Tuesday, July 31, 2012: Japanese electronics maker Panasonic has announced the development of an artificial photosynthesis system, which converts carbon dioxide (CO2) to organic material (called formic acid) by illuminating with sunlight at a world's top efficiency of 0.2 per cent. This development will make it possible to realise a simple and compact system for capturing and converting wasted carbon dioxide from incinerators and electric generation plants, according to the company. The efficiency is said to be on a comparable level with real plants used for biomass energy. What makes this artificial photosynthesis system simple and efficient is the application of a nitride semiconductor.
"We found firstly that a nitride semiconductor has the capability to excite the electrons with enough high energy for the CO2 reduction reaction. Nitride semiconductors have attracted attention for their potential applications in highly efficient optical and power devices for energy saving. However, its potential was revealed to extend beyond solid devices; more specifically, it can be used as a photo-electrode for CO2 reduction. Making a deviced structure through the thin film process for semiconductors, the performance as a photo-electrode has highly improved," the company says in a release.

The release also explains that the CO2 reduction takes place on a metal catalyst at the opposite side of nitride semiconductor photo-electrode. The metal catalyst plays an important role in selecting and accelerating the reaction. Here, it is noted that the system comprises only inorganic materials, which can reduce the CO2 with low energy loss. Because of this, the amount of reaction products is exactly proportional to the light power.

This is one of the merits in such an all-inorganic system while some conventional systems cannot follow the light power in general because of their internal or external rate-limiting processes in the complex structures.