Influence of heavy metal sorption pathway on the structure of biogenic birnessite: Insight from the band structure and photostability
文献类型：期刊论文
| 作者 | Li, Y; Liu, FF; Xu, XM; Liu, YW; Li, YZ; Ding, HR; Chen, N; Yin, H; Lin, H; Wang, CQ |
| 刊名 | GEOCHIMICA ET COSMOCHIMICA ACTA
 |
| 出版日期 | 2019 |
| 卷号 | 256期号:-页码:116—134 |
| 关键词 | ZN ISOTOPIC FRACTIONATION SYNTHETIC NA-BIRNESSITE MANGANESE OXIDES HEXAGONAL-BIRNESSITE REDUCTIVE TRANSFORMATION MOLECULAR CONTROLS SORBED BIRNESSITE RICH BIRNESSITE WATER OXIDATION ELECTRONIC-STRUCTURES |
| ISSN号 | 0016-7037 |
| DOI | 10.1016/j.gca.2018.12.008 |
| 文献子类 | 期刊论文 |
| 英文摘要 | Birnessite, primarily formed by biooxidation, is a common semiconducting Mn oxide in nature and a major controller of heavy metals cycling processes. In turn, the heavy metal sorption pathway alters its structural chemistry and thus the electronic structure. We synthesize three kinds of birnessite, namely biogenic (bio-birnessite), Cu coprecipitated (co-birnessite) and Cu adsorbed birnessite (ad-birnessite), to investigate the influence of Cu(II) occupancy on the structure, semiconducting property and photostability of birnessite. XRD show co-birnessite holds the same hexagonal symmetry as bio-birnessite, whereas ad-birnessite transforms to triclinic symmetry as reflected by the splitting reflections at 2.44 and 1.42 angstrom. The adsorption process is accompanied by a more intense releasing of Mn(II) (156.88 mu M/L) from a bio-birnessite analog delta-MnO2 in light than in dark (19.55 mu M/L), suggesting the photoreductive releasing of Mn(II) promotes structure transformation. Conformably, both the Mn average oxidation state (AOS) (3.32) and mole ratio of Cu/Mn (0.08) in ad-birnessite is lower than those in co-birnessite (AOS: 3.47, Cu/Mn ratio: 0.17). EXAFS demonstrate different Cu complexing features in ad- and co-birnessite that the ratio of Cu incorporated (INC) into vacancies is 1.16 and 0.45 for ad- and co-birnessite, respectively. UV-vis diffuse reflection spectra (DRS) and photoelectron spectrometer (PS) exhibit the band gap (E-g) and valence band (VB) of bio-birnessite are 2.05 and -5.58 eV, while there is 0.1 and 0.05 eV decrease of E-g, and 0.08 and 0.16 eV lowering of VB in co- and ad-birnessite, respectively. The reduced E-g guarantee them to generate photoelectron-hole pairs under mild indoor visible light, and the lower energy level of VB in ad-birnessite makes its VB holes more reactive to accept electrons from electron donors. Further density functional theory (DFT) calculations focus on interpreting the fine structures brought by different Cu sorption pathways on the electronic structure of birnessite. A Mn vacancy in a 2 x 2 x 1 hexagonal birnessite cell significantly reduces E-g from 1.60 to 0.28 eV by hybridizing Mn 3d and O 2p states in VB. The doped Cu reduces E-g mainly through incorporating Cu 3d orbital in VB. The INC Cu in hexagonal birnessite contributes more to reduce E-g (1.60-0.34 eV) than TCS Cu (1.60-1.20 eV), while in triclinic birnessite cell, TCS Cu causes more obvious reduction of E-g (1.68-0.28 eV) than INC Cu (1.68-1.55 eV). Thus, we conclude the vacancy imposes more effect on the electronic structure of hexagonal co-birnessite than doped Cu in TCS or INC sites; and the band structure of co-birnessite is more sensitive to INC Cu, in contrast to TCS Cu affecting more in ad-birnessite. Overall, the crystal structure differs according to Cu fixation pathway, which imposes a comprehensive effect on band structure and photostability contributed by vacancies, Cu occupancy sites and structural symmetry. Cu coprecipitating with birnessite is suggested as a preferred method in practical clean-up of metals such as Cu, due to the higher adsorption capacity for Cu, better stability of TCS Cu and better photostability influenced by Cu. (C) 2018 Elsevier Ltd. All rights reserved. |
| 语种 | 英语 |
| 源URL | [http://ir.sinap.ac.cn/handle/331007/31672]  |
| 专题 | 上海应用物理研究所_中科院上海应用物理研究所2011-2017年 |
| 作者单位 | 1.Huazhong Agr Univ, Coll Resources & Environm, Minist Agr, Key Lab Arable Land Conservat Middle & Lower Reac, Wuhan 430070, Hubei, Peoples R China; 2.Chinese Acad Sci, Shanghai Inst Appl Phys, Pudong New Area, Shanghai Synchrotron Radiat Facil, Shanghai 201204, Peoples R China 3.Canadian Light Source Inc, 44 Innovat Blvd, Saskatoon, SK S7N 2V3, Canada; 4.Cent S Univ, Sch Geosci & Infophys, Changsha 410083, Hunan, Peoples R China; 5.Peking Univ, Sch Earth & Space Sci, Key Lab Orogen Belts & Crustal Evolut, Beijing Key Lab Mineral Environm Funct, Beijing 100871, Peoples R China; |
| 推荐引用方式 GB/T 7714 | Li, Y,Liu, FF,Xu, XM,et al. Influence of heavy metal sorption pathway on the structure of biogenic birnessite: Insight from the band structure and photostability[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2019,256(-):116—134. |
| APA | Li, Y.,Liu, FF.,Xu, XM.,Liu, YW.,Li, YZ.,...&Lu, AH.(2019).Influence of heavy metal sorption pathway on the structure of biogenic birnessite: Insight from the band structure and photostability.GEOCHIMICA ET COSMOCHIMICA ACTA,256(-),116—134. |
| MLA | Li, Y,et al."Influence of heavy metal sorption pathway on the structure of biogenic birnessite: Insight from the band structure and photostability".GEOCHIMICA ET COSMOCHIMICA ACTA 256.-(2019):116—134. |
入库方式： OAI收割
来源：上海应用物理研究所
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