Coupling Plasmonic and Cocatalyst Nanoparticles on N–TiO2 for Visible-Light-Driven Catalytic Organic Synthesis

Abstract

The use of the surface plasmon resonance (SPR) effect of plasmonic metal nanocomposites to promote photocarrier generation is a strongly emerging field for improving the catalytic performance under visible-light irradiation. In this study, a novel plasmonic photocatalyst, AuPt/N–TiO2, was prepared via a photo-deposition–calcination technique. The Au nanoparticles (NPs) were used herein to harvest visible-light energy via the SPR effect, and Pt NPs were employed as a cocatalyst for trapping the energetic electrons from the semiconductor, leading to a high solar-energy conversion efficiency. The Au2Pt2/N–TiO2 catalyst, herein with the irradiation wavelength in the range 460–800 nm, exhibited a reaction rate ~24 times greater than that of TiO2, and the apparent quantum yield at 500 nm reached 5.86%, indicative of the successful functionalization of N–TiO2 by the integration of Au plasmonic NPs and the Pt cocatalyst. Also, we investigated the effects of two parameters, light source intensity and wavelength, in photocatalytic reactions. It is indicated that the as-prepared AuPt/N–TiO2 photocatalyst can cause selective oxidation of benzyl alcohol under visible-light irradiation with a markedly enhanced selectivity and yield.

Review of Experimental Setups for Plasmonic Photocatalytic Reactions

“…Photoluminescence (PL) is also used in characterizing the effect of hot charge recombination in photocatalytic reactions [114][115][116][117][118]. Decreased PL peaks indicate suppressed recombination of photoinduced charge carriers, which can lead to an enhanced photocatalytic reactions.…”

“…They applied a magnetic field by placing a permanent magnet beneath the photocatalytic system. Studies on metal-decorated heterostructure photocatalyst have revealed that PL spectra of original photocatalysts had stronger signals than did those of metal-photocatalyst heterostructures [114][115][116][117]. This indicates the decreased recombination rate of photoinduced charge carriers and enhanced photocatalytic activity of metal-decorated nanoparticles.…”

Reduction-Induced Synthesis of Reduced Graphene Oxide-Wrapped Cu2O/Cu Nanoparticles for Photodegradation of Methylene Blue

“…Sustainable use of material, scalable synthesis, biosafety, and abundance of material have become integral and important considerations in the material development process. Metal oxide semiconductors acting as photoharvesters form a broad class of photocatalytic materials, and TiO 2 , ZnO, WO 3 , CuO, and Cu 2 O are some of the most cost-effective photocatalytic materials being researched. − Optimization of material properties enabling efficient production of electron–hole pairs from abundant solar photons, effective charge separation and transportation with minimal intermediate losses, resistance to photocorrosion, and long-term stability of the material, especially under aqueous environments, have become critically important, while careful choice of an accompanying metal co-catalyst can further enhance the associated photocatalytic redox reaction. , Fujishima and Honda in 1972 realized the first ever electrochemical photolysis of water using TiO 2 , and over the years the material has demonstrated its promise as an excellent photocatalyst in a variety of photocatalytic applications. − However, its wide band gap (>3.0 eV) ,, only allows harvesting the ultraviolet end of the solar spectrum, making its photoelectron yield slightly low for terrestrial applications.…”

“…To reduce undesirable electron–hole recombination or to gain high quantum efficiency, photocatalysts are often decorated with metal nanoparticle co-catalysts (Pt, Pd, Au, Rh, etc.) . These noble-metal nanoparticles improve charge separation and migration by forming a Schottky barrier between them and the semiconductor.…”

Application of New Nanoparticle Structures as Catalysts

“…Y. Wang et al reported on the use of the surface plasmon resonance effect, in this case in a metal nanocomposite, AuPt/N–TiO 2 , used as a photocatalyst [ 6 ]. While the Au nanoparticles were used to obtain energy from visible-light, Pt nanoparticles work as a cocatalyst, trapping the energetic electrons from the semiconductor support.…”