Soliman K, Abdulmalik D, Mitoraj D, Sleim MH, Liedke MO, El-Sayed HA, AlJaber AS, Y. Al-Qaradawi I, Mendoza Reyes O, Abdullah AM. Tailored fabrication of iridium nanoparticle-sensitized titanium oxynitride nanotubes for solar-driven water splitting: experimental insights on the photocatalytic–activity–defects relationship

Uniform and vertically aligned nanotube arrays of titanium oxynitride functionalized with iridium nanoparticles (Ir/TiON-NTs) were fabricated for the solar driven-water splitting.

Photoenergy Conversion Behaviors of Photoluminescence and Photocatalysis in Silver-Coated LiBaPO4:Eu2

LiBaPO₄:Eu²⁺ phosphor and Ag-coated LiBaPO₄:Eu²⁺ composites (Ag/LiBaPO₄:Eu²⁺) were prepared via solid-state reaction and traditional photoreduction methods, respectively. The samples were characterized via XRD, SEM, and UV-vis optical absorption spectroscopy. Two photoenergy conversion processes, namely, photocatalysis and photoluminescence, were investigated in detail. In comparison with as-prepared LiBaPO₄:Eu²⁺ phosphor, Ag-modified composites exhibited the enhanced photocatalytic effects together with the quenched Eu²⁺ luminescence. A Schottky barrier was created on the interface between Ag nanoparticles and LiBaPO₄ host, thereby greatly delaying the recombination between the light-induced holes and electrons. A photoenergy conversion mechanism was suggested and discussed on the basis of the experiments. The Eu²⁺ ion luminescence centers directly participated in the photodegradation with the meditation of Ag nanoparticles on the surface. With the increase of the Ag coating level on the surfaces, some emission peaks corresponding to ⁵D₀ → ⁷F_0,1,2,3,4 transitions of Eu³⁺ ions were detected. Eu²⁺/Eu³⁺ couples also play an important role in improving photocatalysis. LiBaPO₄:Eu²⁺ phosphor is a good candidate for the investigation of multimodal photoenergies of photoluminescence and photocatalysis.

Silver Nanoparticles-Decorated Titanium Oxynitride Nanotube Arrays for Enhanced Solar Fuel Generation

We demonstrate, for the first time, the synthesis of highly ordered titanium oxynitride nanotube arrays sensitized with Ag nanoparticles (Ag/TiON) as an attractive class of materials for visible-light-driven water splitting. The nanostructure topology of TiO2, TiON and Ag/TiON was investigated using FESEM and TEM. The X-ray photoelectron spectroscopy (XPS) and the energy dispersive X-ray spectroscopy (EDS) analyses confirm the formation of the oxynitride structure. Upon their use to split water photoelectrochemically under AM 1.5 G illumination (100 mW/cm2, 0.1 M KOH), the titanium oxynitride nanotube array films showed significant increase in the photocurrent (6 mA/cm2) compared to the TiO2 nanotubes counterpart (0.15 mA/cm2). Moreover, decorating the TiON nanotubes with Ag nanoparticles (13 ± 2 nm in size) resulted in exceptionally high photocurrent reaching 14 mA/cm2 at 1.0 VSCE. This enhancement in the photocurrent is related to the synergistic effects of Ag decoration, nitrogen doping, and the unique structural properties of the fabricated nanotube arrays.

Plasmon-induced charge separation: chemistry and wide applications

Recent development of nanoplasmonics has stimulated chemists to utilize plasmonic nanomaterials for efficient and distinctive photochemical applications, and physicists to boldly go inside the "wet" chemistry world. The discovery of plasmon-induced charge separation (PICS) has even accelerated these trends. On the other hand, some confusion is found in discussions about PICS. In this perspective, we focus on differences between PICS and some other phenomena such as co-catalysis effect and plasmonic nanoantenna effect. In addition, materials and nanostructures suitable for PICS are shown, and characteristics and features unique to PICS are documented. Although it is well known that PICS has been applied to photovoltaics and photocatalysis, here light is shed on other applications that take better advantage of PICS, such as chemical sensing and biosensing, various photochromisms, photoswitchable functionalities and nanoscale photofabrication.

Fabrication of a visible-light-driven plasmonic photocatalyst of AgVO₃@AgBr@Ag nanobelt heterostructures

In this article, AgVO3@AgBr@Ag nanobelt heterostructures were fabricated as an efficient visible-light photocatalyst through a hydrothermal process, an anion-exchange reaction, and a light-induced reduction. SEM and TEM characterization revealed that anion exchange followed by light-induced reduction is an efficient method to synthesize well-dispersed AgBr@Ag nanoparticles on the surface of AgVO3 nanobelts. The composite photocatalyst efficiently combines visible-light active AgBr and AgVO3 with the surface plasmon resonance (SPR) effect of Ag nanoparticles. The obtained catalyst displayed a high performance for removing organic dye in the range of visible light. This improved visible-light response likely originates from a synergistic effect of the different components. This work provides a versatile approach for accessing efficient, stable, and recyclable visible-light-driven plasmonic photocatalysts.

Plasmonic manipulation of color and morphology of single silver nanospheres

Optical control of size, shape, or orientation of a metal nanoparticle is important for development of nanoscale optical devices and elements of photonic circuits. Thus far, however, independent control of two or more parameters has not yet been achieved. Here we place a simple spherical Ag nanoparticle on TiO(2) with high refractive index and separate a plasmon mode localized at the Ag-TiO(2) interface from the other mode distributed over the nanoparticle. Selective excitation of each mode gives rise to a corresponding morphological change and selective suppression of the plasmon mode, resulting in multicolor changes of scattering light from orange to red, green, or a dark color.

Orientation-selective removal of upright Ag nanoplates from a TiO₂ film

Upright Ag nanoplates on a nanoparticulate TiO(2) film are oriented on the basis of plasmon-induced charge separation. Polarized visible light removes nanoplates oriented perpendicularly to polarization via excitation of in-plane transverse mode. Polarized near-infrared light removes nanoplates in parallel geometry via excitation of in-plane longitudinal mode.

One-pot synthesis of visible-light-driven plasmonic photocatalyst Ag/AgCl in ionic liquid

Plasmonic photocatalyst Ag/AgCl was prepared by in situ hydrothermal method with the contribution of 1-octyl-3-methylimidazolium chloride ([Omim]Cl), in which the [Omim]Cl ionic liquid acted not only as a precursor but also as a reducing reagent in the process of formation of Ag⁰. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and thermogravimetric and differential scanning calorimetry (TG-DSC). The photocatalytic activity of the composites were evaluated by degradation of methyl orange (MO) under visible light irradiation. The experimental results showed that the high activity and stability of Ag/AgCl photocatalysts under visible-light irradiation were due to their localized surface plasmon resonance (LSPR). Based on the characterization of the structure and photocatalytic performance, the LSPR was determined by synergetic effect of many factors, such as particle size of metallic Ag, contents of the Ag⁰ nanoparticles, and the extent of metallic Ag dispersing. A photocatalytic mechanism of the Ag/AgCl photocatalyst was also proposed.