Self-template Preparation Of Mesoscopic Palladium-based Composite Catalyst And Its Electrocatalytic Oxidation Of Alcohols

The shortage of energy and the deterioration of the environment lead to the exploration and research of all kinds of clean energy.Direct alcohol fuel cells?DAFCs?have been gradually favored because of their high energy density,wide range of sources and environmental friendliness.However,its anode catalyst metal platinum?Pt?hinders the development of DAFCs due to its few content,high price and easy poisoning.Therefore,in the face of this situation,how to prepare catalysts with good catalytic performance and low price is the key to solve the problem.Due to the high catalytic performance of palladium?Pd?and Pt in alkaline media,a large number of researchers set about synthesizing efficient pd-based catalysts.In this paper,three different types of Pd based catalysts were prepared from the aspects of reducing the cost of catalysts,improving the catalytic activity durability and anti-toxic performance of catalysts.And we investigated its electrocatalytic performance for methanol and ethanol in alkaline medium and the electrocatalytic mechanism.The specific work includes three aspects:?1?We use anatase TiO₂ as the support,which could absorb hollow AgPd particles and complete the load on metal particles due to its different potential with the metal particles.As a hydrophilic oxide,TiO₂ can well absorb hydroxyl?-OH?in the solution,effectively remove toxic intermediates such as carbon monoxide,and improve the toxicity resistance of the catalyst.In addition,TiO₂ can modify the electronic structure of metal particles and the interaction between AgPd can improve the catalytic activity of the catalyst.Compared with the commercial Pd black,the catalyst has excellent electrocatalytic performance.?2?Under alkaline conditions,mesoscopic Ag spheres was rapidly synthesized and used as a template to synthesize mesoscopic hollow AgPdPt trimetal catalyst through redox reaction with Na₂PdCl₄ and H₂PtCl₆.Characterized by TEM,the catalyst is composed of small self-supporting particles,which are not easy to aggregate,thus improving the stability and accelerating the mass transfer efficiency.The electronic effect between the three metals obtained from the XPS results is also beneficial to the activity improvement of the catalyst.Through the investigation of cyclic voltammetry and chronocurrent method,the catalyst has good stability and catalytic activity to methanol,which is about 40 times of the activity of commercial Pd black catalyst.?3?Mesoscopic cauliflower-like Ag particles were synthesized by a simple method,and mesoscopic cauliflower-like hollow AgPd catalyst was synthesized by using this as reducing agent.SEM and TEM characterization showed that the catalyst still retained cauliflower rough surface and was composed of small particles about7-10 nm.The electronic effect between AgPd improves the catalytic activity of the catalyst.The large specific surface area exposed by the hollow structure and the active sites exposed by the rough surface are conducive to the enhancement of the catalytic performance.With the introduction of Ag,the catalyst is easy to adsorb-OH,thus accelerating the release of the active site.The catalytic activity of this material is30 times higher than that of commercial Pd black,and it shows good stability.