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Interfacial Modification of Lithium Metal Anode by Boron Nitride Nanosheets. ACS NANO 2024; 18:3531-3541. [PMID: 38236027 DOI: 10.1021/acsnano.3c11135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
Metallic lithium (Li) is the most attractive anode for Li batteries because it holds the highest theoretical specific capacity (3860 mA h g-1) and the lowest redox potential (-3.040 V vs SHE). However, the poor interface stability of the Li anode, which is caused by the high reactivity and dendrite formation of metallic Li upon cycling, leads to undesired electrochemical performance and safety issues. While two-dimensional boron nitride (BN) nanosheets have been utilized as an interfacial layer, the mechanism on how they stabilize the Li-electrolyte interface remains elusive. Here, we show how BN nanosheet interlayers suppress Li dendrite formation, enhance Li ion transport kinetics, facilitate Li deposition, and reduce electrolyte decomposition. We show through both simulation and experimental data that the desolvation process of a solvated Li ion within the interlayer nanochannels kinetically favors Li deposition. This process enables long cycling stability, reduced voltage polarization, improved interface stability, and negligible volume expansion. Their application as an interfacial layer in symmetric cells and full cells that display significantly improved electrochemical properties is also demonstrated. The knowledge gained in this study provides both critical insights and practical guidelines for designing a Li metal anode with significantly improved performance.
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Specific Ion Effects at the Vapor-Formamide Interface: A Reverse Hofmeister Series in Ion Concentration Depth Profiles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:12618-12626. [PMID: 37642667 DOI: 10.1021/acs.langmuir.3c01286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Employing neutral impact collision ion scattering spectroscopy (NICISS), we have directly measured the concentration depth profiles (CDPs) of various monovalent ions at the vapor-formamide interface. NICISS provides CDPs of individual ions by measuring the energy loss of neutral helium atoms backscattered from the solution interface. CDPs at the vapor-formamide interface of Cl-, Br-, I-, Na+, K+, and Cs+ are measured and compared to elucidate the interfacial specific ion trends. We report a reverse Hofmeister series in the presence of inorganic ions (anion and cation) at the vapor-formamide interface relative to the water-vapor interface, and the CDPs are found to be independent of the counterion for most ions studied. Thus, ions at the surface of formamide follow a "Hofmeister paradigm" where the counterion does not impact the ion series. These specific ion trends are complemented with surface tension and X-ray absorption near-edge structure (XANES) measurements on formamide electrolyte solutions.
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Reduction and Diffusion of Cr-Oxide Layers into P25, BaLa 4Ti 4O 15, and Al:SrTiO 3 Particles upon High-Temperature Annealing. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 36906923 DOI: 10.1021/acsami.3c00250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Chromium oxide (Cr2O3) is a beneficial metal oxide used to prevent the backward reaction in photocatalytic water splitting. The present work investigates the stability, oxidation state, and the bulk and surface electronic structure of Cr-oxide photodeposited onto P25, BaLa4Ti4O15, and Al:SrTiO3 particles as a function of the annealing process. The oxidation state of the Cr-oxide layer as deposited is found to be Cr2O3 on the surface of P25 and Al:SrTiO3 particles and Cr(OH)3 on BaLa4Ti4O15. After annealing at 600 °C, for P25 (a mixture of rutile and anatase TiO2), the Cr2O3 layer diffuses into the anatase phase but remains at the surface of the rutile phase. For BaLa4Ti4O15, Cr(OH)3 converts to Cr2O3 upon annealing and diffuses slightly into the particles. However, for Al:SrTiO3, the Cr2O3 remains stable at the surface of the particles. The diffusion here is due to the strong metal-support interaction effect. In addition, some of the Cr2O3 on the P25, BaLa4Ti4O15, and Al:SrTiO3 particles is reduced to metallic Cr after annealing. The effect of Cr2O3 formation and diffusion into the bulk on the surface and bulk band gaps is investigated with electronic spectroscopy, electron diffraction, DRS, and high-resolution imaging. The implications of the stability and diffusion of Cr2O3 for photocatalytic water splitting are discussed.
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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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Abstract
Specific ion effects (SIE), encompassing the Hofmeister Series, have been known for more than 130 years since Hofmeister and Lewith's foundational work. SIEs are ubiquitous and are observed across the medical, biological, chemical and industrial sciences. Nevertheless, no general predictive theory has yet been able to explain ion specificity across these fields; it remains impossible to predict when, how, and to what magnitude, a SIE will be observed. In part, this is due to the complexity of real systems in which ions, counterions, solvents and cosolutes all play varying roles, which give rise to anomalies and reversals in anticipated SIEs. Herein we review the historical explanations for SIE in water and the key ion properties that have been attributed to them. Systems where the Hofmeister series is perturbed or reversed are explored, as is the behaviour of ions at the liquid-vapour interface. We discuss SIEs in mixed electrolytes, nonaqueous solvents, and in highly concentrated electrolyte solutions - exciting frontiers in this field with particular relevance to biological and electrochemical applications. We conclude the perspective by summarising the challenges and opportunities facing this SIE research that highlight potential pathways towards a general predictive theory of SIE.
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A Review of State of the Art in Phosphine Ligated Gold Clusters and Application in Catalysis. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2105692. [PMID: 35332703 PMCID: PMC9130904 DOI: 10.1002/advs.202105692] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 02/23/2022] [Indexed: 05/28/2023]
Abstract
Atomically precise gold clusters are highly desirable due to their well-defined structure which allows the study of structure-property relationships. In addition, they have potential in technological applications such as nanoscale catalysis. The structural, chemical, electronic, and optical properties of ligated gold clusters are strongly defined by the metal-ligand interaction and type of ligands. This critical feature renders gold-phosphine clusters unique and distinct from other ligand-protected gold clusters. The use of multidentate phosphines enables preparation of varying core sizes and exotic structures beyond regular polyhedrons. Weak gold-phosphorous (Au-P) bonding is advantageous for ligand exchange and removal for specific applications, such as catalysis, without agglomeration. The aim of this review is to provide a unified view of gold-phosphine clusters and to present an in-depth discussion on recent advances and key developments for these clusters. This review features the unique chemistry, structural, electronic, and optical properties of gold-phosphine clusters. Advanced characterization techniques, including synchrotron-based spectroscopy, have unraveled substantial effects of Au-P interaction on the composition-, structure-, and size-dependent properties. State-of-the-art theoretical calculations that reveal insights into experimental findings are also discussed. Finally, a discussion of the application of gold-phosphine clusters in catalysis is presented.
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Surface Passivation of Sputtered NiO x Using a SAM Interface Layer to Enhance the Performance of Perovskite Solar Cells. ACS OMEGA 2022; 7:12147-12157. [PMID: 35449936 PMCID: PMC9016879 DOI: 10.1021/acsomega.2c00509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 03/11/2022] [Indexed: 06/14/2023]
Abstract
Sputtered NiO x (sp-NiO x ) is a preferred hole transporting material for perovskite solar cells because of its hole mobility, ease of manufacturability, good stability, and suitable Fermi level for hole extraction. However, uncontrolled defects in sp-NiO x can limit the efficiency of solar cells fabricated with this hole transporting layer. An interfacial layer has been proposed to modify the sp-NiO x /perovskite interface, which can contribute to improving the crystallinity of the perovskite film. Herein, a 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz) self-assembled monolayer was used to modify an sp-NiO x surface. We found that the MeO-2PACz interlayer improves the quality of the perovskite film due to an enlarged domain size, reduced charge recombination at the sp-NiO x /perovskite interface, and passivation of the defects in sp-NiO x surfaces. In addition, the band tail states are also reduced, as indicated by photothermal deflection spectroscopy, which thus indicates a reduction in defect levels. The overall outcome is an improvement in the device efficiency from 11.9% to 17.2% due to the modified sp-NiO x /perovskite interface, with an active area of 1 cm2 (certified efficiency of 16.25%). On the basis of these results, the interfacial engineering of the electronic properties of sp-NiO x /MeO-2PACz/perovskite is discussed in relation to the improved device performance.
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Mixed Surface Chemistry on Carbon Fibers to Promote Adhesion in Epoxy and PMMA Polymers. Ind Eng Chem Res 2022. [DOI: 10.1021/acs.iecr.1c04409] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Magnetic responsive composites made from a sulfur-rich polymer. Polym Chem 2022. [DOI: 10.1039/d2py00903j] [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
A magnetic responsive composite was made from a sulfur-rich polymer and iron nanoparticles. Diverse applications in mercury remediation, microwave curing, and magnetic responsive actuators were demonstrated.
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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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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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Innentitelbild: Creation of High‐Performance Heterogeneous Photocatalysts by Controlling Ligand Desorption and Particle Size of Gold Nanocluster (Angew. Chem. 39/2021). Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202108478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Inside Cover: Creation of High‐Performance Heterogeneous Photocatalysts by Controlling Ligand Desorption and Particle Size of Gold Nanocluster (Angew. Chem. Int. Ed. 39/2021). Angew Chem Int Ed Engl 2021. [DOI: 10.1002/anie.202108478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Creation of High-Performance Heterogeneous Photocatalysts by Controlling Ligand Desorption and Particle Size of Gold Nanocluster. Angew Chem Int Ed Engl 2021; 60:21340-21350. [PMID: 34038609 PMCID: PMC8518739 DOI: 10.1002/anie.202104911] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 05/18/2021] [Indexed: 12/30/2022]
Abstract
Recently, the creation of new heterogeneous catalysts using the unique electronic/geometric structures of small metal nanoclusters (NCs) has received considerable attention. However, to achieve this, it is extremely important to establish methods to remove the ligands from ligand-protected metal NCs while preventing the aggregation of metal NCs. In this study, the ligand-desorption process during calcination was followed for metal-oxide-supported 2-phenylethanethiolate-protected gold (Au) 25-atom metal NCs using five experimental techniques. The results clearly demonstrate that the ligand-desorption process consists of ligand dissociation on the surface of the metal NCs, adsorption of the generated compounds on the support and desorption of the compounds from the support, and the temperatures at which these processes occurred were elucidated. Based on the obtained knowledge, we established a method to form a metal-oxide layer on the surface of Au NCs while preventing their aggregation, thereby succeeding in creating a water-splitting photocatalyst with high activity and stability.
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Creation of High‐Performance Heterogeneous Photocatalysts by Controlling Ligand Desorption and Particle Size of Gold Nanocluster. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202104911] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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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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Au 101-rGO nanocomposite: immobilization of phosphine-protected gold nanoclusters on reduced graphene oxide without aggregation. NANOSCALE ADVANCES 2021; 3:1422-1430. [PMID: 36132862 PMCID: PMC9417812 DOI: 10.1039/d0na00927j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 01/07/2021] [Indexed: 05/05/2023]
Abstract
Graphene supported transition metal clusters are of great interest for potential applications, such as catalysis, due to their unique properties. In this work, a simple approach to deposit Au101(PPh3)21Cl5 (Au101NC) on reduced graphene oxide (rGO) via an ex situ method is presented. Reduction of graphene oxide at native pH (pH ≈ 2) to rGO was performed under aqueous hydrothermal conditions. Decoration of rGO sheets with controlled content of 5 wt% Au was accomplished using only pre-synthesised Au101NC and rGO as precursors and methanol as solvent. High resolution scanning transmission electron microscopy indicated that the cluster size did not change upon deposition with an average diameter of 1.4 ± 0.4 nm. It was determined that the rGO reduction method was crucial to avoid agglomeration, with rGO reduced at pH ≈ 11 resulting in agglomeration. X-ray photoelectron spectroscopy was used to confirm the deposition of Au101NCs and show the presence of triphenyl phosphine ligands, which together with attenuated total reflectance Fourier transform infrared spectroscopy, advocates that the deposition of Au101NCs onto the surface of rGO was facilitated via non-covalent interactions with the phenyl groups of the ligands. Inductively coupled plasma mass spectrometry and thermogravimetric analysis were used to determine the gold loading and both agree with a gold loading of ca. 4.8-5 wt%. The presented simple and mild strategy demonstrates that good compatibility between size-specific phosphine protected gold clusters and rGO can prevent aggregation of the metal clusters. This work contributes towards producing an agglomeration-free synthesis of size-specific ligated gold clusters on rGO that could have wide range of applications.
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Composition and properties of RF-sputter deposited titanium dioxide thin films. NANOSCALE ADVANCES 2021; 3:1077-1086. [PMID: 36133287 PMCID: PMC9417277 DOI: 10.1039/d0na00861c] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 12/07/2020] [Indexed: 06/16/2023]
Abstract
The photocatalytic properties of titania (TiO2) have prompted research utilising its useful ability to convert solar energy into electron-hole pairs to drive novel chemistry. The aim of the present work is to examine the properties required for a synthetic method capable of producing thin TiO2 films, with well defined, easily modifiable characteristics. Presented here is a method of synthesis of TiO2 nanoparticulate thin films generated using RF plasma capable of homogenous depositions with known elemental composition and modifiable properties at a far lower cost than single-crystal TiO2. Multiple depositions regimes were examined for their effect on overall chemical composition and to minimise the unwanted contaminant, carbon, from the final film. The resulting TiO2 films can be easily modified through heating to further induce defects and change the electronic structure, crystallinity, surface morphology and roughness of the deposited thin film.
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Cyclic Copper Uptake and Release from Natural Seawater-A Fully Sustainable Antifouling Technique to Prevent Marine Growth. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:757-766. [PMID: 33337864 DOI: 10.1021/acs.est.0c06231] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Unwanted growth of fouling organisms on underwater surfaces is an omnipresent challenge for the marine industry, costing billions of dollars every year in the transportation sector alone. Copper, the most widely used biocide in antifouling paints, is at the brink of a total ban in being used in antifouling coatings, as it has become an existential threat to nontargeted species due to anthropogenic copper inputs into protected waters. In the current study, using a porous and cross-linked poly(ethylene imine) structure under marine and fouling environments, available copper from natural seawater was absorbed and electrochemically released back as a potent biocide at 1.3 V vs Ag|AgCl, reducing marine growth by 94% compared to the control electrode (coupon) at 0 V. The coating can also function as an electrochemical copper sensor enabling real-time monitoring of the electrochemical uptake and release of copper ions from natural seawater. This allows tailoring of the electrochemical program to the changing marine environments, i.e., when the vessels move from high-copper-contaminated waters to coastal regions with low concentrations of copper.
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Abstract
A polymer made from sulfur and canola oil can be used as an oil spill sorbent and then repurposed into a sulfur-rich graphitic carbon for mercury removal from water.
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Highly Stable Indacenodithieno[3,2- b]thiophene-Based Donor-Acceptor Copolymers for Hybrid Electrochromic and Energy Storage Applications. Macromolecules 2020; 53:11106-11119. [PMID: 33583955 PMCID: PMC7872426 DOI: 10.1021/acs.macromol.0c02212] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 11/24/2020] [Indexed: 01/05/2023]
Abstract
Stable doping of indacenodithieno[3,2-b]thiophene (IDTT) structures enables easy color tuning and significant improvement in the charge storage capacity of electrochromic polymers, making use of their full potential as electrochromic supercapacitors and in other emerging hybrid applications. Here, the IDTT structure is copolymerized with four different donor-acceptor-donor (DAD) units, with subtle changes in their electron-donating and electron-withdrawing characters, so as to obtain four different donor-acceptor copolymers. The polymers attain important form factor requirements for electrochromic supercapacitors: desired switching between achromatic black and transparent states (L*a*b* 45.9, -3.1, -4.2/86.7, -2.2, and -2.7 for PIDTT-TBT), high optical contrast (72% for PIDTT-TBzT), and excellent electrochemical redox stability (Ired/Iox ca. 1.0 for PIDTT-EBE). Poly[indacenodithieno[3,2-b]thiophene-2,8-diyl-alt-4,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-2-(2-hexyldecyl)-2H-benzo[d][1,2,3]triazole-7,7'-diyl] (PIDTT-EBzE) stands out as delivering simultaneously a high contrast (69%) and doping level (>100%) and specific capacitance (260 F g-1). This work introduces IDTT-based polymers as bifunctional electro-optical materials for potential use in color-tailored, color-indicating, and self-regulating smart energy systems.
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Competing Segregation of Br - and Cl - to a Surface Coated with a Cationic Surfactant: Direct Measurements of Ion and Solvent Depth Profiles. J Phys Chem A 2020; 124:11102-11110. [PMID: 33325710 DOI: 10.1021/acs.jpca.0c08859] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ion-surface scattering experiments can be used to measure elemental depth profiles on the angstrom scale in complex liquid mixtures. We employ NICISS (neutral impact collision ion scattering spectroscopy) to measure depth profiles of dissolved ions and solvent in liquid glycerol containing the cationic surfactant tetrahexylammonium bromide (THA+/Br-) at 0.013 M and mixtures of NaBr + NaCl at 0.4 M total concentration. The experiments reveal that Br- outcompetes Cl- in its attraction to surface THA+, and that THA+ segregates more extensively when more Br- ions are present. Intriguingly, the depths spanned by THA+, Br-, and Cl- ions generally increase with Br- bulk concentration, expanding from ∼10 to ∼25 Å for both Br- and Cl- depth profiles. This broadening likely occurs because of an increasing pileup of THA+ ions in a multilayer region that spreads the halide ions over a wider depth. The experiments indicate that cationic surfactants enhance Br- and Cl- concentrations in the surface region far beyond their bulk-phase values, making solutions coated with these surfactants potentially more reactive toward gases that can oxidize the halide ions.
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Sub-monolayer Au 9 cluster formation via pulsed nozzle cluster deposition. NANOSCALE ADVANCES 2020; 2:4051-4061. [PMID: 36132769 PMCID: PMC9416922 DOI: 10.1039/d0na00566e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 07/17/2020] [Indexed: 05/07/2023]
Abstract
Submonolayer coverages of chemically synthesised triphenylphosphine-protected Au9 clusters on mica and TiO2 substrates were achieved through the development of a Pulsed Nozzle Cluster Deposition (PNCD) technique under high vacuum conditions. This method offers the deposition of pre-prepared, solvated clusters directly onto substrates in a vacuum without the potential for contamination from the atmosphere. AFM and TEM were used to investigate the rate of gold cluster deposition as a function of cluster solution concentration and the number of pulses, with pulse number showing the most effective control of the final deposition conditions. TEM and XPS were used to determine that the clusters retained their unique properties through the deposition process. Methanol solvent deposited in the PNCD process has been shown to be removable through post-deposition treatments. A physical model describing the vapour behaviour and solvent evaporation in a vacuum is also developed and presented.
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Metal Clusters on Semiconductor Surfaces and Application in Catalysis with a Focus on Au and Ru. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1904122. [PMID: 31854037 DOI: 10.1002/adma.201904122] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 09/13/2019] [Indexed: 06/10/2023]
Abstract
Metal clusters typically consist of two to a few hundred atoms and have unique properties that change with the type and number of atoms that form the cluster. Metal clusters can be generated with a precise number of atoms, and therefore have specific size, shape, and electronic structures. When metal clusters are deposited onto a substrate, their shape and electronic structure depend on the interaction with the substrate surface and thus depend on the properties of both the clusters and those of the substrate. Deposited metal clusters have discrete, individual electron energy levels that differ from the electron energy levels in the constituting individual atoms, isolated clusters, and the respective bulk material. The properties of clusters with a focus on Au and Ru, the methods to generate metal clusters, and the methods of deposition of clusters onto substrate surfaces are covered. The properties of cluster-modified surfaces are important for their application. The main application covered here is catalysis, and the methods for characterization of the cluster-modified surfaces are described.
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Experimental Depth Profiles of Surfactants, Ions, and Solvent at the Angstrom Scale: Studies of Cationic and Anionic Surfactants and Their Salting Out. J Phys Chem B 2020; 124:2218-2229. [PMID: 32075369 DOI: 10.1021/acs.jpcb.9b11686] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Neutral impact ion scattering spectroscopy (NICISS) is used to measure the depth profiles of ionic surfactants, counterions, and solvent molecules on the angstrom scale. The chosen surfactants are 0.010 m tetrahexylammonium bromide (THA+/Br-) and 0.0050 m sodium dodecyl sulfate (Na+/DS-) in the absence and presence of 0.30 m NaBr in liquid glycerol. NICISS determines the depth profiles of the elements C, O, Na, S, and Br through the loss in energy of 5 keV He atoms that travel into and out of the liquid, which is then converted into depth. In the absence of NaBr, we find that THA+ and its Br- counterion segregate together because of charge attraction, forming a narrow double layer that is 10 Å wide and 150 times more concentrated than in the bulk. With the addition of NaBr, THA+ is "salted out" to the surface, increasing the interfacial Br- concentration by 3-fold and spreading the anions over a ∼30 Å depth. Added NaBr similarly increases the interfacial concentration of DS- ions and broadens their positions. Conversely, the dissolved Br- ions are significantly depleted over a depth of 0-40 Å from the surface because of charge repulsion from DS- ions within the interfacial region. These different interfacial Br- propensities correlate with previously measured gas-liquid reactivities: gaseous Cl2 readily reacts with Br- ions in the presence of THA+ but drops 70-fold in the presence of DS-, demonstrating that surfactant headgroup charge controls the reactivity of Br- through changes in its depth profile.
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Investigating the Structure of Self-Assembled Monolayers Related to Biological Cell Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:14213-14221. [PMID: 31596586 DOI: 10.1021/acs.langmuir.9b02553] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Tethered bilayer lipid membranes are solid supported lipid membranes, where the inner leaflet is covalently linked to the solid supported substrate through anchorlipids. These anchorlipids form a self-assembled monolayer, which serves as the basis of the membrane and also provides submembrane space. The molecular structure and composition of this monolayer has thus significant influence on the membrane structural and functional properties. The density of the self-assembled monolayer can be tailored by adding small molecules to the monolayer. Here, the structure of fully tethered and sparsely tethered monolayers, where the anchorlipid has been diluted with a small surface-active thiol, has been analyzed using neutral impact collision ion scattering spectroscopy, X-ray photoelectron spectroscopy, and metastable induced electron spectroscopy. Combination of these three techniques allowed description of the self-assembly process in detail. The monolayers have been characterized in terms of layer thickness and orientation of the lipids.
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The effect of TiCl4 treatment on the performance of dye-sensitized solar cells. J Chem Phys 2019; 151:164704. [DOI: 10.1063/1.5125996] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Ultralow surface energy self-assembled monolayers of iodo-perfluorinated alkanes on silica driven by halogen bonding. NANOSCALE 2019; 11:2401-2411. [PMID: 30667012 DOI: 10.1039/c8nr08195f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Compact self-assembled monolayers (SAMs) of perfluorododecyl iodide (I-PFC12) of reproducible thickness (1.2 nm) are shown to form on silicon wafers. The SAMs have a high fluorine content (95%) and convey an extremely low surface energy to the silicon wafers (4.3 mN m-1), lower than previously reported in the literature for perfluorinated monolayers, and stable for over eight weeks. Shorter chain iodo-perfluorinated (I-PFC8) or bromo-perfluorinated molecules (Br-PFC10) led to less dense layers. The monolayers are stable to heating up to 60 °C, with some loss up to 150 °C. The I-PFC12 monolayer increases the work function of silicon wafers from 3.6 V to 4.4 eV, a factor that could be gainfully used in photovoltaic applications. The I-PFC12 monolayers can be transferred into patterns onto silica substrates by micro-contact printing. The NMR data and the reproducible thickness point to an upright halogen bonding interaction between the iodine in I-PFC12 and the surface oxygen on the native silica layer.
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Influence of Moisture on the Energy-Level Alignment at the MoO 3/Organic Interfaces. ACS APPLIED MATERIALS & INTERFACES 2018; 10:44163-44172. [PMID: 30465425 DOI: 10.1021/acsami.8b16725] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
MoO3 is widely used in polymer-based organic solar cells as an anode buffer layer because of its high workfunction and formation of a strong dipole at the MoO3/polymer interface facilitating charge transfer across the MoO3/polymer interface. In the present work, we show that exposure of the MoO3/polymer interface to moisture attracts water molecules to the interface via diffusion. Because of their own strong dipole, water molecules counter the dipole at the MoO3/polymer interface. As a consequence, the charge transfer across the MoO3/polymer will reduce and affect the charge transport across the interface. The outcome of this work thus suggests that it is critical to keep the MoO3/polymer interface moisture-free, which requires special precautions in device fabrications. The composition of the MoO3/P3HT:PC61BM interface is analyzed with X-ray photoelectron spectroscopy and the depth profiling technique, neutral impact collision ion scattering spectroscopy. The results show that the concentration of oxygen increases upon exposure but leaves the oxidation state of Mo unchanged. The valence electron spectroscopy technique shows that the dipole across the MoO3/P3HT:PC61BM interface decreases even for short-time exposure to atmosphere because of the diffusion of water molecules to the interface. The far-ranging consequences for organic electronic devices are discussed.
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In situ recombination junction between p-Si and TiO 2 enables high-efficiency monolithic perovskite/Si tandem cells. SCIENCE ADVANCES 2018; 4:eaau9711. [PMID: 30555921 PMCID: PMC6294601 DOI: 10.1126/sciadv.aau9711] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 11/15/2018] [Indexed: 05/13/2023]
Abstract
Increasing the power conversion efficiency of silicon (Si) photovoltaics is a key enabler for continued reductions in the cost of solar electricity. Here, we describe a two-terminal perovskite/Si tandem design that increases the Si cell's output in the simplest possible manner: by placing a perovskite cell directly on top of the Si bottom cell. The advantageous omission of a conventional interlayer eliminates both optical losses and processing steps and is enabled by the low contact resistivity attainable between n-type TiO2 and Si, established here using atomic layer deposition. We fabricated proof-of-concept perovskite/Si tandems on both homojunction and passivating contact heterojunction Si cells to demonstrate the broad applicability of the interlayer-free concept. Stabilized efficiencies of 22.9 and 24.1% were obtained for the homojunction and passivating contact heterojunction tandems, respectively, which could be readily improved by reducing optical losses elsewhere in the device. This work highlights the potential of emerging perovskite photovoltaics to enable low-cost, high-efficiency tandem devices through straightforward integration with commercially relevant Si solar cells.
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Measuring the Density of States of the Inner and Outer Wall of Double-Walled Carbon Nanotubes. NANOMATERIALS 2018; 8:nano8060448. [PMID: 29921819 PMCID: PMC6027179 DOI: 10.3390/nano8060448] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 06/07/2018] [Accepted: 06/14/2018] [Indexed: 11/27/2022]
Abstract
The combination of ultraviolet photoelectron spectroscopy and metastable helium induced electron spectroscopy is used to determine the density of states of the inner and outer coaxial carbon nanotubes. Ultraviolet photoelectron spectroscopy typically measures the density of states across the entire carbon nanotube, while metastable helium induced electron spectroscopy measures the density of states of the outermost layer alone. The use of double-walled carbon nanotubes in electronic devices allows for the outer wall to be functionalised whilst the inner wall remains defect free and the density of states is kept intact for electron transport. Separating the information of the inner and outer walls enables development of double-walled carbon nanotubes to be independent, such that the charge transport of the inner wall is maintained and confirmed whilst the outer wall is modified for functional purposes.
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Abstract
The surface composition of binary mixtures of the protic ionic liquids ethylammonium nitrate and propylammonium nitrate has been investigated using surface tension measurements and the perfectly surface sensitive method metastable induced electron spectroscopy. Given that the latter technique is sensitive only to the outermost layer, it allows for the determination of the surface fraction occupied by a given species. The piecewise linear relationship between surface fraction and surface tension found in this study can be described by a phase separation within the surface layer.
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EXAFS, ab Initio Molecular Dynamics, and NICIS Spectroscopy Studies on an Organic Dye Model at the Dye-Sensitized Solar Cell Photoelectrode Interface. ACS APPLIED MATERIALS & INTERFACES 2017; 9:19773-19779. [PMID: 28534628 DOI: 10.1021/acsami.7b01779] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The organization of dye molecules in the dye layer adsorbed on the semiconductor substrate in dye-sensitized solar cells has been studied using a combination of theoretical methods and experimental techniques. The model system is based on the simple D-π-A dye L0, which has been chemically modified by substituting the acceptor group CN with Br (L0Br) to offer better X-ray contrast. Experimental EXAFS data based on the Br K-edge backscattering show no obvious difference between dye-sensitized titania powder and titania film samples, thus allowing model systems to be based on powder slurries. Ab initio molecular dynamic (aiMD) calculations have been performed to extract less biased information from the experimental EXASF data. Using the aiMD calculation as input, the EXAFS structural models can be generated a priori that match the experimental data. Our study shows that the L0Br dye adsorbs in the trans-L0Br configuration and that adsorption involves both a proximity to other L0Br dye molecules and the titanium atoms in the TiO2 substrate. These results indicate direct coordination of the dye molecules to the TiO2 surface in contrast to previous results on metal-organic dyes. The molecular coverage of L0Br on mesoporous TiO2 was also estimated using NICIS spectroscopy. The NICISS results emphasized that the L0Br dye on nanoporous titania mainly forms monolayers with a small contribution of multilayer coverage.
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Adsorption and Desorption of Single‐Stranded DNA from Single‐Walled Carbon Nanotubes. Chem Asian J 2017; 12:1625-1634. [DOI: 10.1002/asia.201700446] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 04/11/2017] [Indexed: 02/06/2023]
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Apparatus for the investigation of high-temperature, high-pressure gas-phase heterogeneous catalytic and photo-catalytic materials. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:054101. [PMID: 28571412 DOI: 10.1063/1.4982350] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A high-temperature, high-pressure, pulsed-gas sampling and detection system has been developed for testing new catalytic and photocatalytic materials for the production of solar fuels. The reactor is fitted with a sapphire window to allow the irradiation of photocatalytic samples from a lamp or solar simulator light source. The reactor has a volume of only 3.80 ml allowing for the investigation of very small quantities of a catalytic material, down to 1 mg. The stainless steel construction allows the cell to be heated to 350 °C and can withstand pressures up to 27 bar, limited only by the sapphire window. High-pressure sampling is made possible by a computer controlled pulsed valve that delivers precise gas flow, enabling catalytic reactions to be monitored across a wide range of pressures. A residual gas analyser mass spectrometer forms a part of the detection system, which is able to provide a rapid, real-time analysis of the gas composition within the photocatalytic reaction chamber. This apparatus is ideal for investigating a number of industrially relevant reactions including photocatalytic water splitting and CO2 reduction. Initial catalytic results using Pt-doped and Ru nanoparticle-doped TiO2 as benchmark experiments are presented.
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Poly(4-vinylpyridine): A New Interface Layer for Organic Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2017; 9:10929-10936. [PMID: 28262016 DOI: 10.1021/acsami.6b12687] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Poly(4-vinylpyridine) (P4VP) was used as a cathode interface layer in inverted organic solar cells (OSCs) fabricated using poly[2,3-bis(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1) and PC71BM (phenyl C71 butyric acid methyl ester) as the donor and acceptor materials, respectively. We successfully demonstrate that the work function of underlying indium tin oxide (ITO) electrode can be significantly reduced by ∼0.7 eV, after modification of the surface with a thin film of P4VP. Photoconversion efficiency of 4.7% was achieved from OSCs incorporating P4VP interface layer between the ITO and bulk heterojunction (BHJ). Thin P4VP layer, when used to modify ZnO electron transport layer in inverted OSCs, reduced the ZnO work function from 3.7 to 3.4 eV, which resulted in a noteworthy increase in open-circuit voltage from 840 to 890 mV. On simultaneous modification of ZnO with P4VP and optimization of the BHJ morphology by using solvent additive chloronapthalene, photoconversion efficiency of OSCs was significantly increased from 4.6% to 6.3%. The enhanced device parameters are also attributed to an energetically favorable material stratification, as a result of an enrichment of PC71BM toward the P4VP interface.
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Versatile PbS Quantum Dot Ligand Exchange Systems in the Presence of Pb-Thiolates. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2017; 13:1602956. [PMID: 27860268 DOI: 10.1002/smll.201602956] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2016] [Revised: 10/01/2016] [Indexed: 05/17/2023]
Abstract
A robust solution phase ligand exchange system for lead sulfide (PbS) quantum dots (QDs) in the presence of Pb-thiolate ligands is presented that can better preserve the excitonic absorption and emission features as compared to the conventional ligands. The photoluminescence after ligand exchange of PbS QDs with Pb-thiolate ligand is preserved up to 78% of the original oleate capped PbS QDs.
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A Systematic Density Functional Theory Study of the Complete De-ligation of Ru3(CO)12. ChemistrySelect 2016. [DOI: 10.1002/slct.201600082] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Atomically resolved structure of ligand-protected Au9 clusters on TiO2 nanosheets using aberration-corrected STEM. J Chem Phys 2016; 144:114703. [PMID: 27004889 DOI: 10.1063/1.4943203] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Triphenylphosphine ligand-protected Au9 clusters deposited onto titania nanosheets show three different atomic configurations as observed by scanning transmission electron microscopy. The configurations observed are a 3-dimensional structure, corresponding to the previously proposed Au9 core of the clusters, and two pseudo-2-dimensional (pseudo-2D) structures, newly found by this work. With the help of density functional theory (DFT) calculations, the observed pseudo-2D structures are attributed to the low energy, de-ligated structures formed through interaction with the substrate. The combination of scanning transmission electron microscopy with DFT calculations thus allows identifying whether or not the deposited Au9 clusters have been de-ligated in the deposition process.
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Abstract
Indium-tin-oxide (ITO) electrode surfaces were modified using thin polymeric films of ethoxylated polyethylenimine (PEIE) and poly(3,3′-([(9′,9′-dioctyl-9H,9′H-[2,2′-bifluorene]-9,9-diyl)bis(4,1-phenylene)]bis(oxy))bis(N,N-dimethylpropan-1-amine)) (PFPA-1) to investigate the resultant work function and its stability in ambient atmosphere. Both PEIE and PFPA-1 were found to significantly reduce the ITO work function, as a result of a surface dipole at the ITO–polymer interface. After aging for two weeks in ambient air atmosphere, the N-side groups and OH groups in PEIE-modified ITO were found to realign themselves away from the polymer surface, resulting in an orientation more parallel to the surface normal and thus in an increase in work function from 3.5 to 3.8 eV. The work function of PFPA-1-modified ITO was found to increase from 3.65 to 4.1 eV after two weeks of aging in air due to a complete re-orientation of the polar side chains away from the surface, aligning the dipoles more parallel to the surface normal. In both PEIE and PFPA-1 samples, the hydrophobic aliphatic carbon was found to dominate the polymer surface, after aging.
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Abstract
Au9 clusters forming groups of clusters on titania nanosheets at least partially consist of individual clusters both before and after annealing. Au9 clusters also can attach as individual clusters.
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3D WS2 Nanolayers@Heteroatom-Doped Graphene Films as Hydrogen Evolution Catalyst Electrodes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:4234-41. [PMID: 26061221 DOI: 10.1002/adma.201501692] [Citation(s) in RCA: 171] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 05/14/2015] [Indexed: 05/04/2023]
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Planar silver nanowire, carbon nanotube and PEDOT:PSS nanocomposite transparent electrodes. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2015; 16:025002. [PMID: 27877771 PMCID: PMC5036479 DOI: 10.1088/1468-6996/16/2/025002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 01/13/2015] [Indexed: 05/30/2023]
Abstract
Highly conductive, transparent and flexible planar electrodes were fabricated using interwoven silver nanowires and single-walled carbon nanotubes (AgNW:SWCNT) in a PEDOT:PSS matrix via an epoxy transfer method from a silicon template. The planar electrodes achieved a sheet resistance of 6.6 ± 0.0 Ω/□ and an average transmission of 86% between 400 and 800 nm. A high figure of merit of 367 Ω-1 is reported for the electrodes, which is much higher than that measured for indium tin oxide and reported for other AgNW composites. The AgNW:SWCNT:PEDOT:PSS electrode was used to fabricate low temperature (annealing free) devices demonstrating their potential to function with a range of organic semiconducting polymer:fullerene bulk heterojunction blend systems.
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Back Cover: Change of Surface Structure upon Foam Film Formation (ChemPhysChem 4/2015). Chemphyschem 2015. [DOI: 10.1002/cphc.201590022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Factors influencing the catalytic oxidation of benzyl alcohol using supported phosphine-capped gold nanoparticles. Catal Sci Technol 2015. [DOI: 10.1039/c4cy01168f] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The nature of Au cluster precursor and activation treatments affect catalyst activity in aerobic benzyl alcohol oxidation.
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47
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The effect of counter ions on the far-infrared spectra of tris(triphenylphosphinegold)oxonium dimer salts. RSC Adv 2015. [DOI: 10.1039/c5ra11599j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The far-infrared spectra of two tris(triphenylphosphinegold)oxonium dimer salts in the 50–800 cm−1 region were recorded using synchrotron-based IR radiation, and comprehensively assigned utilising density functional theory calculations.
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Phosphine-stabilised Au9clusters interacting with titania and silica surfaces: The first evidence for the density of states signature of the support-immobilised cluster. J Chem Phys 2014; 141:014702. [DOI: 10.1063/1.4884642] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Identification of the vibrational modes in the far-infrared spectra of ruthenium carbonyl clusters and the effect of gold substitution. Inorg Chem 2014; 53:4340-9. [PMID: 24758282 DOI: 10.1021/ic403040u] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
High-quality far-IR absorption spectra for a series of ligated atomically precise clusters containing Ru3, Ru4, and AuRu3 metal cores have been observed using synchrotron radiation, the latter two for the first time. The experimental spectra are compared with predicted IR spectra obtained following complete geometric optimization of the full cluster, including all ligands, using DFT. We find strong correlations between the experimental and predicted transitions for the low-frequency, low-intensity metal core vibrations as well as the higher frequency and intensity metal-ligand vibrations. The metal core vibrational bands appear at 150 cm(-1) for Ru3(CO)12, and 153 and 170 cm(-1) for H4Ru4(CO)12, while for the bimetallic Ru3(μ-AuPPh3)(μ-Cl)(CO)10 cluster these are shifted to 177 and 299 cm(-1) as a result of significant restructuring of the metal core and changes in chemical composition. The computationally predicted IR spectra also reveal the expected atomic motions giving rise to the intense peaks of metal-ligand vibrations at ca. 590 cm(-1) for Ru3, 580 cm(-1) for Ru4, and 560 cm(-1) for AuRu3. The obtained correlations allow an unambiguous identification of the key vibrational modes in the experimental far-IR spectra of these clusters for the first time.
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Composition of the outermost layer and concentration depth profiles of ammonium nitrate ionic liquid surfaces. Phys Chem Chem Phys 2014; 14:16088-95. [PMID: 23103987 DOI: 10.1039/c2cp43035e] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Differences in the surface structure of protic ionic liquids (ILs) with three different cations and a common anion; ethyl-, propyl- and 2-hydroxyethyl- (or ethanol-) ammonium nitrate (EAN, PAN and EtAN, respectively) have been observed by neutral impact collision ion scattering spectroscopy (NICISS) and metastable induced electron spectroscopy/ultraviolet photoelectron spectroscopy (MIES/UPS). NICISS is used to determine the concentration depth profiles of the elements in each IL and it reveals an enrichment of cation alkyl chains of PAN and EtAN in the outermost layer compared to EAN, and a corresponding depletion of nitrate from the outermost layer of the EtAN surface. MIES probes the molecular orbitals of only the species in the outermost layer of a sample and confirms that, while both the anion and the cation are present to some degree at the surface of all three ILs, the cation is enriched to a greater extent at the surface of PAN and EtAN compared to EAN.
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