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An optimized configuration for nanomaterials in working electrodes is vital to the high performance of dye‐sensitized solar cells (DSSCs). Here, a fabrication method is introduced for multi‐shell TiO 2 hollow nanoparticles (MS‐TiO 2 ‐HNPs) via a sol–gel reaction, calcination, and an etching process. The prepared uniform MS‐HNPs have a high surface area (ca. 171 m 2 g −1 ), multireflection, and facile electrolyte circulation and diffusion. During the MS‐HNP fabrication process, the amount of SiO 2 precursor and H 2 O under reaction has a significant effect on aggregation and side reactions. The etching process to obtain pure TiO 2 is influenced by anatase crystallinity. Additionally, single‐shell (SS)‐TiO 2 ‐HNPs and double‐shell (DS)‐TiO 2 ‐HNPs are synthesized as a control. The MS‐TiO 2 ‐HNPs exhibit a high surface area and enhance light reflectance, compared with the SS‐ and DS‐TiO 2 ‐HNPs of the same size. The power conversion efficiency of the optimized MS‐TiO 2 ‐HNP‐based DSSCs is 9.4%, compared with the 8.0% efficiency demonstrated by SS‐TiO 2 ‐HNP‐DSSCs (a 17.5% improvement). These results enable the utilization of multifunctional MS‐HNPs in energy material applications, such as lithium ion batteries, photocatalysts, water‐splitting, and supercapacitors.
Hwang et al. (Mon,) studied this question.