Highly Enhanced Gas Adsorption Properties in Vertically Aligned MoS2 Layers

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• 作者：Soo-Yeon Cho ; Seon Joon Kim ; Youhan Lee ; Jong-Seon Kim ; Woo-Bin Jung ; Hae-Wook Yoo ; Jihan Kim ; Hee-Tae Jung
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：September 22, 2015
• 年：2015
• 卷：9
• 期：9
• 页码：9314-9321
• 全文大小：629K
• ISSN：1936-086X

文摘

In this work, we demonstrate that gas adsorption is significantly higher in edge sites of vertically aligned MoS₂ compared to that of the conventional basal plane exposed MoS₂ films. To compare the effect of the alignment of MoS₂ on the gas adsorption properties, we synthesized three distinct MoS₂ films with different alignment directions ((1) horizontally aligned MoS₂ (basal plane exposed), (2) mixture of horizontally aligned MoS₂ and vertically aligned layers (basal and edge exposed), and (3) vertically aligned MoS₂ (edge exposed)) by using rapid sulfurization method of CVD process. Vertically aligned MoS₂ film shows about 5-fold enhanced sensitivity to NO₂ gas molecules compared to horizontally aligned MoS₂ film. Vertically aligned MoS₂ has superior resistance variation compared to horizontally aligned MoS₂ even with same surface area exposed to identical concentration of gas molecules. We found that electrical response to target gas molecules correlates directly with the density of the exposed edge sites of MoS₂ due to high adsorption of gas molecules onto edge sites of vertically aligned MoS₂. Density functional theory (DFT) calculations corroborate the experimental results as stronger NO₂ binding energies are computed for multiple configurations near the edge sites of MoS₂, which verifies that electrical response to target gas molecules (NO₂) correlates directly with the density of the exposed edge sites of MoS₂ due to high adsorption of gas molecules onto edge sites of vertically aligned MoS₂. We believe that this observation extends to other 2D TMD materials as well as MoS₂ and can be applied to significantly enhance the gas sensor performance in these materials.