Plasmon-enhanced light harvesting: applications in enhanced photocatalysis, photodynamic therapy and photovoltaics

Plasmonic nanostructures have played a significant role in the development of modern materials science and technology. Plasmon-enhanced solar light harvesting to enhance the efficiency of solar to fuel energy conversion has been one of the most important research areas of the last decade to help meet the worlds growing energy demand. Over the years, both organic and inorganic semiconductor materials, with high stability, environmental compatibility and photocatalytic activity, have been widely used as photocatalysts for direct conversion of solar energy into fuels. However, the efficiency of semiconductors is limited by their inability to absorb visible light due to high band gap. During last few years, great amount of research has been carried out to improve the efficiency of photocatalysts and photovoltaic devices by integration of plasmonic nanoparticles (NPs) with semiconductor materials. The presence of plasmonic NPs leads to increase in the absorption cross-section of semiconductors via strong field enhancement, extension of light absorption to longer wavelengths and enhances electron-hole charge separation in semiconductor medium, thus maximize the efficiency of photocatalytic and photovoltaic devices. In this review, we summarize recent advances made toward the integration of plasmonic nanostructures with semiconductor photocatalytic systems for enhanced light harvesting applications, including dye degradation, water splitting for H-2 generation, photodynamic therapy, chemical transformation and photovoltaics.