Affiliation: | 1. Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, 08826 Republic of Korea School of Chemical and Biological Engineering, Seoul National University, Seoul, 08826 Republic of Korea;2. School of Advanced Materials Engineering, Kookmin University, Seoul, 02707 Republic of Korea;3. Division of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673 Republic of Korea;4. Beamline Department, Pohang Accelerator Laboratory (PAL), Pohang, 37673 Republic of Korea;5. Department of Chemical Engineering, Hoseo University, Asan, 31499 Republic of Korea;6. Laboratory for Molecular Engineering of Optoelectronic Nanomaterials, École Polytechnique Fédérale de Lausanne (EPFL), Station 6, 1015 Lausanne, Switzerland;7. Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208 USA;8. Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, 08826 Republic of Korea |
Abstract: | Nanostructured metal oxide semiconductors have shown outstanding performances in photoelectrochemical (PEC) water splitting, but limitations in light harvesting and charge collection have necessitated further advances in photoelectrode design. Herein, we propose anodized Fe foams (AFFs) with multidimensional nano/micro-architectures as a highly efficient photoelectrode for PEC water splitting. Fe foams fabricated by freeze-casting and sintering were electrochemically anodized and directly used as photoanodes. We verified the superiority of our design concept by achieving an unprecedented photocurrent density in PEC water splitting over 5 mA cm−2 before the dark current onset, which originated from the large surface area and low electrical resistance of the AFFs. A photocurrent of over 6.8 mA cm−2 and an accordingly high incident photon-to-current efficiency of over 50 % at 400 nm were achieved with incorporation of Co oxygen evolution catalysts. In addition, research opportunities for further advances by structual and compositional modifications are discussed, which can resolve the low fill factoring behavior and improve the overall performance. |