PEMFCs - **Widespread Applications:** transport, stationary power generation, and portable devices. - **Functioning:** Operate based on electrochemical reactions and employ a special proton-conducting polymer electrolyte membrane. - **Components:** membrane electrode assembly (MEA), including the electrodes, electrolyte, catalyst, and gas diffusion layers. - **Catalyst Link:** A catalyst ink, containing carbon and electrode, is applied to the solid electrolyte, and carbon paper is pressed on either side to act as protection and electrodes. - **Triple phase boundary (TPB)** within the fuel cell, where the electrolyte, catalyst, and reactants combine, is crucial for the occurrence of cell reactions ### Operating Principle The working principle of a PEMFC involves the **conversion of the chemical energy of hydrogen and oxygen into electrical energy** through electrochemical reactions. At the anode side, hydrogen is catalytically split into protons and electrons, generating an oxidation half-cell reaction. The protons permeate through the polymer electrolyte membrane to the cathode side, while the electrons flow through an external circuit, creating an electric current. At the cathode side, oxygen reacts with the protons and electrons to form water, resulting in a reduction half-cell reaction. The overall reaction of a PEMFC is the combination of these half-cell reactions, converting hydrogen and oxygen into water while producing electrical energy ### Benefits 1. High efficiency: PEMFCs have a high electrical efficiency, allowing for the direct conversion of chemical energy into electrical energy with minimal energy loss. 2. Environmental friendliness: PEMFCs operate using hydrogen as a fuel and produce only water as a byproduct, making them environmentally friendly with no greenhouse gas emissions. 3. Quick start-up and response time: PEMFCs can achieve full power output quickly and respond rapidly to changes in power demand, making them suitable for applications requiring dynamic power generation. 4. Compact and lightweight: PEMFCs have a relatively compact and lightweight design, making them suitable for portable and mobile applications. 5. Low operating temperature: PEMFCs operate at lower temperatures compared to other fuel cell types, which simplifies system design and reduces heat management requirements. 6. Quiet operation: PEMFCs operate silently without any combustion or mechanical moving parts, resulting in quiet operation.