Understanding Pt Nanoparticle Anchoring on Graphene Supports through Surface Functionalization

Abstract

The enhancement of Pt nanoparticle anchoring strength and dispersion on carbon supports is highly desirable in polymer electrolyte membrane fuel cells (PEMFCs) as well as in other catalysis processes. Presented here is a comprehensive study of the interaction between catalyst nanoparticles and carbon supports in terms of the electronic structure change and its effects on the electrocatalytic performance of supported catalysts. Graphene was chosen as an ideal model support because the unique 2-D structure allows the direct investigation of the interaction with supported metal nanoparticles at their interface. We developed a facile strategy to covalently graft p-phenyl SO3Hor p-phenyl NH2groups onto the graphene surface. The functional groups were found to not only facilitate the homogeneous distribution of Pt nanoparticles on the surface of graphene supports and reduce the Pt average particle size but also strengthen the interaction of the Pt atoms with the functional groups and, consequently, minimize the migration/coalescence of the Pt nanoparticles in the course of accelerated durability tests. The experimental results from both X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) demonstrate the electron density shift from Pt to graphene supports with the strength of the Pt–graphene interaction following the trend of Pt/p-phenyl NH2-graphene > Pt/p-phenyl SO3H-graphene > Pt/graphene. This study will shed light on strategies to improve not only the durability but also the activity of the metal nanoparticles via the functionalization of the catalyst supports in the catalysis field.

Polybenzimidazole (PBI) Functionalized Nanographene as Highly Stable Catalyst Support for Polymer Electrolyte Membrane Fuel Cells (PEMFCs)

“…The mildly reduced graphene oxide (mrGO) was collected by centrifuge and washed with DI H 2 O. Subsequently, the mrGO was re-dispersed in DI H 2 O and subjected to the diazonium functionalization reported in our previous studies: 46,47 equal molar of 4-aminobenzoic acid, concentrated hydrochloric acid, and sodium nitrite were added in the mrGO aqueous dispersion that was then kept at 60…”

“…50 wt% on PBI-nanographene or PBI-graphene was carried out using a modified ethylene glycol (EG) method. 46,47,49 Briefly, PBI-nanographene or PBI-graphene was added to an EG aqueous solution (EG/DI H 2 O: 3/2 v/v) and ultra-sonicated for 30 min. After the temperature of the oil bath was elevated to 140…”

Understanding Heteroatom-Mediated Metal–Support Interactions in Functionalized Carbons: A Perspective Review

“…High metal dispersion was detected for different metal species (Au [92], Pd [93], Pt [94,95], Co [87], MoS2 [96]) on several doped carbon surfaces (N and O-doped carbon nanotubes, N-doped mesoporous carbon, N-doped carbon shells, carbon nanosphere, polyaniline (PANI) fibers). The presence of nitrogen has been demonstrated to assure excellent metal dispersion, even at very high metal loading [93].…”

A comprehensive review of Pt electrocatalysts for the oxygen reduction reaction: Nanostructure, activity, mechanism and carbon support in PEM fuel cells

“…It has also been suggested that these functional groups can serve as the anchors or nucleating centres for the controlled growth of NPs. 119 Xin et al 124 developed a facile strategy to covalently gra p-phenyl SO 3 H or p-phenyl NH 2 groups onto the graphene surface. The functional groups were found to not only facilitate the homogeneous distribution of Pt NPs on the surface of graphene supports and reduce the Pt average particle size but also strengthen the interaction of the Pt atoms with the functional groups and, consequently, minimize the migration/coalescence of the Pt NPs in the course of accelerated durability tests.…”