Multi‐Shell Porous TiO₂ Hollow Nanoparticles for Enhanced Light Harvesting in Dye‐sensitized Solar Cells

Abstract

1wileyonlinelibrary.com nanomaterial's size, surface area, and light-scattering ability.Recently, multi-shell hollow nanoparticles (MS-HNPs) have been highlighted as promising materials for DSSC applications, offering a high surface area and strong light scattering. MS-HNPs, composed of inner and outer shells, have a benefi cial confi guration for multirefl ection (of sunlight) and redox reactions with the electrolyte. Moreover, the surface area of MS-HNPs is much larger than that of single-shell (SS)-HNPs having the same size. Various MS-HNPs have been developed, such as multilayerd SnO 2 hollow microspheres coated to TiO 2 , [ 17 ] quintuple-shelled SnO 2 hollow microspheres, [ 18 ] multi-shelled ZnO hollow microspheres, [ 19 ] and shell-in-shell TiO 2 hollow microspheres. [ 20 ] These MS-HNPs improve the power conversion effi ciency of the DSSCs, due to their strong lightscattering effect and increased surface area. However, among the MS-HNPs, the largest surface area of multi-shelled ZnO hollow microspheres was only 47 m 2 g −1 , which is not suffi cient for light absorption in the sensitizer layer. [ 19 ] Additionally, most MS-HNPs are synthesized using a hydrothermal process, which limits the mass production of MS-HNPs. In particular, TiO 2 , commonly used as the working electrode in DSSCs, has several fabrication issues, including diffi culty in controlling the morphology, size, and aggregation, due to the fast reaction rate of the TiO 2 precursor. [ 21,22 ] Therefore, the development of MS-HNPs with nano-scale size, high surface area, and strong light-scattering remains a challenge.Herein, we introduce a fabrication method for nano-sized MS-TiO 2 -HNPs using a sol-gel method, combined with calcination and etching processes. The MS-TiO 2 -HNPs used in this study were composed of three shells: a small inner shell (diameter: 50 nm), a middle shell (diameter: 100 nm), and an outer shell (diameter: 160 nm). The fabricated MS-TiO 2 -HNPs were expected to be multifunctional, due to their large surface area of 171 m 2 g −1 , multi-refl ection capability, and enhanced electrolyte diffusion. Specifi cally, the smallest inner shell of the MS-TiO 2 -HNPs provided a high surface area. Additionally, the multi-shell structure induced multirefl ection for solar devices. We observed an increase in the power conversion effi ciency for the MS-TiO 2 -HNP-DSSCs of 17.5% (from 8.0% for SS-TiO 2 -HNP-DSSCs to 9.4% for MS-TiO 2 -HNP-DSSCs). To our knowledge, this is the fi rst report of nano-sized MS-TiO 2 -HNPs with a high surface area. Multi-Shell Porous TiO 2 Hollow Nanoparticles for Enhanced Light Harvesting in

Preparation of flower-like ZnO architectures assembled with nanosheets for enhanced photocatalytic activity

“…The degradation efficiency of both milled ZnO samples was under 40% even after 45 min. Hence, it was concluded that the photocatalytic activity could be directly related to the 3D flower-like architectures composed of nanosheets, which could enhance the light-scattering ability, thus improving the photocatalytic performance [40].…”

Design and synthesis of H-TiO2/MnO2 core–shell nanotube arrays with high capacitance and cycling stability for supercapacitors

“…3e, the as-anodized TiO 2 shows amorphous nature due to the absence of any characteristic peaks. After the hydrogenation treatment, TiO 2 mainly converts to anatase phase (JCPDS: 21-1272) [36,37], which contains well-defined diffraction peaks at 25.2°, 38.3°, 47.8°and 54.8°. In the meantime, there is also a small fraction of TiO 2 , changed to rutile phase (JCPDS: 87-0710) [38,39].…”

Recent Advances in Nanoparticle Shape and Composition Regulation Based on Galvanic Replacement for Cancer Treatment

“…Porous nanoparticles of metal oxide nanomaterials such as mesoporous silica (SiO2) [186][187][188][189][190][191][192][193], and mesoporous titania (TiO2) [194][195][196][197][198][199] have been extensively studied owing to their facile template assisted formation. In the case of noble metal nanoparticles, no methods for the controlled synthesis of porous nanostructures have been established owing to the need for reducing-agent-mediated synthetic strategies and the importance of crystallinity.…”