Do you remember the content of A-level Chemistry regarding electrochemical cells? We will focus on fuel cell for now! 😊

Fuel Cell

• Work like battery, but they do not run down or need recharging.
• They produce electrcity and heat as long as fuel is supplied. 
• A fuel cell consists of 2 electrode: anode and cathode, sanwiched around an electrolyte. 

Hydrogen burns in air to form water: 2H₂(g) + O₂(g) ➔ 2H₂O(l)

Small amounts of nitrogen oxides are also formed in a reaction between nitrogen and oxygen in the air at high temps.

How It Works:

• Two electrodes are separated by a 
• membrane, which allows H⁺ ions to pass through but not H₂ and O₂ molecules.
• The electrons released by the reaction at the hydrogen electrode are used up at the O

₂ electrode. The p.d. set up pushes electrons through the external circuit, where they do work.

• Anode: H

₂ ➔ 2H⁺ + 2e^-

• Cathode: 2H

⁺ + 2e^- + 1/2O₂ ➔ H₂O

Commonly seen in Fuel Cell powered electric vehicle. 

Methanol-based fuel cells

Methanol is highly flammable, poisonous liquid alcohol, made from non-renewable waste or agricultural waste or the chemical recycling of CO₂. Much easier to store than hydrogen, doesn't need high pressures or low temps.

• Fuel cell operates between 
• 90°C - 120°C and uses the oxidation of methanol on a catalyst layer to form CO₂.
• Electrons are transported through an 

external circuit from anode to cathode.

CH₃OH(g) + 1½O₂(g) --> CO₂(g) + 2H₂O(l)

• Waste products: water and carbon dioxide
• Efficiency is low 
• because methanol can pass through the available membrane materials.
• Cannot power vehicles but are ideal for consumer goods

Ethanol-based fuel cell

Ethanol is produced by fermentation of sugar cane.

• Fuel cell: oxidation of ethanol using platinum-based catalyst (EXPENSIVE!)
• A 
• polymer acts as an electrolyte. The charge is carried by H⁺ ions.
• The liquid ethanol is oxidised at the anode in the presence of water, generating CO

₂, H+ ions and electrons.

• H+ ions travel through the electrolyte, react with oxygen from air and the electrons from the ext. circuit at the cathode forming H

₂O.

References:

• https://www.researchgate.net/figure/Chemical-reactions-of-direct-methanol-fuel-cell-DMFC_fig1_232318194
• https://www.researchgate.net/figure/Chemical-reactions-of-direct-methanol-fuel-cell-DMFC_fig1_232318194
• https://www.sciencedirect.com/science/article/abs/pii/S0360319915027846

This is the end of the topic!! Well done!

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