Park Chae Hee, Lee Chang Min, Choi Jong Won, Park Geun Chul, Joo Jinho
SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University, Suwon, Kyunggi-do 16419, South Korea.
School of Materials Science and Engineering, Sungkyunkwan University, Suwon, Kyunggi-do 16419, South Korea.
J Nanosci Nanotechnol. 2018 Sep 1;18(9):6090-6094. doi: 10.1166/jnn.2018.15611.
Controllable TiO2 architectures with different facets play a key role in the adjustment of the surface area and charge recombination efficiency in photocatalysts. In this study, we synthesized anatase TiO2 mesocrystals with diethanolamine (DEA, 0-5 mM) as a nontoxic capping agent to control the facet of subunits using hydrothermal method, and determine the effect of DEA on subunits, by-products, and consequent photocatalytic performance of TiO2 mesocrystals. The pure TiO2 was spindle-like shaped mesocrystal having bipyramidal subunits with high portion of {101} facets. As DEA concentration was increased, the percentage of {001} exposed facet of subunits increased, but the number of subunits was gradually reduced. When a large amount of DEA (≥3 mM) was added, TiO2 exhibited single crystals rather than mesocrystal, probably because the long chain of DEA interfered with the oriented attachment of subunits. The photocatalytic activity of the TiO2 improved at 0.5 mM of DEA due to low charge recombination rate by increasing {001} facet. On the other hand, subsequent deterioration with further increase of DEA was attributed to the increased by-products and reduced the number of subunits despite the increase in specific surface area. These results imply that charge separation efficiency, rather than specific surface area, is highly responsible for the photocatalytic activity of TiO2.
具有不同晶面的可控二氧化钛结构在调节光催化剂的表面积和电荷复合效率方面起着关键作用。在本研究中，我们以二乙醇胺（DEA，0 - 5 mM）作为无毒封端剂，采用水热法合成锐钛矿型二氧化钛介晶，以控制亚单元的晶面，并确定DEA对二氧化钛介晶的亚单元、副产物以及相应光催化性能的影响。纯二氧化钛是具有双锥体亚单元且{101}晶面比例较高的纺锤状介晶。随着DEA浓度的增加，亚单元{001}暴露晶面的百分比增加，但亚单元数量逐渐减少。当加入大量DEA（≥3 mM）时，二氧化钛呈现出单晶而非介晶，这可能是因为DEA的长链干扰了亚单元的定向附着。由于{001}晶面增加导致电荷复合率降低，二氧化钛在0.5 mM DEA时光催化活性提高。另一方面，随着DEA进一步增加，随后的活性下降归因于副产物增加以及亚单元数量减少，尽管比表面积增加。这些结果表明，电荷分离效率而非比表面积对二氧化钛的光催化活性起高度决定作用。
