Hydrogen Peroxide Formation as a Degradation Factor of Polymer Electrolyte Fuel Cells

Abstract

20wt.% Pt/C catalyst was loaded at different densities (0.28- 56.7 mgcarbon cm-2) on glassy carbon (GC) disk electrode, and the effect of its agglomeration on hydrogen peroxide formation in oxygen reduction reaction (ORR) was investigated by the rotating ring-disk electrode technique. The formation of H2O2 was enhanced with a reduction in agglomeration of Pt/C. Even in the operating potential range of PEFC cathodes (0.6-0.8 V), 20% of hydrogen peroxide was formed on Pt/C loaded at densities lower than 1.41 mgcarbon cm-2 on GC. These results revealed that series 2-electron reduction pathway, which is negligible on clean bulk Pt surface, exists on Pt nanoparticles supported on carbon. A large amount of H2O2 formation was observed on Pt nanoparticles deposited not only on GC, but also on Au, which indicated that H2O2 formation is not specific to Pt nanoparticles on carbon support.

Scientific Aspects of Polymer Electrolyte Fuel Cell Durability and Degradation

“…This fact supported the mechanism proposed by LaConti et al . A recent rotating ring−disk electrode study suggested that H 2 O 2 yield exceeds 80% at Pt/C catalysts dispersed highly on a glassy carbon disk in the anode potential range (∼0 V) . The presence of H 2 O 2 has been confirmed in exhaust gas, in drain water, and directly in the membrane during operation of PEMFCs.…”

“…It is known that H 2 O 2 formation in oxygen reduction on polycrystalline , and single , crystalline Pt as well as Pt/C catalyst − is greatly enhanced in the anode potential region, where atomic hydrogen is adsorbed on Pt. This fact supported the mechanism proposed by LaConti et al .…”

“…160,201 LaConti et al proposed a mechanism that oxygen molecules permeate through the membrane from the cathode side and are reduced at the anode Pt catalyst to form hydrogen peroxide. 202,203 It is known that H 2 O 2 formation in oxygen reduction on polycrystalline 204,205 and single 206,207 crystalline Pt as well as Pt/C catalyst [208][209][210] is greatly enhanced in the anode potential region, where atomic hydrogen is adsorbed on Pt. This fact supported the mechanism proposed by LaConti et al A recent rotating ring-disk electrode study suggested that H 2 O 2 yield exceeds 80% at Pt/C catalysts dispersed highly on a glassy carbon disk in the anode potential range (∼0 V).…”

Synthesis of a Pt/Carbon-Sphere Catalyst and Evaluation of Its Oxygen Reduction Reaction Activity in Acidic Environments

“…In this study, the catalyst loading on the GC rod was fixed at 7.23 (μg-Pt) cm –2 , that is, less than half that specified in the Fuel Cell Commercialization Conference of Japan (FCCJ) protocol. A decrease in the catalyst loading results in the kinetically controlled region at around 0.8 to 1.0 V in a linear sweep voltammetry (LSV) curve shifting to a negative potential. − The limiting current, which indicates the diffusion-controlled region, becomes tiny, and the ORR current decreases (see Figure S1). A high-performance catalyst with a large number of active sites shows the early formation of a diffusion-controlled region.…”

Hybrids of Reduced Graphene Oxide Aerogel and CNT for Electrochemical O2 Reduction

“…A catalyst with high activity and high selectivity towards the 4e − reduction is needed to overcome the sluggish ORR kinetics occurring at the cathode of a fuel cell [1,2]. Regarding selectivity, the O 2 reduction with 2e − is detrimental for fuel cell performance because reduces its efficiency and the produced H 2 O 2 damages the membrane fuel cell [3]. Nevertheless, high selectivity to 2e − reduction is desired for decentralized H 2 O 2 production as an alternative to the established industrial anthraquinone process [4,5].…”