Developing Pt-free counter electrodes (CEs) material for dye-sensitized solar cells (DSSCs) is significant. Herein, we fabricate a catalyst of Fe-N-C by employing N-doped hollow carbon flower (NHCF) as a matrix on which Fe-Nx coordination sites and Fe/Fe₃C nanocrystals (Fe/Fe₃C@NHCF) are mounted and coupled. The DSSC with Fe/Fe₃C@NHCF CE achieves power conversion efficiency (PCE) of 9.37% and highly outperforms the one with Pt CE (7.77%). It is uncovered that Fe/Fe₃C nanocrystals and Fe-Nx coordination sites generate a synergetic effect to enhance catalytic activity of the tri-iodide reduction reaction. The reasons are as follows: (1) Fe/Fe₃C nanocrystals, which possess abundant interfaces and effectively promote the adsorption of reactants on the catalyst surface and charge transfer; (2) Atomically Fe-Nx configurations reduce charge density of Fe atomic centers and quicken reaction kinetics; (3) The unique structure of NHCF matrix almost utilizes all Fe/Fe₃C nanocrystals, providing coupling bridge for nanocrystals with Fe-Nx sites.

开发用于染料敏化太阳能电池 (DSSC) 的无 Pt 对电极 (CE) 材料具有重要意义。在此，我们通过采用 N 掺杂的空心碳花 (NHCF) 作为基体，在其上安装 Fe-N x配位点和 Fe/Fe ₃ C 纳米晶体 (Fe/Fe ₃ C@NHCF) 来制造 Fe-NC 催化剂和耦合。带有 Fe/Fe ₃ C@NHCF CE的 DSSC实现了 9.37% 的功率转换效率 (PCE)，并且远远优于带有 Pt CE的 DSSC (7.77%)。结果表明，Fe/Fe ₃ C 纳米晶体和Fe-N x配位位点产生协同效应，以提高三碘化物还原反应的催化活性。原因如下： (1) Fe/Fe ₃C纳米晶，具有丰富的界面，有效促进反应物在催化剂表面的吸附和电荷转移；(2) Fe-N x原子构型降低了Fe原子中心的电荷密度，加快了反应动力学；(3) NHCF基体的独特结构几乎利用了所有的Fe/Fe ₃ C纳米晶，为具有Fe-N x位点的纳米晶提供了耦合桥。