Abstract
Direct methanol fuel cells (DMFCs) are electrochemical devices that efficiently produce electricity and are characterized by a large flexibility for portable applications and high energy density. Methanol crossover is one of the main obstacles for DMFC commercialization, forcing the search for highly electro-active and methanol tolerant cathodes. In the present work, carbon-supported Pd and PdFe catalysts were synthesized using a sodium borohydride reduction method and physico-chemically characterized using transmission electron microscopy (TEM) and X-ray techniques such as photoelectron spectroscopy (XPS), diffraction (XRD) and energy dispersive spectroscopy (EDX). The catalysts were investigated as DMFC cathodes operating at different methanol concentrations (up to 10 M) and temperatures (60 °C and 90 °C). The cell based on PdFe/C cathode presented the best performance, achieving a maximum power density of 37.5 mW·cm−2 at 90 °C with 10 M methanol, higher than supported Pd and Pt commercial catalysts, demonstrating that Fe addition yields structural changes to Pd crystal lattice that reduce the crossover effects in DMFC operation.
Highlights
High energy conversion systems are required to satisfy global consumption demand
direct methanol fuel cells (DMFCs) are used in portable systems due to their versatility and easy re-fueling and because they are very appealing from economic and environmental points of view [2,3,4]
A few technical barriers restrict DMFC commercialization; the main concerns are (i) the slow electro-kinetics of methanol oxidation and oxygen reduction at the anode and cathode, respectively, at low temperatures, forcing the use of platinum-based catalysts [3]; (ii) membrane degradation; (iii) performance loss due to methanol crossover caused by the low tolerance to permeated methanol of the cathodic catalysts commonly used (Pt) [4,5]
Summary
High energy conversion systems are required to satisfy global consumption demand. Fossil fuel usage is causing gradual environmental deterioration due to CO2 emission into the atmosphere [1], and the search for novel substitute sources is vital. Direct methanol fuel cells (DMFCs) are supplied with methanol solutions as fuel at the anode. DMFCs are used in portable systems due to their versatility and easy re-fueling and because they are very appealing from economic and environmental points of view [2,3,4]. A few technical barriers restrict DMFC commercialization; the main concerns are (i) the slow electro-kinetics of methanol oxidation and oxygen reduction at the anode and cathode, respectively, at low temperatures, forcing the use of platinum-based catalysts [3]; (ii) membrane degradation; (iii) performance loss due to methanol crossover caused by the low tolerance to permeated methanol of the cathodic catalysts commonly used (Pt) [4,5]. The methanol crossover above refers to the permeation of methanol through the Materials 2017, 10, 580; doi:10.3390/ma10060580 www.mdpi.com/journal/materials
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
