Preparation And Electrical Properties Of High Active Alcohol Platinum And Palladium Catalysts

Alcohol fuel cells（DAFCs） are directly convert chemical energy to electronic energy, and which are promising candidates for new energy sources due to their high efficiency, high-energy density and environmentally friendly nature, especially for portable electronic devices and transportation applications. The main problem in the development of DAFC is that the electrocatalytic activity of the anode catalyst to the alcohol molecule is too low. Therefore, it is urgent to prepare of highly efficient catalysts and reduce their required usage in such applications.In this paper, different types of catalysts were prepared by optimizing the catalyst structure, carrier materials and synthesis methods. In addition, their electrocatalytic performances of methanol and ethanol in alkaline medium were investigated in detail.（1）We successfully synthesized a dandelion-like Pt Pd heterogeneous structure via a facile one-pot hydrothermal route by reducing Na₂ Pd Cl₄ and H₂ Pt Cl₆ with ascorbic acid in the presence of hexadecylpyridinium chloride monohydrate. Hexadecylpyridinium chloride monohydrate acted as the shape-directing agent, which is critical to the reproducible formation of dandelion-like PtPd nanoclusters（DPt Pd NC）. The prepared DPt Pd NC with an average diameter of 40 nm composed of dozens of branched arm assembled by Pt and Pd heterogeneous nanoseeds. DPtPd NC had a strong electron-electron interaction. What’s more, there were numerous nanoscale steps, kinks and edges in DPtPd NC open channel structure. As a result, an optimized DPt Pd NC made by fine-tuning ratio of the Pt（7%） and Pd（93%） showed hugely active surface sites and a superior electrocatalytic performance for ethanol oxidation was well as a long durability.（2）Pt Pd nanoparticles supported on anatase TiO₂ by reducing metal ions use ascorbic acid as reducing agent were prepared and used as a catalyst for DMFC because anatase TiO₂ has higher electron conductivity than rutile. TiO₂ in this design has several roles: Firstly, the strong metal-support interactions（SMSI） between TiO₂ and nanoparticles may modify the electronic structure. Secondly, by using titania as a corrosion-resistant support can prevent nanopaticles from aggregation and greatly improve the activity and stability. What’s more, possible synergetic interactions between Pt and Pd further change the d-orbital energy.（3）In this communication, we report the direct electrodeposition of PtPd with 40 nm using a programmed electrodeposition method. An alternative signal to the common pulse galvanic deposition is proposed to reduce the particle size. The growth of the PtPd nuclei was achieved by applying a square-wave potential with lower（EL） and upper（EH） potential limits of 0.10 and 0.70 V, respectively. This preparation method is simple and controllable, in comparison with the other chemical reduction method. Pt Pd based electrode was characterized SEM and electrochemical techniques. The as-prepared PtPd alloy films showed enhanced electrocatalytic activities toward the electrooxidation of ethanol in alkaline solution.