Pt/C Electrocatalyst Durability Enhancement by Inhibition of Pt Nanoparticle Growth Through Microwave Pretreatment of Carbon Support

Abstract

Durability enhancement of Pt supported on carbon (Pt/C) electrocatalysts through a simple microwave (MW) pretreatment of the carbon support has been studied. Vulcan XC 72 carbon (either in suspension or dry state) was subjected to MW irritation for a short period of time (~5 min) prior to synthesis of the Pt/C electrocatalysts (20 wt.% Pt) through a polyol route. Platinum deposited onto MW-pretreated and unmodified carbons demonstrated similar initial Pt particle size distributions (average particle size~3.3 nm) and electrochemical surface area (ECSA). However, ECSA evolution based on an accelerated stress test (AST) in acidic conditions suggested a clear durability enhancement of the MW-pretreated Pt/C samples over the unmodified equivalent. Transmission electron microscope (TEM) images of the post-AST samples reveal spherical and nanorod morphologies of the Pt nanoparticles for the untreated and the MW-pretreated carbon supports, respectively. X-ray photoelectron spectroscopy (XPS) evidences presence of surface active sites (CÀ O*) on the carbon support generated from the MW irradiation. Those active sites turned out to be suitable nucleation sites for redeposition of the dissolved Pt species to form new Pt nanoparticles during AST. The mechanism reduces the rate of Pt nanoparticle active surface area loss, and thus provides increased durability. The proposed concept opens a new territory for a scalable process to further advance the electrocatalyst.

Recovery of Pt and Ru from Spent Low-Temperature Polymer Electrolyte Membrane Fuel Cell Electrodes and Recycling of Pt by Direct Redeposition of the Dissolved Precursor on Carbon

“…This may be due to a difference in the nature of the carbon supports arising from factors such as the different processing conditions during preparation of support carbon and/or Pt/C, the presence of different surface functional groups, etc. However, the Vulcan XC 72 carbon used as the support for the Pt/C-R catalyst shows similar changes in DLC values for the Pt/C catalysts synthesized using different synthesis routes, e.g., microwave-assisted polyol synthesis . Hence, the observed DLC variation for Pt/C-R is not related to the synthesis route but is a property of the support carbon.…”

“…However, the Vulcan XC 72 carbon used as the support for the Pt/C-R catalyst shows similar changes in DLC values for the Pt/C catalysts synthesized using different synthesis routes, e.g., microwaveassisted polyol synthesis. 41 Hence, the observed DLC variation for Pt/C-R is not related to the synthesis route but is a property of the support carbon. Overall, the recycled Pt/C exhibits electrochemical performance comparable to that of the commercial Pt/C.…”

Materials Engineering toward Durable Electrocatalysts for Proton Exchange Membrane Fuel Cells

“…presented a facile microwave pretreatment of carbon support to create suitable nucleation centers for Pt redeposition. [ 147 ] After an accelerated stress test, microwave‐treated carbon‐supported Pt catalysts exhibited obviously enhanced durability when compared to the unmodified equivalent. It is suggested the C–* active sites generated from microwave irradiation could act as potential nucleation sites for the renucleation of dissolved Pt ions during aging test, thus increasing the Pt retention rate.…”

Advanced Methods of Controlling the Morphology, Activity, and Durability of Pt/C Electrocatalysts

“…Such NPs are formed under the iced photochemical reduction of the Pt precursor. The catalysts containing them showed higher stability than the commercial Pt/C analogues. − A combination of the narrow-dimensional dispersion of platinum nanoparticles and their uniform spatial distribution over the carbon support surface leads not only to increasing the ESA value and activity in the ORR, but also to advancing their robustness against degradation. , …”

“…23−25 A combination of the narrow-dimensional dispersion of platinum nanoparticles and their uniform spatial distribution over the carbon support surface leads not only to increasing the ESA value and activity in the ORR, but also to advancing their robustness against degradation. 9,26 Unfortunately, many laboratory techniques of obtaining highly active Pt/C catalysts suffer from several shortcomings, among which are the complexity of the technologies, problems of reproducibility of the product characteristics, and synthesis scalability. Meanwhile, technological, scalable, and wellreproducible working methods are required to obtain highly stable electrocatalysts with increased ESA and activity in the ORR.…”