Yes, light can split water molecules through a process called photocatalysis or photoelectrolysis. This process involves using light energy to drive a chemical reaction that separates water (H2O) into its constituent elements, hydrogen (H2) and oxygen (O2).
Photocatalysis typically requires a photocatalyst, which is a material that can absorb light energy and initiate the desired chemical reaction. One commonly used photocatalyst for water splitting is titanium dioxide (TiO2). When light is absorbed by the photocatalyst, it creates electron-hole pairs, where an electron is excited to a higher energy level and leaves behind a positively charged hole. These electrons and holes can then participate in chemical reactions.
In the case of water splitting, when the photocatalyst is illuminated with light, the excited electrons can reduce water molecules at the surface of the photocatalyst, leading to the production of hydrogen gas. The positively charged holes can oxidize water molecules, resulting in the release of oxygen gas. The overall reaction can be represented as:
2H2O -> 2H2 + O2
It's important to note that while light can split water molecules, the process is not spontaneous and requires an external energy source, such as sunlight or artificial light, to provide the necessary photons for the reaction to occur.