Advanced electrocatalyst development for direct alcohol fuel cells (DAFCs); direct methanol fuel cell (DMFCs), direct ethanol fuel cell (DEFCs), and direct ethylene glycol fuel cell (DEGFCs)
Background
Direct alcohol fuel cells (DAFCs) are electrochemical devices that can be directly fed with alcohol fuel to produce electricity via electrochemical oxidation. Among all DAFCs types, the most attractive liquid fuels are methanol, ethanol and ethylene glycol having high energy density compared to others (as shown in Figure 1), and also low cost. The most complicated challenge for the DAFC development is sluggish in kinetics for bond breaking of fuels (methanol, ethanol and ethylene glycol) in the electrooxidation processes at an anode site due to complex multiple-electron process involving many intermediates and products. Therefore, the design of electrocatalyst materials for DAFCs, which can accelerate their reactions, is a significant requirement. Our research team has developed advanced catalyst materials providing high electrocatalytic activity for C-C bond breaking and tolerance stability.
Figure 1: Volumetric electrical energy density in kWh/l for different fuels, compressed gaseous hydrogen (CGH2), liquid hydrogen (LH2), methanol, ethanol and ethylene glycol.
Ethanol Oxidation
Direct ethanol fuel cells (DEFCs) are one of the most promising carbon- neutral, sustainable, and efficient power sources for powering portable, mobile, and stationary devices.
Methanol Oxidation
Direct methanol fuel cells (DMFCs) are one of the most promising alternative power sources for powering portable devices. DMFCs offer a number of advantages such as high density of liquefied methanol, high-energy conversion efficiency (~40%), high electron density (6 electrons a methanol molecule), and low operating temperature (50–200 °C).
However, there are a number of drawbacks inhibiting practical uses of DMFCs. The first one is that direct oxidation of methanol within a fuel cell stack requires large quantities of precious catalysts, e.g. Pt. The second problem is the self-poisoning of Pt by CO, one of intermediates in methanol oxidation, leading to relatively slow reaction kinetics. A key challenge in the development of fuel cell technology is therefore the development of stable, high activity, and lower cost catalytic materials. Therefore, an ultraporous Pd nanostructure was electrodeposited on rGO-coated CFP. The as-fabricated catalyst exhibits excellent poisoning tolerance to carbonaceous species for the electrooxidation of methanol.
Ethylene Glycol Oxidation
Direct ethylene glycol fuel cells (DEGFCs) are of interest and being studied as a candidate of direct alcohol fuel cells. This is because ethylene glycol (EG) has low toxicity, available in supply chain (not yet for methanol), inflammability, high boiling point of 198 °C (64.7 °C for methanol), and superior energy density (7.56 kWh dm
-3) or high theoretical capacity of 4.8 Ah ml
-1 (4.0 Ah ml
-1 for methanol).
The Pd/3D graphene aerogel paper exhibits higher catalytic activity toward the electro- oxidation of ethylene glycol in alkaline media and higher excellent tolerance stability than other electrodes due to ultra-high porosity of the 3D graphene support leading to high active electrochemical surface area of the as-fabricated Pd catalyst electrode.
The development of highly active Pd and Pd-based catalyst anode electrodes with high If/Ib ratio is consequently crucial for the practical use of ADEFCs. We found that the ultra porous Pd/rGO/CFP is one of the best electro-catalysts for DEFCs.
- A. Krittayavathananon; M. Sawangphruk, Electrocatalytic oxidation of ethylene glycol on palladium coated on 3D reduced graphene oxide aerogel paper in alkali media: Effects of carbon supports and hydrodynamic diffusion (DOI: 10.1016/j.electacta.2016.06.162.)
- M. Sawangphruk; A. Krittayavathananon; N. Chinwipas; P. Srimuk; T. Vatanatham;S. Limtrakul; J. S. Foord, Fuel Cells, 13, 5,881–888, 2013
- M. Sawangphruk; A. Krittayavathananon; N. Chinwipas, J. Mater. Chem. A, 2013, 1,1030
Dr. Montree Sawangphruk (Assistant Professor)
Dr. Kanokwan Kongpatpanich (Lecturer)
Dr. Saran Kalasina (Postdoctoral Research Fellow)
Ms. Atiweena Krittayavathananon
Mr. Poramane Chiochan
Mr. Chan Tanggarnjanavalukul
Ms. Montakan Suksomboon
Mr. Nutthaphon Phattharasupakun
Ms. Juthaporn Wutthiprom
Ms. Siriroong Kaewruang
Mr. Jakkrit Khuntilo
Ms. Phansiri Suktha
Mr. Pawin Iamprasertkun
Mr. Tanut Pettong
Ms. Pichamon Sirisinudomkit
International Research Collaborator:
Prof. John S Foord
University of Oxford
Wangchan Valley 555 Moo 1 Payupnai, Wangchan, Rayong 21210 Thailand
