Plasmonic Water Splitting

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Science  08 Mar 2013:
Vol. 339, Issue 6124, pp. 1125
DOI: 10.1126/science.339.6124.1125-a

One issue in harvesting the energy in sunlight to split water for hydrogen generation is utilizing the lower-energy visible-light component. Mubeen et al. report on an integrated platform in which plasmons excited in gold nanorods (∼50 nm in diameter) create electron-hole pairs for driving the reaction. The nanorods are capped with a thin layer of titanium dioxide decorated with platinum nanoparticles, which act as the hydrogen generation catalysts. The sides of the nanorods are decorated with an inorganic cobalt-based oxygen evolution catalyst, so the nanorod also acts as the wire that completes the circuit. The plasmonic nature of the excitation generation was verified by showing that when operated as a photocathode (no cobalt catalyst but with a counterelectrode), the current generated tracked the changes in visible light intensity with wavelength. Indeed, the device operates less efficiently when illuminated only in the ultraviolet. Although the photon-to-hydrogen conversion efficiency is still low (∼0.1%), improvements such as increasing the surface area devoted to the platinum catalyst could be made. The device could also be used in tandem with devices that are more efficient in the ultraviolet than in the visible range.

Nat. Nanotechnol. 10.1038/nnano.2013.18 (2013).

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