The main problem of PEMFCs and DMFCs, is linked with the high price of Pt-based electrocatalysts, on one side, and durability issues, on the other side. In this work electrocatalysts for oxygen reduction reaction (ORR) were developed, synthesized and tested for the fuel cell systems based on hydrogen or methanol. Moreover, tests under sub-freezing conditions at temperatures below 0°C, were conducted to assess the performance of FCs systems in harsh environmental conditions. Specifically, the electrochemical performance of three types of electrocatalysts for the oxygen reduction reaction, based respectively on a hollow core mesoporous shell carbon (HCMSC), an ultrasonic spray pyrolysis mesoporous carbon (USPMC) and a graphene reduced oxide (GRO) were compared. These catalysts were then evaluated electrochemically in a three-electrode one-compartment cell, using a 0.5 M H2SO4 solution as electrolyte, an auxiliary electrode and a reversible hydrogen electrode (RHE), as counter and reference electrodes, respectively. X-ray photoelectron spectroscopy (XPS), X-ray scattering (XRD), Brunauer-Emmett-Teller (BET) and Transmission electron microscopy (TEM) were carried out in order to understand chemical-physical phenomenon, and electrochemical tests were conducted via linear sweet voltammetry (LSV) and cyclic voltammetry (CV). On the other hand, the effects of methanol concentration, temperature, freezing/thawing (F/T) tests and cell purging time, evaluating the performance of a single direct methanol fuel cell (DMFC), were investigated. Specific purging conditions were optimized to increase the durability of MEAs. SEM analysis of MEAs after F/T cycles showed that a significant MEA degradation occurred when the produced water is not removed. Such a degradation affected the subsequent cell performance and durability, which depend of the purging procedure, purging time, and purge flow. By opportunely modifications of the purging procedure, the performance of single DMFCs remained almost constant after 25 F/Ts.

Non-Noble Metal Cathodic Electrocatalysts for PEM Fuel Cells and Direct Methanol Fuel Cells / MONTEVERDE VIDELA, ALESSANDRO HUGO. - STAMPA. - (2013).

Non-Noble Metal Cathodic Electrocatalysts for PEM Fuel Cells and Direct Methanol Fuel Cells

MONTEVERDE VIDELA, ALESSANDRO HUGO
2013

Abstract

The main problem of PEMFCs and DMFCs, is linked with the high price of Pt-based electrocatalysts, on one side, and durability issues, on the other side. In this work electrocatalysts for oxygen reduction reaction (ORR) were developed, synthesized and tested for the fuel cell systems based on hydrogen or methanol. Moreover, tests under sub-freezing conditions at temperatures below 0°C, were conducted to assess the performance of FCs systems in harsh environmental conditions. Specifically, the electrochemical performance of three types of electrocatalysts for the oxygen reduction reaction, based respectively on a hollow core mesoporous shell carbon (HCMSC), an ultrasonic spray pyrolysis mesoporous carbon (USPMC) and a graphene reduced oxide (GRO) were compared. These catalysts were then evaluated electrochemically in a three-electrode one-compartment cell, using a 0.5 M H2SO4 solution as electrolyte, an auxiliary electrode and a reversible hydrogen electrode (RHE), as counter and reference electrodes, respectively. X-ray photoelectron spectroscopy (XPS), X-ray scattering (XRD), Brunauer-Emmett-Teller (BET) and Transmission electron microscopy (TEM) were carried out in order to understand chemical-physical phenomenon, and electrochemical tests were conducted via linear sweet voltammetry (LSV) and cyclic voltammetry (CV). On the other hand, the effects of methanol concentration, temperature, freezing/thawing (F/T) tests and cell purging time, evaluating the performance of a single direct methanol fuel cell (DMFC), were investigated. Specific purging conditions were optimized to increase the durability of MEAs. SEM analysis of MEAs after F/T cycles showed that a significant MEA degradation occurred when the produced water is not removed. Such a degradation affected the subsequent cell performance and durability, which depend of the purging procedure, purging time, and purge flow. By opportunely modifications of the purging procedure, the performance of single DMFCs remained almost constant after 25 F/Ts.
File in questo prodotto:
File Dimensione Formato  
Non-Noble Metal Cathodic Electrocatalysts for PEM Fuel Cells and Direct Methanol Fuel Cells_Alessandro Monteverde.pdf

non disponibili

Tipologia: Tesi di dottorato
Licenza: Non Pubblico - Accesso privato/ristretto
Dimensione 3.85 MB
Formato Adobe PDF
3.85 MB Adobe PDF   Visualizza/Apri   Richiedi una copia
Pubblicazioni consigliate

Caricamento pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11583/2506285
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo