Photochemical conversion refers to the conversion of solar light radiation energy into chemical energy storage, or the use of sunlight to achieve certain specific chemical reaction processes.
There are two types of power generation using photochemical conversion: photochemical cells and photobiological power generation.
The light radiation energy of the sun is converted into electrical energy through a certain chemical reaction process, which is called photochemical power generation. It usually refers to the phenomenon that a semiconductor electrode immersed in a solution is exposed to light, and there is a current output on the electrode. Photochemical power generation can generally be subdivided into liquid junction photochemical cells, photoelectrolytic cells, and photocatalytic cells.
The liquid junction photochemical cell contains only one redox substance in the electrolyte, and the redox reversible reaction can be carried out between the positive and negative electrodes. Under the action of light, the interfacial barrier (called liquid junction) between the semiconductor electrode and the solution separates the photogenerated electron and hole pairs, and provides electrical energy to the outside world, and the electrolyte body does not change.
In the photoelectrolysis battery, there are two redox ions in the electrolyte, which undergo chemical changes under the action of light, effectively converting light energy into chemical energy.
The photocatalytic battery provides the activation energy required for chemical reactions by light energy, and the electrolyte undergoes chemical changes after illumination.
Photochemical power generation has a liquid phase component, and it is easy to make a solar photochemical battery for direct energy storage. However, at present, photochemical power generation is still in the research and test stage.
②Photobioelectric power generation
The photosynthesis of green plants is also a photochemical conversion process. The process of converting solar energy into biomass energy through photosynthesis is called photobiological utilization. Plants for this purpose mainly include fast-growing plants, oil crops and giant seaweeds. These plants can be used as fuels for power generation or the production of liquid fuels such as ethanol.
Photobiological power generation usually refers to the generation of green cells, which is also a photochemical conversion process. Chlorophyll can generate electric current under the action of light, which is one of the most common biological phenomena. However, due to the continuous metabolism of chlorophyll cells, it is still difficult to make a stable chlorophyll battery.
Some people refer to the photosynthesis process and propose that a variety of dyes are coated on porous titanium oxide semiconductors to form a solid-state biomimetic photosynthesis cell, which can achieve a photoelectric conversion efficiency of 10%. This kind of battery has the advantages of low cost and high efficiency, but there are also serious problems such as light aging that need to be solved.
The energy conversion process used by solar energy is in addition to the utilization form of photochemical conversion. There are also solar power generation and other forms of utilization. If you want to know more, this site has more knowledge about solar energy and its utilization .