鐵鉑合金應用於染料敏化太陽能電池對電極及其形狀效應於碘還原催化之影響

Abstract

染料敏化太陽能電池文獻中指出鉑金屬作為相對電極具有多種功用，其中最重要的是與電解液的交互作用中對碘的還原催化效果。因此，我們將鐵鉑合金粒子應用於染料敏化太陽能電池之相對電極改質，偵測鐵鉑合金對於I-/I3-的催化效果，並藉此達成鉑在相對電極使用量減少的目的，以降低染料敏化太陽能電池的材料成本。並與鉑金屬作為對電極的染料敏化太陽能電池比較，其能量轉換效率的表現有提升。此外，我們將金屬前驅物、有機界面活性劑加入油相中反應，經由多元醇還原之反應步驟合成奈米級鐵鉑合金粒子，利用有機界面活性劑對於合金晶面吸附能力的差異，以達到形狀控制的效果。由於粒子形狀的不同意指其裸露晶面不同例如: {111}, {100}及{311}面，進而影響對碘的還原催化效果。另外，再進一步調整金屬前驅物之比例，合成出形狀相同而比例不同的合金粒子。由於合金比例不同，給予電子的能力便不盡相同，這些皆會讓碘的還原催化效果有所差異，所以就針對合金的形狀與比例差異加以探討其碘還原催化活性的趨勢。

Many papers had pointed out that the pure Pt counter electrode (CE) mainly played as a catalyst for the redox reaction of iodide/tri-iodide (I-/I3-) in dye-sensitized solar cells (DSSCs). For the first time, PtFe alloy nanoparticles were employed as the CE for DSSCs. The CV measurements demonstrated the electrocatalytic activity of PtFe nanoparticles in the I-/I3- redox reaction . Further, the J-V characteristics exhibited that PtFe alloy nanoparticles as CE for DSSCs achieved a good power conversion efficiency(7.37% for PtFe concave cube; 7.19% for PtFe polyhedron), closed to the performance of DSSCs using Pt CE (7.32%). In this study, various PtFe nanostructures enclosed by the different oriented surfaces, such as {111}, {100} and {311} facets, were prepared through the fine adjustment of specific surfactant-crystal facet binding. When PtFe nanostructures, including polyhedron, nanocube and concave cube, were employed as the CE for DSSCs, the photovoltaic results exhibited the shape-dependent activity in the I-/I3- redox reaction. Also, the controlled alloying composition of all PtFe nanostructures was able to influence the activity of I-/I3- redox reaction due to the change of electronic state of Pt. Finally, the shape- and composition-sensitivity of these PtFe nanostructures in terms of the I-/I3- redox activity were discussed in this study.