The two gases used to produce electricity in fuel cells are hydrogen (H2) as the fuel and oxygen (O2) as the oxidant. In a fuel cell, hydrogen is fed to the anode (negative electrode) and oxygen is supplied to the cathode (positive electrode), where they react to produce water, heat, and electricity through an electrochemical process called the oxidation-reduction reaction.
The main fuel source for the work of the cell is the mitochondria.
There are a few different types of vehicles that use hydrogen fuel. You can find cars and other forms of transport that use hydrogen, but the biggest consumer would have to be hydrogen fueled space rockets.
Fuel cells are an important part of a nuclear reactor. The component that powers the nuclear reactor is the reactor core and the fuel cells are found inside and hold uranium dioxide.