玻璃碳球磨细化对催化还原碘三离子的影响

Effect of ball-milling of glassy carbon powder on catalytic activities for tri-iodide reduction

通过改变球磨时间实现玻璃碳不同程度的粒径细化,将玻璃碳作为催化材料引入染料敏化太阳电池(DSC)用对电极,着重考察了球磨细化对玻璃碳还原电解质中碘三离子(I3-)的催化活性的影响。结果表明,球磨细化不仅使玻璃碳的中值粒径从起始的20μm不断下降到球磨时间为8 h时的6μm,而且引起玻璃碳晶体结构的微变,具体体现为玻璃碳中组成类石墨微晶的单层石墨层片间距d(002)从0.364 nm逐渐减小到0.353 nm。粒径和晶体结构的变化通过不同方式影响玻璃碳表面的催化活性点,最终改变了玻璃碳的催化活性。随球磨时间的延长,催化活性先增后减,2 h时出现最优值。将玻璃碳对电极组装成DSC后,光电性能随球磨时间的变化规律几乎与催化活性随球磨时间的变化规律一致。

The refined glassy carbon particles with different size were obtained through changing the ball-milling time, and then employed as catalytic material for counter electrodes in dye-sensitized solar cells （DSC）. The influence of ball-milling refinement on the catalytic activity of glassy carbons for reduction of tri-iodide in electrolyte was researched. The results show that the ball-milling refinement not only reduces the median particle size of glassy carbon from initial 20 μm to 6μm after milling for 8 h, but also results in slight change of the crystal structure of glassy carbon. The layer distance d（002） of graphene sheets in glassy carbon gradually decreases from 0.364 nm to 0.353 nm. The variations of particle size and crystal structure affect catalytic active site on the surface of glassy carbon in different ways, resulting in the change of catalytic activity of glassy carbon. As ball-milling time increases, the catalytic activity increases firstly and then decreases,showing an optimum value at 2 h. The variation law of the photovoltaic properties of the glassy carbon based DSC with different ball-milling time follows the catalytic activity of glassy carbon.