Fuel cells convert the chemical energy stored in hydrogen (H2) into electrical energy by electrochemically "combusting" hydrogen gas with oxygen (O2) from the air into water (H2O),thereby generating electricity. As a result, future electric automobiles might be operated fairly well with fuel cells instead of with heavy batteries. But for "cold" combustion of hydrogen and oxygen to function well, or the anode and cathode of the fuel cell must be coated with extremely active catalysts. The problem is that the platinum-based catalysts employed for this contribute approximately 25 per cent of the total fuel-cell costs.
Source: phys.org