NiCoSe₂ microspheres have been successfully synthesized by a facile one-step hydrothermal method at different hydrothermal temperatures. The prepared samples are divided according to their reaction temperatures (90, 120, 150 and 180 °C) and named NiCoSe₂-90, NiCoSe₂-120, NiCoSe₂-150 and NiCoSe₂-180, respectively. The diameters of the NiCoSe₂ microspheres strongly depend on the different hydrothermal temperatures. When the temperature is increased to 150 °C, the size of the resultant NiCoSe₂ microspheres changes from 200 to 800 nm, and the interior of NiCoSe₂-150 possesses a flocculent structure. However, NiCoSe₂-180 displays a cauliflower-like aggregated structure. The prepared NiCoSe₂ alloys are used as high-performance Pt-free counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). Cyclic voltammogram measurement indicates that NiCoSe₂-150 CE has larger current density than Pt CE. Electrochemical impedance spectroscopy shows that NiCoSe₂-150 CE has a low charge-transfer resistance of 1.8 Ω cm². Due to their unique morphologies and well-defined interior and exterior structures, DSSCs based on NiCoSe₂-120 and NiCoSe₂-150 CEs achieve high power conversion efficiencies of 8.48% and 8.76%, respectively, which are higher than that of the solar cell based on Pt CE (8.31%).

中文翻译：

---

NiCoSe2微球的尺寸可控合成作为染料敏化太阳能电池的对电极

NiCoSe ₂微球已通过简便的一步水热法在不同的水热温度下成功合成。制备的样品根据其反应温度（90、120、150和180°C）进行划分，分别命名为NiCoSe ₂ -90、NiCoSe ₂ -120、NiCoSe ₂ -150和NiCoSe ₂ -180。NiCoSe ₂微球的直径很大程度上取决于不同的热液温度。当温度升高到150℃时，所得NiCoSe ₂微球的尺寸从200nm变为800nm，NiCoSe ₂ -150内部具有絮状结构。然而，NiCoSe ₂-180 显示菜花状聚合结构。制备的 NiCoSe ₂合金用作染料敏化太阳能电池 (DSSC) 的高性能无 Pt 对电极 (CE)。循环伏安测量表明 NiCoSe ₂ -150 CE 具有比 Pt CE 更大的电流密度。电化学阻抗谱表明，NiCoSe ₂ -150 CE 具有 1.8 Ω cm ²的低电荷转移电阻。基于NiCoSe ₂ -120和NiCoSe ₂ -150 CE的DSSC由于其独特的形貌和明确的内部和外部结构，分别实现了8.48%和8.76%的高功率转换效率，高于太阳能电池。基于铂 CE (8.31%)。