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

A new class of hybrids with the unique electrocatalytic nanoarchitecture of Fe1–xS anchored on Fe3C-encapsulated and N-doped carbon nanotubes (Fe1–xS/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 Fe1–xS/Fe3C–NCNT hybrid with advanced structural and electronic properties, in which the Fe vacancy-contained Fe1–xS 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 Fe1–xS/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 ...