Preparation And Structural Properties Of PtCu / CeO_x / C / Nafion Electrode

Because of excellent catalytic performance, high reaction selectivity and long service life of platinum (Pt), Pt-based catalysts are widely used in petrochemical industry, energy industry, fuel cell, the automotive industry and other fields. However, Pt is very expensive, there is a hotspot of Pt-based catalysts that to reduce Pt loading capacity and improve catalytic performance. Rare earth element cerium (Ce) has a unique catalytic properties, high temperature stability and high dispersion characteristics, which has a good synergistic effect with precious metal Pt. And also CeOx can improve the density of electron cloud of Pt on the catalytic activity site and then enhance catalytic activity. Copper (Cu) atoms has unstable space, it can be used as catalyst in catalytic reaction. Both of Cu and Pt are face centered cubic structure, Cu can be used as a transition metal element which can be doped in Pt-based catalyst and form a substitution solid solution with the main phase catalytic Pt, modifying the particle distribution of main catalytic phase with reducing Pt loading capacity and improving catalytic performance.In this paper, PtCu/CeOx/C, PtCu/C, PtCu/CeOx/C/Nafion and PtCu/C/Nafion membrane catalyst electrodes were prepared by ion beam sputtering (IBS). Then, the catalytic performance, phase composition, element valence and microstructure of the catalyst electrodes were analyzed by the CV, LSV, i-t, XRD, ICP-AES, XPS, AFM and HR-TEM. The results showed that:(1) PtCu/CeOx/C membrane catalytic electrodes which were etched in 0.5 mol/L H2SO4 solution at 50℃ have a larger surface roughness and a higher hydrogen evolution performance.(2) With PtCu targets deviating from the origin, Cu loading capacity increased and platinum loading capacity decreased. PtCu/C membrane catalyst electrodes formed PtiCui or PtiCu3 alloys, and its performance decreased with Cu loading capacity increasing. However, Cu loading capacity of PtCu/C membrane catalyst electrodes decreased remarkably, the porous structure occurred on the electrodes surface, and the surface roughness increased remarkably after PtCu/C membrane catalyst electrodes were etched in H2SO4. At the same time, the catalytic performance of PtCu/C increased with Cu loading capacity increasing gradually. The PtCu/C membrane catalyst electrodes have lower Pt loading compared and higher catalytic performance after electrolytic corrosion, compared to Pt/C catalyst.(3) Using ultrasonic machine dispersed PtCu/CeOx/C and PtCu/C catalysts into Nafion solution (0.5%Wt), and then let them stand for a period of time. PtCu/C/Nafion and PtCu/CeOx/C/Nafion catalytic particles can be obtained from the solution, and the particles were small. Let them stand for 300 min after ultrasonic dispersion, the particles which extracted solution from supernatant liquid were smaller than from supernviaould liquid, and the size of the minimum particles were about 4nm. The particles included Cu particles, PtCu particles or PtCu-CeOx particles. The nano-particles can improve its catalytic efficiency.