Conductive Graphitic Networks: From Atoms to Fuel Cells

Conductive Graphitic Networks: From Atoms to Fuel Cells

Negro, E.

van Esch, J.H. (promotor)
Picken, S.J. (promotor)
Koper, G.J.M. (promotor)

Applied Sciences

Chemical Engineering

2014-11-14

Graphitic materials have attracted a great interest in the field of sustainable energy production and storage because of their excellent electrical, mechanical and chemical properties. This thesis modestly contributes to this global research by investigating new interconnected carbon nanostructures, here called Carbon Nano-Networks (CNNs). The work is divided into two parts. The first part deals with the synthesis of CNNs consisting of Chemical Vapor Deposition (CVD) of ethene over metal catalyst nanoparticles (NPs) synthesized in bicontinuous microemulsions (BMEs). Chapter 1 focuses on the characterization of dense microemulsions, both experimentally and computationally, using a coarse-grained molecular dynamics simulation tool. Bicontinuity of microemulsions is visualized. Chapter 2 describes the synthesis of NPs in BMEs. The effect of the precursors and of the microemulsion composition on the size, polidispersity and stability of the NPs is analyzed. Finally a mechanism of formation of NPs in BMEs is proposed. Chapter 3 investigates the synthesis of CNNs via CVD of ethene over metallic particles synthesized in BMEs. The effect of synthesis parameters on the final structure is studied. Properties of CNNs, such as porosity and conductivity are investigated. The second part deals with the use of CNNs as catalyst support in Polymer electrolyte membranes (PEM) Fuel Cells. Chapter 4 gives a brief overview of PEM Fuel Cells basics, materials and challenges. In Chapter 5, activity and durability of Pt deposited over CNNs is compared to Pt over carbon nano-tubes and to commercial catalyst. In Chapter 6, CNNs are used as support for non-noble metal catalyst. Performances are evaluated in-situ and ex-situ. Chapter 7 deals with an innovative manufacturing technique for an electrode: CNNs are grown directly over carbon paper. Resistance to corrosion as a function of synthesis parameters is evaluated. Pt is electrodeposited over the synthesized electrode support, and its activity and durability is evaluated and compared to commercial catalyst. The results presented in terms of cost, activity or durability are either superior to commercial catalyst or of the same order of magnitude of state-of-the-art catalyst. Nevertheless, the simplicity of CNNs synthesis procedure, the low price of catalyst precursor and the reduction of manufacturing steps make this novel electrode promising as material for fuel cells. In conclusion, the work described in this thesis certainly does not lead to immediate improvements in efficiency of fuel cells but it does provide for new and potentially more sustainable material solutions with which it may well be possible to attain these improvements in the near future.

pem fuel cell
durability
carbon corrosion
graphitic carbon
Chemical Vapor Deposition
nanoparticle
microemulsion
molecular dynamics
non noble metal catalyst
platinum

https://doi.org/10.4233/uuid:6adc60af-f5ac-41dc-8d5e-0de0566a2c6a

9789462593749

Institutional Repository

doctoral thesis

(c) 2014 Negro, E.