How do hydrogen fuel cells convert chemical energy to electrical energy?

Hydrogen fuel cells convert chemical energy to electrical energy through a process called electrochemical reaction.

In a hydrogen fuel cell, hydrogen and oxygen are used to produce electricity, with water and heat as by-products. This process is known as an electrochemical reaction because it involves both electricity and chemistry. The hydrogen fuel cell consists of two electrodes - an anode and a cathode, separated by an electrolyte.

At the anode, hydrogen gas (H2) is introduced where it gets split into two hydrogen ions (H+) and two electrons (e-) through a process called oxidation. This is facilitated by a catalyst, usually made of platinum, which speeds up the reaction. The hydrogen ions then move through the electrolyte towards the cathode.

Meanwhile, the electrons that were separated from the hydrogen atoms cannot move through the electrolyte. Instead, they are forced to travel along an external circuit to the cathode, creating an electric current which can be used to power electrical devices.

At the cathode, oxygen gas (O2) is introduced. Here, it combines with the hydrogen ions and the electrons that have travelled along the external circuit, to form water (H2O). This process is called reduction.

The overall reaction in a hydrogen fuel cell is: 2H2 + O2 → 2H2O + electricity + heat. This reaction is exothermic, meaning it releases energy. The electricity produced can be used directly to power a motor, or it can be stored in a battery for later use.

In summary, hydrogen fuel cells convert chemical energy into electrical energy by splitting hydrogen gas at the anode to produce ions and electrons. The ions move through the electrolyte to the cathode, while the electrons create an electric current in an external circuit. At the cathode, the ions and electrons combine with oxygen to form water, completing the circuit and the electrochemical reaction.