The electrocatalytic performance of Fe3C@C composites as efficient Pt-free counter electrode for triiodide reduction in dye-sensitized solar cells

Modification and reallocation of the composition of transition metal compounds (TMCs) to replace the tradi-tional Pt as a counter electrode (CE) catalyst is one of the unique ways to promote the power conversion effi-ciency (PCE) of dye-sensitized solar cells (DSSCs). Herein, four different Fe3C@C composites were prepared by high temperature thermal synthesis using the different morphologies and sizes of Fe2O3 (nanorings (NR), nanocubes (NC), nanoballs (NB), and nanodiscus (ND)) as Fe source assisted by urea and hexadecyltrimethyl ammonium chloride, and then were further utilized in the encapsulated DSSCs. The obtained different Fe3C@C composites had been characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and N2 adsorption-desorption. The electrochemical activity of Fe3C@C composites existed a sig-nificant morphological dependence on Fe2O3 as a Fe source, which were confirmed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Tafel polarization experiments. The DSSCs with Fe3C@C composites CEs achieved a high PCEs of 7.58%(NR), 7.39%(NC), 7.13%(NB) and 6.59%(ND) to regenerate traditional I3 /I- shuttles by the photocurrent-photovoltage (J-V) test, respectively, which can be due to the synergistic effect between Fe3C and C to improve electrical conductivity and promote a high number of active catalytic sites, implying a remarkable alternative of Pt-free catalyst that can be applied to the encapsulated DSSCs as Pt-free CEs.