Photoelectrochemistry of core–shell tandem junction n–p+-Si/n-WO3microwire array photoelectrodes
By Shaner, Matthew R.; Fountaine, Katherine T.; Ardo, Shane; Coridan, Rob H.; Atwater, Harry A. & Lewis, Nathan S.
Published in Energy Environ. Sci.
The Royal Society of Chemistry
2014
Abstract
Tandem junction (n-p+-Si/ITO/WO3/liquid) core-shell microwire devices for solar-driven water splitting have been designed, fabricated and investigated photoelectrochemically. The tandem devices exhibited open-circuit potentials of Eoc = -1.21 V versus E0[prime or minute](O2/H2O), demonstrating additive voltages across the individual junctions (n-p+-Si Eoc = -0.5 V versus solution; WO3/liquid Eoc = -0.73 V versus E0[prime or minute](O2/H2O)). Optical concentration (12[times], AM1.5D) shifted the open-circuit potential to Eoc = -1.27 V versus E0[prime or minute](O2/H2O) and resulted in unassisted H2 production during two-electrode measurements (anode: tandem device, cathode: Pt disc). The solar energy-conversion efficiencies were very low, 0.0068% and 0.0019% when the cathode compartment was saturated with Ar or H2, respectively, due to the non-optimal photovoltage and band-gap of the WO3 that was used in the demonstration system to obtain stability of all of the system components under common operating conditions while also insuring product separation for safety purposes.