Photoelectrochemical oxidation is when sunlight (or other light) is used to make a chemical reaction happen. It's like using the sun's energy to do something that normally needs electricity.
Imagine you have a toy car and you want to make it move. You could push it with your hands, but that would be a lot of work. Instead, you could use a remote control to make the car move without touching it.
In photoelectrochemical oxidation, the sunlight acts like a remote control for the chemical reaction. The reaction is like the toy car - it needs energy to move. The sunlight provides the energy so the reaction can happen.
When the sunlight hits the material, it makes electrons move. Those electrons can then be used to make a chemical reaction happen. It's like the sunlight is the key that unlocks a door so the reaction can happen.
For example, photoelectrochemical oxidation can be used to clean dirty water. When sunlight hits a special material in the water, it makes a chemical reaction happen that breaks down pollutants into harmless molecules. It's like using the sun's energy to clean the water without needing electricity.
So in summary, photoelectrochemical oxidation is using the energy from sunlight to make a chemical reaction happen without needing electricity.