Morphology-Governed Performance of Plasmonic Photocatalysts

Abstract

Plasmonic photocatalysts have been extensively studied for the past decade as a possible solution to energy crisis and environmental problems. Although various reports on plasmonic photocatalysts have been published, including synthesis methods, applications, and mechanism clarifications, the quantum yields of photochemical reactions are usually too low for commercialization. Accordingly, it has been proposed that preparation of plasmonic photocatalysts with efficient light harvesting and inhibition of charge carriers’ recombination might result in improvement of photocatalytic activity. Among various strategies, nano-architecture of plasmonic photocatalysts seems to be one of the best strategies, including the design of properties for both semiconductor and noble-metal-deposits, as well as the interactions between them. For example, faceted nanoparticles, nanotubes, aerogels, and super-nano structures of semiconductors have shown the improvement of photocatalytic activity and stability. Moreover, the selective deposition of noble metals on some parts of semiconductor nanostructures (e.g., specific facets, basal or lateral surfaces) results in an activity increase. Additionally, mono-, bi-, and ternary-metal-modifications have been proposed as the other ways of performance improvement. However, in some cases, the interactions between different noble metals might cause unwanted charge carriers’ recombination. Accordingly, this review discusses the recent strategies on the improvements of the photocatalytic performance of plasmonic photocatalysts.

Sulvanites: The Promise at the Nanoscale

“…Furthermore, in photocatalysis, it was proved that the preparation of plasmonic photocatalysts with improved light harvesting, reduced carrier recombination, and thus, improved photocatalytic activity benefit from nano-architectures. Among such morphologies, faceted nanoparticles, nanotubes, aerogels, and other nanostructures of semiconductors showed improved photocatalytic activity and stability [ 68 ].…”

Morphology-Governed Performance of Multi-Dimensional Photocatalysts for Hydrogen Generation

“…However, it should be stressed that, considering the mechanism via charge transfer, the direction of electron transfer is opposite during plasmonic photocatalysis than that during hydrogen evolution, i.e., from noble metal to titania. Therefore, though plasmonic photocatalysts are active under vis irradiation for various reactions, usually there is no (or very low, as compared with that under UV light) activity for hydrogen generation under sole vis irradiation [62][63][64][65]. Accordingly, either two kinds of metals (first for plasmonic excitation and second for hydrogen evolution) or more advanced structures (for example, the "advanced superstructure system", i.e., the composite of titania meso-crystals with deposits of noble metals [66,67] (discussed in Section 6)), have been proposed.…”

Novel Structures and Applications of Graphene-Based Semiconductor Photocatalysts: Faceted Particles, Photonic Crystals, Antimicrobial and Magnetic Properties

“…Although the composites of G/GO/rGO/wide-bandgap semiconductors are widely investigated for various photocatalytic applications, the function of graphene has not been completely understood yet, as comprehensively summarized by Giovannetti et al [14]. It has been proposed that electrons from conduction band (CB) of wide-bandgap semiconductor under UV irradiation migrate to graphene, due to its more positive Fermi level, and thus hindering recombination of photogenerated charge carriers (e − /h + ), whereas the opposite direction of electron migration is expected under vis irradiation, i.e., from photoexcited state of graphene to CB of titania (similarly to plasmonic photocatalysis [15]).…”

“…Figure15. Schematic mechanism of photodegradation of organic pollutants on BiFeO3-graphene heterojunction.…”