Hierarchically porous silicon with significantly improved photocatalytic oxidation capability for phenol degradation
Hierarchically porous silicon with significantly improved photocatalytic oxidation capability for phenol degradation
复制标题
分级多孔硅显着提高光催化氧化苯酚降解能力
DOI：
10.1016/j.apcatb.2013.03.014
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发表时间：
2013-07
期刊：
影响因子：
--
通讯作者：
Wang, Hua
中科院分区：
文献类型：
--
作者：
Su, Jingyang;Yu, Hongtao;Quan, Xie;Chen, Shuo;Wang, Hua
本文以硅片为衬底，采用电辅助化学腐蚀方法制备了多孔硅。平均直径约为100毫米的气孔。1200 nm（大孔），大孔表面均匀分布着大量直径小于5 nm的纳米孔，形成了大孔纳米孔分级多孔硅（NP-MPSi）结构。UV-vis漫反射测量表明，由于纳米孔的量子限制效应，纳米MPSi的禁带宽度为2.12eV，比原硅片的禁带宽度提高了1.0eV。Mott-Schottky实验进一步证明了NP-MPSi带隙的增加来自于价带电势的正移，这提高了其光催化氧化的能力。NP-MPSi表现出比大孔硅（MPSi）更高的光电化学稳定性，大孔硅是缺乏纳米孔的比较样品。以苯酚为例，光催化实验下的照射下，与白炽灯表明，苯酚降解和总有机碳去除的动力学常数使用NP-MPSi的近3.5倍和8.0倍，分别比使用MPSi。因此，这种独特的多孔硅材料是环境应用中有吸引力的光催化剂。
In this work, hierarchically porous silicon was fabricated through electro-assisted chemical etching using a silicon wafer as a substrate. Pores with an average diameter of ca. 1200nm (macropores) were observed and a large number of nanopores with a diameter of less than 5nm were uniformly distributed over the surface of the macropore, forming the hierarchically porous silicon with nanopores in macropores structure (NP-MPSi). UV–vis diffuse reflection measurements indicated that NP-MPSi has a bandgap of 2.12eV, which is 1.0eV higher than that of the original silicon wafer because of the quantum confinement effect caused by the nanopores. Mott–Schottky experiments further demonstrated that the increase in bandgap of NP-MPSi arises from a positive shift of the valence band potential, which improves its capability for photocatalytic oxidation. NP-MPSi exhibited higher photoelectrochemical stability than macroporous silicon (MPSi), a comparison sample lacking nanopores. Using phenol as an example, photocatalytic experiments under irradiation with a Xe lamp demonstrated that the kinetic constants of phenol degradation and total organic carbon removal using NP-MPSi were nearly 3.5 and 8.0 times larger, respectively, than those using MPSi. This unique porous silicon material is therefore an attractive photocatalyst for environmental applications.
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