Abstract
Plasmonic photocatalysis enables innovation by harnessing photonic energy across a broad swathe of the solar spectrum to drive chemical reactions. This review provides a comprehensive summary of the latest developments and issues for advanced research in plasmonic hot electron driven photocatalytic technologies focusing on TiO2–noble metal nanoparticle heterojunctions. In-depth discussions on fundamental hot electron phenomena in plasmonic photocatalysis is the focal point of this review. We summarize hot electron dynamics, elaborate on techniques to probe and measure said phenomena, and provide perspective on potential applications—photocatalytic degradation of organic pollutants, CO2 photoreduction, and photoelectrochemical water splitting—that benefit from this technology. A contentious and hitherto unexplained phenomenon is the wavelength dependence of plasmonic photocatalysis. Many published reports on noble metal-metal oxide nanostructures show action spectra where quantum yields closely follow the absorption corresponding to higher energy interband transitions, while an equal number also show quantum efficiencies that follow the optical response corresponding to the localized surface plasmon resonance (LSPR). We have provided a working hypothesis for the first time to reconcile these contradictory results and explain why photocatalytic action in certain plasmonic systems is mediated by interband transitions and in others by hot electrons produced by the decay of particle plasmons.
Highlights
Solar energy is among the cleanest, and most abundant renewable energy sources available to the world
This review provides a survey of the current landscape of research in the field of plasmonic photocatalysis with specific focus on the development of artificial photosynthetic systems
The quantum yields achieved for localized surface plasmon resonance (LSPR)-driven photocatalytic reactions by a number of experimental reports, and the estimates of quantum efficiencies from spectroscopic studies for hot electron injection from noble metal nanoparticles into the conduction band of TiO2, significantly exceed the theoretical limits placed by the conventional sequential mechanism of surface plasmon dephasing and hot electron equilibration
Summary
Solar energy is among the cleanest, and most abundant renewable energy sources available to the world. Large-scale commercialization of semiconductor photocatalytic technology in the environmental and energy industries is still at its advent and remains to be fully exploited This is because despite their obvious advantages, critical and debilitating material-sensitive limitations have surfaced over the years concerning semiconductor photocatalysts. Plasmonic photocatalysts have emerged as a promising technology for harvesting and converting solar energy [31,32,33,34,35] This is achieved by the generation and transfer of energetic charge carriers or “hot electrons” via resonant interaction of incident light with the collective and coherent motion of electrons in metal nanostructures to initiate, enhance, and promote photocatalytic activity. We strongly believe this information will be valuable to both new researchers entering the field and even to experienced researchers who might have not considered a technique outside the suite of techniques they’re comfortable with
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