Active sites-enriched carbon matrix enables efficient triiodide reduction in dye-sensitized solar cells: An understanding of the active centers. (December 2018)

• Record Type: Journal Article
• Authors: Meng, Xiangtong; Yu, Chang; Zhang, Xuepeng; Huang, Longlong; Rager, Matthew; Hong, Jiafu; Qiu, Jieshan; Lin, Zhiqun
• Is Part Of: Nano energy. Volume 54(2018)
• Page Start: 138
• Page End: 147
• Publication Date: 2018-12
• Subjects: Dye-sensitized solar cell -- Counter electrode -- Nitrogen-doped carbon nanowire -- Electrocatalytic activity -- Active site; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2018.09.070
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Understanding the activity origins of electrocatalysts for the triiodide (I3 - ) reduction is highly desirable in dye-sensitized solar cells (DSSCs). Herein, we report a robust strategy to craft nitrogen-doped carbon nanowires (NCWs) through combining oxidation polymerization from p-phenylenediamine with carbonization process. Owing to the abundant edges of the graphite microcrystals embedded in the NCWs and the incorporated N species, the NCWs synthesized at 700 °C exhibit a superior response to the I3 - reduction in DSSCs with a high power conversion efficiency of 8.90%, outperforming the Pt reference (8.09%), and a high stability is also manifested. Theoretical calculations reveal that, of various doped N species within NCWs, the quaternary N species can significantly decrease the ionization energy and modulate the spin density distribution of carbon frameworks, thus promoting the electron transfer from the external circuit to the electrolyte. Natural population analysis further reveals that the active centers within the NCWs for the I3 - reduction are those positively charged carbon atoms adjacent to the quaternary N. As such, this work will pave an avenue for rational design and engineering of inexpensive yet high-efficiency carbon electrocatalysts for the advanced energy applications. Graphical abstract: Highlights: Active site-enriched nitrogen-doped carbon nanowires (NCWs) are crafted. DSSC with the NCW CE prepared at 700 °C shows excellent photovoltaic performance. The impacts of different N species in the NCWs on the I3 - reduction are theoretically revealed. The carbon atoms adjacent to the quaternary N species function as the active sites to the I3 - reduction.