatalytic performance toward ORR, which mainly predominated by a four-electron pathway and displayed improved catalytic activity and high stability for MOR.(4) Bimetallic PdAu alloyed nanochain networks (PdAu NCNs) were facilely prepared by a simple wet-chemical method with the assistance of allantoin as the structure-directing agent and stabilizing agent. Allantoin played an important role in formation of chain-like networks. The as-prepared PdAu NCNs had enlarged electrochemical active surface area, and displayed enhanced electrocatalytic activity toward ORR and MOR.(5) A one-pot wet-chemical coreduction route was designed for preparation of porous dandelion-like core-shell nanostructures (Au@Pd) in-situ growth on reduced graphene oxide (Au@Pd/rGO), without using any premade seed. Their shell thickness, particle size, composition and catalytic activity were tunable by adjusting the concentration of iodide ion (I-) with the assistance of cetyltrimethylammonium chloride (CTAC). The as-synthesized nanocomposites exhibited higher catalytic activity and stronger tolerance to carbonaceous species poisoning for MOR.