Development of plurimetallic electrocatalysts prepared by decomposition of polymeric precursors for EtOH/O2 fuel cell

Abstract

Este trabalho teve como objetivo desenvolver eletrocatalisadores plurimetálicos contendo Pt, Ru, Ni e Sn suportados em C pelo método de decomposição de precursores poliméricos (DPP), na razão metal:carbono de 40:60% em massa, para aplicação em célula a combustível de etanol direta (DEFC). As nanopartículas obtidas foram caracterizadas físico-quimicamente por difração de raios X (DRX) e energia dispersiva de raios X. Os resultados de DRX revelaram cristalitos com estrutura cúbica de face centrada da Pt com evidências de que os átomos de Ni, Ru e Sn foram incorporados à estrutura da Pt. A caracterização eletroquímica das nanopartículas foi realizada por voltametria cíclica e cronoamperometria em meio ácido (H 2 SO 4 0,05 mol L -1 ), na ausência e presença de etanol. A adição de Sn para os catalisadores PtRuNi/C deslocou significativamente o potencial de início de oxidação de etanol e CO para valores mais baixos, aumentando assim a atividade catalítica, especialmente para a composição Pt 64 Sn 15 Ru 13 Ni 8 /C. Eletrólises de solução de etanol em 0,4 V vs. ERH permitiram a determinação de acetaldeído e ácido acético como principais produtos da reação. A presença de Ru nas ligas favoreceu a formação de ácido acético como produto principal da oxidação do etanol. O catalisador Pt 64 Sn 15 Ru 13 Ni 8 /C exibiu o melhor desempenho para DEFC.This work aimed to develop plurimetallic electrocatalysts composed of Pt, Ru, Ni, and Sn supported on C by decomposition of polymeric precursors (DPP), at a constant metal:carbon ratio of 40:60 wt.%, for application in direct ethanol fuel cell (DEFC). The obtained nanoparticles were physico-chemically characterized by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). XRD results revealed a face-centered cubic crystalline Pt with evidence that Ni, Ru, and Sn atoms were incorporated into the Pt structure. Electrochemical characterization of the nanoparticles was accomplished by cyclic voltammetry (CV) and chronoamperometry (CA) in slightly acidic medium (0.05 mol L -1 H 2 SO 4 ), in the absence and presence of ethanol. Addition of Sn to PtRuNi/C catalysts significantly shifted the ethanol and CO onset potentials toward lower values, thus increasing the catalytic activity, especially for the quaternary composition Pt 64 Sn 15 Ru 13 Ni 8 /C. Electrolysis of ethanol solutions at 0.4 V vs. RHE allowed determination of acetaldehyde and acetic acid as the main reaction products. The presence of Ru in alloys promoted formation of acetic acid as the main product of ethanol oxidation. The Pt 64 Sn 15 Ru 13 Ni 8 /C catalyst displayed the best performance for DEFC. Keywords: DEFC, ethanol, decomposition of polymeric precursor method (DPP), metallic catalyst IntroductionThe development of clean technologies for power generation with renewable fuels is required if we are to overcome the increase in environmental problems. In this context, the use of ethanol as fuel is promising because it is renewable, easy to store and handle, and contains high energy density (8 kW h kg -1 ),...

Ethanol Electrooxidation by Plurimetallic Pt-Based Electrocatalysts Prepared by Microwave Assisted Heating

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Addition of iron oxide to Pt-based catalyst to enhance the catalytic activity of ethanol electrooxidation

“…3 (FTIR) [39][40][41][42][43], and High Performance Liquid Chromatography (HPLC) [16,44,45], which have helped to identify the reaction products. Acetaldehyde and acetic acid always emerge as the main products and reflect the stability of the C-C bond at lower DAFC operating temperatures 80-100 o C.…”

Direct Ethanol Fuel Cell on Carbon Supported Pt Based Nanocatalysts

“…The formed products can be determined ex situ using both fuel cells and electrochemical cells by the application of different techniques. Several studies on the electrooxidation of ethanol have been devoted to the identification and quantification of the adsorbed intermediates and by-products onto the electrode by means of various techniques, such as Differential Electrochemical Mass Spectrometry (DEMS) [141][142][143][144][145][146], in situ Fourier-Transform Infrared Spectroscopy (FTIR) [24,147,148], and High Performance Liquid Chromatography (HPLC) [22,62,149,150]. …”