Abstract
We report on a highly improved CO2 to HCOOH conversion system using a tandem photo-electrode (TPE) of InGaN and two Si p-n junctions. To improve its efficiency, narrow-band-gap InGaN was applied as the photo-absorption layer. In the TPE structure, the current matching between GaN-based photo-absorption layer and two Si p-n junctions is crucial for the improvement of the efficiency. The energy conversion efficiency for HCOOH production reached 0.97%, which is greater than average of global biological photosynthetic one. (C) 2015 AIP Publishing LLC.