Plasmonic Photoanodes for Solar Water Splitting with Visible Light

• Published in: Nano letters 2012-09, Vol.12 (9), p.5014-5019
• Main Authors: Lee, Joun, Mubeen, Syed, Ji, Xiulei, Stucky, Galen D, Moskovits, Martin
• Format: Article
• Language: English
• Subjects: Arrays; Catalytic methods; Collective excitations (including excitons, polarons, plasmons and other charge-density excitations); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electrochemistry - instrumentation; Electrodes; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Equipment Design; Equipment Failure Analysis; Exact sciences and technology; Gold; Hot electrons; Hydrogen - chemistry; Hydrogen - isolation & purification; Light; Materials science; Methods of nanofabrication; Nanocrystalline materials; Nanorods; Nanoscale materials and structures: fabrication and characterization; Nanostructure; Nanostructures - chemistry; Nanostructures - radiation effects; Nanostructures - ultrastructure; Nanotubes; Oxygen - chemistry; Oxygen - isolation & purification; Physics; Plasmonics; Semiconductors; Solar Energy; Surface and interface electron states; Surface Plasmon Resonance - instrumentation; Titanium - chemistry; Titanium - radiation effects; Titanium dioxide; Water - chemistry; Water splitting
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl302796f

We report a plasmonic water splitting cell in which 95% of the effective charge carriers derive from surface plasmon decay to hot electrons, as evidenced by fuel production efficiencies up to 20-fold higher at visible, as compared to UV, wavelengths. The cell functions by illuminating a dense array of aligned gold nanorods capped with TiO2, forming a Schottky metal/semiconductor interface which collects and conducts the hot electrons to an unilluminated platinum counter-electrode where hydrogen gas evolves. The resultant positive charges in the Au nanorods function as holes and are extracted by an oxidation catalyst which electrocatalytically oxidizes water to oxygen gas.