Pt nanoparticles in polyelectrolyte multilayers: Polymer effects on the electrocatalytic activity for methanol oxidation

SANTIAGO HERRERA; MARIO TAGLIAZUCCHI; FEDERICO WILLIAMS; ERNESTO JULIO CALVO

JOURNAL OF ELECTROANALYTICAL CHEMISTRY - (Print)

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2023 vol. 938 p. 117430 - 117430

1572-6657

The layer-by-layer (LbL) self-assembly technique is a simple and versatile tool for the controlled chemical conversionof metal ions into nanoparticles. In this work, we prepared LbL thin films containing Pt nanoparticleselectroactive towards electro-oxidation of methanol by a two-step process, involving the exchange of differentPt precursor ions into the film, followed by their chemical reduction. We addressed the influence of the Pt precursor(Pt(NH3)42+ and PtCl62−) and polyelectrolyte-pairs (poly(diallyldimethylammonium chloride) (PDDA)/Nafion and poly(allylamine hydrochloride) (PAH)/poly(acrylic acid) (PAA)) on the properties and electrocatalyticactivity of the nanoparticles. NPs synthesized from Pt(NH3)42+ outperformed those growth from PtCl62−,the precursor used in previous works to prepared Pt NPs within LbL films. The combination of Pt(NH3)42+ andPDDA/Nafion films produced the best electrocatalytical performance with a specific activity of 0.8 mA.cm−2Pt .By varying the number of exchange/reduction cycles (n) between 1 and 5, a marked increase in the catalytic activitywas observed for the first 2 cycles, followed by a saturation regime. The peak potential of the Pt/Pt oxide peakalso increases in the first cycles and approaches a constant value close to that of a bulk Pt electrode coated withPDDA/Nafion. These behaviors are explained in terms of a strong polymer-Pt surface interaction that decreaseswith increasing n and stabilizes for n > 2.