Seawater-Mediated Solar-to-Sodium Conversion by Bismuth Vanadate Photoanode- Photovoltaic Tandem Cell: Solar Rechargeable Seawater Battery

• Published in: iScience Vol. 19; pp. 232 - 243
• Main Authors: Kim, Jin Hyun, Hwang, Soo Min, Hwang, Inchan, Han, Jinhyup, Kim, Jeong Hun, Jo, Yim Hyun, Seo, Kwanyong, Kim, Youngsik, Lee, Jae Sung
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 27.09.2019; Elsevier
• Subjects: Electrochemical Energy Conversion; Energy Storage; Materials Characterization; Materials Characterization; Electrochemical Energy Conversion; Energy Storage
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2019.07.024

Conversion of sunlight to chemical energy based on photoelectrochemical (PEC) processes has been considered as a promising strategy for solar energy harvesting. Here, we propose a novel platform that converts solar energy into sodium (Na) as a solid-state solar fuel via the PEC oxidation of natural seawater, for which a Na ion-selective ceramic membrane is employed together with photoelectrode (PE)-photovoltaic (PV) tandem cell. Using an elaborately modified bismuth vanadate-based PE in tandem with crystalline silicon PV, we demonstrate unassisted solar-to-Na conversion (equivalent to solar charge of seawater battery) with an unprecedentedly high efficiency of 8% (expected operating point under 1 sun) and measured operation efficiency of 5.7% (0.2 sun) and long-term stability, suggesting a new benchmark for low-cost, efficient, and scalable solid solar fuel production. The sodium turns easily into electricity on demand making the device a nature-friendly, monolithic solar rechargeable seawater battery. [Display omitted] •Solar rechargeable battery using natural seawater as a medium was realized•Solar charge was achieved by metal oxide-based photoelectrodes, especially BiVO4•BiVO4-c-Si tandem cell achieved unbiased charge with a high efficiency up to 8% Electrochemical Energy Conversion; Energy Storage; Materials Characterization