1
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Howard-Fabretto L, Gorey TJ, Li G, Osborn DJ, Tesana S, Metha GF, Anderson SL, Andersson GG. The interaction of size-selected Ru 3 clusters with TiO 2: depth-profiling of encapsulated clusters. Phys Chem Chem Phys 2024; 26:19117-19129. [PMID: 38957118 DOI: 10.1039/d4cp00263f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
Ru is a metal of interest in catalysis. Monodisperse Ru3 clusters as catalytic sites are relevant for the development of catalysts because clusters use significantly lower amounts of precious materials for forming active sites due to the small size of the cluster. However, retaining the mono-dispersity of the cluster size after deposition is a challenge because surface energy could drive both agglomeration and encapsulation of the clusters. In the present work Ru3 clusters are deposited by chemical vapor deposition (CVD) of Ru3(CO)12 and cluster source depositions of bare Ru3 onto radio frequency sputter-deposited TiO2 (RF-TiO2) substrates, TiO2(100), and SiO2. When supported on RF-TiO2, bare Ru3 is encapsulated by a layer of titania substrate material during deposition with a cluster source. Ligated Ru3(CO)12 is also encapsulated by a layer of titania when deposited onto sputter-treated RF-TiO2, but only through heat treatment which is required to remove most of the ligands. The titania overlayer thickness was determined to be 1-2 monolayers for Ru3(CO)12 clusters on RF-TiO2, which is thin enough for catalytic or photocatalytic reactions to potentially occur even without clusters being part of the very outermost layer. The implication for catalysis of the encapsulation of Ru3 into the RF-TiO2 is discussed. Temperature-dependent X-ray photoelectron spectroscopy (XPS), angle-resolved XPS, and temperature-dependent low energy ion scattering (TD-LEIS) are used to probe how the cluster-surface interaction changes due to heat treatment and scanning transmission electron microscopy (STEM) was used to image the depth of the surface from side-on.
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Affiliation(s)
- Liam Howard-Fabretto
- Flinders Institute for Nanoscale Science and Technology, Flinders University, Physical Sciences Building (2111) GPO Box 2100, Adelaide 5001, South Australia 5042, Australia.
- Flinders Microscopy and Microanalysis, College of Science and Engineering, Flinders University, Adelaide, South Australia 5042, Australia
| | - Timothy J Gorey
- Chemistry Department, University of Utah, 315 S. 1400 E., Salt Lake City, UT 84112, USA
| | - Guangjing Li
- Chemistry Department, University of Utah, 315 S. 1400 E., Salt Lake City, UT 84112, USA
| | - D J Osborn
- Department of Chemistry, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Siriluck Tesana
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Physical and Chemical Sciences, University of Canterbury, Christchurch 8041, New Zealand
- National Isotope Centre, GNS Science, Lower Hutt 5010, New Zealand
| | - Gregory F Metha
- Department of Chemistry, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Scott L Anderson
- Chemistry Department, University of Utah, 315 S. 1400 E., Salt Lake City, UT 84112, USA
| | - Gunther G Andersson
- Flinders Institute for Nanoscale Science and Technology, Flinders University, Physical Sciences Building (2111) GPO Box 2100, Adelaide 5001, South Australia 5042, Australia.
- Flinders Microscopy and Microanalysis, College of Science and Engineering, Flinders University, Adelaide, South Australia 5042, Australia
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2
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Hernández-Rodríguez F, Garza-Hernández R, Alfaro-Cruz M, Torres-Martínez LM. Tunable structure of TiO 2 deposited by DC magnetron sputtering to adsorb Cr (VI) and Fe (III) from water. Heliyon 2024; 10:e27359. [PMID: 38501005 PMCID: PMC10945184 DOI: 10.1016/j.heliyon.2024.e27359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 02/27/2024] [Accepted: 02/28/2024] [Indexed: 03/20/2024] Open
Abstract
TiO2 thin films with mixtures of the anatase, rutile, and brookite phases were deposited on glass substrates via magnetron sputtering. Based on XRD and Raman results, the TiO2-0.47 and TiO2-3.47 films principally contained the brookite phase, while the TiO2-1.27 and TiO2-2.13 films were primarily anatase. The capacities of the TiO2 films to adsorb heavy metals were tested with Cr(VI) and Fe(III) solutions, and the maximum Cr(VI) and Fe(III) adsorption capacities were realized with the TiO2-0.47 film (334.5 mg/g) and TiO2-3.47 film (271.3 mg/g), respectively. SEM‒EDS results revealed the presence of Cr and Fe on the surfaces of the films, thus corroborating the ability of the TiO2 films to adsorb and remove heavy metals. They are strong candidates for use in wastewater treatment plants.
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Affiliation(s)
- F.A. Hernández-Rodríguez
- Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Av. Universidad S/N Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, C.P. 66455, Mexico
| | - R. Garza-Hernández
- Centro de Investigaciones en Óptica, A.C., Loma del Bosque 115, Col. Lomas del Campestre León, Guanajuato, C.P. 37150, Mexico
| | - M.R. Alfaro-Cruz
- Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Av. Universidad S/N Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, C.P. 66455, Mexico
- CONAHCYT-Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, C.P. 66455, Mexico
| | - Leticia M. Torres-Martínez
- Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Av. Universidad S/N Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, C.P. 66455, Mexico
- Centro de Investigación en Materiales Avanzados, S. C. (CIMAV), Miguel de Cervantes No. 120, Complejo Industrial Chihuahua, Chih., CP, 31136, Mexico
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3
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Thirumalaisamy L, Wei Z, Davies KR, Allan MG, McGettrick J, Watson T, Kuehnel MF, Pitchaimuthu S. Dual Shield: Bifurcated Coating Analysis of Multilayered WO 3/BiVO 4/TiO 2/NiOOH Photoanodes for Sustainable Solar-to-Hydrogen Generation from Challenging Waters. ACS SUSTAINABLE CHEMISTRY & ENGINEERING 2024; 12:3044-3060. [PMID: 38425834 PMCID: PMC10900524 DOI: 10.1021/acssuschemeng.3c06528] [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: 10/09/2023] [Revised: 01/22/2024] [Accepted: 01/24/2024] [Indexed: 03/02/2024]
Abstract
The heterostructure WO3/BiVO4-based photoanodes have garnered significant interest for photoelectrochemical (PEC) solar-driven water splitting to produce hydrogen. However, challenges such as inadequate charge separation and photocorrosion significantly hinder their performance, limiting overall solar-to-hydrogen conversion efficiency. The incorporation of cocatalysts has shown promise in improving charge separation at the photoanode, yet mitigating photocorrosion remains a formidable challenge. Amorphous metal oxide-based passivation layers offer a potential solution to safeguard semiconductor catalysts. We examine the structural, surface morphological, and optical properties of two-step-integrated sputter and spray-coated TiO2 thin films and their integration onto WO3/BiVO4, both with and without NiOOH cocatalyst deposition. The J-V experiments reveal that the NiOOH cocatalyst enhances the photocurrent density of the WO3/BiVO4 photoanode in water splitting reactions from 2.81 to 3.87 mA/cm2. However, during prolonged operation, the photocurrent density degrades by 52%. In contrast, integrated sputter and spray-coated TiO2 passivation layer-coated WO3/BiVO4/NiOOH samples demonstrate a ∼88% enhancement in photocurrent density (5.3 mA/cm2) with minimal degradation, emphasizing the importance of a strategic coating protocol to sustain photocurrent generation. We further explore the feasibility of using natural mine wastewater as an electrolyte feedstock in PEC generation. Two-compartment PEC cells, utilizing both fresh water and metal mine wastewater feedstocks exhibit 66.6 and 74.2 μmol/h cm2 hydrogen generation, respectively. Intriguingly, the recovery of zinc (Zn2+) heavy metals on the cathode surface in the mine wastewater electrolyte is confirmed through surface morphology and elemental analysis. This work underscores the significance of passivation layer and cocatalyst coating methodologies in a sequential order to enhance charge separation and protect the photoanode from photocorrosion, contributing to sustainable hydrogen generation. Additionally, it suggests the potential of utilizing wastewater in electrolyzers as an alternative to freshwater resources.
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Affiliation(s)
- Logu Thirumalaisamy
- SPECIFIC,
Materials Research Centre, Faculty of Science and Engineering, Swansea University (Bay Campus), Swansea SA1 8EN, U.K.
- Department
of Physics, G T N Arts College, Dindigul, Tamil Nadu 624005, India
| | - Zhengfei Wei
- SPECIFIC,
Materials Research Centre, Faculty of Science and Engineering, Swansea University (Bay Campus), Swansea SA1 8EN, U.K.
| | - Katherine Rebecca Davies
- SPECIFIC,
Materials Research Centre, Faculty of Science and Engineering, Swansea University (Bay Campus), Swansea SA1 8EN, U.K.
| | - Michael G. Allan
- Department
of Chemistry, Swansea University, Singleton Park, Swansea SA2 8PP, U.K.
| | - James McGettrick
- SPECIFIC,
Materials Research Centre, Faculty of Science and Engineering, Swansea University (Bay Campus), Swansea SA1 8EN, U.K.
| | - Trystan Watson
- SPECIFIC,
Materials Research Centre, Faculty of Science and Engineering, Swansea University (Bay Campus), Swansea SA1 8EN, U.K.
| | - Moritz F. Kuehnel
- Department
of Chemistry, Swansea University, Singleton Park, Swansea SA2 8PP, U.K.
- Fraunhofer
Institute for Microstructure of Materials and Systems IMWS, Walter-Hülse-Strasse 1, Halle 06120, Germany
| | - Sudhagar Pitchaimuthu
- SPECIFIC,
Materials Research Centre, Faculty of Science and Engineering, Swansea University (Bay Campus), Swansea SA1 8EN, U.K.
- Research
Centre for Carbon Solutions (RCCS), Institute of Mechanical, Processing
and Energy Engineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH144AS, U.K.
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4
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Rathore C, Yadav VK, Amari A, Meena A, Chinedu Egbosiuba T, Verma RK, Mahdhi N, Choudhary N, Sahoo DK, Chundawat RS, Patel A. Synthesis and characterization of titanium dioxide nanoparticles from Bacillus subtilis MTCC 8322 and its application for the removal of methylene blue and orange G dyes under UV light and visible light. Front Bioeng Biotechnol 2024; 11:1323249. [PMID: 38260746 PMCID: PMC10800539 DOI: 10.3389/fbioe.2023.1323249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 12/18/2023] [Indexed: 01/24/2024] Open
Abstract
Over the last decade there has been a huge increase in the green synthesis of nanoparticles. Moreover, there is a continuous increase in harnessing the potential of microorganisms for the development of efficient and biocompatible nanoparticles around the globe. In the present research work, investigators have synthesized TiO2 NPs by harnessing the potential of Bacillus subtilis MTCC 8322 (Gram-positive) bacteria. The formation and confirmation of the TiO2 NPs synthesized by bacteria were carried out by using UV-Vis spectroscopy, Fourier transforms infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDX/EDS). The size of the synthesized TiO2 NPs was 80-120 nm which was spherical to irregular in shape as revealed by SEM. FTIR showed the characteristic bands of Ti-O in the range of 400-550 cm-1 and 924 cm-1 while the band at 2930 cm-1 confirmed the association of bacterial biomolecules with the synthesized TiO2 NPs. XRD showed two major peaks; 27.5° (rutile phase) and 45.6° (anatase phase) for the synthesized TiO2 NPs. Finally, the potential of the synthesized TiO2 NPs was assessed as an antibacterial agent and photocatalyst. The remediation of Methylene blue (MB) and Orange G (OG) dyes was carried out under UV- light and visible light for a contact time of 150-240 min respectively. The removal efficiency for 100 ppm MB dye was 25.75% and for OG dye was 72.24% under UV light, while in visible light, the maximum removal percentage for MB and OG dye was 98.85% and 80.43% respectively at 90 min. Moreover, a kinetic study and adsorption isotherm study were carried out for the removal of both dyes, where the pseudo-first-order for MB dye is 263.269 and 475554.176 mg/g for OG dye. The pseudo-second-order kinetics for MB and OG dye were 188.679 and 1666.667 mg/g respectively. In addition to this, the antibacterial activity of TiO2 NPs was assessed against Bacillus subtilis MTCC 8322 (Gram-positive) and Escherichia coli MTCC 8933 (Gram-negative) where the maximum zone of inhibition in Bacillus subtilis MTCC 8322 was about 12 mm, and for E. coli 16 mm.
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Affiliation(s)
- Chandani Rathore
- Department of Biosciences, School of Liberal Arts and Sciences, Mody University of Science and Technology, Sikar, Rajasthan, India
| | - Virendra Kumar Yadav
- Department of Life Sciences, Hemchandracharya North Gujarat University, Patan, Gujarat, India
| | - Abdelfattah Amari
- Department of Chemical Engineering, College of Engineering, King Khalid University, Abha, Saudi Arabia
| | - Abhishek Meena
- Department of Physics and Semiconductor Science, Dongguk University, Seoul, Republic of Korea
| | - Titus Chinedu Egbosiuba
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, United States
| | - Rakesh Kumar Verma
- Department of Biosciences, School of Liberal Arts and Sciences, Mody University of Science and Technology, Sikar, Rajasthan, India
| | - Noureddine Mahdhi
- Laboratory Materials Organizations and Properties, Tunis El Manar University, Tunis, Tunisia
| | - Nisha Choudhary
- Department of Life Sciences, Hemchandracharya North Gujarat University, Patan, Gujarat, India
| | - Dipak Kumar Sahoo
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Rajendra Singh Chundawat
- Department of Biosciences, School of Liberal Arts and Sciences, Mody University of Science and Technology, Sikar, Rajasthan, India
| | - Ashish Patel
- Department of Life Sciences, Hemchandracharya North Gujarat University, Patan, Gujarat, India
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5
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Sagidolda Y, Yergaliyeva S, Tolepov Z, Ismailova G, Orynbay B, Nemkayeva R, Prikhodko O, Peshaya S, Maksimova S, Guseinov N, Mukhametkarimov Y. Peculiarities of the Structure of Au-TiO 2 and Au-WO 3 Plasmonic Nanocomposites. MATERIALS (BASEL, SWITZERLAND) 2023; 16:6809. [PMID: 37895790 PMCID: PMC10608088 DOI: 10.3390/ma16206809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 10/19/2023] [Accepted: 10/20/2023] [Indexed: 10/29/2023]
Abstract
As nanotechnology continues to advance, the study of nanocomposites and their unique properties is at the forefront of research. There are still various blank spots in understanding the behavior of such composite materials, especially regarding plasmonic effects like localized surface plasmon resonance (LSPR) which is essential for developing advanced nanotechnologies. In this work, we explore the structural properties of composite thin films consisting of oxide matrices and gold nanoparticles (Au NPs), which were prepared by radio-frequency magnetron sputtering. Titanium dioxide (TiO2) and tungsten trioxide (WO3) were chosen as the host matrices of the composites. Such composite thin films owing to the presence of Au NPs demonstrate the LSPR phenomenon in the visible region. It is shown, that spectroscopic study, in particular, Raman spectroscopy can reveal peculiar features of structures of such composite systems due to LSPR and photoluminescence (PL) of Au NPs in the visible spectrum. In particular, defect peaks of TiO2 (700-720 cm-1) or WO3 (935 cm-1) in Raman spectra can be clearly observed when the samples are illuminated with a 633 nm excitation laser. Excitation with 532 nm leads to a decrease in the intensity of the defect peak, which totally disappears at 473 nm excitation. Such dependences of the defect peaks on excitation laser wavelength are probably related to the polarization of the matrix's defective regions close to the interface with gold NPs.
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Affiliation(s)
- Yerulan Sagidolda
- Department of Physics and Technology, Al-Farabi Kazakh National University, Al-Farabi av. 71, Almaty 050040, Kazakhstan; (Y.S.); (O.P.); (S.P.)
- National Nanotechnology Laboratory of Open Type, Al-Farabi av. 71/23, Almaty 050040, Kazakhstan
| | - Saule Yergaliyeva
- Department of Physics and Technology, Al-Farabi Kazakh National University, Al-Farabi av. 71, Almaty 050040, Kazakhstan; (Y.S.); (O.P.); (S.P.)
| | - Zhandos Tolepov
- Department of Physics and Technology, Al-Farabi Kazakh National University, Al-Farabi av. 71, Almaty 050040, Kazakhstan; (Y.S.); (O.P.); (S.P.)
- National Nanotechnology Laboratory of Open Type, Al-Farabi av. 71/23, Almaty 050040, Kazakhstan
| | - Guzal Ismailova
- Department of Physics and Technology, Al-Farabi Kazakh National University, Al-Farabi av. 71, Almaty 050040, Kazakhstan; (Y.S.); (O.P.); (S.P.)
| | - Bakytzhan Orynbay
- Department of Physics and Technology, Al-Farabi Kazakh National University, Al-Farabi av. 71, Almaty 050040, Kazakhstan; (Y.S.); (O.P.); (S.P.)
- National Nanotechnology Laboratory of Open Type, Al-Farabi av. 71/23, Almaty 050040, Kazakhstan
| | - Renata Nemkayeva
- National Nanotechnology Laboratory of Open Type, Al-Farabi av. 71/23, Almaty 050040, Kazakhstan
| | - Oleg Prikhodko
- Department of Physics and Technology, Al-Farabi Kazakh National University, Al-Farabi av. 71, Almaty 050040, Kazakhstan; (Y.S.); (O.P.); (S.P.)
| | - Svetlana Peshaya
- Department of Physics and Technology, Al-Farabi Kazakh National University, Al-Farabi av. 71, Almaty 050040, Kazakhstan; (Y.S.); (O.P.); (S.P.)
| | - Suyumbika Maksimova
- Department of Physics and Technology, Al-Farabi Kazakh National University, Al-Farabi av. 71, Almaty 050040, Kazakhstan; (Y.S.); (O.P.); (S.P.)
| | - Nazim Guseinov
- National Nanotechnology Laboratory of Open Type, Al-Farabi av. 71/23, Almaty 050040, Kazakhstan
| | - Yerzhan Mukhametkarimov
- Department of Physics and Technology, Al-Farabi Kazakh National University, Al-Farabi av. 71, Almaty 050040, Kazakhstan; (Y.S.); (O.P.); (S.P.)
- National Nanotechnology Laboratory of Open Type, Al-Farabi av. 71/23, Almaty 050040, Kazakhstan
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6
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Alotabi AS, Yin Y, Redaa A, Tesana S, Metha GF, Andersson GG. Effect of TiO 2 Film Thickness on the Stability of Au 9 Clusters with a CrO x Layer. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:3218. [PMID: 36145007 PMCID: PMC9506353 DOI: 10.3390/nano12183218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 09/01/2022] [Accepted: 09/09/2022] [Indexed: 06/16/2023]
Abstract
Radio frequency (RF) magnetron sputtering allows the fabrication of TiO2 films with high purity, reliable control of film thickness, and uniform morphology. In the present study, the change in surface roughness upon heating two different thicknesses of RF sputter-deposited TiO2 films was investigated. As a measure of the process of the change in surface morphology, chemically -synthesised phosphine-protected Au9 clusters covered by a photodeposited CrOx layer were used as a probe. Subsequent to the deposition of the Au9 clusters and the CrOx layer, samples were heated to 200 ℃ to remove the triphenylphosphine ligands from the Au9 cluster. After heating, the thick TiO2 film was found to be mobile, in contrast to the thin TiO2 film. The influence of the mobility of the TiO2 films on the Au9 clusters was investigated with X-ray photoelectron spectroscopy. It was found that the high mobility of the thick TiO2 film after heating leads to a significant agglomeration of the Au9 clusters, even when protected by the CrOx layer. The thin TiO2 film has a much lower mobility when being heated, resulting in only minor agglomeration of the Au9 clusters covered with the CrOx layer.
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Affiliation(s)
- Abdulrahman S. Alotabi
- Flinders Institute for Nanoscale Science and Technology, Flinders University, Adelaide, SA 5042, Australia
- Department of Physics, Faculty of Science and Arts in Baljurashi, Albaha University, Baljurashi 65655, Saudi Arabia
- Flinders Microscopy and Microanalysis, College of Science and Engineering, Flinders University, Adelaide, SA 5042, Australia
| | - Yanting Yin
- Flinders Institute for Nanoscale Science and Technology, Flinders University, Adelaide, SA 5042, Australia
- Flinders Microscopy and Microanalysis, College of Science and Engineering, Flinders University, Adelaide, SA 5042, Australia
| | - Ahmad Redaa
- Department of Earth Sciences, University of Adelaide, Adelaide, SA 5005, Australia
- Faculty of Earth Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Siriluck Tesana
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Physical and Chemical Sciences, University of Canterbury, Christchurch 8041, New Zealand
- National Isotope Centre, GNS Science, Lower Hutt 5010, New Zealand
| | - Gregory F. Metha
- Department of Chemistry, University of Adelaide, Adelaide, SA 5005, Australia
| | - Gunther G. Andersson
- Flinders Institute for Nanoscale Science and Technology, Flinders University, Adelaide, SA 5042, Australia
- Flinders Microscopy and Microanalysis, College of Science and Engineering, Flinders University, Adelaide, SA 5042, Australia
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7
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Alotabi AS, Yin Y, Redaa A, Tesana S, Metha GF, Andersson GG. Cr 2O 3 layer inhibits agglomeration of phosphine-protected Au 9 clusters on TiO 2 films. J Chem Phys 2021; 155:164702. [PMID: 34717368 DOI: 10.1063/5.0059912] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The properties of semiconductor surfaces can be modified by the deposition of metal clusters consisting of a few atoms. The properties of metal clusters and of cluster-modified surfaces depend on the number of atoms forming the clusters. Deposition of clusters with a monodisperse size distribution thus allows tailoring of the surface properties for technical applications. However, it is a challenge to retain the size of the clusters after their deposition due to the tendency of the clusters to agglomerate. The agglomeration can be inhibited by covering the metal cluster modified surface with a thin metal oxide overlayer. In the present work, phosphine-protected Au clusters, Au9(PPh3)8(NO3)3, were deposited onto RF-sputter deposited TiO2 films and subsequently covered with a Cr2O3 film only a few monolayers thick. The samples were then heated to 200 °C to remove the phosphine ligands, which is a lower temperature than that required to remove thiolate ligands from Au clusters. It was found that the Cr2O3 covering layer inhibited cluster agglomeration at an Au cluster coverage of 0.6% of a monolayer. When no protecting Cr2O3 layer was present, the clusters were found to agglomerate to a large degree on the TiO2 surface.
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Affiliation(s)
- Abdulrahman S Alotabi
- Flinders Institute for Nanoscale Science and Technology, Flinders University, Adelaide, South Australia 5042, Australia
| | - Yanting Yin
- Flinders Institute for Nanoscale Science and Technology, Flinders University, Adelaide, South Australia 5042, Australia
| | - Ahmad Redaa
- Department of Earth Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Siriluck Tesana
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Physical and Chemical Sciences, University of Canterbury, Christchurch 8141, New Zealand
| | - Gregory F Metha
- Department of Chemistry, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Gunther G Andersson
- Flinders Institute for Nanoscale Science and Technology, Flinders University, Adelaide, South Australia 5042, Australia
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8
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Shamsaldeen AA, Kloo L, Yin Y, Gibson C, Adhikari SG, Andersson GG. Influence of TiO 2 surface defects on the adsorption of N719 dye molecules. Phys Chem Chem Phys 2021; 23:22160-22173. [PMID: 34581338 DOI: 10.1039/d1cp02283k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Surface defects influence the dye adsorption on TiO2 used as a substrate in dye-sensitized solar cells (DSSCs). In this study, we have used different Ar+ sputtering doses to create a controlled density of defects on a TiO2 surface exposed to different pre-heating temperatures in order to analyse the influence of defects on the N719 dye adsorption. TiO2 was pre-treated using two different treatments. The first treatment involved heating to 200 °C with subsequent sputtering at different doses. The second treatment included heating only, but at four different temperatures starting at 200 °C. After the pre-treatments, the TiO2 samples were immersed into an N719 dye solution for 24 hours at room temperature to dye the TiO2 substrates. The amount of Ti3+ surface defects introduced by the different pre-treatments and their influence on dye adsorption onto the TiO2 surface were examined by X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS) and metastable induced electron spectroscopy (MIES). Neutral impact collision ion scattering spectroscopy (NICISS) was used to determine the coverage of the TiO2 surface by adsorbed dye molecules. It was found that Ti3+ surface defects were formed by Ar+ sputtering but not by pre-treatment through heating alone. MIES analysis of the outer-most layer and density of states calculations show that the thiocyanate ligand of the N719 dye becomes directed away from the TiO2 surface. Both XPS and NICISS results indicate that the amount of adsorbed N719 dye decreases with increasing density of Ti3+ surface defects. Thus, the generation of surface defects reduces the ability of the TiO2 surface to adsorb the dye molecules. Heating alone as pre-treatment of the TiO2 substrates instead increases the dye adsorption, without causing detectable defects on the TiO2 surface.
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Affiliation(s)
- Altaf A Shamsaldeen
- Flinders Institute for NanoScale Science and Technology, Flinders University, PO Box 2100, Adelaide SA 5001, Australia.
| | - Lars Kloo
- Applied Physical Chemistry, Department of Chemistry, School of Chemical Science and Engineering, KTH-Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Yanting Yin
- Flinders Microscopy and Microanalysis, College of Science and Engineering, Flinders University, Bedford Park 5042, Australia
| | - Christopher Gibson
- Flinders Institute for NanoScale Science and Technology, Flinders University, PO Box 2100, Adelaide SA 5001, Australia. .,Flinders Microscopy and Microanalysis, College of Science and Engineering, Flinders University, Bedford Park 5042, Australia
| | - Sunita Gautam Adhikari
- Flinders Institute for NanoScale Science and Technology, Flinders University, PO Box 2100, Adelaide SA 5001, Australia.
| | - Gunther G Andersson
- Flinders Institute for NanoScale Science and Technology, Flinders University, PO Box 2100, Adelaide SA 5001, Australia. .,Flinders Microscopy and Microanalysis, College of Science and Engineering, Flinders University, Bedford Park 5042, Australia
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9
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Howard-Fabretto L, Gorey TJ, Li G, Tesana S, Metha GF, Anderson SL, Andersson GG. The interaction of size-selected Ru 3 clusters with RF-deposited TiO 2: probing Ru-CO binding sites with CO-temperature programmed desorption. NANOSCALE ADVANCES 2021; 3:3537-3553. [PMID: 36133710 PMCID: PMC9418929 DOI: 10.1039/d1na00181g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 04/17/2021] [Indexed: 06/16/2023]
Abstract
Small Ru clusters are efficient catalysts for chemical reactions such as CO hydrogenation. In this study 3-atom Ru3 clusters were deposited onto radio frequency (RF)-deposited TiO2 which is an inexpensive, nanoparticulate form of TiO2. TiO2 substrates are notable in that they form strong metal-substrate interactions with clusters. Using temperature programmed desorption to probe Ru-CO binding sites, and X-ray photoelectron spectroscopy to provide chemical information on clusters, differences in cluster-support interactions were studied for Ru3 deposited using both an ultra-high vacuum cluster source and chemical vapour deposition of Ru3(CO)12. The TiO2 was treated with different Ar+ sputter doses prior to cluster depositions, and SiO2 was also used as a comparison substrate. For cluster source-deposited Ru3, heating to 800 K caused cluster agglomeration on SiO2 and oxidation on non-sputtered TiO2. For cluster source-deposited Ru3 on sputtered TiO2 substrates, all Ru-CO binding sites were blocked as-deposited and it was concluded that for the binding sites to be preserved for potential catalytic benefit, sputtering of TiO2 before cluster deposition cannot be applied. Conversely, for Ru3(CO)12 on sputtered TiO2 the clusters were protected by their ligands and Ru-CO binding sites were only blocked once the sample was heated to 723 K. The mechanism for complete blocking of CO sites on sputtered TiO2 could not be directly determined; however, comparisons to the literature indicate that the likely reasons for blocking of the CO adsorption sites are encapsulation into the TiO x layer reduced through sputtering and also partial oxidation of the Ru clusters.
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Affiliation(s)
- Liam Howard-Fabretto
- Flinders Institute for Nanoscale Science and Technology, Flinders University Adelaide South Australia 5042 Australia
- Flinders Microscopy and Microanalysis, College of Science and Engineering, Flinders University Adelaide South Australia 5042 Australia
| | - Timothy J Gorey
- Chemistry Department, University of Utah 315 S. 1400 E. Salt Lake City UT 84112 USA
| | - Guangjing Li
- Chemistry Department, University of Utah 315 S. 1400 E. Salt Lake City UT 84112 USA
| | - Siriluck Tesana
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Physical and Chemical Sciences, University of Canterbury Christchurch 8141 New Zealand
| | - Gregory F Metha
- Department of Chemistry, University of Adelaide Adelaide South Australia 5005 Australia
| | - Scott L Anderson
- Chemistry Department, University of Utah 315 S. 1400 E. Salt Lake City UT 84112 USA
| | - Gunther G Andersson
- Flinders Institute for Nanoscale Science and Technology, Flinders University Adelaide South Australia 5042 Australia
- Flinders Microscopy and Microanalysis, College of Science and Engineering, Flinders University Adelaide South Australia 5042 Australia
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