The leaf is actually a thin sandwich of inorganic materials that uses the energy of sunlight to break the chemical bonds holding hydrogen and oxygen atoms together in ordinary H2O. The leaf works because the middle of the sandwich is what's called a photovoltaic wafer, which converts sunlight into wireless electricity, and that electricity is then channeled to the outer layer of the "leaf," which is coated with different chemical catalysts on either side. One accelerates the formation of hydrogen gas, the other oxygen.