Design and Demonstration of Large Scale Cu 2 O Photocathodes with Metal Grid Structure for Photoelectrochemical Water Splitting

Upscaling of photoelectrode for a practical photoelectrochemical (PEC) water splitting system is still challenging because the PEC performance of large-scale photoelectrode is significantly low, compared to the lab scale photoelectrode. In an effort to overcome this challenge, sputtered gold (Au) and copper (Cu) grid lines were introduced to improve the PEC performance of large-scale cuprous oxide (Cu 2 O) photocathode in this work. It was demonstrated that Cu grid lines are more effective than Au grid lines to improve the PEC performance of large-scale Cu 2 O photocathode because its intrinsic conductivity and quality of grid lines are better than ones containing Au grid lines. As a result, the PEC performance of a 25-cm 2 scaled Cu 2 O photocathode with Cu grid lines was almost double than one without grid lines, resulting in an improved charge transport in the large area substrate by Cu grid lines. Finally, a 50-cm 2 scaled Cu 2 O photocathode with Cu grid lines was tested in an outdoor condition under natural sun. This is the first outdoor PEC demonstration of large-scale Cu 2 O photocathode with Cu grid lines, which gives insight into the development of efficient upscaled PEC photoelectrode.