Mechanisms and Applications of Plasmon-Induced Charge Separation at TiO₂ Films Loaded with Gold Nanoparticles

TLDR

Au‑nanoparticle‑loaded porous TiO₂ films were fabricated by photocatalytic deposition and used to study visible‑light plasmon‑induced photoelectrochemistry. The Au‑TiO₂ composites exhibit plasmon‑driven charge separation that matches the gold absorption spectrum, enabling a Fe(2+/3+)‑mediated photovoltaic cell to reach 26 % IPCE and photocatalytic oxidation of ethanol and methanol under visible light, indicating promise for new photocatalysts and photovoltaic fuel cells.

Abstract

Plasmon-induced photoelectrochemistry in the visible region was studied at gold nanoparticle-nanoporous TiO(2) composites (Au-TiO(2)) prepared by photocatalytic deposition of gold in a porous TiO(2) film. Photoaction spectra for both the open-circuit potential and short-circuit current were in good agreement with the absorption spectrum of the gold nanoparticles in the TiO(2) film. The gold nanoparticles are photoexcited due to plasmon resonance, and charge separation is accomplished by the transfer of photoexcited electrons from the gold particle to the TiO(2) conduction band and the simultaneous transfer of compensative electrons from a donor in the solution to the gold particle. Besides its low-cost and facile preparation, a photovoltaic cell with the optimized electron mediator (Fe(2+/3+)) exhibits an optimum incident photon to current conversion efficiency (IPCE) of 26%. The Au-TiO(2) can photocatalytically oxidize ethanol and methanol at the expense of oxygen reduction under visible light; it is potentially applicable to a new class of photocatalysts and photovoltaic fuel cells.