Photo-induced CO₂ reduction with GaN electrode in aqueous system

CO₂ reduction with water and light illumination is realized using a gallium nitride (GaN) photoelectrode in which excited electrons induce CO₂ conversion at the counter electrode. For the counter electrode, a copper (Cu) plate was chosen. The low affinity and wide gap of the nitride semiconductor enable us to create an electron-hole pair which has a sufficient energy for both CO₂ reduction and water oxidation, in spite of the fact that a high energy for CO₂ reduction is required. Within this system, the generation of formic acid (HCOOH) with 3% Faradic efficiency was confirmed by light illumination alone.