Degenerating Plasmonic Modes to Enhance the Performance of Surface Plasmon Resonance for Application in Solar Energy Conversion

Abstract

generation of photoinduced charge carriers which is a fundamental issue in the fi eld of solar energy conversion. [ 2 ] Undoubtedly, this work will provide guidance on how to take full advantages of the SPR effect in applications, such as future designing plasmonic devices in the fi elds of solar energy conversions.This study based on the combining our improved ultrathin alumina membrane (UTAM) technique with atomic layer deposition (ALD) method. [ 17,18 ] As known, SPR property is very sensitive to structural parameters of nanoparticles including dimension, shape, distribution, and so on. [ 1,6,15,19 ] Compared with the dipole SPR mode, multipole modes are much more sensitive to the uniformity, distribution, and ordering of nanostructures. [ 17 ] Recently, we improved the UTAM technique, which ensured plasmonic metallic nanoparticles can be distributed orderly on large substrates (>cm 2 ) with identical shape, uniform size, and distance. [ 17 ] Different SPR modes focus consequently on their own positions. [ 17 ] Therefore, sharp and clear SPR peaks for both dipole and quadrupole modes of Ag nanoparticle arrays can be detected. On the other hand, ALD method allows us to control highly uniform dielectric shells (TiO 2 , Al 2 O 3 , etc.) with atomic spatial resolution normal to the plasmonic nanoparticle surface, [ 18 ] which provides a chance to study the effect of shell on different SPR modes extensively. [ 20 ] UTAMs with the thickness of ≈300 nm were prepared and carefully mounted on substrates according to our innovative template transferring method described recently. [ 17 ] Using these UTAMs as patterning masks, Ag nanoparticles were fabricated on ITO (indium tin oxide)-coated glass by electron beam evaporation. After removing the UTAM, a uniform TiO 2 shell layer was coated on the Ag nanoparticles by ALD to form Ag@TiO 2 core-shell nanocapsule structures. The fabrication process is outlined in Figure 1 a and details are described in the Experimental Section. Figure 1 b-e is the corresponding SEM (scanning electron microscopy) images. In the tilted (45°) SEM images of Figure 1 b,c, parts of the UTAM are remained intentionally. As can be seen from these images, the transferred UTAM is of highly ordered arrangement of nanopores and ideally mounted on the substrate. The prepared Ag nanoparticles completely inherit the regularity of the UTAM template. As shown in Figure 1 d, monodispersed Ag nanoparticles have uniform size and distances. Larger area SEM images of the UTAM and nanoparticle array are shown in Figure S1 (Supporting Information). The cross-sectional AFM (atomic force microscopy) profi le shown in Figure 1 f illustrates that the height and period of Ag nanoparticles are ≈42 and 100 nm, respectively. Considering the broadening effect resulting from the size of the AFM tip, the actual shape of the nanoparticles should be sharper than that in the cross-sectional profi le. [ 21 ] Figure 1 e is a top-view Adv. Energy Mater. 2015, 5, 1501654

Photoelectrocatalytic Materials for Solar Water Splitting

“…Coating Ag with TiO 2 shells, the quadrupole SPR mode of ordered Ag nanoparticles in UV region was degenerated to coincide with dipole mode in visible region through changing the deviations of refractive index between Ag core and outer dielectric TiO 2 shells. This degeneracy of SPR modes greatly promoted the generation of photoinduced charge carriers and enhanced the photocatalytic activity . The plasmon resonance wavelength and line width of plasmonic nanoparticles can also be adjusted through varying the shell thickness and aspect ratio of the bimetallic core–shell nanostructures.…”

Plasmon‐Dictated Photo‐Electrochemical Water Splitting for Solar‐to‐Chemical Energy Conversion: Current Status and Future Perspectives

“…For example, it has been reported that metal nitrides (ZrN and TiN) can be used as alternative to plasmonic metals for vis‐NIR‐responsive photocatalysis . Since plasmonic resonances are closely associated with the material properties, we strongly envisage that new plasmonic materials will definitely bring more degree of freedom for spectral design, thereby resulting in the production of more diverse plasmonic electrodes for PEC water splitting.…”

Silver nanoparticles-sensitized cobalt complex for highly-efficient photocatalytic activity

“…S2 and Table 1, the grain sizes of composite 1-5 were between 3.4 and 11.7 nm. It can be observed that Ag NPs have been obtained with narrow size distributions [20]. This study indicates that the porous structure facilitate the separation of photo-generated electron-hole pairs [52].…”

“…Among various candidates, Ag NPs is one of the most effective sensitizers in photocatalytic H 2 evolution [18,19], due to their relative low cost, facile preparation and high efficiency under near-neutral pH conditions [20,21]. It is also proved that Ag NPs displays strong surface plasmon resonance (SPR) effect even its size decreases to below 10 nm [20,22]. As for their promising light-harvesting and electron transfer properties, Ag NPs have been successfully incorporated with M-complexes and underexplored in photocatalytic applications [11,23].…”