Abstract
Enhanced plasmonic fields are a promising way to increase the efficiency of photocatalytic water splitting. The availability of atomically thin materials opens up completely new opportunities. We report photocatalytic water splitting on ultrathin CdSe nanoplatelets placed in plasmonic nanogaps formed by a flat gold surface and a gold nanoparticle. The extreme field intensity created in these gaps increases the electron–hole pair production in the CdSe nanoplatelets and enhances the plasmon-mediated interfacial electron transfer. Compared to individual nanoparticles commonly used to enhance photocatalytic processes, gap-plasmons produce several orders of magnitude higher field enhancement, strongly localized inside the semiconductor sheet thus utilizing the entire photocatalyst efficiently.
Highlights
Existing technologies are generally complicated and of low efficiency, it has been demonstrated that the strongly enhanced electric field created by plasmonic nanostructures can lead to increased electron−hole pair (e−h-pair) production in nearby semiconductor crystals, which facilitates hydrogen production using solar energy.[4−11] The availability of metallic nanoparticles of widely different shapes and sizes allows specific matching of the plasmonic resonance conditions to the semiconductor absorption bands and, optimizing the e−h-pair production.[12,13]
Compared to plasmons occurring in the vicinity of individual nanoparticles, up to 100-fold higher electric field enhancements are sustained in gaps of only few nanometers between two nanoparticles or a nanoparticle spaced above a flat metallic surface.[15,16]
The plasmonic enhancement of individual nanoparticles for solar water splitting has been widely studied,[17−19] no previous reports have focused on the enhanced photocatalysis generated in plasmonic nanogaps by using the much higher field intensities available
Summary
Existing technologies are generally complicated and of low efficiency, it has been demonstrated that the strongly enhanced electric field created by plasmonic nanostructures can lead to increased electron−hole pair (e−h-pair) production in nearby semiconductor crystals, which facilitates hydrogen production using solar energy.[4−11] The availability of metallic nanoparticles of widely different shapes and sizes allows specific matching of the plasmonic resonance conditions to the semiconductor absorption bands and, optimizing the e−h-pair production.[12,13]. Due to the strong localization of the optical field near plasmonic nanoparticles, the light intensity is channelled to the surface layers of the photocatalyst. Plasmon-enhanced photocatalytic water splitting from cadmium selenide (CdSe) nanoplatelets with a thickness of only 5 atomic layers or 1.7 nm[21] is demonstrated (Figure 1b,c).
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