Search

Sustainable development compliant with environment and human health protection motivates researchers to explore green solutions towards improved economic and social wellbeing. These objectives, still very far from being achieved especially in developing countries, must necessarily be pursued through the tailored fabrication of low-cost, eco-friendly, efficient and stable multi-functional materials. In particular, nanostructures based on first-row transition metal oxides are amenable candidates for clean energy production, air purification and self-cleaning/anti-fogging purposes, especially if obtained through fabrication strategies allowing a careful modulation of their characteristics. In this highlight, after a brief introduction of the above issues, we provide selected representative examples of green oxide-based nanoarchitectures for the targeted end-uses. Attention is focused on the interplay between the material chemico-physical properties and the resulting functional performances, with the aim of providing some hints to control material behavior by design. In addition, we provide a critical outlook not only on the unique opportunities, but also on the main open challenges related to the use of the above multi-functional materials, in an attempt to stimulate further advancements in these emerging research areas. [ABSTRACT FROM AUTHOR]

Abstract Mn 3 O 4 thin films were fabricated on SrTiO 3 (111) and Y 3 Al 5 O 12 (100) substrates by chemical vapor deposition (CVD) under O 2 atmospheres, starting from a fluorinated Mn(II) diketonate-diamine adduct. The obtained systems were investigated by a multi-technique characterization in order to elucidate the interplay between preparation conditions and their chemico-physical properties. The results highlighted the formation of phase-pure and homogeneous α-Mn 3 O 4 (haussmannite) films, characterized by a smooth morphology, an appreciable Vis light absorption and structural features directly dependent on the used substrate. The target systems were uniformly doped with fluorine, due to the used Mn compound acting as a single-source precursor for both Mn and F. In addition, magnetic force microscopy measurements revealed the formation of spin domains and long-range magnetic order in the target materials, paving the way to their future implementation as magnetic media toward device integration for data storage. Graphical abstract F-doped phase-pure α-Mn 3 O 4 films were grown by a convenient chemical vapor deposition route on single-crystal substrates and characterized by magnetic force microscopy for the first time. Image 1 Highlights • First report on the chemical vapor deposition of Mn 3 O 4 films on Y 3 Al 5 O 12 (100) and SrTiO 3 (111). • Fluorine-doped α-Mn 3 O 4 (haussmannite) systems with tailored structure and morphology. • Compositional, optical and magnetic force microscopy investigation of the target materials. [ABSTRACT FROM AUTHOR]

A sequential Chemical Vapor Deposition (CVD) – Radio Frequency (RF)-sputtering approach was adopted to fabricate supported nanocomposites based on the scarcely investigated ε-iron(III) oxide polymorph. In particular, ε-Fe 2 O 3 nanorod arrays were obtained by CVD, and their subsequent functionalization with Au and CuO nanoparticles (NPs) was carried out by RF-sputtering under mild operational conditions. Beside a multi-technique characterization of material structure, morphology and chemical composition, particular efforts were dedicated to the investigation of their magnetic properties. The pertaining experimental data, discussed in relation to the system chemico-physical characteristics, are directly dependent on the actual chemical composition, as well as on the spatial distribution of Au and CuO nanoparticles. The approach adopted herein can be further implemented to control and tailor different morphologies and phase compositions of iron oxide-based nanomaterials, meeting thus the open requests of a variety of technological utilizations. [ABSTRACT FROM AUTHOR]

Molecular engineering of manganese(II) diamine diketonate precursors is a key issue for their use in the vapor deposition of manganese oxide materials. Herein, two closely related β-diketonate diamine MnII adducts with different fluorine contents in the diketonate ligands are examined. The target compounds were synthesized by a simple procedure and, for the first time, thoroughly characterized by a joint experimental-theoretical approach, to understand the influence of the ligand on their structures, electronic properties, thermal behavior, and reactivity. The target compounds are monomeric and exhibit a pseudo-octahedral coordination of the MnII centers, with differences in their structure and fragmentation processes related to the ligand nature. Both complexes can be readily vaporized without premature side decompositions, a favorable feature for their use as precursors for chemical vapor deposition (CVD) or atomic layer deposition applications. Preliminary CVD experiments at moderate growth temperatures enabled the fabrication of high-purity, single-phase Mn3O4 nanosystems with tailored morphology, which hold great promise for various technological applications. [ABSTRACT FROM AUTHOR]

Photo-activated processes have been widely recognized as cost-effective and environmentally friendly routes for both renewable energy generation and purification/cleaning technologies. We report herein on a plasma-assisted approach for the synthesis of Fe 2 O 3 -TiO 2 nanosystems functionalized with Au nanoparticles. Fe 2 O 3 nanostructures were grown by plasma enhanced-chemical vapor deposition, followed by the sequential sputtering of titanium and gold under controlled conditions, and final annealing in air. The target nanosystems were subjected to a thorough multi-technique characterization, in order to elucidate the interrelations between their chemico-physical properties and the processing conditions. Finally, the functional performances were preliminarily investigated in both sunlight-assisted H 2 O splitting and photocatalytic activity tests in view of self-cleaning applications. The obtained results highlight the possibility of tailoring the system behaviour and candidate the present Fe 2 O 3 -TiO 2 -Au nanosystems as possible multi-functional low-cost platforms for light-activated processes. [ABSTRACT FROM AUTHOR]

Nanocomposite Fe2O3Co3O4 photoanodes for photoelectrochemical H2O splitting were prepared by a plasma-assisted route. Specifically, Fe2O3 nanostructures were grown by plasma enhanced-chemical vapor deposition, followed by cobalt sputtering for different process durations. The systems were annealed in air after, or both prior and after, sputtering of Co, to analyze the treatment influence on functional performances. The interplay between processing conditions and chemico-physical features was investigated by a multi-technique characterization. Photocurrent density measurements in sunlight-assisted H2O splitting revealed a performance improvement upon Co3O4 loading. A cathodic shift of the onset potential was also observed, highlighting Co3O4 activity as catalyst for the oxygen evolution reaction. [ABSTRACT FROM AUTHOR]

Multilayer assemblies of two crown-typetype heteropolyanions (HPA),[Cu20Cl(OH)24(H2O)12(P8W48O184)]25–and Ni4(P8W48O148)(WO2)]28–, have been immobilized onto glassy carbonelectrode surfaces via the layer-by-layer (LBL) technique employingpolycathion-stabilized silver nanoparticles (AgNP) as the cationiclayer within the resulting thin films characterized by electrochemicaland physical methods. The redox behaviors of both HPA monitored duringLBL assembly with cyclic voltammetry and impedance spectroscopy revealedsignificant changes by immobilization. The presence of AgNPs led tothe retention of film porosity and electronic conductivity, whichhas been shown with impedance and voltammeric studies of film permeabilitiestoward reversible redox probes. The resulting films have been characterizedby physical methods. Finally, the electrocatalytic performance ofobtained films with respect to nitrite and nitrate electrocatalyticreduction has been comparatively studied for both catalysts. Nickelatoms trapped inside HPA exhibited a higher specific activity forreduction. [ABSTRACT FROM AUTHOR]

Sunlight-driven hydrogen production via photoreforming of aqueous solutions containing renewable compounds is an attractive option for sustainable energy generation with reduced carbon footprint. Nevertheless, the absence of photocatalysts combining high efficiency and stability upon solar light activation has up to date strongly hindered the development of this technology. Herein, two scarcely investigated iron(III) oxide polymorphs, β- and ε-Fe2O3, possessing a remarkable activity in sunlight-activated H2 generation from aqueous solutions of renewable oxygenates (i.e., ethanol, glycerol, glucose) are reported. For β-Fe2O3 and ε-Fe2O3, H2 production rates up to 225 and 125 mmol h−1 m−2 are obtained, with significantly superior performances with respect to the commonly investigated α-Fe2O3. [ABSTRACT FROM AUTHOR]

Si(100)-supported Fe2O3 nanomaterials were developed by a chemical vapor deposition (CVD) approach. The syntheses, which were performed at temperatures between 400 and 550 °C, selectively yielded the scarcely studied β- and ϵ-Fe2O3 polymorphs under O2 or O2 + H2O reaction environments, respectively. Correspondingly, the observed morphology underwent a progressive evolution from interconnected nanopyramids to vertically aligned nanorods. The present study aims to provide novel insights into Fe2O3 nano-organization by a systematic investigation of the system structure/morphology and of their interrelations with growth conditions. In particular, for the first time, the β- and ϵ-Fe2O3 preparation process has been accompanied by a thorough multitechnique investigation, which, beyond X-ray photoelectron spectroscopy (XPS) and field-emission scanning electron microscopy (FESEM), is carried out by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDXS), atomic force microscopy (AFM), high-resolution transmission electron microscopy (HRTEM), electron diffraction (ED), scanning TEM electron energy-loss spectroscopy (STEM-EELS), and high-angle annular dark-field STEM (HAADF-STEM). Remarkably, the target materials showed a high structural and compositional homogeneity throughout the whole thickness of the nanodeposit. In particular, spatially resolved EELS chemical maps through the spectrum imaging (SI) technique enabled us to gain important information on the local Fe coordination, which is of crucial importance in determining the system reactivity. The described preparation method is in fact a powerful tool to simultaneously tailor phase composition and morphology of iron(III) oxide nanomaterials, the potential applications of which include photocatalysis, magnetic devices, gas sensors, and anodes for Li-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: The development of efficient photocatalytic nanomaterials is of outstanding importance for the conversion of electromagnetic radiation into chemical energy. Among the various technological options, photoreforming of aqueous media containing suitable organic oxygenates is an attractive strategy towards a sustainable H2 generation. In this regard, the present contribution will provide a survey of our recent research activities on photoactivated H2 production over supported oxide-based nanosystems. Their preparation is carried out by original synthetic routes based on chemical vapor deposition (CVD), either thermal or plasma-enhanced (PE-CVD), in some cases combined with radio frequency (RF) sputtering. In particular, we will present and discuss the synthesis, characterization and functional performances of two material classes: (i) single-phase undoped (Cu x O, with x =1, 2; Co3O4) and anion-doped (F:Co3O4) metal oxides; (ii) oxide-based nanocomposites (Ag/ZnO and CuO/ZnO). Beside highlighting the potential of CVD routes in achieving specific nanosystem properties, the future challenges and perspectives for research advancements in these fields will also be outlined. [Copyright &y& Elsevier]

Abstract: The synthesis and characterization of the gold(III) complexes [(HSDT)AuX2] and [(HSDT)2Au]X (X=Cl, Br; HSDT=sarcosinedithiocarbamate (N-methylglycinedithiocarbamate)) are reported. In the discussed compounds coordination takes place through the sulfur atoms in a square-planar geometry around the gold(III) metal center. The characterization of the complexes has been carried out by means of elemental analysis, conductance measurements, FT-IR, 1H and 13C NMR spectroscopy, and thermogravimetric analysis. In addition, the molecular structure of the 1:1 metal-to-ligand complexes has been further investigated by means of density functional calculations, confirming the conclusions reached upon application of the other chemical characterization techniques. The complex [(HSDT)3Au] has been also synthesized and characterized by mass spectrometry, FT-IR, NMR and X-ray photoelectron spectroscopy, even if a definitive determination of its structure has not been undoubtedly accomplished. [Copyright &y& Elsevier]

Focuses on chemisorption of carbon monoxide on a ceramic. Nature of surface termination lawyer; Thorough description of the adsorbate-substrate interaction; Insights into the surface relaxation driving force; Molecular adsorption of carbon monoxide; Angle-resolved photoelectron spectra.

Presents a study on inorganic chemistry, investigating the chemisorption of H2 and CO on the zinc oxide (ZnO) surface. Methodology used to conduct the study; Information on the clean and Cu doped ZnO(1010) surface; Details on the heterolytic chemisorption on H2 ZnO(1010) surface; Findings of the study.

MnO2 nanostructures were fabricated by plasma assisted-chemical vapor deposition (PA-CVD) using a fluorinated diketonate diamine manganese complex, acting as single-source precursor for both Mn and F. The syntheses were performed from Ar/O2 plasmas on MgAl2O4(100), YAlO3(010), and Y3Al5O12(100) single crystals at a growth temperature of 300 °C, in order to investigate the substrate influence on material chemico-physical properties. A detailed characterization through complementary analytical techniques highlighted the formation of highly pure and oriented F-doped systems, comprising the sole β-MnO2 polymorph and exhibiting an inherent oxygen deficiency. Optical absorption spectroscopy revealed the presence of an appreciable Vis-light harvesting, of interest in view of possible photocatalytic applications in pollutant degradation and hydrogen production. The used substrates directly affected the system structural features, as well as the resulting magnetic characteristics. In particular, magnetic force microscopy (MFM) measurements, sensitive to the out-of-plane magnetization component, highlighted the formation of spin domains and long-range magnetic ordering in the developed materials, with features dependent on the system morphology. These results open the door to future engineering of the present nanostructures as possible magnetic media for integration in data storage devices. [ABSTRACT FROM AUTHOR]

NiO-based nanomaterials have attracted considerable interest for different applications, which have stimulated the implementation of various synthetic approaches aimed at modulating their chemico-physical properties. In this regard, their bottom-up preparation starting from suitable precursors plays an important role, although a molecular-level insight into their reactivity remains an open issue to be properly tackled. In the present study, we focused on the fragmentation of Ni(II) diketonate-diamine adducts, of interest as vapor-phase precursors for Ni(II) oxide systems, by combining electrospray ionization mass spectrometry (ESI-MS) with multiple collisional experiments (ESI-MSn) and theoretical calculations. The outcomes of this investigation revealed common features in the fragmentation pattern of the target compounds: (i) in the first fragmentation, the three complexes yield analogous base-peak cations by losing a negatively charged diketonate moiety; in these cations, Ni-O and Ni-N interactions are stronger and the Ni positive charge is lower than in the parent neutral complexes; (ii) the tendency of ligand electronic charge to migrate towards Ni further increases in the subsequent fragmentation, leading to the formation of a tetracoordinated Ni environment featuring an interesting cation-π intramolecular interaction. [ABSTRACT FROM AUTHOR]

The development of catalysts with high intrinsic activity towards the oxygen evolution reaction (OER) plays a critical role in sustainable energy conversion and storage. Herein, we report on the development of efficient (photo)electrocatalysts based on functionalized MnO2 systems. Specifically, β‐MnO2 nanostructures grown by plasma enhanced‐chemical vapor deposition on fluorine‐doped tin oxide (FTO) or Ni foams were decorated with Co3O4 or Fe2O3 nanoparticles by radio frequency sputtering. Upon functionalization, FTO‐supported materials yielded a performance increase with respect to bare MnO2, with current densities at 1.65 V vs. the reversible hydrogen electrode (RHE) up to 3.0 and 3.5 mA/cm2 in the dark and under simulated sunlight, respectively. On the other hand, the use of highly porous and conductive Ni foam substrates enabled to maximize cooperative interfacial effects between catalyst components. The best performing Fe2O3/MnO2 system provided a current density of 17.9 mA/cm2 at 1.65 V vs. RHE, an overpotential as low as 390 mV, and a Tafel slope of 69 mV/decade under dark conditions, comparing favorably with IrO2 and RuO2 benchmarks. Overall, the control of β‐MnO2/substrate interactions and the simultaneous surface property engineering pave the way to an efficient energy generation from abundant natural resources. [ABSTRACT FROM AUTHOR]

NiO-based films and nanostructured materials have received increasing attention for a variety of technological applications. Among the possible strategies for their fabrication, atomic layer deposition (ALD) and chemical vapor deposition (CVD), featuring manifold advantages of technological interest, represent appealing molecule-to-material routes for which a rational precursor design is a critical step. In this context, the present study is focused on the coordination sphere engineering of three heteroleptic Ni(II) β-diketonate–diamine adducts of general formula [NiL2TMEDA] [L = 1,1,1-trifluoro-2,4-pentanedionate (tfa), 2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedionate (fod) or 2,2,6,6-tetramethyl-3,5-heptanedionate (thd), and TMEDA = N,N,N′,N′-tetramethylethylenediamine]. Controlled variations in the diketonate structure are pursued to investigate the influence of steric hindrance and fluorination degree on the chemico-physical characteristics of the compounds. A multi-technique investigation supported by density functional calculations highlights that all complexes are air-insensitive and monomeric and that their thermal properties and fragmentation patterns are directly dependent on functional groups in the diketonate ligands. Preliminary thermal CVD experiments demonstrate the precursors' suitability for the obtainment of NiO films endowed with flat and homogeneous surfaces, paving the way to future implementation for CVD end-uses. [ABSTRACT FROM AUTHOR]

Front Cover: Solar hydrogen production via photoelectrochemical (PEC) water splitting stands as a viable solution to the increasing global energy demand. Herein, a plasmaassisted route to Fe2O3‐Co3O4 photoanodes is proposed that, under optimized conditions, yields a remarkable photocurrent increase and onset potential cathodic shift (40% and 50 mV, respectively, compared to bare Fe2O3). These results disclose attractive perspectives to enhance Fe2O3 photoanode photoefficiency, avoiding more rare and expensive systems. Further details can be found in the article by Giorgio Carraro et al. on page 191. [ABSTRACT FROM AUTHOR]

High purity porous ZnO nanopyramids with controllable properties are grown on their tips on Si(100) substrates by means of a catalyst-free vapor phase deposition route in a wet oxygen reaction environment. The system degree of preferential [001] orientation, as well as nanopyramid size, geometrical shape, and density distribution, can be finely tuned by varying the growth temperature between 300 and 400 °C, whereas higher temperatures lead to more compact systems with a three-dimensional (3D) morphology. A growth mechanism of the obtained ZnO nanostructures based on a self-catalytic vapor-solid (VS) mode is proposed, in order to explain the evolution of nanostructure morphologies as a function of the adopted process conditions. The results obtained by a thorough chemico-physical characterization enable us to get an improved control over the properties of ZnO nanopyramids grown by this technique. Taken together, they are of noticeable importance not only for fundamental research on ZnO nanomaterials with controlled nano-organization but also to tailor ZnO functionalities in view of various potential applications. [ABSTRACT FROM AUTHOR]

In the present work, a two-step vapor-phase route was implemented for the tailored design of ZnO–WO3 nanoheterostructures supported on fluorine-doped tin oxide (FTO) substrates. Under optimized conditions, the sequential use of chemical vapor deposition (CVD) and radio frequency (RF)-sputtering for the deposition of zinc and tungsten oxides respectively, resulted in the growth of calyx-like ZnO nanostructures uniformly decorated by a conformal dispersion of low-sized WO3 nanoparticles. The target materials were characterized by means of a multi-technique approach, with particular regard to their structural, compositional, morphological and optical properties. Finally, their photocatalytic performances were preliminarily tested in the abatement of NOX gases (NO and NO2). Due to the unique porous morphology of the ZnO nanodeposit and the high density of ZnO–WO3 heterojunctions, WO3-decorated ZnO revealed appealing De-NOX characteristics in terms of both degradation efficiency and selectivity. Such features, along with the photoinduced superhydrophilicity and self-cleaning properties of the present nanomaterials, candidate them as promising functional platforms for applications in smart windows and building materials for environmental remediation. [ABSTRACT FROM AUTHOR]

Chemical vapor deposition of Fe2O3 nanomaterials on Si(100) at temperatures between 400 and 550 °C selectively yields β- and ε-Fe2O3 polymorphs under dry oxygen or oxygen and water vapor reaction environments, respectively. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (gCN) is a promising n-type semiconductor widely investigated for photo-assisted water splitting, but less studied for the (photo)electrochemical degradation of aqueous organic pollutants. In these fields, attractive perspectives for advancements are offered by a proper engineering of the material properties, e.g., by depositing gCN onto conductive and porous scaffolds, tailoring its nanoscale morphology, and functionalizing it with suitable cocatalysts. The present study reports on a simple and easily controllable synthesis of gCN flakes on Ni foam substrates by electrophoretic deposition (EPD), and on their eventual decoration with Co-based cocatalysts [CoO, CoFe2O4, cobalt phosphate (CoPi)] via radio frequency (RF)-sputtering or electrodeposition. After examining the influence of processing conditions on the material characteristics, the developed systems are comparatively investigated as (photo)anodes for water splitting and photoelectrocatalysts for the degradation of a recalcitrant water pollutant [potassium hydrogen phthalate (KHP)]. The obtained results highlight that while gCN decoration with Co-based cocatalysts boosts water splitting performances, bare gCN as such is more efficient in KHP abatement, due to the occurrence of a different reaction mechanism. The related insights, provided by a multi-technique characterization, may provide valuable guidelines for the implementation of active nanomaterials in environmental remediation and sustainable solar-to-chemical energy conversion. [ABSTRACT FROM AUTHOR]

The iron(III) β-diketonate Fe(dpm)3 (dpm = 2,2,6,6-tetramethyl-3,5-heptanedionate) is investigated as precursor for the thermally-assisted chemical vapor deposition (CVD) of hematite (α-Fe2O3) nanostructures. To this aim, the compound gas-phase reactivity is first elucidated by in-situ infrared spectroscopy both under N2 and N2 + O2 atmospheres. Subsequently, Fe(dpm)3 is tested in CVD experiments on various substrates, as a function of the growth temperature, to evaluate the precursor applicability in the preparation of diversified hematite-based materials, potentially addressing various technological end-uses. In this study, relevant results concerning the gas-phase behavior of Fe(dpm)3 and the compositional, structural, morphological, and optical properties of the resulting α-Fe2O3 deposits are presented and critically discussed. [ABSTRACT FROM AUTHOR]

Fe 2 O 3 -TiO 2 nanocomposites on activated carbon fibers (ACFs) have been fabricated by a two-step plasma-assisted route, involving the plasma enhanced-chemical vapor deposition (PE-CVD) of iron oxide followed by radio frequency (RF) titanium sputtering for different process durations. A multi-technique characterization of the developed systems has been performed by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission-scanning electron microscopy (FE-SEM), scanning transmission electron microscopy (STEM), and energy dispersive X-ray spectroscopy (EDXS). The adopted approach enabled the successful preparation of high purity composite nanomaterials, with high surface area and characterized by the co-presence of Fe 2 O 3 and TiO 2 in tailored amounts. The homogeneous coverage of ACFs by Fe 2 O 3 -TiO 2 , along with the optimal deposit adhesion to the support, candidate the present Fe 2 O 3 -TiO 2 @ACF nanocomposites as attractive systems for photocatalytic applications. [ABSTRACT FROM AUTHOR]

Fe2O3 nanostructures are fabricated on Si(100) and SiO2 by plasma enhanced (PE)CVD from a FeIII β-diketonate precursor. Depositions are carried out in Ar-O2 plasmas, devoting particular attention to the influence of growth temperature (from 60 to 400 °C) on material chemico-physical properties. Remarkably, high purity, single-phase α-Fe2O3 nanostructures are obtained at temperatures as low as 60 °C. Furthermore, the deposit nano-organization can be tuned from <110>-oriented 2D nanoblade arrays to denser nanocolumns upon increasing the deposition temperature. A possible growth model is proposed to account for the observed structural/morphological features and light absorption properties of the target materials. [ABSTRACT FROM AUTHOR]

A series of Dawson-type heteropolyanions (HPAs) mono-substituted with transitional metal ions ( α2 -[P 2 W 17 O 61 Fe III ] 8− , α2 -[P 2 W 17 O 61 Cu II ] 8− and α2 -[P 2 W 17 O 61 Ni II ] 8− ) have exhibited electrocatalytic properties towards nitrate and nitrite reduction in slightly acidic media (pH 4.5). The immobilization of these HPAs into water-processable films developed via layer-by layer assembly with polymer-stabilized silver nanoparticles led to the fabrication of the electrocatalytic interfaces for both nitrate and nitrite reduction. The LBL assembly as well as the changes in the HPA properties by immobilization has been characterized by electrochemical methods. The effects of the substituent ions, outer layers and the cationic moieties utilized for the films assembly of the developed film on the performances of nitrate electrocatalysis has been elucidated. [ABSTRACT FROM AUTHOR]

Layer-by-layer (LbL) assembly strategies were exploited to decorate wild-type TMV (tobacco mosaic virus) 1D nanoscaffolds with a totally inorganic, multiredox, tetraruthenate complex belonging to the class of polyoxometalate catalysts. The hybrid capsids give rise to an entangled network of fibrils and ribbon-like nanoassemblies, whose functional activity was probed towards H2O2 dismutation in neutral water. Combined solid-state and surface characterization evidence, including Z-potential, electronic microscopy, thermogravimetry and XPS, delineate a favorable tunability of the nanohybrid material as a function of the added cationic binder. [ABSTRACT FROM AUTHOR]

In this work, photothermal beam deflection (PBD) experiments have been used to characterize the thermooptical and transport properties of ε-Fe 2 O 3 -based nanocomposites. In particular, iron(III) nanostructures have been functionalized with Au, Ag and Cu nanoparticles, tailoring both their nano-organization and their chemical state. In order to elucidate the correlation between the thermooptical and transport parameters, the structural, compositional and morphological properties of Fe 2 O 3 -based systems were studied by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). It was observed that the optothermal and transport parameters were influenced by the nature and oxidation state of the nanoparticles, which can serve as a key tool to master the material properties for their application in light-assisted processes. [ABSTRACT FROM AUTHOR]

β-Fe2O3/CuO nanosystems were synthesised by using a two-step plasma-assisted strategy. β-Fe2O3 nanostructures (host) were initially deposited by plasma assisted-chemical vapour deposition (PA-CVD) on indium tin oxide (ITO) substrates. Subsequently, CuO nanoparticles (NPs, guest) were over-deposited on host matrices by means of radio frequency (RF) sputtering under mild conditions. The combined use of structural, morphological and chemical analyses evidenced the formation of pure and homogeneous β-Fe2O3/CuO systems possessing a high dispersion of CuO NPs in/on β-Fe2O3 hosts. The target nanomaterials were characterized by an intimate contact between the two oxides, with CuO NP size and tuneable content as a function of sputtering time. These features, along with the tailored nano-organization, make the present β-Fe2O3/CuO nanosystems attractive candidates for diverse technological applications involving solar light harvesting. [ABSTRACT FROM AUTHOR]

Iron(III) oxide nanosystems are actually the focus of an intensive attention due to their low cost, non-toxicity, ample abundance, and attractive chemico-physical properties. In this work, iron(III) oxide nanomaterials were deposited by chemical vapor deposition (CVD) under O2 atmospheres in the temperature range 500-800 °C, starting from the scarcely investigated tris( tert-butyl acetoacetato)iron(III) precursor. All nanodeposits were found to consist of the α-Fe2O3 ( hematite) polymorph. Surface and in-depth analyses demonstrated the presence of high purity Fe2O3, indicating the occurrence of a clean precursor decomposition under the adopted conditions. Interestingly, the system morphology could be controlled by varying the deposition temperature and ranged from the circular assembly of ordered nanosheets, to rough vortices, up to dense deposits characterized by the copresence of nanosheets and nanocolumns. The unique surface features offer great properties for advanced applications in various technological fields, such as catalysis and photocatalysis, solid state gas sensing, and magnetic recording media. [ABSTRACT FROM AUTHOR]

Abstract: The present work is devoted to the investigation of photoinduced superhydrophilicity (PSH) and photocatalytic oxidation (PCO) activity of quasi-2D zinc oxide nanoplatelets obtained by Chemical Vapor Deposition (CVD). In the case of PCO, the degradation of a fatty compound layer (methyl stearate) was chosen as a test reaction. The peculiar textural and morphological features of such systems resulted in a PSH behavior and in a PCO activity appreciably higher than those of a reference commercial Pilkington® ActivTM Glass. Relevant results are presented and discussed as a function of the structure and morphology of these systems, whose control enables a direct tailoring of the functional response. [Copyright &y& Elsevier]

Abstract: The availability of soft synthetic processes for the preparation of SiO2 films with tailored features plays a key role for several technological applications, from optics to electronics, from surface modifications to barrier coatings. In such context, this work presents the development and optimization of a Plasma Enhanced-Chemical Vapor Deposition route towards high-purity SiO2 films at near room temperature. Depositions were performed from Ar and Ar–O2 plasmas using tetramethoxysilane as precursor, devoting particular attention to the interplay between film properties and process parameters (RF- (Radio Frequency-) power, total pressure, O2/(Ar+O2) ratio and precursor vaporization temperature). Real-time information on the growth process was gained by Laser Reflection Interferometry, while the chemical composition and bonding structure of the obtained layers were analyzed by Fourier Transform Infrared Spectroscopy and X-ray Photoelectron Spectroscopy. Scanning Electron and Atomic Force Microscopies were adopted to analyze the surface and cross-sectional film morphology. The system structural and optical properties were investigated by means of Glancing Incidence X-Ray Diffraction and UV–Vis spectroscopy. Finally, nanoindentation measurements were performed to investigate film hardness. Under optimized conditions, very pure silica films, characterized by a remarkable optical transparency and favorable mechanical properties, were obtained even at RF-power values as low as 5 W and in the absence of O2 in the plasma. [Copyright &y& Elsevier]

Abstract: Two nanostructured bulk LaCoO3 powders were prepared by co-precipitation and with the citrate gel method and compared with the two nanocomposites obtained depositing, by wet impregnation, cobalt oxide on the La2O3 surface. All the prepared samples were characterized by means of X-ray photoelectron (XP) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopic techniques, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal analysis. XRD results suggest that only the citrate gel method allows to obtain a single phase lanthanum cobaltite powder having a rhombohedral perovskite structure. Moreover, SEM images confirm the wide scale homogeneity. In contrast, a lanthanum hydroxide phase (hexagonal) is also evident in the sample obtained by co-precipitation method. In the nanocomposite richer in cobalt, besides the rhombohedral perovskite, the hexagonal lanthanum oxide and hydroxide phases are also detectable. Perovskite phase does not form when the amount of deposited cobalt oxide is too low. Both in the nanostructured sample prepared by citrate gel method and nanocomposite with [Co/La]nominal =1.0 XPS, DRIFT and TGA outcomes suggest a lower presence of hydroxyl groups and carbonates species. The reactivity of the powders with respect to carbon monoxide was studied (at atmospheric pressure, between RT and 573K) by means of the diffuse reflectance infrared Fourier transform spectroscopy. A significant signal around 2058cm−1 testifies about the interaction of CO with the Lewis acidic sites distributed on the surface of all the samples. The two nanostructured bulk LaCoO3 show a high reactivity toward CO oxidation since 423K. A similar oxidation capability is observed also for the nanocomposite richer in cobalt. In contrast, a rather low reactivity is displayed from the nanocomposite with lower Co/La nominal atomic ratio and La2O3. [Copyright &y& Elsevier]

Abstract: A potentiostatic single-pulse technique was employed to prepare silver nanoclusters deposited on glassy carbon (GC) from CH3CN+0.1M LiCO4 plating solutions containing 1–2mM AgClO4. The morphology of the particles, obtained at a constant voltage pulse of variable duration, was examined by scanning electron microscopy. Clusters with particle diameter of 100–400nm, which are uniformly distributed over the GC surface, can be prepared on a time-scale of 30–90s. The Ag clusters exhibit remarkable electrocatalytic activity for the reduction of benzyl chloride. The supported Ag nanoclusters and bulk Ag metal have comparable electrocatalytic activities, both anticipating the reduction potential of PhCH2Cl by ca. 0.5V with respect to bare GC. The Ag-modified electrode was used in preparative scale electrocatalytic reduction of benzyl chloride in different experimental conditions. Good yields of toluene or phenylacetic acid were obtained, depending on experimental conditions, whereas no loss of catalytic activity could be observed, even when the electrode was repeatedly used over a period of several days. [Copyright &y& Elsevier]

Density functional molecular cluster calculations have been used to investigate the interaction of SO2 with defect-free TiO2(110) and Ti2O3(101̄2) surfaces. Adsorbate geometries and chemisorption enthalpies have been computed and discussed. Several local minima have been found for TiO2(110), but only one seems to be relevant for the catalytic conversion of SO2 to S. In agreement with experiment, the bonding of SO2 to Ti2O3(101̄2) is much stronger than that on TiO2(110). Moreover, our results are consistent with the surface oxidation and the formation of strong Ti−O and Ti−S bonds. On both substrates, the bonding is characterized by a two-way electron flow involving a donation from the SO2 HOMO into virtual orbitals of surface Lewis acid sites (), assisted by a back-donation from surface states into the SO2 LUMO. However, the localization of surface states and the strength of back-donation are very different on the two surfaces. On TiO2(110), back-donation is weaker, and it involves unsaturated bridging O atoms, while on Ti2O3(101̄2), it implies the -based valence band maximum and significantly weakens the S−O bond. [ABSTRACT FROM AUTHOR]

Co3O4 thin films and nanosystems are implemented in a broad range of functional systems, including gas sensors, (photo)catalysts, and electrochemical devices for energy applications. In this regard, chemical vapor deposition (CVD) is a promising route for the fabrication of high-quality films in which the precursor choice plays a key role in the process development. In this work, a heteroleptic cobalt complex bearing fluorinated diketonate ligands along with a diamine moiety [Co(tfa)2·TMEDA; tfa = 1,1,1-trifluoro-2,4-pentanedionate and TMEDA = N,N,N′,N′-tetramethylethylenediamine] is investigated as a potential Co molecular precursor for the CVD of Co3O4 systems. For the first time, the compound is characterized by crystal structure determination and comprehensive analytical studies, focusing also on its thermal properties and fragmentation patterns, important figures of merit for a CVD precursor. The outcomes of this investigation, accompanied by detailed theoretical studies, highlight its very favorable properties for CVD applications. In fact, growth experiments under oxygen atmospheres containing water vapor revealed the suitability of Co(tfa)2·TMEDA for the fabrication of high-quality, phase-pure Co3O4 thin films. The versatility of the proposed strategy in tailoring Co3O4 structural/morphological features highlights its potential to obtain multi-functional films with controllable properties for a variety of eventual technological end-uses. [ABSTRACT FROM AUTHOR]

• Quasi-1D MnO 2 nanocomposites are fabricated via a two-step plasma-assisted approach. • The developed systems are applied as gas sensors for hazardous gas detection. • MnO 2 decoration yields promising sensor responses, detection limits and selectivity. • p – n and n – n junctions modulate the resulting functional performances.. Quasi-1D MnO 2 nanocomposite materials (A/MnO 2 with A = CuO, SnO 2) were developed by a two-step plasma-assisted process, involving the plasma enhanced-chemical vapor deposition (PE-CVD) of MnO 2 nanomaterials and their functionalization with copper or tin oxides by radio frequency (RF)-sputtering. A thorough characterization by means of specific surface analytical techniques highlighted the formation of high purity nanocomposites, endowed with a controlled morphology and a tailored spatial dispersion of the functionalizing agents. The target materials were tested as gas sensors for the recognition of hazardous gases [H 2 and di(propyleneglycol) monomethyl ether (DPGME) / dimethyl methyl phosphonate (DMMP), the latter used as simulants for chemical warfare agents]. Functional data evidenced the obtainment of low detection limits and promising gas responses, whose improvement with respect to the pristine MnO 2 was traced back to the formation of built-in p - n and n - n junctions for CuO/MnO 2 and SnO 2 /MnO 2 systems, respectively. The possibility of discriminating between the target analytes depending on the functionalizing species already at moderate working temperatures demonstrates the potential of the developed materials for eventual gas sensing applications under real-world conditions. [ABSTRACT FROM AUTHOR]

Among oxide semiconductors, p-type Mn3O4 systems have been exploited in chemo-resistive sensors for various analytes, but their use in the detection of H2, an important, though flammable, energy vector, has been scarcely investigated. Herein, we report for the first time on the plasma assisted-chemical vapor deposition (PA-CVD) of Mn3O4 nanomaterials, and on their on-top functionalization with Ag and SnO2 by radio frequency (RF)-sputtering, followed by air annealing. The obtained Mn3O4-Ag and Mn3O4-SnO2 nanocomposites were characterized by the occurrence of phase-pure tetragonal α-Mn3O4 (hausmannite) and a controlled Ag and SnO2 dispersion. The system functional properties were tested towards H2 sensing, yielding detection limits of 18 and 11 ppm for Mn3O4-Ag and Mn3O4-SnO2 specimens, three orders of magnitude lower than the H2 explosion threshold. These performances were accompanied by responses up to 25% to 500 ppm H2 at 200 °C, superior to bare Mn3O4, and good selectivity against CH4 and CO2 as potential interferents. A rationale for the observed behavior, based upon the concurrence of built-in Schottky (Mn3O4/Ag) and p-n junctions (Mn3O4/SnO2), and of a direct chemical interplay between the system components, is proposed to discuss the observed activity enhancement, which paves the way to the development of gas monitoring equipments for safety end-uses. [ABSTRACT FROM AUTHOR]

A series of multilayer electrode assemblies have been fabricated through the layer by layer (LBL) technique composed of the water soluble Cu-phthalocyanine (Alcian Blue 8GX) cationic species and a range of Dawson type polyoxometalates (POMs) on glassy carbon electrodes in pH 7.0. Electrochemistry for both the cationic phthalocyanine and the incorporated POMs is clearly visible. The layers were characterized by cyclic voltammetry, AC impedance, X-ray photoelectron spectroscopy (XPS), Field Emission-Scanning Electron Microscopy (FE-SEM) and Atomic Force Microscopy (AFM). The layers were found to electrocatalytically reduce phosphate at pH 7. • Multilayer assemblies of Polyoxometalates and Cu-Phthalocyanine. • Electrocatalysis of Phosphate. • Surface analysis of Modified electrodes. • Electrochemical Impedance spectroscopy analysis of modified electrodes. • Cu-Phthalocyanine as a conducting material. [ABSTRACT FROM AUTHOR]

Wells-Dawson type polyoxometalate (POM) [(n- C 3 H 7) 4 N] 4 S 2 W 18 O 62 (S 2 W 18) was successfully immobilised with a conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), by chronocoulometry technique. The immobilised films with different surface thicknesses were characterised by various electrochemical techniques. The S 2 W 18 -doped PEDOT film gave four couples of redox waves, the first one corresponds to the redox process of the polymer itself and the other three couples are electron transfer at tungstate in the framework. The films exhibited inherent pH-dependent redox activity and stability of S 2 W 18 in the thin layer up to 100 mV/s. Only slight changes were observed in the magnitude of peak currents after continuous redox cycling, indicating the relative stability of the S 2 W 18 in the conducting PEDOT. The conductive behaviour of the film was investigated with electrochemical impedance spectroscopy. The study of electrochemical bromate ion sensing based on S 2 W 18 -doped PEDOT film employing chronoamperometric technique revealed that at an applied potential of -0.1 V, the S 2 W 18 -doped PEDOT film can detect bromate at concentrations between 100 μmol L−1 and 2000 μmol L−1. Moreover, the S 2 W 18 -doped PEDOT film shows a detection limit of 4 μmol L−1 without interference from other common ions present in the water. Hybrid films exhibit significant catalytic activity with high selectivity at a low reduction potential of -0.1 V. Chemico-physical characterization of the target systems was performed using atomic force microscopy, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Novel organic‐inorganic polyoxometalates (POMs) decorated with covalent fluorescent tags have been designed for cell internalization. Their localization within model HEK cells is readily accomplished by confocal fluorescence microscopy. While cell internalization is dictated by the formation of the amphiphilic POM‐based nanostructures, their cytoplasmic‐nuclear trafficking appears to be regulated by a subtle interplay of the organic‐inorganic domains of the nanoassemblies which, in turn, impacts their dynamic behavior and capability to interact with cell membranes. Polyoxometalates with appended fluorescent tags form nanoparticles that can internalize into cells, with a localization depending on their composition. [ABSTRACT FROM AUTHOR]

Multilayer assemblies composed of the crown type polyoxometalate, Ni 4 [(P 8 W 48 O 148 )(WO 2 )] 28− , and silver nanoparticles, have been immobilised onto glassy carbon electrode surfaces through the layer-by-layer (LBL) technique. The resulting thin films have been characterised by electrochemical and surface based techniques with the multilayers showing electrocatalytic ability towards the reduction of chlorate in solution. The layers exhibited redox activity for both the POM and silver nanoparticle moieties with the layers showing good stability towards redox cycling and thin layer behaviour. The layers were found to be highly conductive due to the presence of the nanoparticles as shown by AC impedance and resulting charge transfer resistance values (Rct) obtained for the layers. A clear and significant catalytic ability of Ni 4 [(P 8 W 48 O 148 )(WO 2 )] 28 /AgNP's assembly towards the chlorate reduction was observed with a measured sensitivity of 32.3mAcm −2 /(μM). [ABSTRACT FROM AUTHOR]

[Display omitted] • Graphitic carbon nitride (g-C 3 N 4) is deposited by decantation and functionalized with CoO and CoFe 2 O 4 co-catalysts. • Pure g-C 3 N 4 -based composite systems, featuring an intimate contact with CoO and CoFe 2 O 4 nanoparticles, are obtained. • The construction of p - n g-C 3 N 4 -CoO and Z -scheme g-C 3 N 4 -CoFe 2 O 4 junctions is effective in enhancing oxygen evolution performances. • The present results pave the way to the implementation of stable, cheap and active anodes for solar water splitting. The ever-increasing energy demand from the world population has made the intensive use of fossil fuels an overarching threat to global environment and human health. An appealing alternative is offered by sunlight-assisted photoelectrochemical water splitting to yield carbon-free hydrogen fuel, but kinetic limitations associated to the oxygen evolution reaction (OER) render the development of cost-effective, eco-friendly and stable electrocatalysts an imperative issue. In the present work, OER catalysts based on graphitic carbon nitride (g-C 3 N 4) were deposited on conducting glass substrates by a simple decantation procedure, followed by functionalization with low amounts of nanostructured CoO and CoFe 2 O 4 by radio frequency (RF)-sputtering, and final annealing under inert atmosphere. A combination of advanced characterization tools was used to investigate the interplay between material features and electrochemical performances. The obtained results highlighted the formation of a p - n junction for the g-C 3 N 4 -CoO system, whereas a Z -scheme junction accounted for the remarkable performance enhancement yielded by g-C 3 N 4 -CoFe 2 O 4. The intimate contact between the system components also afforded an improved electrocatalyst stability in comparison to various bare and functionalized g-C 3 N 4 -based systems. These findings emphasize the importance of tailoring g-C 3 N 4 chemico-physical properties through the dispersion of complementary catalysts to fully exploit its applicative potential. [ABSTRACT FROM AUTHOR]

A facile two-step vapor phase synthetic approach is proposed for the fabrication of Mn3O4 thin films chemically modified with fluorine, and eventually functionalized with silver or titania. The adopted strategy exploits the initial chemical vapor deposition (CVD) of Mn3O4 on Si(100) substrates starting from a diamine diketonate Mn(ii) complex, followed by the controlled radio frequency (RF)-sputtering of silver or titania. Complementary analytical techniques were employed to investigate the crystallinity (X-ray diffraction), chemical composition (X-ray photoelectron spectroscopy, secondary ion mass spectrometry, energy dispersive X-ray spectroscopy), morphology and nano-organization (field emission-scanning electron microscopy, atomic force microscopy, transmission electron microscopy) of both pristine and functionalized manganese oxide thin films. Under the adopted operating conditions, the target Mn(ii) complex acted as a single-source precursor for both Mn and F, leading to the formation of phase-pure hausmannite Mn3O4 films characterized by a uniform in-depth fluorine content. In addition, the obtained results gave evidence of the formation of high purity Ag/F:Mn3O4 and TiO2/F:Mn3O4 composites with a close contact between the single constituents. This work outlines an amenable and efficient method for the vapor phase growth of composite Mn3O4-based thin films, which are favorable candidates for diverse technological applications, from photocatalysis to gas sensing. [ABSTRACT FROM AUTHOR]

Indium tin oxide (ITO) substrates were functionalized with fluoroalkylsilanes (FAS) having formula R F C(O)N(R)(CH 2 ) 3 Si(OMe) 3 ( 1 , R = H, R F  = C 5 F 11 ; 2 , R = CH 3 , R F  = C 5 F 11; 3 , R = H, R F  = C 3 F 7 ) and containing embedded amide moieties between the perfluoroalkyl chain and the syloxanic moiety. Subsequently, Au nanoparticle deposition (AuNP) onto the ITO-FAS functionalized surfaces was carried out by immersion into a solution of citrate-stabilized AuNP. The ITO-FAS and AuNP/ITO-FAS modified systems were characterized by various complementary techniques and compared with AuNP/ITO modified with R F (CH 2 ) 2 Si(OEt) 3 ( 4 , R F  = C 6 F 13 ), free from functional groups between the fluorinated tail and the syloxanic moiety. The results showed that only ITO glasses modified with 1 , 2 and 3 displayed an oleophobic, as well as hydrophobic, behaviour and that the AuNP Surface Coverage (SC %) directly depended on the fluoroalkylsilane nature with the following trend: 60% ITO-2  > 16% ITO-3  > 9% ITO-1  > 3% ITO-4 . The obtained results revealed that, in organosilane 2 , the presence of a methyl group on the amide nitrogen increases the steric hindrance in the rotation around the N CO bond, resulting in the co-presence of two stable conformers in comparable amounts. Their co-presence in solution, combined with the lack of intermolecular N H⋯OC N hydrogen bonds among the anchored molecules, has dramatic influences on the functionalized ITO, yielding a disorderedly packed coating able to accommodate a large quantity of AuNP. These results indicate that AuNP can act as excellent probes to evaluate the coating layer quality but, at the same time, it is possible to tune the gold loading on electroactive surfaces depending on the chemical structure of the used fluorinated silane. [ABSTRACT FROM AUTHOR]

Photoreforming promoted by metal oxide nanophotocatalysts is an attractive route for clean and sustainable hydrogen generation. In the present work, we propose for the first time the use of supported Mn3O4 nanosystems, both pure and functionalized with Au nanoparticles (NPs), for hydrogen generation by photoreforming. The target oxide systems, prepared by chemical vapor deposition (CVD) and decorated with gold NPs by radio frequency (RF) sputtering, were subjected to a thorough chemico-physical characterization and utilized for a proof-of-concept H2 generation in aqueous ethanolic solutions under simulated solar illumination. Pure Mn3O4 nanosystems yielded a constant hydrogen production rate of 10 mmol h–1 m–2 even for irradiation times up to 20 h. The introduction of Au NPs yielded a significant enhancement in photocatalytic activity, which decreased as a function of irradiation time. The main phenomena causing the Au-containing photocatalyst deactivation have been investigated by morphological and compositional analysis, providing important insights for the design of Mn3O4-based photocatalysts with improved performances. [ABSTRACT FROM AUTHOR]

• Ability to surface immobilise a Mn(II) polyoxometalate (POM) onto a carbon electrode surface. • Successful employment of a conducting polymer PEDOT for Mn POM immobilisation. • Ability to redox switch incorporated POM within PEDOT film. • Surface characterisation of film completed with morphology identified. A MnIII-substituted Wells-Dawson-type polyoxoanion, [MnIII 4 (H 2 O) 2 (P 2 W 15 O 56) 2 ]12− (Mn 4 (P 2 W 15) 2), was surface immobilised within the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) on a glassy carbon electrode (GCE) surface. The resulting immobilised films were characterised by electrochemical techniques and subjected to a compositional and morphological characterization by means of X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM). The redox activity of the entrapped Mn 4 (P 2 W 15) 2 was observed within the polymer phase. The conducting polymer films exhibited a pH-dependant redox activity associated with the polyanion Mn 4 (P 2 W 15) 2 and thin layer behaviour up to 100 mVs−1 with enhanced stability towards redox cycling. [ABSTRACT FROM AUTHOR]

Fluorophilic polyoxotungstates perform the selective epoxidations of internal and terminal double bonds by hydrogen peroxide (H2O2) activation in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), under mild temperature conditions. A hybrid synergy of supramolecular interactions, involving the inorganic cluster and the fluorinated solvent, is envisaged to boost H2O2 activation and the oxygen transfer mechanism. 1,2-Epoxides have been obtained with ＞99% selectivity and 98% yield at T = 40–70 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] • Graphitic carbon nitride (g-CN) is developed via electrophoresis and functionalized with Ag and Au by sputtering. • Pure g-CN-based composites containing atomically dispersed (Ag), low-sized (Au) or alloyed nanoparticles (Au + Ag), are obtained. • The higher performances produced by Au nanoparticle introduction depends on Schottky junctions and surface plasmon resonance (SPR). • The reported results open the door to improved photocatalysts for carbon–neutral energy production. The strategic interest in the production of green hydrogen by sunlight-activated water splitting has stimulated significant efforts aimed at the implementation of active and cost-effective catalysts for the oxygen evolution reaction (OER), the overall process bottleneck. Herein, we report on an original fabrication route to OER electrocatalysts based on graphitic carbon nitride. In particular, the target systems were deposited on conductive glass substrates via a simple electrophoretic technique and functionalized with highly dispersed noble metals (Au, Ag or Au + Ag) in low amounts by radio frequency (RF)-sputtering under mild conditions. An advanced material characterization revealed the possibility of tailoring carbon nitride morphology as a function of the used precursor and of achieving a homogeneous spatial distribution of the functionalizing metals. The latter ranged from atomically dispersed (silver), to low-sized nanoaggregates (gold) or partially alloyed core–shell nanoparticles (gold+silver), with an intimate metal-nitride interfacial contact. Functional tests evidenced a remarkable sensitivity to Vis light even at low applied potentials, and photoelectrocatalytic performances directly dependent on the nature of metal species and on the features of the underlying carbon nitride deposit. These evidences, rationalized mainly on the basis of Schottky junctions and the possible concurrence of surface plasmon resonance (SPR), candidate the proposed strategy as a versatile route to cheap and efficient OER electrocatalysts for energy conversion. [ABSTRACT FROM AUTHOR]

Metal/organosilane/oxide sandwich structures were prepared via a two-step self-assembly method. First, indium tin oxide (ITO) substrates were functionalized with the following fluoroalkylsilanes (FAS): R F C(O)N(H)(CH 2 ) 3 Si(OMe) 3 ( 1 , R F = C 5 F 11 ), containing an embedded amide between the perfluoroalkyl chain and the syloxanic moiety, and R F (CH 2 ) 2 Si(OEt) 3 ( 2 , R F = C 6 F 13 ). Subsequently, Au nanoparticles (Au NPs ) introduction in the obtained systems was carried out by controlled immersion into a solution of citrate-stabilized Au NPs . The physico-chemical properties of the target materials were thoroughly investigated by using various complementary techniques. Finally, the application of such systems as catalysts for methanol electro-oxidation under alkaline conditions was investigated, revealing the synergistical role played by FAS and Au NPs in promoting a remarkable electrocatalytic activity. [ABSTRACT FROM AUTHOR]