| 초록 |
Metal oxide semiconductors are promising photoelectrode materials due to their robustness in aqueous solutions, earth abundance and low cost. However, their relatively large band gaps limit the range of solar light utilization and thereby solar-to-hydrogen conversion efficiency (ηSTH). In this talk, I will present a novel strategy to improve ηSTH of metal oxides, i.e. hetero-type dual photoelectrodes, in which two photoanodes of different band gaps are connected in parallel for extended light harvesting. Thus, a PEC device made of modified BiVO4 and α-Fe2O3 as dual photoanodes utilize visible light up to 610 nm for water splitting, and showed stable photocurrents of 7.0 ±0.2 mA/cm2 at 1.23 V vs. RHE under 1 sun irradiation. This represents the highest value ever reported for metal oxide photoelectrodes under these conditions. When the dual photoanodes were integrated with a silicon solar cell, the tandem cell demonstrates stable and continuous unbiased water splitting with an STH efficiency of 7.7 %. The results represent a significant step forward en route to the goal of 10 % ηSTH required for practical solar hydrogen production using metal oxide semiconductors. |
