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Dos Santos IFS, Edwards HGM, de Faria DLA. Hematite colour revisited: Particle size and electronic transitions. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 310:123810. [PMID: 38232630 DOI: 10.1016/j.saa.2023.123810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 12/13/2023] [Accepted: 12/22/2023] [Indexed: 01/19/2024]
Abstract
Hematite has been used as a pigment since ancient times, due to its natural abundance and colour that ranges from vivid red to purple. Caput mortuum is a purple α-Fe2O3 whose colour has been ascribed as originating from particle size. In this work, submicrometric synthetic, natural and commercial hematites were investigated by diffuse reflectance spectroscopy (DRS), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and Raman microscopy aiming to clarify the origin of the purple colour. From the results it was concluded that the purple colour is associated with crystallinity, that promotes a significant decrease in absorption below 500 nm and, simultaneously, an increase in the 6A1(6S) → 4T1(4G) d-d transition at ca. 880 nm. The behaviour of the ca. 880 nm band can be explained by the more extensive magnetic interaction between adjacent Fe3+ ions in crystalline samples but cannot explain the spectral behaviour in the green-blue region considering only the d-d transitions. A plausible explanation is that in the distorted FeO6 octahedra, both the Fe-O distances and the Fe-O-Fe angles area are affected, thus interfering in the low energy oxygen-to-iron charge transfer transition, whose tail span the 400 nm - 500 nm region and is more intense than the d-d transitions in hematite nanoparticles, nanofilms and defective (red) Fe2O3 samples. The decrease in the intensity of the charge transfer band as a consequence of the FeO6 octahedral distortion is yet to be confirmed by further experiments, but the experimental results clearly show that the purple colour of hematite is due to a decrease in optical absorption below 500 nm.
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Affiliation(s)
- Isabela F S Dos Santos
- Paulista Museum, University of São Paulo, 04263-000 São Paulo - SP, Brazil; Institute of Chemistry, University of São Paulo, 05508-000 São Paulo - SP, Brazil.
| | - Howell G M Edwards
- School of Chemistry and Biosciences, Faculty of Life Sciences, University of Bradford, Bradford, BD7 1DP, UK
| | - Dalva L A de Faria
- Institute of Chemistry, University of São Paulo, 05508-000 São Paulo - SP, Brazil; Museum of Archeology and Ethnology, Interunit Postgraduate Program in Museology (PPGMus), University of São Paulo, 05508-970 São Paulo - SP, Brazil
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2
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Hu S, Zheng L, Zhang H, Chen G, Yang Y, Ouyang Z, Chen S, Gao K, Liu C, Wang Q, Liu T. Hematite-mediated Mn(II) abiotic oxidation under oxic conditions: pH effect and mineralization. J Colloid Interface Sci 2023; 636:267-278. [PMID: 36634396 DOI: 10.1016/j.jcis.2023.01.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 12/26/2022] [Accepted: 01/06/2023] [Indexed: 01/09/2023]
Abstract
Interactions between manganese (Mn) and iron (Fe) are widespread processes in soils and sediments, however, the abiotic transformation mechanisms are not fully understood. Herein, Mn(II) oxidation on hematite were investigated at various pH under oxic condition. Mn(II) oxidation rates increased from 3 × 10-4 to 8 × 10-2 h-1 as pH increased from 7.0 to 9.0, whereas hematite enhanced Mn(II) oxidation rates to 1 h-1. During oxidation process, high pH could promote the oxidation of Mn(II) into Mn minerals, resulting in the rapid consumption of the newly-formed H+, and high pH facilitated Mn(II) adsorption and oxidation by altering Mn(II) reactivity and speciation. Only granule-like hausmannite was found on the hematite surface at pH 7.0, whereas hausmannite particles and feitknechtite and manganite nanowires were formed at pH from 7.5 to 9.0. Moreover, a co-shell structured nanowire composed of manganite and feitknechtite was observed owing to autocatalytic reactions. Specifically, electron transfers between Mn(II) and O2 occurred on the surface or through bulk phase of hematite, and direct electron transfers in the O2-Mn(II) complex and indirect electron transfers in the O2-Fe(II/III)-Mn(II) complex may both have contribution to the overall reactions. The findings provide a comprehensive interpretation of Fe-Mn interaction and have implications for the formation of soil Fe-Mn oxyhydroxides with unique properties in controlling element cycling.
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Affiliation(s)
- Shiwen Hu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, People's Republic of China; State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of the Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Lirong Zheng
- Beijing Synchrotron Radiation Facility (BSRF), Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Hanyue Zhang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guojun Chen
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, People's Republic of China
| | - Yang Yang
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, People's Republic of China
| | - Zhuozhi Ouyang
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, People's Republic of China
| | - Shuling Chen
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of the Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Kun Gao
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of the Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Chongxuan Liu
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of the Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Qi Wang
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, People's Republic of China
| | - Tongxu Liu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, People's Republic of China.
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3
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Peršić A, Popov N, Kratofil Krehula L, Krehula S. The Influence of Different Hematite (α-Fe 2O 3) Particles on the Thermal, Optical, Mechanical, and Barrier Properties of LDPE/Hematite Composites. MATERIALS (BASEL, SWITZERLAND) 2023; 16:706. [PMID: 36676443 PMCID: PMC9863952 DOI: 10.3390/ma16020706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/06/2023] [Accepted: 01/09/2023] [Indexed: 06/17/2023]
Abstract
There is an increasing need to develop new polymer composites with improved properties compared to conventional pure polymer materials. This work aims to develop composites of low-density polyethylene (LDPE) and iron oxide hematite particles. For this purpose, different types of hematite particles with well-defined shapes and narrow size distributions were synthesized: HC2 sample with pseudocubic hematite particles of an average diameter of 1020 nm, HE1 sample with ellipsoidal hematite particles of an average diameter of 533 nm, and HS1 sample with spherical hematite particles of an average diameter of 168 nm. The mass fractions of hematite in the composites were 0.25%, 0.5%, and 1%. Prepared LDPE/hematite composites were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and diffuse reflectance ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. The mechanical and barrier properties were also studied. The obtained results showed that all prepared composites have improved properties compared to the pure LDPE, especially the composites with pseudocubic hematite particles of well-defined shapes. The results of this study indicate that LDPE/hematite composites can be promising materials for a wide range of applications, especially as packaging materials where improved thermal and mechanical properties as well as resistance to ultraviolet (UV) irradiation are required.
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Affiliation(s)
- Ana Peršić
- Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev Trg 19, 10000 Zagreb, Croatia
| | - Nina Popov
- Division of Materials Chemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Ljerka Kratofil Krehula
- Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev Trg 19, 10000 Zagreb, Croatia
| | - Stjepko Krehula
- Division of Materials Chemistry, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
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4
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Tan W, Liang Y, Xu Y, Wang M. Structural-controlled formation of nano-particle hematite and their removal performance for heavy metal ions: A review. CHEMOSPHERE 2022; 306:135540. [PMID: 35779679 DOI: 10.1016/j.chemosphere.2022.135540] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 06/20/2022] [Accepted: 06/26/2022] [Indexed: 06/15/2023]
Abstract
Hematite is ubiquitous in nature and holds great promise for a wide variety of applications in many frontiers of environmental issues such as heavy metal remediation in environment. Over the past decades, numerous efforts have been made to control and tailor the crystal structures of hematite to improve its adsorption performance for heavy metal ions (HMIs). It is now well established that the adsorption behavior of hematite nanocrystals is strongly affected by their particle sizes, crystal facet contributions, and defective structures. This review examined the size- and facet-dependent hematite, as well as the defective hematite according to their fabrication methods and growth mechanisms. Furthermore, the adsorption performance of various hematite particles for HMIs were introduced and compared to clarify the structure-active relationships of hematite. We also overviewed the advances in charge distribution (CD)-multisite complexation (MUSIC) modeling studies about the HMIs adsorption at the hematite-water interface and the binding parameters. The Present review systematically describes how the formation conditions impact the structural and surface properties of hematite particles, thereby providing new strategies for enhancing the performance of hematite for environmental remediation.
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Affiliation(s)
- Wenfeng Tan
- State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Yu Liang
- State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China; Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China
| | - Yun Xu
- Soil Chemistry and Chemical Soil Quality Group, Wageningen University, 6708 PB, Wageningen, the Netherlands
| | - Mingxia Wang
- State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
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5
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Elishav O, Stone D, Tsyganok A, Jayanthi S, Ellis DS, Yeshurun T, Maor II, Levi A, Beilin V, Shter GE, Yerushalmi R, Rothschild A, Banin U, Grader GS. Composite Indium Tin Oxide Nanofibers with Embedded Hematite Nanoparticles for Photoelectrochemical Water Splitting. ACS APPLIED MATERIALS & INTERFACES 2022; 14:41851-41860. [PMID: 36094823 PMCID: PMC9501920 DOI: 10.1021/acsami.2c05424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 08/28/2022] [Indexed: 06/15/2023]
Abstract
Hematite is a classical photoanode material for photoelectrochemical water splitting due to its stability, performance, and low cost. However, the effect of particle size is still a question due to the charge transfer to the electrodes. In this work, we addressed this subject by the fabrication of a photoelectrode with hematite nanoparticles embedded in close contact with the electrode substrate. The nanoparticles were synthesized by a solvothermal method and colloidal stabilization with charged hydroxide molecules, and we were able to further use them to prepare electrodes for water photo-oxidation. Hematite nanoparticles were embedded within electrospun tin-doped indium oxide nanofibers. The fibrous layer acted as a current collector scaffold for the nanoparticles, supporting the effective transport of charge carriers. This method allows better contact of the nanoparticles with the substrate, and also, the fibrous scaffold increases the optical density of the photoelectrode. Electrodes based on nanofibers with embedded nanoparticles display significantly enhanced photoelectrochemical performance compared to their flat nanoparticle-based layer counterparts. This nanofiber architecture increases the photocurrent density and photon-to-current internal conversion efficiency by factors of 2 and 10, respectively.
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Affiliation(s)
- Oren Elishav
- The
Nancy & Stephen Grand Technion Energy Program (GTEP), Technion−Israel Institute of Technology, Haifa 3200002, Israel
| | - David Stone
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Anton Tsyganok
- Department
of Materials Science and Engineering, Technion−Israel
Institute of Technology, Haifa 3200002, Israel
| | - Swetha Jayanthi
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - David S. Ellis
- Department
of Materials Science and Engineering, Technion−Israel
Institute of Technology, Haifa 3200002, Israel
| | - Tamir Yeshurun
- Faculty
of Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Itzhak I. Maor
- The
Wolfson Department of Chemical Engineering, Technion−Israel Institute of Technology, Haifa 3200003 Israel
| | - Adar Levi
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Vadim Beilin
- The
Wolfson Department of Chemical Engineering, Technion−Israel Institute of Technology, Haifa 3200003 Israel
| | - Gennady E. Shter
- The
Wolfson Department of Chemical Engineering, Technion−Israel Institute of Technology, Haifa 3200003 Israel
| | - Roie Yerushalmi
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Avner Rothschild
- The
Nancy & Stephen Grand Technion Energy Program (GTEP), Technion−Israel Institute of Technology, Haifa 3200002, Israel
- Department
of Materials Science and Engineering, Technion−Israel
Institute of Technology, Haifa 3200002, Israel
| | - Uri Banin
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Gideon S. Grader
- The
Nancy & Stephen Grand Technion Energy Program (GTEP), Technion−Israel Institute of Technology, Haifa 3200002, Israel
- The
Wolfson Department of Chemical Engineering, Technion−Israel Institute of Technology, Haifa 3200003 Israel
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6
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Trenczek-Zajac A, Synowiec M, Zakrzewska K, Zazakowny K, Kowalski K, Dziedzic A, Radecka M. Scavenger-Supported Photocatalytic Evidence of an Extended Type I Electronic Structure of the TiO 2@Fe 2O 3 Interface. ACS APPLIED MATERIALS & INTERFACES 2022; 14:38255-38269. [PMID: 35969717 PMCID: PMC9412959 DOI: 10.1021/acsami.2c06404] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Heterostructures of TiO2@Fe2O3 with a specific electronic structure and morphology enable us to control the interfacial charge transport necessary for their efficient photocatalytic performance. In spite of the extensive research, there still remains a profound ambiguity as far as the band alignment at the interface of TiO2@Fe2O3 is concerned. In this work, the extended type I heterojunction between anatase TiO2 nanocrystals and α-Fe2O3 hematite nanograins is proposed. Experimental evidence supporting this conclusion is based on direct measurements such as optical spectroscopy, X-ray photoemission spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), and the results of indirect studies of photocatalytic decomposition of rhodamine B (RhB) with selected scavengers of various active species of OH•, h•, e-, and •O2-. The presence of small 6-8 nm Fe2O3 crystallites at the surface of TiO2 has been confirmed in HRTEM images. Irregular 15-50 nm needle-like hematite grains could be observed in scanning electron micrographs. Substitutional incorporation of Fe3+ ions into the TiO2 crystal lattice is predicted by a 0.16% decrease in lattice parameter a and a 0.08% change of c, as well as by a shift of the Raman Eg(1) peak from 143 cm-1 in pure TiO2 to 149 cm-1 in Fe2O3-modified TiO2. Analysis of O 1s XPS spectra corroborates this conclusion, indicating the formation of oxygen vacancies at the surface of titanium(IV) oxide. The presence of the Fe3+ impurity level in the forbidden band gap of TiO2 is revealed by the 2.80 eV optical transition. The size effect is responsible for the absorption feature appearing at 2.48 eV. Increased photocatalytic activity within the visible range suggests that the electron transfer involves high energy levels of Fe2O3. Well-programed experiments with scavengers allow us to eliminate the less probable mechanisms of RhB photodecomposition and propose a band diagram of the TiO2@Fe2O3 heterojunction.
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Affiliation(s)
- Anita Trenczek-Zajac
- Faculty
of Materials Science and Ceramics, AGH University
of Science and Technology, Krakow 30-059, Poland
| | - Milena Synowiec
- Faculty
of Materials Science and Ceramics, AGH University
of Science and Technology, Krakow 30-059, Poland
| | - Katarzyna Zakrzewska
- Faculty
of Computer Science, Electronics and Telecommunications, AGH University of Science and Technology, Krakow 30-059, Poland
| | - Karolina Zazakowny
- Faculty
of Materials Science and Ceramics, AGH University
of Science and Technology, Krakow 30-059, Poland
| | - Kazimierz Kowalski
- Faculty
of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Krakow 30-059, Poland
| | - Andrzej Dziedzic
- Institute
of Physics, College of Natural Sciences, University of Rzeszow, Rzeszow 35-310, Poland
| | - Marta Radecka
- Faculty
of Materials Science and Ceramics, AGH University
of Science and Technology, Krakow 30-059, Poland
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7
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Risk of colloidal and pseudo-colloidal transport of actinides in nitrate contaminated groundwater near a radioactive waste repository after bioremediation. Sci Rep 2022; 12:4557. [PMID: 35296759 PMCID: PMC8927300 DOI: 10.1038/s41598-022-08593-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 03/04/2022] [Indexed: 11/28/2022] Open
Abstract
The possible role of biogeochemical processes in the transport of colloidal and pseudo-colloidal U, Np, and Pu during bioremediation of radionuclide- and nitrate-contaminated groundwater was investigated. In two laboratory experiments with water samples taken from contaminated aquifers before and post bioremediation, we found that microbial processes could cause clayed, ferruginous, and actinide colloids to coagulate. The main mechanisms are biogenic insoluble ferrous iron species formations (goethite, pyrrhotite, siderite, troilite, and ferrihydrite), the aggregation of clay particles by microbial metabolites, and the immobilization of actinides in the bacterial cells, large polymers, and iron and clayed sediments. This process decreases the risk of colloidal and pseudo-colloidal transport of actinides.
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8
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Eid K, Sliem MH, Abdullah AM. Tailoring the defects of sub-100 nm multipodal titanium nitride/oxynitride nanotubes for efficient water splitting performance. NANOSCALE ADVANCES 2021; 3:5016-5026. [PMID: 36132349 PMCID: PMC9419868 DOI: 10.1039/d1na00274k] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 07/09/2021] [Indexed: 05/31/2023]
Abstract
Deciphering the photocatalytic-defect relationship of photoanodes can pave the way towards the rational design for high-performance solar energy conversion. Herein, we rationally designed uniform and aligned ultrathin sub-100 nm multipodal titanium nitride/oxynitride nanotubes (TiON x NTs) (x = 2, 4, and 6 h) via the anodic oxidation of Ti-foil in a formamide-based electrolyte followed by annealing under ammonia gas for different durations. XPS, XPS imaging, Auger electron spectra, and positron annihilation spectroscopy disclosed that the high nitridation rate induced the generation of a mixture of Ti-nitride and oxynitride with various vacancy-type defects, including monovacancies, vacancy clusters, and a few voids inside TiO x NTs. These defects decreased the bandgap energy to 2.4 eV, increased visible-light response, and enhanced the incident photon-to-current collection efficiency (IPCE) and the photocurrent density of TiON x NTs by nearly 8 times compared with TiO2NTs, besides a quick carrier diffusion at the nanotube/electrolyte interface. The water-splitting performance of sub-100 nm TiON6NT multipodal nanotubes was superior to the long compacted TiON x NTs with different lengths and TiO2 nanoparticles. Thus, the optimization of the nitridation rate tailors the defect concentration, thereby achieving the highest solar conversion efficiency.
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Affiliation(s)
- Kamel Eid
- Gas Processing Center, College of Engineering, Qatar University P. O. Box 2713 Doha Qatar
| | - Mostafa H Sliem
- Center for Advanced Materials, Qatar University P. O. Box 2713 Doha Qatar
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9
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Grave DA, Ellis DS, Piekner Y, Kölbach M, Dotan H, Kay A, Schnell P, van de Krol R, Abdi FF, Friedrich D, Rothschild A. Extraction of mobile charge carrier photogeneration yield spectrum of ultrathin-film metal oxide photoanodes for solar water splitting. NATURE MATERIALS 2021; 20:833-840. [PMID: 33875852 DOI: 10.1038/s41563-021-00955-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 02/10/2021] [Indexed: 06/12/2023]
Abstract
Light absorption in strongly correlated electron materials can excite electrons and holes into a variety of different states. Some of these excitations yield mobile charge carriers, whereas others result in localized states that cannot contribute to photocurrent. The photogeneration yield spectrum, ξ(λ), represents the wavelength-dependent ratio between the contributing absorption that ultimately generates mobile charge carriers and the overall absorption. Despite being a vital material property, it is not trivial to characterize. Here, we present an empirical method to extract ξ(λ) through optical and external quantum efficiency measurements of ultrathin films. We applied this method to haematite photoanodes for water photo-oxidation, and observed that it is self-consistent for different illumination conditions and applied potentials. We found agreement between the extracted ξ(λ) spectrum and the photoconductivity spectrum measured by time-resolved microwave conductivity. These measurements revealed that mobile charge carrier generation increases with increasing energy across haematite's absorption spectrum. Low-energy non-contributing absorption fundamentally limits the photoconversion efficiency of haematite photoanodes and provides an upper limit to the achievable photocurrent that is substantially lower than that predicted based solely on absorption above the bandgap. We extended our analysis to TiO2 and BiVO4 photoanodes, demonstrating the broader utility of the method for determining ξ(λ).
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Affiliation(s)
- Daniel A Grave
- Department of Materials Science and Engineering, Technion - Israel Institute of Technology, Haifa, Israel.
- Department of Materials Engineering and Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Be'er Sheva, Israel.
| | - David S Ellis
- Department of Materials Science and Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Yifat Piekner
- The Nancy & Stephen Grand Technion Energy Program (GTEP), Technion - Israel Institute of Technology, Haifa, Israel
| | - Moritz Kölbach
- Institute for Solar Fuels, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany
| | - Hen Dotan
- Department of Materials Science and Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Asaf Kay
- Department of Materials Science and Engineering, Technion - Israel Institute of Technology, Haifa, Israel
| | - Patrick Schnell
- Institute for Solar Fuels, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany
| | - Roel van de Krol
- Institute for Solar Fuels, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany
| | - Fatwa F Abdi
- Institute for Solar Fuels, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany
| | - Dennis Friedrich
- Institute for Solar Fuels, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany
| | - Avner Rothschild
- Department of Materials Science and Engineering, Technion - Israel Institute of Technology, Haifa, Israel.
- The Nancy & Stephen Grand Technion Energy Program (GTEP), Technion - Israel Institute of Technology, Haifa, Israel.
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10
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Kim JG, Kim HB, Choi JH, Baek K. Bifunctional iron-modified graphitic carbon nitride (g-C 3N 4) for simultaneous oxidation and adsorption of arsenic. ENVIRONMENTAL RESEARCH 2020; 188:109832. [PMID: 32798950 DOI: 10.1016/j.envres.2020.109832] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 05/24/2020] [Accepted: 06/11/2020] [Indexed: 06/11/2023]
Abstract
Iron-modified graphitic carbon nitride (FG materials) was prepared through a simple and cost-effective method using iron oxide and melamine to achieve simultaneous oxidation and adsorption of arsenic. We hypothesized that graphitic carbon nitride oxidizes As(III) to As(V) under light irradiation, and the converted As(V) is adsorbed by the amorphous iron phase on FG materials. FG materials were characterized by X-ray diffraction, Fourier transform infrared spectra, field-emission scanning electron microscopy, specific surface area, ultraviolet-visible light spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy. As(III) was efficiently transformed to As(V) due to the photocatalytic-oxidation ability of graphic carbon nitride under visible and UV light irradiation, the oxidized As(V) was adsorbed by the amorphous iron phases, and As species were removed from the system. The removal efficiency of As(III) decreased from 50%, 41%, and 33% under UV light, visible light and dark, respectively. FG materials exhibited the photocatalytic-oxidation ability and adsorption capacity, and a synergistic effect was observed between graphitic carbon nitride and iron oxide. Removal of As can be achieved even under visible light, confirming the field applicability of low-cost FG materials.
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Affiliation(s)
- Jong-Gook Kim
- Department of Environmental Engineering and Soil Environment Research Center, Jeonbuk National University, 567 Baekje-daero, Deokjin, Jeonju, Jeollabukdo 54896, Republic of Korea
| | - Hye-Bin Kim
- Department of Environmental Engineering and Soil Environment Research Center, Jeonbuk National University, 567 Baekje-daero, Deokjin, Jeonju, Jeollabukdo 54896, Republic of Korea
| | - Jeong-Hwan Choi
- Department of Environmental Engineering and Soil Environment Research Center, Jeonbuk National University, 567 Baekje-daero, Deokjin, Jeonju, Jeollabukdo 54896, Republic of Korea
| | - Kitae Baek
- Department of Environmental Engineering and Soil Environment Research Center, Jeonbuk National University, 567 Baekje-daero, Deokjin, Jeonju, Jeollabukdo 54896, Republic of Korea.
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11
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Sazama P, Moravkova J, Sklenak S, Vondrova A, Tabor E, Sadovska G, Pilar R. Effect of the Nuclearity and Coordination of Cu and Fe Sites in β Zeolites on the Oxidation of Hydrocarbons. ACS Catal 2020. [DOI: 10.1021/acscatal.9b05431] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Petr Sazama
- Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, 182 23 Prague, Czech Republic
| | - Jaroslava Moravkova
- Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, 182 23 Prague, Czech Republic
| | - Stepan Sklenak
- Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, 182 23 Prague, Czech Republic
| | - Alena Vondrova
- Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, 182 23 Prague, Czech Republic
| | - Edyta Tabor
- Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, 182 23 Prague, Czech Republic
| | - Galina Sadovska
- Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, 182 23 Prague, Czech Republic
| | - Radim Pilar
- Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, 182 23 Prague, Czech Republic
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12
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Abstract
Fe2O3has drawn significant attention in photocatalysis due to its natural abundance, thermodynamic stability, environmental compatibility, low toxicity and narrow bandgap.
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Affiliation(s)
- Zhaoyong Lin
- State Key Laboratory of Optoelectronic Materials and Technologies
- Nanotechnology Research Center
- School of Materials Science & Engineering
- Sun Yat-sen University
- Guangzhou 510275
| | - Chun Du
- State Key Laboratory of Optoelectronic Materials and Technologies
- Nanotechnology Research Center
- School of Materials Science & Engineering
- Sun Yat-sen University
- Guangzhou 510275
| | - Bo Yan
- State Key Laboratory of Optoelectronic Materials and Technologies
- Nanotechnology Research Center
- School of Materials Science & Engineering
- Sun Yat-sen University
- Guangzhou 510275
| | - Guowei Yang
- State Key Laboratory of Optoelectronic Materials and Technologies
- Nanotechnology Research Center
- School of Materials Science & Engineering
- Sun Yat-sen University
- Guangzhou 510275
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13
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Grave DA, Yatom N, Ellis DS, Toroker MC, Rothschild A. The "Rust" Challenge: On the Correlations between Electronic Structure, Excited State Dynamics, and Photoelectrochemical Performance of Hematite Photoanodes for Solar Water Splitting. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1706577. [PMID: 29504160 DOI: 10.1002/adma.201706577] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 12/31/2017] [Indexed: 06/08/2023]
Abstract
In recent years, hematite's potential as a photoanode material for solar hydrogen production has ignited a renewed interest in its physical and interfacial properties, which continues to be an active field of research. Research on hematite photoanodes provides new insights on the correlations between electronic structure, transport properties, excited state dynamics, and charge transfer phenomena, and expands our knowledge on solar cell materials into correlated electron systems. This research news article presents a snapshot of selected theoretical and experimental developments linking the electronic structure to the photoelectrochemical performance, with particular focus on optoelectronic properties and charge carrier dynamics.
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Affiliation(s)
- Daniel A Grave
- Department of Materials Science and Engineering, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
| | - Natav Yatom
- Department of Materials Science and Engineering, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
| | - David S Ellis
- Department of Materials Science and Engineering, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
| | - Maytal Caspary Toroker
- Department of Materials Science and Engineering, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
| | - Avner Rothschild
- Department of Materials Science and Engineering, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
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14
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Sádovská G, Tabor E, Bernauer M, Sazama P, Fíla V, Kmječ T, Kohout J, Závěta K, Tokarová V, Sobalík Z. FeOx/Al2O3 catalysts for high-temperature decomposition of N2O under conditions of NH3 oxidation in nitric acid production. Catal Sci Technol 2018. [DOI: 10.1039/c8cy00383a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The δ and θ Al2O3 phases well stabilized Fe(iii) in Td or Oh coordination, which were identified as the active species in high temperature decomposition of N2O in a complex gas mixture produced by oxidation of ammonia.
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Affiliation(s)
- Galina Sádovská
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences
- CZ-182 23 Prague 8
- Czech Republic
- University of Pardubice
- Faculty of Chemical Technology
| | - Edyta Tabor
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences
- CZ-182 23 Prague 8
- Czech Republic
| | - Milan Bernauer
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences
- CZ-182 23 Prague 8
- Czech Republic
| | - Petr Sazama
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences
- CZ-182 23 Prague 8
- Czech Republic
| | - Vlastimil Fíla
- University of Chemistry and Technology
- Faculty of Chemical Technology
- CZ-166 28 Prague 6
- Czech Republic
| | - Tomáš Kmječ
- Joint Laboratory for Mössbauer Spectroscopy
- Faculty of Mathematics and Physics
- Charles University in Prague
- CZ -180 00 Prague 8
- Czech Republic
| | - Jaroslav Kohout
- Joint Laboratory for Mössbauer Spectroscopy
- Faculty of Mathematics and Physics
- Charles University in Prague
- CZ -180 00 Prague 8
- Czech Republic
| | - Karel Závěta
- Joint Laboratory for Mössbauer Spectroscopy
- Faculty of Mathematics and Physics
- Charles University in Prague
- CZ -180 00 Prague 8
- Czech Republic
| | - Věnceslava Tokarová
- Unipetrol Centre for Research and Education
- CZ- 400 01 Ústí nad Labem
- Czech Republic
| | - Zdeněk Sobalík
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences
- CZ-182 23 Prague 8
- Czech Republic
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15
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Schwaminger SP, Fraga-García P, Selbach F, Hein FG, Fuß EC, Surya R, Roth HC, Blank-Shim SA, Wagner FE, Heissler S, Berensmeier S. Bio-nano interactions: cellulase on iron oxide nanoparticle surfaces. ADSORPTION 2016. [DOI: 10.1007/s10450-016-9849-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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16
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Barik R, Leung KT, Mohapatra M. Solvent specific synthesis of nano corpse flowery lithiated iron oxide as an energy storage and gas sensing material. NEW J CHEM 2016. [DOI: 10.1039/c5nj02058a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Unusual nano flowery shaped Li based iron oxides (LiFeO2) and their pseudo capacitive behaviour.
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Affiliation(s)
- Rasmita Barik
- Hydro & Electrometallurgy Department
- CSIR-Institute of Minerals and Materials Technology
- India
| | - K. T. Leung
- WATLab
- Department of Chemistry
- University of Waterloo
- Waterloo
- Canada
| | - Mamata Mohapatra
- Hydro & Electrometallurgy Department
- CSIR-Institute of Minerals and Materials Technology
- India
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17
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Oulego P, Villa-García MA, Laca A, Diaz M. The effect of the synthetic route on the structural, textural, morphological and catalytic properties of iron(iii) oxides and oxyhydroxides. Dalton Trans 2016; 45:9446-59. [DOI: 10.1039/c6dt00247a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Precipitation and microemulsion methods allowed obtaining mesoporous and nanostructured materials, namely amorphous hematite and ferrihydrite, which exhibited great catalytic activity.
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Affiliation(s)
- Paula Oulego
- Department of Chemical and Environmental Engineering
- University of Oviedo
- Oviedo
- Spain
| | | | - Adriana Laca
- Department of Chemical and Environmental Engineering
- University of Oviedo
- Oviedo
- Spain
| | - Mario Diaz
- Department of Chemical and Environmental Engineering
- University of Oviedo
- Oviedo
- Spain
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18
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Amani-Ghadim AR, Alizadeh S, Khodam F, Rezvani Z. Synthesis of rod-like α-FeOOH nanoparticles and its photocatalytic activity in degradation of an azo dye: Empirical kinetic model development. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.molcata.2015.06.037] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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19
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Barik R, Mohapatra M. Solvent mediated surface engineering of α-Fe2O3nanomaterials: facet sensitive energy storage materials. CrystEngComm 2015. [DOI: 10.1039/c5ce01369k] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The surface chemical properties of iron oxide nanomaterials are keenly studied to explore their potential for many future applications.
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Affiliation(s)
- Rasmita Barik
- Hydro & Electrometallurgy Department
- CSIR-Institute of Minerals and Materials Technology
- Bhubaneswar-751 013, India
| | - Mamata Mohapatra
- Hydro & Electrometallurgy Department
- CSIR-Institute of Minerals and Materials Technology
- Bhubaneswar-751 013, India
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20
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Elsaesser A, Quinn RC, Ehrenfreund P, Mattioda AL, Ricco AJ, Alonzo J, Breitenbach A, Chan YK, Fresneau A, Salama F, Santos O. Organics Exposure in Orbit (OREOcube): A next-generation space exposure platform. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:13217-13227. [PMID: 24851720 DOI: 10.1021/la501203g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The OREOcube (ORganics Exposure in Orbit cube) experiment on the International Space Station (ISS) will investigate the effects of solar and cosmic radiation on organic thin films supported on inorganic substrates. Probing the kinetics of structural changes and photomodulated organic-inorganic interactions with real-time in situ UV-visible spectroscopy, this experiment will investigate the role played by solid mineral surfaces in the (photo)chemical evolution, transport, and distribution of organics in our solar system and beyond. In preparation for the OREOcube ISS experiment, we report here laboratory measurements of the photostability of thin films of the 9,10-anthraquinone derivative anthrarufin (51 nm thick) layered upon ultrathin films of iron oxides magnetite and hematite (4 nm thick), as well as supported directly on fused silica. During irradiation with UV and visible light simulating the photon flux and spectral distribution on the surface of Mars, anthrarufin/iron oxide bilayer thin films were exposed to CO2 (800 Pa), the main constituent (and pressure) of the martian atmosphere. The time-dependent photodegradation of anthrarufin thin films revealed the inhibition of degradation by both types of underlying iron oxides relative to anthrarufin on bare fused silica. Interactions between the organic and inorganic thin films, apparent in spectral shifts of the anthrarufin bands, are consistent with presumed free-electron quenching of semiquinone anion radicals by the iron oxide layers, effectively protecting the organic compound from photodegradation. Combining such in situ real-time kinetic measurements of thin films in future space exposure experiments on the ISS with postflight sample return and analysis will provide time-course studies complemented by in-depth chemical analysis. This will facilitate the characterization and modeling of the chemistry of organic species associated with mineral surfaces in astrobiological contexts.
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Affiliation(s)
- Andreas Elsaesser
- Leiden Institute of Chemistry, Leiden University , Leiden 2333CC, The Netherlands
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21
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Peña-Flores JI, Palomec-Garfias AF, Márquez-Beltrán C, Sánchez-Mora E, Gómez-Barojas E, Pérez-Rodríguez F. Fe effect on the optical properties of TiO2:Fe2O3 nanostructured composites supported on SiO2 microsphere assemblies. NANOSCALE RESEARCH LETTERS 2014; 9:499. [PMID: 25276103 PMCID: PMC4177376 DOI: 10.1186/1556-276x-9-499] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 09/06/2014] [Indexed: 05/30/2023]
Abstract
The effect of Fe ion concentration on the morphological, structural, and optical properties of TiO2 films supported on silica (SiO2) opals has been studied. TiO2:Fe2O3 films were prepared by the sol-gel method in combination with a vertical dip coating procedure; precursor solutions of Ti and Fe were deposited on a monolayer of SiO2 opals previously deposited on a glass substrate by the same procedure. After the dip coating process has been carried out, the samples were thermally treated to obtain the TiO2:Fe2O3/SiO2 composites at the Fe ion concentrations of 1, 3, and 5 wt%. Scanning electron microscopy (SEM) micrographs show the formation of colloidal silica microspheres of about 50 nm diameter autoensembled in a hexagonal close-packed fashion. Although the X-ray diffractograms show no significant effect of Fe ion concentration on the crystal structure of TiO2, the μ-Raman and reflectance spectra do show that the intensity of a phonon vibration mode and the energy bandgap of TiO2 decrease as the Fe(+3) ion concentration increases.
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Affiliation(s)
- Jesús I Peña-Flores
- Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Post. J-48, Puebla Pue. 72570, México
| | - Abraham F Palomec-Garfias
- Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Post. J-48, Puebla Pue. 72570, México
| | - César Márquez-Beltrán
- Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Post. J-48, Puebla Pue. 72570, México
| | - Enrique Sánchez-Mora
- Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Post. J-48, Puebla Pue. 72570, México
| | - Estela Gómez-Barojas
- CIDS-IC, Benemérita Universidad Autónoma de Puebla, Apdo. Post. 196, Puebla Pue. 72000, México
| | - Felipe Pérez-Rodríguez
- Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Post. J-48, Puebla Pue. 72570, México
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22
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Chernyshova IV, Ponnurangam S, Somasundaran P. Linking interfacial chemistry of CO2 to surface structures of hydrated metal oxide nanoparticles: hematite. Phys Chem Chem Phys 2013; 15:6953-64. [DOI: 10.1039/c3cp44264k] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Ponnurangam S, Chernyshova IV, Somasundaran P. Rational design of interfacial properties of ferric (hydr)oxide nanoparticles by adsorption of fatty acids from aqueous solutions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:10661-10671. [PMID: 22694303 DOI: 10.1021/la300995g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Notwithstanding the great practical importance, still open are the questions how, why, and to what extent the size, morphology, and surface charge of metal (hydr)oxide nanoparticles (NPs) affect the adsorption form, adsorption strength, surface density, and packing order of organic (bio)molecules containing carboxylic groups. In this article, we conclusively answer these questions for a model system of ferric (hydr)oxide NPs and demonstrate applicability of the established relationships to manipulating their hydrophobicity and dispersibility. Employing in situ Fourier transform infrared (FTIR) spectroscopy and adsorption isotherm measurements, we study the interaction of 150, 38, and 9 nm hematite (α-Fe(2)O(3)) and ∼4 nm 2-line ferrihydrite with sodium laurate (dodecanoate) in water. We discover that, independent of morphology, an increase in size of the ferric (hydr)oxide NPs significantly improves their adsorption capacity and affinity toward fatty acids. This effect favors the formation of bilayers, which in turn promotes dispersibility of the larger NPs in water. At the same time, the local order in self-assembled monolayer (SAM) strongly depends on the morphological compatibility of the NP facets with the geometry-driven well-packed arrangements of the hydrocarbon chains as well as on the ratio of the chemisorbed to the physically adsorbed carboxylate groups. Surprisingly, the geometrical constraints can be removed, and adsorption capacity can be increased by negatively polarizing the NPs due to promotion of the outer-sphere complexes of the fatty acid. We interpret these findings and discuss their implications for the nanotechnological applications of surface-functionalized metal (hydr)oxide NPs.
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Affiliation(s)
- Sathish Ponnurangam
- NSF I/UCRC Center for Particulate & Surfactant Systems (CPaSS), Columbia University, New York, New York 10027, United States
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Chernyshova IV, Ponnurangam S, Somasundaran P. Adsorption of fatty acids on iron (hydr)oxides from aqueous solutions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:10007-10018. [PMID: 21711036 DOI: 10.1021/la2017374] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The interaction of iron (hydr)oxides with fatty acids is related to many industrial and natural processes. To resolve current controversies about the adsorption configurations of fatty acids and the conditions of the maximum hydrophobicity of the minerals, we perform a detailed study of the adsorption of sodium laurate (dodecanoate) on 150 nm hematite (α-Fe(2)O(3)) particles as a model system. The methods used include in situ FTIR spectroscopy, ex situ X-ray photoelectron spectroscopy (XPS), measurements of the adsorption isotherm and contact angle, as well as the density functional theory (DFT) calculations. We found that the laurate adlayer is present as a mixture of inner-sphere monodentate mononuclear (ISMM) and outer-sphere (OS) hydration shared complexes independent of the solution pH. Protonation of the OS complexes does not influence the conformational order of the surfactant tails. One monolayer, which is filled through the growth of domains and is reached at the micellization/precipitation edge of laurate, makes the particles superhydrophobic. These results contradict previous models of the fatty acid adsorption and suggest new interpretation of literature data. Finally, we discovered that the fractions of both the OS laurate and its molecular form increase in D(2)O, which can be used for interpreting complex spectra. We discuss shortcomings of vibrational spectroscopy in determining the interfacial coordination of carboxylate groups. This work advances the current understanding of the oxide-carboxylate interactions and the research toward improving performance of fatty acids as surfactants, dispersants, lubricants, and anticorrosion reagents.
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Affiliation(s)
- Irina V Chernyshova
- NSF I/UCRC Center for Particulate & Surfactant Systems, Columbia University, New York, New York 10027, United States.
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