Airo Mildred A, Otieno Francis, Mxakaza Lineo, Ipadeola Adewale, Kadzutu-Sithole Rudo S, Machogo-Phao Lerato F E, Billing Caren, Moloto Makwena, Moloto Nosipho
Molecular Science Institute, School of Chemistry, University of the Witwatersrand Private Bag 3, Wits 2050 Republic of South Africa
Department of Chemistry, Vaal University of Technology Private Bag X021 Vanderbijlpark 1900 Republic of South Africa.
RSC Adv. 2020 Oct 28;10(65):39509-39520. doi: 10.1039/d0ra06150f. eCollection 2020 Oct 27.
Nickel selenide (Ni Se ) systems have received much attention in recent years as potential low cost counter electrodes (CEs) in dye sensitized solar cells (DSSCs). Their electrocatalytic activities are comparable to that of the conventional platinum CE. Despite their achievements, the effect of stoichiometry on their catalytic performance as CEs in DSSCs still remains unclear, hence the motivation for this work. Different stoichiometries of Ni Se were synthesized a colloidal method in oleylamine or oleylamine/oleic acid mixture at the appropriate synthetic temperature and Ni to Se precursor ratio. X-ray diffraction revealed that different stoichiometries of nickel selenide were formed namely, NiSe, NiSe, NiSe, NiSe and NiSe. Scanning electron microscopy showed that all the stoichiometries had predominantly spherical-like morphologies. Cyclic voltammetry, electrochemical impedance spectroscopy analysis and the photovoltaic performances of the DSSCs fabricated using the different Ni Se CEs revealed that selenium rich stoichiometries performed better than the nickel rich ones. Consequently, the catalytic activity towards the redox reaction of the triiodide/iodide electrolyte and hence the power conversion efficiency (PCE) followed the order of NiSe > NiSe > NiSe > NiSe > NiSe with PCE values of 3.31%, 3.25%, 3.17%, 2.35% and 1.52% respectively under ambient conditions.
近年来，硒化镍（NiₓSeₙ）体系作为染料敏化太阳能电池（DSSC）中潜在的低成本对电极（CE）受到了广泛关注。它们的电催化活性与传统铂对电极相当。尽管取得了这些成果，但化学计量比在DSSC中作为对电极的催化性能方面的影响仍不明确，因此开展了这项工作。通过在适当的合成温度和镍与硒前驱体比例下，采用油胺或油胺/油酸混合物中的胶体法合成了不同化学计量比的NiₓSeₙ。X射线衍射表明形成了不同化学计量比的硒化镍，即NiSe、Ni₃Se₂、Ni₂Se₃、NiSe₂和Ni₃Se₄。扫描电子显微镜显示所有化学计量比的产物主要呈球形形态。循环伏安法、电化学阻抗谱分析以及使用不同NiₓSeₙ对电极制备的DSSC的光伏性能表明，富硒化学计量比的表现优于富镍的。因此，对三碘化物/碘化物电解质氧化还原反应的催化活性以及功率转换效率（PCE）遵循NiSe₂ > Ni₃Se₄ > Ni₂Se₃ > Ni₃Se₂ > NiSe的顺序，在环境条件下PCE值分别为3.31%、3.25%、3.17%、2.35%和1.52%。
