Mposa Esmie, Sithole Rudo K, Ndala Zakhele, Ngubeni Grace N, Mubiayi Kalenga P, Shumbula Poslet M, Machogo-Phao Lerato F E, Moloto Nosipho
Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand Private Bag 3 Wits 2050 South Africa
Department of Chemistry, University of Limpopo Private Bag X1106 Sovenga 0727 South Africa.
RSC Adv. 2022 Apr 28;12(20):12882-12890. doi: 10.1039/d2ra00568a. eCollection 2022 Apr 22.
Studies to improve the efficiency of dye-sensitized solar cells (DSSCs) include, but are not limited to, finding alternatives such as 2D layered materials as replacement counter electrodes (CEs) to the commonly used Pt. Herein, we report for the first time, the use of AuSe as a counter electrode for the reduction of triiodide ions (I ) to iodide ions (I). The colloidal synthesis of gold selenide nanostructures produced α-AuSe and β-AuSe dominated products as determined by XRD. Electron microscopy showed α-AuSe having belt-like structures while β-AuSe had a plate-like morphology. EDS mapping confirmed the elemental composition and homogeneity of the AuSe CEs. Cyclic voltammetry curves of the AuSe CEs displayed the double set of reduction-oxidation peaks associated with the reactions in the I /I electrolyte and therefore were comparable to the Pt CV curve. The α-AuSe CE showed better electrocatalytic activity with a reduction current of 6.1 mA than that of β-AuSe and Pt CEs, which were 4.2 mA and 4.8 mA, respectively. The peak-to-peak separation (Δ ) for the α-AuSe CE was also more favourable with a value of 532 mV over that of the β-AuSe CE of 739 mV however, both values were larger than that of the Pt CE, which was found to be 468 mV. The EIS and Tafel plot data showed that α-AuSe had the best catalytic activity compared to β-AuSe and was comparable to Pt. The DSSC using α-AuSe as a CE had the highest PCE (6.94%) as compared to Pt (4.89%) and β-AuSe (3.47%). The lower efficiency for Pt was attributed to the poorer fill factor. With these novel results, α-AuSe is an excellent candidate to be used as an alternative CE to Pt in DSSCs.
旨在提高染料敏化太阳能电池（DSSC）效率的研究包括但不限于寻找替代材料，如二维层状材料，以取代常用的铂作为对电极（CE）。在此，我们首次报道了使用硒化金作为对电极将三碘离子（I）还原为碘离子（I）。通过XRD测定，硒化金纳米结构的胶体合成产生了以α-AuSe和β-AuSe为主的产物。电子显微镜显示α-AuSe具有带状结构，而β-AuSe具有板状形态。EDS映射证实了硒化金对电极的元素组成和均匀性。硒化金对电极的循环伏安曲线显示了与I/I电解质中反应相关的两组还原-氧化峰，因此与铂的循环伏安曲线具有可比性。α-AuSe对电极表现出更好的电催化活性，还原电流为6.1 mA，优于β-AuSe和铂对电极，后者的还原电流分别为4.2 mA和4.8 mA。α-AuSe对电极的峰峰间距（Δ）也更有利，为532 mV，高于β-AuSe对电极的739 mV，然而，这两个值都大于铂对电极的468 mV。电化学阻抗谱（EIS）和塔菲尔曲线数据表明，与β-AuSe相比，α-AuSe具有最佳的催化活性，与铂相当。使用α-AuSe作为对电极的DSSC具有最高的光电转换效率（PCE）（6.94%），相比之下，铂对电极的PCE为4.89%，β-AuSe对电极的PCE为3.47%。铂对电极效率较低归因于填充因子较差。基于这些新颖的结果，α-AuSe是在DSSC中用作铂替代对电极的极佳候选材料。
