Charge carrier dynamics and light harvesting ability are most important for the performance of a photoanode in photoelectrochemical (PEC) systems. In this work, through a facile flame surface treatment process in a reducing atmosphere, oriented WO3 nanoneedles are grown on pre-formed vertically aligned nanohelices. Nanohelices have excellent light harvesting abilities on their own; however, the addition of nanoneedles to the top of nanohelices increases the light harvesting abilities even further. More importantly, the reducing atmosphere for the post-treatment process enhances the metallic properties of WO3, changes the band position to facilitate hole transport, and modifies the flat band potential, all of which contribute to an improved performance in terms of photocurrent density and onset. The as-fabricated WO3 nanohelices/nanoneedles with a metallic interface have also been used for heterojunction photoanode fabrication for water oxidation through two- and four-electron pathways for H2O2 and O2 production, respectively.
Bibliographical noteFunding Information:
This work was supported by the NRF of Korea Grant funded by the Ministry of Science, ICT, and Future Planning (2013R1A2A1A09014038, 2015M1A2A2074663, NRF-2017M3A7B4041987). This work was supported in part by the Yonsei University Future-Leading Research Initiative of 2015 (2015-22-0067). X. L. Z. acknowledges generous nancial support from the Stanford Natural Gas Initiative (NGI) and the Stanford Precourt Institute of Energy (PIE). We also acknowledge Lauren Vallez for her support in English editing of this work.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)