Yanjiao Ma

The Effect of PtRuIr Nanoparticle Crystallinity in Electrocatalytic Methanol Oxidation

Two structural forms of a ternary alloy PtRuIr/C catalyst, one amorphous and one highly crystalline, were synthesized and compared to determine the effect of their respective structures on their activity and stability as anodic catalysts in methanol oxidation. Characterization techniques included TEM, XRD, and EDX. Electrochemical analysis using a glassy carbon disk electrode for cyclic voltammogram and chronoamperometry were tested in a solution of 0.5 mol L−1 CH3OH and 0.5 mol L−1 H2SO4. Amorphous PtRuIr/C catalyst was found to have a larger electrochemical surface area, while the crystalline PtRuIr/C catalyst had both a higher activity in methanol oxidation and increased CO poisoning rate. Crystallinity of the active alloy nanoparticles has a big impact on both methanol oxidation activity and in the CO poisoning rate.

Synthesis of ultrafine amorphous PtP nanoparticles and the effect of PtP crystallinity on methanol oxidation

In this study we report that ultrafine amorphous metallic nanoparticles have a surface structure that is rich in both low-coordination sites and defects that coincides with increased methanol oxidation activity. Ultrafine amorphous platinum-phosphorous nanoparticles supported on Vulcan carbon (PtPa/C) were synthesized, followed by increasing degrees of heat treatment to obtain higher levels of crystallinity in the supported PtP particles. Structural and compositional analysis by various techniques allowed correlation between the structures of various PtP states and their resultant catalytic methanol oxidation activity. Increasing heat treatment temperature increased both the crystallinity and average size of the supported PtP particles. Both factors coincided with decreased methanol oxidation activity and lower carbon monoxide tolerance. The most amorphous PtP nanoparticles had the highest catalytic methanol oxidation activity and strongest tolerance for carbon monoxide.

Synthesis of carbon-supported PdSn–SnO2 nanoparticles with different degrees of interfacial contact and enhanced catalytic activities for formic acid oxidation

The conjunction of the PdSn alloy and SnO2 is of interest for improving catalytic activity in formic acid oxidation (FAO). Here, we report the synthesis of PdSn-SnO2 nanoparticles and a study of their catalytic FAO activity. Different degrees of interfacial contact between SnO2 and PdSn were obtained using two different stabilizers (sodium citrate and EDTA) during the reduction process in catalyst preparation. Compared to the PdSn alloy, PdSn-SnO2 supported on carbon black showed enhanced FAO catalytic activity due to the presence of SnO2 species. It was also found that interfacial contact between the PdSn alloy and the SnO2 phase has an impact on the activity towards CO oxidation and FAO.