ChemInform Abstract: Agglomeration of Platinum Particles Supported on Carbon in Phosphoric Acid

Abstract

is investigated under fuel cell operating conditions (205 °C, 1 atm) by means of a potential perturbation method.

Durability Studies of PBI‐based High Temperature PEMFCs

“…Figure 3b shows the results for another para-PBI membrane fuel cell test at 160 C. There were also some unintended facility events and one of them at 537 h caused a sharp increase in PA loss from the cathode. The voltage degradation rate over 2,500 h was 4.9 lV h -1 and the PA loss rate from the cathode ) was significantly higher than observed in the test at 160 C, and it could be due to many factors such as Pt dissolution [20], Pt agglomeration [21] and carbon support corrosion [22,23] ) was lower than that of para-PBI membrane fuel cell (45 lV h -1 ) at 80 C which may be due to more stable instrument operation. Figure 4b shows long-term operation of 2OH-PBI membrane fuel cell operated at 160 C. The voltage degradation rate at 160 C was 5.8 lV h -1 , which is similar to values reported for the fuel cells with commercial PA doped-PBI membrane (5 lV h -1 operated at 0.2 A cm -2 , 160 C for 6,300 h) [13] and similar to our work in this study for para-PBI at 160 C. Although the voltage degradation rate at 160 C was lower than that at 80 C, the PA loss rate at 160 C (7.1 ng cm -2 h -1 from the cathode) was similar to the value at 80 C (7.6 ng cm -2 h -1 from the cathode).…”

Review: Durability and Degradation Issues of PEM Fuel Cell Components

“…In this mechanism Brownian motion is the driving force, causing surface diffusion of particles with random collisions leading to coalescence [85]. Usually the fact that sintering does not occur significantly in catalysts in the gas phase at temperatures below 500°C is considered to be an indication that coalescence is not the prevailing mechanism [10,83,84]. In recent PEMFC studies it was found that both potential and increased humidity enhance the particle growth [86,87], which favours the dissolution/redeposition mechanism.…”

“…coalescence [10,70,[83][84][85]. In this mechanism Brownian motion is the driving force, causing surface diffusion of particles with random collisions leading to coalescence [85].…”

Effects of Surface‐Active Agents on Platinum Dispersion Supported on Acetylene Black

“…Some mechanisms of agglomeration have been reported (4)(5)(6)(7)(8), and the present authors have also studied a mechanism for platinum supported on acetylene black Prepared by the reduction of chloroplatinic acid with methyl alcohol and a surface-active agent (9). In the latter results, several platinum particles were found to form a kind of colony in the catalyst, and the colony became a single platinum particle through dissolution and redeposition.…”

“…It h a s b e e n p r o p o s e d t h a t this colony c h a n g e s into a single p l a t i n u m particle d u r i n g fuel cell operation a n d t h a t t h e p l a t i n u m surface area d e c r e a s e s accordingly (9). B u t several p l a t i n u m particles a g g r e g a t e d a n d f o r m e d a k i n d of colony.…”