Preparation Of Pt/Pd-based Catalysts By Electrochemical Dealloying And Their Electrocatalytic Applications

Pt-based catalysts are the most efficient catalysts for low-temperature fuel cells.To enhance continuely their catalytic performance,the tailored design of the morphology and structure are developed by a lot of work.Among them,metal-based particle network as promising structure has gained attention due to high catalytic performance result from its structure of high surface-to-volume ratio.However,the authors focused on tunning the composition of the network for improving the catalytic performance in these reports,few artificially design the structure of its nanoparticles of the network.In the present study,we first fabricate a flocculent core-shell precursor with a green and environmental protection method.The precursor was then dealloyed by electrochemical cycling to successfully produce a precious metal network assembly comprising nanoparticles.This paper consists of the following three parts:(1)Herein,we use a flocculent core-shell PtNi@Ni to produce PtNi network catalysts with nanoparticle intraporosity after carefully controlled electrochemical dealloying.Physical characterization shows a hierarchical level of nanoporosity(intrapores within nanoparticles and pores between them)evolves during the controlled electrochemical dealloying,and that a Pt-rich surface also forms after 22 cycles of Ni leaching.The obtained catalyst has good ORR catalytic activity.(2)In this study a different and innovative approach was adopted to yield a network-like PtCo catalyst composed of intraporous nanoparticles used a cotton-like PtCo precursor material.It was found that the network-like structure and intrapores within the nanoparticles could co-evolve after careful controlled electrochemical dealloying.Electrochemical data also showed that the mass and area activity of the obtained PtCo networks toward methanol oxidation reaction(MOR)was higher than that of commercial Pt/C,PtRu/C catalyst.(3)In this study,PdNi particle networks(PdNi NN)were prepared by voltammetric dealloying using a PdNi precursor.Electron microscopy and X-ray diffraction were employed to show the evolution of the morphology of the as-prepared catalysts.The results generated from the cyclic voltammetry experiments showed that PdNi NN was electrocatalytically active toward the Ethanol Oxidation Reaction(EOR).Compared with PdNi/C and commercial Pd/C,the oxidation peak potential of PdNi NN shifted positively by +105 and +168 mV and the peak current density increased by 1.53 and 3.75 times.