PhD Dissertation: Begüm Yarar Kaplan

PhD Dissertation: Begüm Yarar Kaplan

GAS DIFFUSION ELECTRODES BASED ON CARBON AND GRAPHENE FOR PEM FUEL CELL

 

 

Begüm Yarar Kaplan
MAT, PhD Dissertation, 2017

 

Thesis Jury

Assoc. Prof. Dr. Selmiye Alkan Gürsel (Thesis Advisor), Prof. Dr. Serhat Yeşilyurt

Assoc. Prof. Dr. Melih Papila, Assoc. Prof. Osman Öztürk, Assist. Prof. Dr. Oktay Demircan

 

 

Date & Time: 12th July, 2017 –  10:00 AM

Place: SUNUM G111

Keywords : Gas Diffusion Electrode, Wet-Laying, Electrosprayed Catalyst Layer, Hybrid Electrocatalyst, PEM Fuel Cell

 

Abstract

 

 

All the components of gas diffusion electrodes (GDE) of PEM fuel cells were developed in this thesis. In the first part, new carbon and cellulose fiber-based composite gas diffusion layer (GDL) were employed for PEM fuel cell by using a green and environmentally friendly ‘wet-laying’ process. Electrically conducting composite GDLs with excellent flexibility, uniformity, and porosity were achieved. Moreover, PEM fuel cell performance of the fabricated composite GDL was investigated. It was determined that these GDLs exhibited promising power output especially in mass transport losses region of polarization curve due to its unique porous structure (87% porosity) compared to commercial AvCarb®MGL carbon paper (77% porosity).  In second part of the thesis, Pt nanoparticles impregnated on graphene oxide (GO) and carbon black (CB) hybrid carbon supports with varying ratios with using rapid one-pot microwave irradiation. CB was used as an intercalating agent to avoid restacking of reduced graphene oxide (rGO) sheets, Pt/rGO-CB hybrid electrocatalyst with low CB content (25% wt.) delivered superior catalytic activity and fuel cell performance and power output (max. power density 1091 mW cm-2) compared to those of Pt/CB and Pt/rGO for 0.4 mgPt/cm2 loading. In third part of the thesis, a novel electrode preparation approach with Pt/graphene and Pt/graphene–CB hybrids by electrospraying for PEM fuel cells were investigated. Electrosprayed catalyst layer (CL) provided uniform and small size Pt distribution, and with introducing graphene-CB hybrids highly conductive and porous catalyst layer was obtained. Compared to conventional air-sprayed CL, and electrospayed CL was showed better PEM fuel cell performance with the maximum power densities of 441 mW cm-2 for electrosprayed electrode, and 327 mW cm-2 for sprayed electrode, were obtained at a relativelylow Pt loading.