Cluster Deposition Research Articles

Cubic MOF coated stainless steel mesh with underwater superoleophobicity for highly efficient oil/water separation

A novel superhydrophilic and underwater superoleophobic material (MOF-5/PDA/SSM) with high flux, outstanding oil/water separation performance and durability was prepared. The stainless steel mesh (SSM) was modified by MOF-5 crystals and PDA. The introduction of MOF-5 can improve the hydrophilicity of SSM and achieve high water flux at the same time. PDA is a substance with strong adhesion which can be used as an effective bonding intermediate. The preparation strategy includes the self-polymerization of dopamine and the deposition of cubic clusters on SSM via hydrothermal reaction. The MOF-5 particles on the mesh are cubic hexahedral crystal with a uniform size diameter, which can trap water in the rough microstructure, forming a strong hydration barrier layer or composite water-solid interface on its surface, hindering the penetration of oil. The super-hydrophilicity and underwater superoleophobicity of the modified meshes were introduced by pre-wetting surface. The FTIR, XRD, XPS and SEM characterizations demonstrated that the successfully growth of MOF-5 and a rough structure was obtained on the mesh. The special wetting and the robustness of the fabricated mesh led to the outstanding separation efficiency (up to 99.5%), excellent recyclability (about 20 cycles) and high water flux (53.9 k L m−2 h−1). The mesh also showed remarked water flux and various oil/water mixtures separation performance. Particularly, the successfully prepared materials were found to be significant stable under various physical and chemical extremes environments, including maintain UWOCA>150 under acid/alkali media, marvelous performance after 120 min of continuous separation and high anti-oil intrusion pressure. The combination of metal organic framework and stainless steel mesh may provide a candidate application to effective oil-water separation.

Experimental study of the process of gravitational settling of a monodisperse cluster of drops under the influence of an external air flow

A technique and an experimental setup for studying the dynamics of gravitational settling of a monodisperse cluster of distilled water droplets under external influence of an air flow are presented. A qualitative picture of the dynamics of deposition of a monodisperse cluster of 60 drops is presented. It is shown that with an increase in the speed of the ascending airflow from 0 to 1 m/s, the average sedimentation velocity of a monodisperse droplet cluster decreases from 3.8 m/s to 2.8 m/s. The results of comparing the deposition rate of a cluster and individual droplets included in it are presented.

Gas phase deposition of well-defined bimetallic gold-silver clusters for photocatalytic applications.

Cluster beam deposition is employed for fabricating well-defined bimetallic plasmonic photocatalysts to enhance their activity while facilitating a more fundamental understanding of their properties. AuxAg1-x clusters with compositions (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1) spanning the metals' miscibility range were produced in the gas-phase and soft-landed on TiO2 P25-coated silicon wafers with an optimal coverage of 4 atomic monolayer equivalents. Electron microscopy images show that at this coverage most clusters remain well dispersed whereas EXAFS data are in agreement with the finding that the deposited clusters have an average size of ca. 5 nm and feature the same composition as the ablated alloy targets. A composition-dependant electron transfer from Au to Ag that is likely to impart chemical stability to the bimetallic clusters and protect Ag atoms against oxidation is additionally evidenced by XPS and XANES. Under simulated solar light, AuxAg1-x clusters show a remarkable composition-dependent volcano-type enhancement of their photocatalytic activity towards degradation of stearic acid, a model compound for organic fouling on surfaces. The Formal Quantum Efficiency (FQE) is peaking at the Au0.3Ag0.7 composition with a value that is twice as high as that of the pristine TiO2 P25 under solar simulator. Under UV the FQE of all compositions remains similar to that of pristine TiO2. A classical electromagnetic simulation study confirms that among all compositions Au0.3Ag0.7 features the largest near-field enhancement in the wavelength range of maximal solar light intensity, as well as sufficient individual photon energy resulting in a better photocatalytic self-cleaning activity. This allows ascribing the mechanism for photocatalysis mostly to the plasmonic effect of the bimetallic clusters through direct electron injection and near-field enhancement from the resonant cluster towards the conduction band of TiO2. These results not only demonstrate the added value of using well-defined bimetallic nanocatalysts to enhance their photocatalytic activity but also highlights the potential of the cluster beam deposition to design tailored noble metal modified photocatalytic surfaces with controlled compositions and sizes without involving potentially hazardous chemical agents.

Anisotropic nanocluster arrays to a diminished zone: different regimes of surface deposition of gold nanocolloids.

Evaporation-induced assembly of nanoparticles has emerged as a versatile technique for the production of large-scale ordered structures and materials with complex features. In this study, we show that a dried particulate of an anisotropic nanocolloid undergoes non-ubiquitous surface morphological transitions at varying particle concentrations. Below 5 nM, deposits reveal the formation of linear arrays of AuNR clusters outside of the coffee ring and an annular CTAB-rich depletion zone in the inner vicinity of the coffee ring. For nanoparticle concentrations ≥5 nM, the outer cluster deposits disappear and a region of reduced AuNR density, sandwiched between the coffee ring and the depletion zone, analogous to the diminished zone, is observed. Within the coffee-ring deposits, nanoscale smectic AuNR assembly occurs via the expulsion of the cetyltrimethyl ammonium bromide (CTAB) bilayer, which contributes to the inward solutal Marangoni flow. An enhanced inward solutal Marangoni flow at high particle concentrations assists in the formation of a wider depletion zone, the emergence of the diminished zone and suppression of the width of the coffee-ring deposits. Through detailed analysis of data from ex situ (scanning electron microscopy, SEM) and in situ (contact angle and confocal imaging) measurements, we establish a direct correlation between the different evaporation modes and the various deposition regimes. A detailed mechanism for the surface morphology modulation of AuNR deposits by tuning the nanoparticle concentration in the drying sessile drop is discussed.

An integrated instrument of a tandem quadrupole mass spectrometer for cluster reaction and soft-landing deposition.

We have developed an integrated instrument system of a multiple-ion laminar flow tube (MIFT) reactor combined with a tandem quadrupole mass spectrometer (TQMS) and soft-landing deposition (SD) apparatus. A customized water-cooling magnetron sputtering (MagS) source is designed, by which we are able to attain a highly efficient preparation of metal clusters of 1-30 atoms with tunable size distributions. Following the MagS source, a laminar flow tube reactor is designed, allowing for sufficient gas-collision reactions of the as-prepared metal clusters, which is advantageous for probing magic clusters and minimizing wall effects when probing the reaction dynamics of such clusters. The customized TQMS analyzer involves a conical octupole, two linear octupoles, a quadruple ion deflector, and a 19mm quadruple mass analyzer, allowing to decrease the pressure stepwise (from ∼5 to ∼10-9 Torr), thus ensuring high sensitivity and high resolution of the mass spectrometry analysis. In addition, we have designed a dual SDapparatus for the mass-selected deposition of clusters and their reaction products. For the whole system, abbreviated as MagS-MIFT-TQMS-SD, we have performed a detailed ions-fly simulation and quantitatively estimated the ions transfer efficiency under vacuum conditions determined by real experiments. Taking these advantages, well-resolved Pbn +, Agn +, and Nbn + clusters have been produced, allowing for meticulous studies of cluster reactions under sufficient gas-phase collisions free of electric field trapping. Also, we have tested the efficiency of the dual SD.

Structural and Mining Geology of a Copper site with Epigenetic-type auriferous levels in the region of Imi Nisk in M’goun, Central High Atlas, Rural town of Abachkou, Azilal. Morocco

Our initial intention was to use point geochemical data in relation to regional and/or local geology to identify and quantify the mineral potential of these Paleozoic formations, and the nature of the soil in relation to weathering by external climatic agents. The mineralogical study of the substrates proved to be essential to confirm the results of the spot sampling by channel sampling of the mineralized structures. From there, it was decided to focus on structural geology, regional tectonics, geochemistry, geomorphology, and the extension of veins from other deposits around this site. Because it is located at the Ordovician-Devonian contact, the copper mineralization at the future Imi Nisk mine site in the Central High Atlas has been interpreted in terms of sulfides-rich cluster deposits (Chalcopyrite, Azurite and Covellite) in Ankerite or siderite, and quartzite. The new structural and mineralogical data presented in this work favor the hypothesis of epigenetic mineralization, meaning that it was formed after the host rock. The present work consists in establishing a preliminary research in order to give a general idea and a very precise overview of the gitology, geology and geochemistry of the mineralized structures and veins located in this research permit in mining exploration of Imi Nisk. Also, no study has been published in this thematic on this site.

Effect of TiO2 Film Thickness on the Stability of Au9 Clusters with a CrOx Layer.

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.

Effects of three-body diamond abrasive polishing on silicon carbide surface based on molecular dynamics simulations

Recently, SiC has gained considerable interest owing to its avant-garde nature and relevance in future applications. Molecular dynamics simulation was performed to investigate nanopolishing of three-body diamond abrasives on workpieces that had undergone cluster deposition and annealing processes. The coordination number, temperature, atomic distribution, kinetic energy, friction coefficient, crystallization, and average height of the workpiece were determined. Further, the effects of different polishing depths and polishing speeds on the physical properties of the workpiece were determined. Results show that polishing depth considerably affects the coordination number, surface morphology, friction coefficient, crystallization, and temperature of the workpiece. The surface of the workpiece was polished while maintaining the crystallization rate at a polishing depth of 20 Å. With an increase in the polishing rate, the coefficient of friction decreased, the temperature of the workpiece increased, and the polishing trajectory became clearer, with a better crystallization at 1 Å/ps.

Growth mechanisms of large, faceted crystals grown from solutions

The paper describes optical techniques and methods used to study growth mechanisms and phenomena occurring on multiple faces of real bulk crystals grown from aqueous and organic solutions. Using examples of ionic KDP and molecular trans-stilbene crystals, it shows how in-situ and ex-situ surface observations can be applied to identify growth structures characteristic for the dislocation, two-dimensional (2D), and 3D cluster deposition mechanisms. Results are analyzed and applied to understanding of defects origins and methods for their elimination in practical growth of large, high optical quality crystals.

Site‐Selective Bipolar Electrodeposition of Gold Clusters on Graphene Oxide Microsheets at a 3D Air|Liquid Interface

AbstractAn innovative wireless approach is proposed for asymmetric site‐selective deposition of gold clusters on graphene oxide microsheets by performing bipolar electrochemistry at the 3D air|liquid interface present in an assembly of bubbles constituting a foam. Exfoliated graphene oxide (EGO) microsheets are introduced into a bipolar electrochemical cell, which is filled with the foam composed of a nonionic surfactant, water, and a gold metal precursor. The EGO microparticles are located exclusively at the air|liquid interface, providing a unique 2D reaction space for bipolar electrodeposition, deployed in the 3D volume of the reactor. The application of an external electric field on such a medium enables a focalization of the polarization potential gradient and simultaneously restricts the mobility of the EGO particles, leading to their preferential in‐plane orientation with respect to the electric field lines, greatly facilitating their successful site selective modification with gold clusters.

Integrating trace ruthenium cluster with cobalt boride toward superior overall water splitting in neutral media

Cobalt boride which is an active bifunctional water splitting catalyst in alkaline media shows poor activity in neutral media. We found that trace ruthenium (Ru) cluster deposition (80 μg·cm−2) on cobalt boride by simple wet chemical reduction method can dramatically improve both its hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity in neutral solution. The electron transfer from Co-B to Ru may result in the easier water dissociation step so as to facilitate the catalytic process. The resulting Ru@Co-B/Ni binder-free electrode could supply 10 mA cm−2 at overpotentials of 56 mV for HER and 280 mV for OER in 0.5 M phosphate buffer electrolyte. This work proposed a fruitful approach to advance the water splitting performance of transition metal boride in neutral media.

Influence of Cd salt concentration on the photoconductivity of CdS thin films prepared by chemical bath technique

Herein, a comparative study of the photodetection properties of CdS thin films deposited via the CBD method at different cadmium chloride concentrations of Cd (0.008) M, Cd (0.02) M, and Cd (0.08) M has been reported. The increase in cadmium salt concentration dominated the cluster deposition mechanism of the chemical bath deposition (CBD) method, leading to the cubic crystal phase and the thicker CdS thin films. Also, with the increase in cadmium salt concentration, the photosensivity decreased. After all investigations, it was concluded that the value of photosensivity strongly depends on the film thickness and the quantum confinement effect, as well as the amount of sulfur vacancy of samples grown by the CBD method. The quantum confinement effect of sample Cd (0.008 M) was proved by the blue shift of the optical band gap and the grain size of this sample shown by Transmission Electron Microscope (TEM). The structural properties, surface morphology, compositional properties, film thickness and optical properties of CdS thin films were studied by X-Ray Diffractometer (XRD), Field Emission-Scanning Electron Microscopy (FE-SEM), TEM, Energy Dispersive X-ray Spectroscopy (EDXS), Cross-Section Microscopy (CSM), UV–Vis Spectroscopy, and Photoluminescence Spectroscopy (PL), respectively. Besides, the optical sensor characteristics of these samples were analyzed by the I–V curves at a bias voltage of 5V. The results showed more than 200 times the photosensivity of sample Cd (0.008 M) compared to the sample Cd (0.08 M); 265 vs.1.3.

SnO2 clusters embedded in TiO2 nanosheets: Heterostructures and gas sensing performance

SnO2 clusters were embedded in superior thin TiO2 nanosheets to form heterostructures via a two-step solvothermal synthesis. Superior thin TiO2(B) nanosheets were firstly prepared, in which these nanosheets exhibited homogeneously sheet structure without aggregation. After deposition of SnO2 clusters, the mixture phase consisted of anatase and TiO2(B) was obtained even though the nanosheet morphology remained unchanged. The ratio of SnO2 and TiO2 was adjusted to get enhanced gas sensing performance. The gas sensing activity of samples for volatile organic compounds including acetone, ethanol and triethylamine was tested. Results indicates that SnO2/TiO2 heterostructure with an optimal SnO2 weight ratio of 10% is remarkably responsive to acetone, ethanol and triethylamine. Especially, the response time to triethylamine is only 10 s. In the case of 2 ppm, the sample still revealed a significant response to triethylamine. The enhanced sensing performance has to ascribed to the significant increase of reactive active sites by loading SnO2 clusters. In addition, ultra-thin morphology and mixed phase composition of TiO2 also enhance the property of the composite. This work supplied an idea for the preparation of SnO2 based gas sensors.

First-principles modelling of the new generation of subnanometric metal clusters: Recent case studies

The very recent development of highly selective techniques making possible the synthesis and experimental characterization of subnanometric (subnanometer-sized) metal clusters (even single atoms) is pushing our understanding far beyond the present knowledge in materials science, driving these clusters as a new generation of quantum materials at the lower bounds of nanotechnology. When the size of the metal cluster is reduced to a small number of atoms, the d-band of the metal splits into a subnanometric d-type molecular orbitals network in which all metal atoms are inter-connected, with the inter-connections having the length of a chemical bond (1–2 Å). These molecular characteristics are at the very core of the high stability and novel properties of the smallest metal clusters, with their integration into colloidal materials interacting with the environment having the potential to further boost their performance in applications such as luminescence, sensing, bioimaging, theranostics, energy conversion, catalysis, and photocatalysis. Through the presentation of very recent case studies, this Feature Article is aimed to illustrate how first-principles modelling, including methods beyond the state-of-the-art and an interplay with cutting-edge experiments, is helping to understand the special properties of these clusters at the most fundamental level. Moreover, it will be discussed how superfluid helium droplets can act both as nano-reactors and carriers to achieve the synthesis and surface deposition of metal clusters. This concept will be illustrated with the quantum simulation of the helium droplet-assisted soft-landing of a single Au atom onto a titanium dioxide (TiO2) surface. Next, it will be shown how the application of first-principles methods have disclosed the fundamental reasons why subnanometric Cu5 clusters are resistant to irreversible oxidation, and capable of increasing and extending into the visible region the solar absorption of TiO2, of augmenting its efficiency for photo-catalysis beyond a factor of four, also considering the decomposition and photo-activation of CO2 as a prototypical (photo-) catalytic reaction. Finally, I will discuss how the modification of the same material with subnanometric Ag5 clusters has converted it into a “reporter” of a surface polaron property as well as a novel two-dimensional polaronic material.

Palladium clusters, free and supported on surfaces, and their applications in hydrogen storage.

Palladium is a late transition metal element in the 4d row of the periodic table. Palladium nanoparticles show efficient catalytic activity and selectivity in a number of chemical reactions. In this paper, we review the structural and electronic properties of palladium nanoclusters, both isolated and deposited on the surface of different substrates. Careful experiments and extensive calculations have been performed for small Pd clusters which provide ample information on their properties. Work on large Pd clusters is less abundant and more difficult to perform and interpret. Cluster deposition is a method to modify material surfaces for different applications, and we report the known results for the deposition of Pd clusters on the surfaces of a number of interesting substrates: carbonaceous substrates like graphene and some layered novel materials related to graphene, metal oxide substrates, silicon and silicon-related substrates and metallic alloy substrates. Emphasis is placed on revealing how the structural, electronic and magnetic properties change when the clusters are deposited on the substrate surfaces. Some examples of chemical reactions catalyzed by supported Pd clusters and nanoparticles are reported. An issue discussed in detail is the influence of Pd on the storage of hydrogen in porous materials. Experimental work shows that the amount of stored hydrogen increases when the absorbing material is doped with Pd atoms, clusters and nanoparticles, and a spillover mechanism from the metal particle to the substrate is usually accepted as the explanation. To shed light on this issue, a critical analysis based on density functional simulations of the mechanisms of hydrogen spillover in perfect and defective graphene doped with palladium clusters is presented.

X-ray photoelectron spectroscopy study of Pt-cluster-induced electronic-state change of CeO2(111) surfaces

We investigated the reduction of a CeO2(111) surface after the deposition of size-selected Pt8 clusters on it via x-ray photoelectron spectroscopy (XPS). Electron transfer from Pt to CeO2(111) results in the reduction of Ce4+ to Ce3+ and the subsequent formation of Ptδ+ atoms at the interface. We quantitatively estimated the reduction from the Ce3+/(Ce3+ + Ce4+) ratio determined from the Ce3d spectra. Approximately 30% of Ce4+ under or in the perimeter of the Pt8 cluster was reduced to Ce3+. The XPS spectra showed an increase in the ratio of Ce3+/(Ce3+ + Ce4+) with an increase in the amount of Pt8 clusters deposited on the CeO2(111) surface. The reduction of 3.7 Ce4+ to Ce3+ per Pt8 clusters, followed by the formation of 3.7 Ptδ+ atoms per Pt8 clusters was observed at 0.006 ML (mono layer) Pt coverage. The actual Ce3+ formation influenced by Pt deposition was approximately 2.5%. We estimate that approximately 30% of Ce4+ under or in the perimeter of a Pt8 cluster was reduced to Ce3+. At a higher coverage of 0.015 ML, the reduction of 2.2 Ce4+ to Ce3+ per Pt8 cluster, followed by the formation of 3.2 Ptδ+ atoms per Pt8 cluster was observed. This implies the aggregation of Pt clusters occurred at a higher Pt coverage. Atomically precise quantification of the electron transfer across the Pt–CeO2(111) interface can enable an improved understanding of the metal-support interaction.

Deposition of Pt clusters onto MOFs-derived CeO2 by ALD for selective hydrogenation of furfural

The selective hydrogenation of furfural (FAL) to furfuryl alcohol (FOL) in liquid phase has drawn tremendous attention, while designing and preparing efficient catalysts with satisfied selectivity remains a challenge due to the coexistence of two conjugated CO and CC groups within FAL molecule. This work has depicted a simple-yet-effective strategy to load small sized Pt (<2 nm) onto MOFs-derived CeO2 via atomic layer deposition (ALD) technique. Special aberration-corrected scanning transmission electron microscopy (AC-STEM) confirmed the dominant presence of Pt nanoclusters. Physicochemical properties of Pt/M-CeO2 were investigated by a various of characterizations, inclusive of XRD, SEM, TEM, BET, XPS, Raman, CO-DRIFTS and FAL-DRIFTS. In comparison to Pt/commercial CeO2 (Pt/C-CeO2), the Pt/M-CeO2 one displayed the superior catalytic activity, yielding 100% conversion of FAL and 98% selectivity to FOL. The high catalytic activity of Pt/M-CeO2 can be reasonably assigned to Pt clusters with clean surface, strongly interacting between Pt and M-CeO2, and rich oxygen vacancy/porous structure of the M-CeO2 support. This work highlights an effective approach towards deposition of noble metal clusters onto MOFs-derived metal oxides, offering an alternative way to reasonable design highly efficient catalyst in selective hydrogenation reactions.

Physicochemical mechanisms of the growth of oxide crystals on the surface of tungsten conductors heated by electric current

Physical and mathematical modeling of stationary thermal modes of heating and oxidation of tungsten conductors heated by electric current in air has been carried out. The dependences of the stationary temperature of the conductor on the strength of the heating current are obtained. The critical values of the current strength are found, which determine the transitions to the unsteady oxidation regime. The results of calculating the temperature regimes describe well the experimental data obtained by us using the electrothermographic method.&#x0D; As a result of experimental studies, the features of the appearance and growth of crystalline oxide structures on the surface of an oxidizing tungsten conductor have been studied. The temperatures at which filamentous crystals appear on the tungsten surface are determined, and the regularities of their growth are investigated. A physicochemical mechanism of the formation and growth of crystalline oxide structures on the surface of a tungsten conductor is proposed. It was found that carbon particles, which are part of the impurity, are the reason for the formation of nitrate crystals of tungsten trioxide on the basic oxide. With an increase in the temperature of the sample, the filaments grow, branch out and transform into dendritic structures of a complex bush-like shape. It has been proven that the rapid growth of crystal structures occurs due to the deposition of clusters and microgranules of WO3 oxide from the gas phase on the crystallization centers on the surface of the conductor. At the initial stage, these are impurity particles or mechanical inhomogeneities of the basic oxide, then a growing crystal. Clusters arise due to large temperature gradients at the surface of the conductor. It has been established that carbon atoms can migrate along the branches of oxide crystal structures.&#x0D; It was found that at the initial stage the crystals grow more intensively in the longitudinal direction. However, upon reaching a certain height, they begin to expand intensively in the transverse direction. The growth rates of crystal structures in the longitudinal and transverse directions are found.

Complement-mediated M2/M1 macrophage polarization may be involved in crescent formation in lupus nephritis

The function of the complement and macrophage crosstalk during the formation of crescents in lupus nephritis has not yet been reported. This study therefore aimed to explore the association of crescents, complements, and M2 macrophages with clinical features in lupus nephritis. We assessed a Chinese cohort comprising 301 patients with lupus nephritis. Renal biopsy specimens were collected from 64 patients with proliferative lupus nephritis (class III/III + V or IV/IV + V). The renal deposition of cluster of differentiation (CD) 68, inducible nitric oxide synthase, CD163, and C3a receptor (C3aR) was evaluated by immunostaining. The associations among crescents, complements, and M2 macrophages were also analyzed. Next, the underlying mechanism was investigated in vitro using C3a-treated macrophages. We found that M2-phenotype macrophages (CD163+) were the dominant subpopulation in human lupus nephritis. Additionally, a significant association was observed among the CD163+ macrophages, crescents, and complement activation. C3aR co-localized with CD163 and correlated with crescents and could induce polarization of macrophages to an M2 phenotype. Overall, these results suggest that complement-mediated M2/M1 macrophage polarization may contribute to the formation of crescents in lupus nephritis.

Cr2O3 layer inhibits agglomeration of phosphine-protected Au9 clusters on TiO2 films.

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.