Strategic Design of Vacancy-Enriched Fe1- xS Nanoparticles Anchored on Fe3C-Encapsulated and N-Doped Carbon Nanotube Hybrids for High-Efficiency Triiodide Reduction in Dye-Sensitized Solar Cells

Ming Chen; Gui-Chang Wang; Leng-Leng Shao; Zhong-Yong Yuan; Xing Qian; Qiang-Shan Jing; Zhong-Yuan Huang; Dong-Li Xu; Shuang-Xia Yang

doi:10.1021/acsami.8b08489

Strategic Design of Vacancy-Enriched Fe_{1- x}S Nanoparticles Anchored on Fe₃C-Encapsulated and N-Doped Carbon Nanotube Hybrids for High-Efficiency Triiodide Reduction in Dye-Sensitized Solar Cells

ACS Appl Mater Interfaces. 2018 Sep 19;10(37):31208-31224. doi: 10.1021/acsami.8b08489. Epub 2018 Jul 24.

Authors

Ming Chen¹, Gui-Chang Wang, Leng-Leng Shao², Zhong-Yong Yuan, Xing Qian³, Qiang-Shan Jing¹, Zhong-Yuan Huang^{1

4}, Dong-Li Xu¹, Shuang-Xia Yang¹

Affiliations

¹ College of Chemistry and Chemical Engineering , Xinyang Normal University , Xinyang 464000 , China.
² Grirem Advanced Materials Co., Ltd, General Research Institute for Nonferrous Metals , Beijing 100088 , China.
³ College of Chemical Engineering , Fuzhou University , Fuzhou 350116 , China.
⁴ Department of Chemistry , Xavier University of Louisiana , New Orleans , Louisiana 700125 , United States.

PMID: 29999302
DOI: 10.1021/acsami.8b08489

Abstract

A new class of hybrids with the unique electrocatalytic nanoarchitecture of Fe_{1- x}S anchored on Fe₃C-encapsulated and N-doped carbon nanotubes (Fe_{1- x}S/Fe₃C-NCNTs) is innovatively synthesized through a facile one-step carbonization-sulfurization strategy. The efficient synthetic protocols on phase structure evolution and dynamic decomposition behavior enable the production of the Fe_{1- x}S/Fe₃C-NCNT hybrid with advanced structural and electronic properties, in which the Fe vacancy-contained Fe_{1- x}S showed the 3d metallic state electrons and an electroactive Fe in +2/+3 valence, and the electronic structure of the CNT was effectively modulated by the incorporated Fe₃C and N, with the work function decreased from 4.85 to 4.63 eV. The meticulous structural, electronic, and compositional control unveils the unusual synergetic catalytic properties for the Fe_{1- x}S/Fe₃C-NCNT hybrid when developed as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs), in which the Fe₃C- and N-incorporated CNTs with reduced work function and increased charge density provide a highway for electron transport and facilitate the electron migration from Fe₃C-NCNTs to ultrahigh active Fe_{1- x}S with the electron-donating effect, and the Fe vacancy-enriched Fe_{1- x}S nanoparticles exhibit ultrahigh I₃^- adsorption and charge-transfer ability. As a consequence, the DSSC based on the Fe_{1- x}S/Fe₃C-NCNT CE delivers a high power conversion efficiency of 8.67% and good long-term stability with a remnant efficiency of 8.00% after 168 h of illumination, superior to those of traditional Pt. Furthermore, the possible catalytic mechanism toward I₃^- reduction is creatively proposed based on the structure-activity correlation. In this work, the structure engineering, electronic modulation, and composition control opens up new possibilities in constructing the novel electrocatalytic nanoarchitecture for highly efficient CEs in DSSCs.

Keywords: counter electrode; dye-sensitized solar cell; electrocatalytic activity; multi-component nanohybrid; synergistic effect.