Nano Letters · 2011 · 896 citations · 39 references
Natural SciencesMaterials EngineeringMaterials ScienceElectrochemistryNanomaterialsNanotechnologyElectrochemical Energy ConversionElectrode MaterialsElectrode-electrolyte InterfacesNanostructured Energy MaterialsPhotoelectrochemical MaterialsPhotoelectrochemistryCarrier CollectionCharge Carrier DensityCharge CollectionCharge SeparationNanorodsNanostructured PhotoelectrodesPhotocurrent GenerationSurface Area
We report a hierarchically branched TiO(2) nanorod structure that serves as a model architecture for efficient photoelectrochemical devices as it simultaneously offers a large contact area with the electrolyte, excellent light-trapping characteristics, and a highly conductive pathway for charge carrier collection. Under Xenon lamp illumination (UV spectrum matched to AM 1.5G, 88 mW/cm(2) total power density), the branched TiO(2) nanorod array produces a photocurrent density of 0.83 mA/cm(2) at 0.8 V versus reversible hydrogen electrode (RHE). The incident photon-to-current conversion efficiency reaches 67% at 380 nm with an applied bias of 0.6 V versus RHE, nearly two times higher than the bare nanorods without branches. The branches improve efficiency by means of (i) improved charge separation and transport within the branches due to their small diameters, and (ii) a 4-fold increase in surface area which facilitates the hole transfer at the TiO(2)/electrolyte interface.
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Electrochemical Photolysis of Water at a Semiconductor Electrode
Akira Fujishima, Kenichi Honda · Nature · 1972 · 33.7K citations