Nanogold plasmonic photocatalysis for organic synthesis and clean energy conversion

Plasmon-driven photoregeneration of cofactor molecules

Platinum-doped gold nanorods are able to regenerate cofactor molecules under visible and infrared light irradiation. Our results suggest promising use of plasmonic particles in biochemical reactions.

Recent Development of Plasmonic Resonance-Based Photocatalysis and Photovoltaics for Solar Utilization

Increasing utilization of solar energy is an effective strategy to tackle our energy and energy-related environmental issues. Both solar photocatalysis (PC) and solar photovoltaics (PV) have high potential to develop technologies of many practical applications. Substantial research efforts are devoted to enhancing visible light activation of the photoelectrocatalytic reactions by various modifications of nanostructured semiconductors. This review paper emphasizes the recent advancement in material modifications by means of the promising localized surface plasmonic resonance (LSPR) mechanisms. The principles of LSPR and its effects on the photonic efficiency of PV and PC are discussed here. Many research findings reveal the promise of Au and Ag plasmonic nanoparticles (NPs). Continual investigation for increasing the stability of the plasmonic NPs will be fruitful.

Energy transfer in plasmonic photocatalytic composites

Among the many novel photocatalytic systems developed in very recent years, plasmonic photocatalytic composites possess great potential for use in applications and are one of the most intensively investigated photocatalytic systems owing to their high solar energy utilization efficiency. In these composites, the plasmonic nanoparticles (PNPs) efficiently absorb solar light through localized surface plasmon resonance and convert it into energetic electrons and holes in the nearby semiconductor. This energy transfer from PNPs to semiconductors plays a decisive role in the overall photocatalytic performance. Thus, the underlying physical mechanism is of great scientific and technological importance and is one of the hottest topics in the area of plasmonic photocatalysts. In this review, we examine the very recent advances in understanding the energy transfer process in plasmonic photocatalytic composites, describing both the theoretical basis of this process and experimental demonstrations. The factors that affect the energy transfer efficiencies and how to improve the efficiencies to yield better photocatalytic performance are also discussed. Furthermore, comparisons are made between the various energy transfer processes, emphasizing their limitations/benefits for efficient operation of plasmonic photocatalysts.

Bismuth functionalized PVA film: field, plasmonic and pH effect on PVA originated broad photoluminescence

Bismuth (Bi) NPs have been synthesized by Laser Ablation Synthesis in Solution (LASiS) at different pH in different aqueous solutions [viz. H₂O (H), H₂O + NaOH (HN), and H₂O + HCl (HC)].

Gold nanoparticle-modified TiO2/SBA-15 nanocomposites as active plasmonic photocatalysts for the selective oxidation of aromatic alcohols

The catalytic performance of noble-metal on mesoporous silica hosts has been widely investigated because the effects of surface plasmon resonance can open new avenues for the improvement of catalytic performance under light irradiation.

Macroporous TiO2encapsulated Au@Pd bimetal nanoparticles for the photocatalytic oxidation of alcohols in water under visible-light

A novel macroporous photocatalyst Au@Pd@TiO₂has been reported and showed excellent catalytic activity and stability in the aerobic oxidation of alcohols in water at ambient temperature when using air as the oxidizing agent under visible light irradiation.

Au@ZnO core–shell nanostructures with plasmon-induced visible-light photocatalytic and photoelectrochemical properties

Au@ZnO core–shell nanostructures exhibit enhanced photocatalysis under both simulated sunlight and monochromatic LED light due to the synergistic effect between the plasmonic Au-nanosphere cores and the semiconducting ZnO shells.

Plasmonic Au/TiO2nanostructures for glycerol oxidation

Visible light irradiation of the reaction volume results in boosted conversion for glycerol oxidation due to plasmonic properties of Au/TiO₂.

Rational design of plasmonic catalysts: matching the surface plasmon resonance with lamp emission spectra for improved performance in AgAu nanorings

Improved plasmonic catalytic activities were obtained by designing nanorings displaying extinction that matches the emission spectra of a commercial lamp.

In situ growth of TiO2 on TiN nanoparticles for non-noble-metal plasmonic photocatalysis

A novel plasmonic composite photocatalyst of TiN/TiO₂ demonstrated good visible-light-activated photocatalytic activity without noble metal components.

Titania modification with a ruthenium(ii) complex and gold nanoparticles for photocatalytic degradation of organic compounds

Interaction between two kinds of titania modifiers, i.e., a ruthenium complex and gold nanoparticles, influenced the resultant properties and photocatalytic activities of hybrid photocatalysts under UV and/or vis light irradiation.

Thermal activation process of Au/TiO2 system: a molecular spectroscopy study

Concatenated reactions involved in the thermal activation process of the AuNPs/TiO₂ system were evidenced by an in situ molecular spectroscopy study.

The application of heterogeneous visible light photocatalysts in organic synthesis

The recent advances of organic synthesis reactions based on heterogeneous visible-light photocatalysis are reviewed.

Enhanced photocatalytic activity of Bi25FeO40–Bi2WO6 heterostructures based on the rational design of the heterojunction interface

Based on the rational design of heterojunction interface, a novel and efficient Bi₂₅FeO₄₀–Bi₂WO₆ heterostructure photocatalyst was successfully constructed by a facile hydrothermal process.

UV-visible and near-infrared active NaGdF4:Yb:Er/Ag/TiO2 nanocomposite for enhanced photocatalytic applications

A near infra-red (NIR) active NaGdF₄:Yb:Er/Ag/TiO₂ nanocomposite photocatalyst was successfully synthesized by a one-pot thermal decomposition method.

Multifunctional Single-Phase Photocatalysts: Extended Near Infrared Photoactivity and Reliable Magnetic Recyclability

A practical photocatalyst should be able to integrate together various functions including the extended solar conversion, a feasible and economic recyclability, and above the room temperature operation potential, et al., in order to fulfill the spreading application needs in nowadays. In this report, a multifunctional single-phase photocatalyst which possesses a high photoactivity extended into the near infrared region, an easy magnetic recyclability and the high temperature stability was developed by doping Co into a new layer-structured Bi₇Fe₃Ti₃O₂₁ material. Light absorption and photocatalytic activity of the resulted Bi₇Fe_3-xCo_xTi₃O₂₁ photocatalyst were extended to the long wavelength as far as 800 nm. Its strong ferromagnetism above the room temperature enables the nanopowders fully recyclable in viscous solutions simply with a magnet bar in an experimental demonstration. Furthermore, such photoactivity and magnetic recyclability were heavily tested under high-temperature and high-viscosity conditions, which was intended to simulate the actual industrial environments. This work brings the bright light to a full availability of a new multifunctional photocatalyst, via integrating the much enhanced ferromagnetic, ferroelectric, optoelectronic properties, most importantly, into a single-phase structure.

Fabricating a Homogeneously Alloyed AuAg Shell on Au Nanorods to Achieve Strong, Stable, and Tunable Surface Plasmon Resonances

Colloidal metal nanocrystals with strong, stable, and tunable localized surface plasmon resonances (SPRs) can be useful in a corrosive environment for many applications including field-enhanced spectroscopies, plasmon-mediated catalysis, etc. Here, a new synthetic strategy is reported that enables the epitaxial growth of a homogeneously alloyed AuAg shell on Au nanorod seeds, circumventing the phase segregation of Au and Ag encountered in conventional synthesis. The resulting core-shell structured bimetallic nanorods (AuNR@AuAg) have well-mixed Au and Ag atoms in their shell without discernible domains. This degree of mixing allows AuNR@AuAg to combine the high stability of Au with the superior plasmonic activity of Ag, thus outperforming seemingly similar nanostructures with monometallic shells (e.g., Ag-coated Au NRs (AuNR@Ag) and Au-coated Au NRs (AuNR@Au)). AuNR@AuAg is comparable to AuNR@Ag in plasmonic activity, but that it is markedly more stable toward oxidative treatment. Specifically, AuNR@AuAg and AuNR@Ag exhibit similarly strong signals in surface-enhanced Raman spectroscopy that are some 30-fold higher than that of AuNR@Au. When incubated with a H(2)O(2) solution (0.5 m), the plasmonic activity of AuNR@Ag immediately and severely decayed, whereas AuNR@AuAg retained its activity intact. Moreover, the longitudinal SPR frequency of AuNR@AuAg can be tuned throughout the red wavelengths (≈620-690 nm) by controlling the thickness of the AuAg alloy shell. The synthetic strategy is versatile to fabricate AuAg alloyed shells on different shaped Au, with prospects for new possibilities in the synthesis and application of plasmonic nanocrystals.

Mechanistic Understanding of the Plasmonic Enhancement for Solar Water Splitting

H2 generation by solar water splitting is one of the most promising solutions to meet the increasing energy demands of the fast developing society. However, the efficiency of solar-water-splitting systems is still too low for practical applications, which requires further enhancement via different strategies such as doping, construction of heterojunctions, morphology control, and optimization of the crystal structure. Recently, integration of plasmonic metals to semiconductor photocatalysts has been proved to be an effective way to improve their photocatalytic activities. Thus, in-depth understanding of the enhancement mechanisms is of great importance for better utilization of the plasmonic effect. This review describes the relevant mechanisms from three aspects, including: i) light absorption and scattering; ii) hot-electron injection and iii) plasmon-induced resonance energy transfer (PIRET). Perspectives are also proposed to trigger further innovative thinking on plasmonic-enhanced solar water splitting.

Au@TiO₂ yolk-shell hollow spheres for plasmon-induced photocatalytic reduction of CO₂ to solar fuel via a local electromagnetic field

An electric field in a photocatalytic system consisting of Au@TiO2 yolk-shell hollow spheres is created to enhance the generation of electron-hole pairs and remit the charge-carrier recombination. Local surface plasmon resonance (LSPR)-mediated local electromagnetic field nearby Au nanoparticles cannot only enhance the local generation and subsequent separation of electron-hole pairs in TiO2 shells to improve the photoreduction yield of CO2, but also facilitate chemical reactions involving multiple e(-)/H(+) transfer processes to allow the formation of high-grade carbon species (C2H6), which was rarely observed in precedent CO2 photocatalytic reduction systems. The work may provide a new viewpoint for designing photocatalysts for artificial photosynthesis involving multiple reactions.

Solar-Light-Driven Renewable Butanol Separation by Core-Shell Ag@ZIF-8 Nanowires

Core-shell Ag@ZIF-8 nanowires, where single Ag nanowires are coated with uniform zeolitic-imidazolate-framework-8 (ZIF-8) shells, successfully realize renewable adsorptive separation of low concentrations of butanol from an aqueous medium under solar light irradiation by taking advantage of the exceptional adsorption capability of the ZIF-8 shells toward butanol and the unique plasmonic photothermal effect of the Ag nanowire cores. Impressively, the high separation efficiency is maintained as almost unchanged, even after 10 adsorption/desorption cycles.

Gold and gold-palladium alloy nanoparticles on heterostructured TiO2 nanobelts as plasmonic photocatalysts for benzyl alcohol oxidation

Plasmonic photocatalysts composed of Au and bimetallic Au-Pd alloy nanoparticles (NPs) on one-dimensional TiO2 nanobelts (TiO2-NBs) were used for the aerobic oxidation of benzyl alcohol under visible light irradiation. Remarkable light-promoted activity was observed for the as-synthesized M/TiO2-NB (M = Au, Au-Pd) nanostructures based on the TiO2(B)/anatase heterostructured nanobelt. The difference in band structure and the well matched interface between the TiO2(B) and anatase phases, coupled with the one-dimensional nanostructure, enable an enhanced charge transfer within the heterostructured nanobelt. This inter-phase charge transfer greatly facilitates the flow of hot electrons from the metal NPs to TiO2 and promotes benzyl alcohol oxidation. This efficient electron transfer was identified by the much higher photocurrent response measured for the Au/TiO2-NB nanostructure with the TiO2(B)/anatase heterojunction than those with either of the single phases under visible light irradiation. Alloying Au with Pd in Au-Pd/TiO2-NB results in a significant improvement in the visible light-promoted activity compared to the monometallic Au/TiO2-NB sample. It is supposed that the plasmon-mediated charge distribution within the alloy NPs is mainly responsible for the enhanced photocatalytic activity of the bimetallic nanostructures.

Gold nanoparticles-sensitized wide and narrow band gap TiO2 for visible light applications: a comparative study

Photocatalytic degradation of dyes and organic compounds by Au/P-TiO₂ and Au/M-TiO₂ nanocomposites under visible light irradiation.

One-dimension-based spatially ordered architectures for solar energy conversion

The current status, future developments, and challenges of one-dimension-based spatially ordered architectures in solar energy conversion are discussed and elucidated.

In situ growth of Au nanoparticles on 3D Bi2O2CO3 for surface plasmon enhanced visible light photocatalysis

The highly visible light active 3D Au/Bi₂O₂CO₃ heterostructure was fabricated by a one-pot in situ hydrothermal method.

Synergetic effect enhanced photoelectrocatalysis

We report synergetic effect enhanced photoelectrocatalysis, in which Fe³⁺ and Br⁻ are used as the acceptors of photogenerated charges on TiO₂ nanoparticles.

Green synthesis, photocatalytic and photoelectrochemical performance of an Au–Graphene nanocomposite

Visible light-induced photocatalytic degradation of pollutants using an Au–Graphene nanocomposite.

Mesoporous titanium dioxide coating on gold modified silica nanotubes: a tube-in-tube titanium nanostructure for visible-light photocatalysts

A novel tube-in-tube structured titanium dioxide (TiO₂) based visible-light photocatalyst with non-metal doping and plasmonic metal decoration was fabricated and characterized.

Novel Cu2S quantum dots coupled flower-like BiOBr for efficient photocatalytic hydrogen production under visible light

The BiOBr act as excellent supporting materials to improve the dispersion of the Cu₂S QDs and the well-matched overlapping band-structures greatly accelerate the separation of photogenerated carriers.

Single molecule level plasmonic catalysis – a dilution study of p-nitrothiophenol on gold dimers

Surface plasmons on isolated gold dimers can initiate reactions of single adsorbedp-nitrothiophenol molecules.