Views: 0 Author: Site Editor Publish Time: 2024-11-20 Origin: Site
4 Components of a PEM Fuel Cell
– The anode, the negative terminal of the fuel cell, has several roles. It conducts electrons released from hydrogen molecules so that they can be used in an external circuit. It has channels etched into it to evenly disperse hydrogen gas over the surface of the catalyst.
– The cathode, the positive terminal of the fuel cell, has channels etched into it to distribute oxygen gas to the surface of the catalyst. It also conducts electrons from the external circuit back to the catalyst, where they can recombine with hydrogen ions and oxygen to form water.
– The electrolyte is a proton exchange membrane. This specially treated material looks like regular kitchen wrap and conducts only positively charged ions. The membrane blocks electrons. For a PEMFC, the membrane must be hydrated to function and remain stable.
– A catalyst is a special material that promotes the reaction of oxygen and hydrogen. It is usually made of platinum nanoparticles thinly coated on carbon paper or cloth. The catalyst is rough and porous so that the maximum surface area of the platinum can be exposed to hydrogen or oxygen. The platinum-coated side of the catalyst faces the PEM.
The heart of the cell is the proton exchange membrane. It allows protons to pass through almost unimpeded, while electrons are blocked. So when H2 hits the catalyst and splits into protons and electrons (remember, protons are the same as H+ ions), the protons go straight to the cathode side, while the electrons are forced through an external circuit. In the process, they do useful work, like lighting a light bulb or driving a motor, and then combine with protons and oxygen on the other side to produce water.
How does it work? Pressurized hydrogen gas (H2) enters the anode side of the fuel cell. This gas is forced through the catalyst under pressure. When the H2 molecule comes into contact with the platinum on the catalyst, it splits into two H+ ions and two electrons (e-). The electrons are conducted through the anode and through an external circuit (doing useful work, like turning a motor) and back to the cathode side of the fuel cell.
Meanwhile, on the cathode side of the fuel cell, oxygen (O2) is forced through the catalyst to form two oxygen atoms. Each of these atoms has a strong negative charge. This negative charge attracts two H+ ions across the membrane where they combine with an oxygen atom and two electrons from the external circuit to form a water molecule (H2O).