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光催化材料在解决能源短缺和环境污染等问题方面具有广泛的应用前景，本文通过构建BiOI纳米薄膜并将其与石墨烯复合起来，得到具有较高的比表面积和良好的光催化活性的纳米复合物光催化材料.采用基于密度泛函理论的第一性原理方法分别计算了单层和双层BiOI纳米片及其与石墨烯复合结构的电子结构和光学性质，并考虑了BiOI中的Bi，O，I三种空位缺陷对电子结构和光学特性的影响.计算结果表明，由于BiOI和石墨烯之间的相互作用，在石墨烯和BiOI界面处自发发生电荷转移，形成电子-空穴对，且石墨烯衬底可有效提高BiOI对可见光的光吸收，提高其光催化活性.对空位缺陷的计算表明，Bi空位缺陷可促进石墨烯和BiOI之间的电荷转移，形成更多的层间电子-空穴对；相反，O和I空位缺陷则抑制层间电荷转移，减少电子-空穴对的生成.Photocatalytic technology has wide potential applications in the fields of energy generation and pollutant purification due to its advantages of low cost and environmental friendliness. Besides traditional photocatalysts of TiO2 and ZnO, the developing of new photocatalyst with novel properties of strong oxidation, reduction ability, and visible light response has received more attention. Bismuth compounds, such as BiOX (X=Cl, Br, I), exhibit highly efficient photocatalytic activity because of its layered structure and electronic characteristics. The special layered structure, resulting in built-in-field, is favorable for the separation and migration of photogenerated electrons and holes. Among BiOX compounds, BiOI has the best optical absorption characteristics in the range of visible light, and also has the best photocatalytic activity for the degradation of organic pollutants under visible light irradiation. Graphene is an ideal two-dimensional crystal with zero band gap and a high specific surface area. Many researches have shown that graphene can effectively reduce recombination probability of hole and electron because of its unique electron transport property, and it can improve the photocatalytic activity and light stability of the composite catalytic materials. In this paper, by constructing BiOI nanosheets and hybrid graphene/BiOI, the nanocomposite photocatalytic materials each with a high specific surface area and good photocatalytic activity are obtained. First-principle calculation based on density functional theory is used to investigate the electronic and optical properties of single/double layer BiOI nanosheets and their nanocomposites with graphene. Three kinds of vacancy defects, such as Bi, O and I in BiOI, are also considered. The calculated results show that the spontaneous charge transfer from graphene to BiOI takes place, forming electron-hole puddle because of the interface interaction between graphene and BiOI. Additionally, the hybrid graphene/BiOI complex displays an enhanced optical absorption behavior in the visible light region, improving its photocatalytic activity. The calculated results about the vacancy defects show that the Bi vacancy enhances the charge transfer between BiOI and graphene and forms more electron-hole puddles. In contrast, O and I defects restrain the charge separation between two layers and reduce the formation of electron-hole puddles.
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Keywords:
- photocatalytic /
- density functional theory /
- charge transfer /
- electron-hole puddles
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[1] Rauf M A, Ashraf S S 2009 Chem. Eng. J. 151 10
[2] Akpan U G, Hameed B H 2009 J. Hazard. Mater. 170 520
[3] Chen Y, Wang J Y, Li W Z, Ju M T 2016 J. Mater. Eng. 44 103(in Chinese) [陈昱, 王京钰, 李维尊, 鞠美庭 2016 材料工程 44 103]
[4] Wang Z Y, Huang B B, Dai Y 2017 Mater. China 36 7(in Chinese) [王泽岩, 黄柏标, 戴瑛 2017 中国材料进展 36 7]
[5] Jin T, Dai Y 2017 Acta Phys. Chem. Sin. 33 295(in Chinese) [荆涛, 戴瑛 2017 物理化学学报 33 295]
[6] Huang H W, Han X, Li X W, Wang S H, Chu P K, Zhang Y H 2015 Acs Appl. Mater. Interfaces 7 482
[7] Jiang J, Zhang X, Sun P B, Zhang L Z 2011 J. Phys. Chem. C 115 20555
[8] Huang H W, He Y, Lin Z S, Kang L, Zhang Y H 2013 J. Phys. Chem. C 117 22986
[9] Wei Y P, Yang Q L, Guo L 2009 Prog. Chem. 21 1734(in Chinese) [魏平玉, 杨青林, 郭林 2009 化学进展 21 1734]
[10] Wang J J, Zhang M, Meng J, Li Q X, Yang J L 2017 RSC Adv. 7 24446
[11] Zhao Z Y, Dai W W 2015 Inorg. Chem. 54 10732
[12] Chen J H, Jang C, Xiao S, Ishigami M, Fuhrer M S 2008 Nat Nanotechnol. 3 206
[13] Du A J, Sanvito S, Li Z, Wang D W, Jiao Y, Liao T, Sun Q, Yun H N, Zhu Z H, Amal R, Smith S C 2012 J. Am. Chem. Soc. 134 4393
[14] Gao H T, Li X H, L J, Liu G J 2013 J. Phys. Chem. C 117 16022
[15] Kresse G, Furthmller J 1996 Phys. Rev. B 54 169
[16] Kresse G, Joubert D 1999 Phys. Rev. B 59 1758
[17] Perdew J P, Burke K, Ernzerhof M 1996 Phys. Rev. Lett. 77 3865
[18] Monkhorst H J, Pack D 1976 Phys. Rev. B 13 5188
[19] Grimme S 2006 J. Comp. Chem. 27 1787
[20] Zhang H, Liu L, Zhou Z 2012 RSC Adv. 2 9224
[21] Garg R, Dutta N K, Choudhury N R 2014 Nanomate- rials 4 267
[22] Gajdos M, Hummer K, Kresse G, Furthmller J, Bechstedt F 2006 Phys. Rev. B 73 045112
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