Pt/Ru/C nanocomposites for methanol electrooxidation: how Ru nanocrystals’ surface structure affects catalytic performance of deposited Pt particles

Abstract

The surface structure of supporting materials has great effect on the catalytic performance of supported catalysts. In this work, three kinds of Ru nanocrystals with different morphologies and surface structures, namely triangular plates (TPs), capped columns (CCs) and nanospheres (NSs), were used as substrates for the deposition of Pt particles through an aqueous adsorption-reduction approach. By testing the catalytic activity and stability of these composite catalysts towards methanol electrooxidation, the relationship between the surface structure of Ru nanocrystals and the catalytic performances of Pt particles was built up. Pt/Ru TPs/C exhibited higher catalytic activity and stability than Pt/Ru CCs/C, indicating that the closest packed facet of Ru serves as better substrate for the deposition of Pt particles than the high index facets of Ru for methanol electrooxidation. Pt particles and Ru NSs formed a self-supported network structure in Pt/Ru NSs/C, which increased the level of dispersion of Pt particles and guaranteed higher catalytic activity and stability compared with Pt/Ru CCs/C. This work demonstrated how to use shape controlled metal nanocrystals to study the surface structure effect of supports in catalytic reactions.

The effect of temperature and concentration for methanol electrooxidation on Pt-Ru catalyst synthesized by microwave assisted route

“…In conclusion, one could note that microwave irradiation increases the catalyst activity. 26 Comparing the activity of M-PtRu@C and M-Pt@C catalysts, one can see that the addition of the Ru improves MOR activity as previously reported in the literature. Chronoamperomograms were taken of these catalysts in 0.5 M H 2 SO 4 + 1.0 M CH 3 OH solution at 0.6 V ( Figure 6).…”

“…Similarly, Gu et al reported that by the addition of Ru MOR activity of Pt particles was enhanced at different levels by introducing Ru nanoparticles. 26 M-PtRu@C catalyst showed the highest initial current and the highest current at the longer time, confirming that this catalyst had higher electrocatalytic activity and higher resistance to CO. Depending on these CA measurements, the turnover number (TON), the number of methanol molecules that react per catalyst surface site per second, was calculated by using the following equation: 40 T ON (molecules/s.site) = [I(mA/cm…”

“…In addition, it is clear that the surface structure of the metal substrate influences the catalytic performance of the catalysts supported on the metal surface. 26 Researchers concentrated on the effect of Ru addition on the MOR to improve MOR activity. Tripkovic et al 27 also reported that the addition of Ru increases MOR activity.…”

“…Thus, the surface structure of the supporting materials has a great effect on the catalytic performance of the supported catalysts. Gu et al 26 reported the MOR activities for three kinds of Ru nanocrystals with different morphologies and surface structures, namely triangular plates (TPs), capped columns (CCs), and nanospheres (NSs) as Pt@C > Pt-Ru CCs@C > Pt-Ru NSs@C ≈ Pt-RuTPs@C. From these results, one can understand that these nanocomposites exhibited dramatically different catalytic activity and stability. In addition, it is clear that the surface structure of the metal substrate influences the catalytic performance of the catalysts supported on the metal surface.…”

Tailoring ruthenium exposure to enhance the performance of fcc platinum@ruthenium core–shell electrocatalysts in the oxygen evolution reaction

“…The high index structure of the dendritic shell may allow for rearrangement and dissolution during the oxidation and reduction cycles due to its higher surface area and less stable facets compared to the low index facets of the cuboctahedral shell. 37…”