Preparation And Electrocatalytic Properties Of Nanoporous Pd Metals By Dealloying Co-Pd-Sn And Cu-Pd-Si Solid Solution Alloys

The preparation of nanoporous metals and their electrocatalytic properties are the hot research fields in recent years. Solid solution alloy is a good precursor for the preparation of nanoporous metals. In this paper, the solid solution alloys of two series of Co-Pd-Sn and Cu-Pd-Si were studied, and the nanoporous Pd alloy was prepared by electrochemical dealloying method. Then the morphology, phase structure and catalytic properties were characterized and analyzed by X-ray diffraction (XRD), scanning/transmission electron microscopy (SEM/TEM), spectrum analysis technique (EDX) and electrochemical analysis methods. The research contents are as follows:(1)Micro alloying method was used to add trace amounts of Sn to Co-Pd binary solid solution alloy, and prepared Co79Pd20Sn1? Co80Pd19Sn1? Co80Pd19.5Sn0.5 alloy ribbon samples by means of melt-spinning and arc-melting, the width of the ribbon was about 5mm and the thickness was about 60?m. The analysis of XRD and TEM showed that the phase structure of the alloy was the FCC Co-Pd solid solution matrix and the precipitates of the FCC intermetallic compound. Upon electrochemical dealloying the samples in 0.1 M H2SO4 aqueous solution, nanoporous structures with a pore size of 5-20nm were prepared which were associated with good mechanical integrity. Compared with the obvious cracking of Co80Pd20 binary alloy after dealloying, the strength and integrity of solid solution alloys added with Sn were obviously improved.(2) Ribbon samples of Cu-Pd-Si solid solution alloys with 11 components were prepared by melt-spinning. Dynamic potential polarization curves were performed in 0.5M H2SO4 solution, the results showed that only two components Cu75Pd20Si5, Cu80Pd15Si5 could be dealloyed. Upon dealloying in appropriate conditions, nanoporous Pd alloys with a pore size of about 5-10nm were formed in Cu75Pd20Si5 alloy, however, in CugoPd15Si5 alloy, the porous structure was not uniform and the connectivity was not good. The addition of Si element made the FCC solid solution matrix have a new precipitated phase Pd2Si, the precipitated phase played a role in strengthening the matrix to prevent alloys from appearing large area cracking after dealloying.(3)The electrocatalytic properties of the nanoporous Pd alloys which were made by dealloying Co80Pd19Sn1 and Cu75Pd20Si5 were measured with cyclic voltammetry curves in 1M KOH and 0.5M methanol mixed solution. The experimental results showed that the prepared nanoporous Pd had remarkable catalytic activity and good stability towards the electro-oxidation of methanol in alkaline solution.