Abstract
We demonstrated that the selectivity of photo electrochemical CO2 reduction can be controlled in an inorganic artificial photosynthesis system using an AlGaN/GaN photo electrode. By increasing input light intensity and the use of a gold cathode, the Faradaic efficiency of CO dramatically increases from 30% to over 80% while that of H-2 decreases. We observed that the cathode potential resulting from illumination determines the ratio of CO and H-2. With this system, it is possible to switch the main reaction product from CO to HCOOH, which is also effective even under intense illumination. (c) 2013 The Japan Society of Applied Physics