**Mohammed Rahman and Abdullah Mohammed Asiri** King Abdulaziz University,

Kingdom of Saudi Arabia

**IV**

scales and prodigious surface-to-volume ratios of AuNPs, radiation damage effects are typically dominated by sputtering and surface interactions and can vary drastically from bulk behavior and classical models. Here, they report on contemporary experimental and computational modeling efforts that have contributed to the current understanding of how ionizing radiation environments affect the structure and properties of AuNPs. Finally, the future potential for elucidating the active mechanisms in AuNPs exposed to ionizing radiation and the subsequent ability to predictively model the radiation stability and ion beam modification parameters are

Sivakumar et al. develop a promising technique for photodegradation of various hazardous chemicals that are encountered in waste waters. Here, they investigate the performance of various semiconductors. The anatase phase of TiO2 affords the best compromise between catalytic performance and stability in aqueous medium. Apart from many positive attributes of TiO2, the main drawbacks associated with this catalyst are (1) large band gap (*E*g > 3.2 eV), which can be excited only by UV light, and (2) recombination of excitons. Dye sensitization, coupling of semiconductors, transitional metal doping, etc., are some methods to shift the optical response from UV to the visible spectral range. They also introduce another important approach to shift the optical response of TiO2 from UV to the visible spectral range, i.e., by doping of noble metals with TiO2. Here, they research nanoparticles of different noble metals such as Ag, Au, and Pt deposited on synthesized TiO2, characterized by using various instrumental techniques such as XRD, TEM, FT-IR, BET, UV-Vis, and AAS and subjected to the degradation of textile dyes, namely TAZ, RY-17, and RB-5 under both UV and visible irradiations. Reaction conditions such as catalyst concentration, dye concentration, pH, irradiation time, light intensity, and additives were optimized for complete decolorization and are discussed in

Chen and Shon review intriguing catalytic studies that are accomplished by employing a variety of catalysts such as metal complexes, supported materials, supported metal complexes, and nanosized materials for polyene hydrogenation. Additionally, unsupported colloidal nanoparticle catalysts, which exhibit excellent activity and selectivity toward polyene hydrogenation, are introduced. The high activity of colloidal metal nanoparticle catalysts often allows reactions to be completed under mild conditions at atmospheric pressure and at room temperature. The important fundamental understandings of the influence of chemical environments (solvents, ligands, dopants, etc.) and compositions (metal complexes, metals, alloys, etc.) towards the catalytic activity and selectivity of various catalysts in homogeneous, heterogeneous, and semi-heterogeneous conditions are discussed. Systematic evaluation is also discussed in this review chapter, which paves the way to further develop chemo-, regio-, and stereoselective catalysts for polyene

Finally, Puszkiel discusses hydride-forming binary as well as complex materials for their potential hydrogen storage properties, which possess high volumetric and gravimetric hydrogen capacities. Tuning the kinetic behavior of these hydrideforming materials involves different approaches and their combinations are discussed in this chapter. Herein, basic concepts of the chemical reaction for hydride compound formation/decomposition, thermodynamics, kinetics, and applied strategies to enhance the kinetic behavior of hydride compounds and systems are

discussed in his chapter.

detail in this chapter.

hydrogenation.

comprehensively described and discussed.

**1**

Section 1

State-of-Art Gold

Nanoparticles

Section 1
