The integration of perovskite oxides on silicon remains a technological bottleneck, particularly for the growth of thin SrTiO3 (STO) films used as buffer or template layers for epitaxy. While Atomic Layer Deposition (ALD) offers scalability and conformality, achieving crystalline STO on silicon is hindered by low-temperature constraints and silicon diffusion during post-deposition annealing. This study explores STO growth via Direct Liquid InjectionALD using Titanium Tetra-IsoPropoxide [Ti(O-iPr)4] and Strontium bis(2,2,6,6-tetramethyl-3,5heptanedionate) (Sr(thd)2), with engineered buffer layers to enhance crystallization and suppress interdiffusion. We first investigate cationic stoichiometry control by adjusting the number of TiO2 and Sr-O sub-cycles. Scanning Transmission Electron Microscopy analysis confirms STO layer formation but reveals silicon diffusion that impedes crystallization. To address this, we introduce 10 nm-thick binary oxide layers (TiO2 and Sr-O) and [Ca2Nb3O10]- nanosheets (NNS) as diffusion barriers. A crystallized TiO2 layer further improves STO structural quality, while NNS promote [001]-oriented STO growth on silicon. These results demonstrate a viable route for large-area crystalline STO deposition on silicon, with implications for the integration of functional oxides requiring controlled orientation and crystallinity. The STO/NNS platform offers a scalable template for subsequent oxide growth, paving the way for multifunctional oxide electronics on silicon and other technologically relevant substrates.

The development of technologies for CO2 sequestration and its conversion into value-added chemicals has received considerable and growing attention. However, achieving high conversion efficiency and product selectivity under mild conditions remains a major challenge. This study investigates the photocatalytic CO2 reduction activity of Zr-based porphyrinic MOF-545 derivatives synthesized by varying the percentages of two porphyrin linkers: tetrakis(4-carboxyphenyl)porphyrin (TCPP) and its β-pyrrolic chlorinated analogue (TCPPCl8). A comprehensive set of spectroscopic and analytical techniques was employed to characterize the materials, revealing the impact of linker chlorination on the optical band gap, particle size and crystallinity. The incorporation of chlorine-substituted linkers significantly enhanced the photocatalytic activity. Notably, under visible light irradiation and using triethanolamine (TEOA) as a sacrificial electron donor, the MOF-545 derivative containing 50% TCPPCl8 achieved the highest formate production, with a rate 2.6 times greater than that of pristine MOF-545, with a production rate of 625 μmol g-1 h-1 after 2 h. Density Functional Theory (DFT) calculations were also performed to gain insight into the electronic properties of the chlorinated porphyrinic materials. These calculations showed the stabilization of both the HOMO and LUMO energy levels upon chlorination of the porphyrin linkers, with a more pronounced stabilisation of the LUMO, leading to a smaller band gap, in line with optical measurements. Additionally, the stabilisation of the HOMO level is expected to increase the oxidizing power of the photogenerated holes, thus facilitating TEOA oxidation and enhancing the overall photocatalytic activity, and this rationalizes the experimental observations.

A novel approach for the surface-initiated atom transfer radical polymerization (SI-ATRP) of methoxyethyl methacrylate (MEMA) and 3-azidopropyl methacrylate (AZMA) on macroporous silicon substrates and their postfunctionalization by click chemistry with asymmetric catalysts is presented. Crystalline silicon was first used to monitor the multistep functionalization by quantitative IR-ATR spectroscopy. The attachment of an alkynyl FTIR marker on crystalline silicon demonstrated the effectiveness of the methodology, which was then applied onto macroporous silicon to anchor an enantiopure chromium-salen complex as a first step toward the development of new supported asymmetric organometallic catalysts on silicon-based materials. SEM and EDS measurements clearly show good homogeneity of the polymer growth through the porous layers with a uniform distribution of the catalysts (even deep inside the pores). The successful functionalization of macroporous silicon has confirmed the transferability of the technique to porous materials, highlighting its potential for application to even larger surface area substrates in future catalytic studies.

We observe defect formation at the metal halide perovskite (MHP)/ALD-NiO x interface, as revealed by HAXPES. Introduction of an organic buffer layer minimizes these defects, leading to improved device performance.

Nickel oxide (NiOx) is widely utilized as an inorganic hole transport layer (HTL) in inverted metal halide perovskite (MHP) solar cells due to its high bandgap, transparency, stability, and scalability. However, its high surface reactivity and the presence of interfacial defects at the NiOx/MHP interface negatively impact the device performance. To address these issues, the community has explored ultraviolet ozone (UVO) post-treatment of NiOx and the use of organic molecules for surface passivation. Nevertheless, the individual effects of these processes and their influence on the bulk and surface characteristics of NiOx, as well as the NiOx/MHP interface, have not been thoroughly investigated and understood. This study based on photoemission analyses reveals that the UVO process increases the NiOx reactivity and introduces defects. We identify the nature of defect states at the interface of pristine and UVO-treated NiOx with MHP and demonstrate that the implementation of MeO-2PACz (M2P) as an organic interlayer mitigates this issue. Additionally, we find that neither UVO treatment nor M2P molecule anchoring significantly impacts the bulk properties of NiOx.

Designing heterogeneous catalysts that ensure efficient recycling and reuse of the catalyst in a wide range of transformations remains a real challenge. In this contribution, targeted copolymers are used as supports for the development of heterogeneous asymmetric catalysts. They are made up of two methacrylate monomers, 3‐azidopropylmethacrylate (AZMA), and 2‐methoxyethyl methacrylate (MEMA) used as a diluting agent. Polymerization was carried out using Cu(0)‐mediated reversible deactivation radical polymerization (RDRP), yielding two copolymers with controlled MEMA/AZMA compositions of 70/30 and 30/70 with moderate dispersity control (Ð = 1.32‐1.54), targeting polymers with a similar molar mass, which is important to achieve precise control of the catalyst loading to implement asymmetric catalysis. The copolymers were post‐functionalized using click chemistry with two salen complexes containing a chromium or a cobalt center, these species being recognized for their broad range of applications. The supported catalysts were evaluated in two reactions and recovered by precipitation and filtration techniques. The first reaction involved the asymmetric ring opening (ARO) of cyclohexene oxide with trimethylsilylazide, catalyzed by the chromium sites, the second reaction was the dynamic kinetic resolution (DKR) of epibromohydrin with water, promoted by the cobalt sites. The recycling was effective, demonstrating the robustness and viability of the procedure.

Interface science is at the forefront of advanced materials design, particularly in catalysis, where surface properties critically determine performance. Among emerging techniques, ion beam irradiation has shown strong potential for modifying the catalytic behavior of solid materials by introducing surface and sub-surface defects. In this study, the effect of nitrogen ion irradiation on the catalytic and redox properties of a ceria-zirconia-based oxidation catalyst (Ce0.68Zr0.32O2), both in its unmodified form and when combined with supported Pt nano-particles, was systematically investigated through a series of catalytic tests (TPO/TPR), operando FTIR, HRTEM, and XPS analyses. Ion bombardment was found to induce significant modifications to nanoparticle distribution, surface morphology, and defect structure-most notably the formation of oxygen vacancies and enhanced oxygen mobility. These changes resulted in improved catalytic performance for the oxidation of light alkanes and CO, with consistent reductions in To0 values and a notable increase in aging resistance. The enhanced reducibility observed, particularly in Pt-containing systems, suggests a strong impact at the metal/support interface. Overall, this work highlights post-synthesis ion irradiation as an effective tool for activating and stabilizing redox catalysts, providing new opportunities for designing durable materials for environmental and energy applications.

With the rapidly advancing perovskite solar cell (PSC) technology, dedicated interface engineering is critical for improving device stability. Atomic layer deposition (ALD) grown metal oxide films have drawn immense attention for the fabrication of stable PSC. Despite the advantages of ALD, the deposition of metal oxides directly on bare perovskite has so far not been achieved without damaging the perovskite layer underneath. In addition, the changes to the physicochemical and electronic properties at the perovskite interface upon exposure to the ALD precursors can alter the material and hence device functionality. Herein, we report on a synchrotron-based hard X-ray photoelectron spectroscopy (HAXPES) investigation of the interface between metal halide perovskite (MHP) absorber and ALD-SnO2 electron transport layer. We found clear evidence for the formation of new chemical species (nitrogen compound, lead dihalides) and an upward band bending in the MHP and downward band bending in the SnO2 towards the MHP/ALD-SnO2 interface. The upward bending at the interface forms an electron barrier layer of ~400meV, which is detrimental to the PSC performance. In addition, we assess the effectiveness of introducing a thin interlayer of the organic electron transport material Phenyl-C61-butyric acid methyl ester (PCBM) between MHP and ALD-SnO2 to mitigate the effects of ALD deposition.

Nanodiamonds (ND) exhibit exceptional chemical, electronic, thermal, and optical properties, making them valuable for applications in nanomedicine, energy, quantum technologies, advanced lubricants, and polymer composites. Surface analysis techniques such as X-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS) and reflection electron energy loss spectroscopy (REELS) are critical for understanding the surface properties of nanomaterials, including nanodiamonds. This study investigates hydrogenated milled nanodiamonds (H-MND) by integrating UPS and XPS measurements with REELS. Through in situ annealing within an ultra-high vacuum (UHV) chamber, we examine the impact of surface termination on surface conductivity, focusing on the role of adsorbates. Our findings reveal that a surface transfer doping mechanism, akin to that observed in bulk diamond, governs a pseudo p-type conductivity in H-MND. The conductivity dependence on ambient exposure, water, and subsequent annealing demonstrates its reversibility. The study also discusses the nature of electron acceptors and the influence of ND facets on conductivity.

Surfaces of InP substrates with different crystallographic orientations are investigated when facing HCl solutions. The immersion of InP(100) in HCl solutions with a wide concentrations range showed that the frontier between deoxidation and dissolution is around 6 m, with a morphological destructuration. However, no chemical evolutions are noticed even at high concentrations. Similar observations were performed with other crystallographic orientations (polycrystalline and InP(111) substrates), with topographic surface modifications but no chemical ones.

In the search of low cost and more efficient electronic devices, here the properties of SrVO3 transparent conductor oxide (TCO) thin film are investigated, both visible-range optically transparent and highly conductive, it stands as a promising candidate to substitute the standard indium-tin-oxide (ITO) in applications. Its surface stability under water (both liquid and vapor) and other gaseous atmospheres is especially addressed. Through the use of spectroscopy characterizations, X-ray photoemission and operando X-ray absorption measurements, the formation of a thin Sr-rich V5+ layer located at the surface of the polycrystalline SrVO3 film with aging is observed, and for the first time how it can be removed from the surface by solvating in water atmosphere. The surface recovery is associated to an etching process, here spectroscopically characterized in operando conditions, allowing to follow the stoichiometric modification under reaction. Once exposed in oxygen atmosphere, the Sr-rich V5+ layer forms again. The findings improve the understanding of aging effects in perovskite oxides, allowing for the development of functionalized films in which it is possible to control or to avoid an insulating surface layer. This constitutes an important step towards the large-scale use of V-based TCOs, with possible implementations in oxide-based electronics.

TiO2 ultrathin films are required in many material research areas. The anatase phase was found to be more stable in case of atomic layer deposition growth, nevertheless a critical thickness of around 10 nm appears necessary to obtain crystallization on native silicon oxide on Si (001). This work focuses on direct liquid injection Atomic Layer Deposition (ALD) of TiO2 films with thicknesses about some nanometers, using titanium tetra-isopropoxide as precursor and H2O as oxidant. A particular care to the treatment of ellipsometric measurements is employed. Below the threshold value, films remain amorphous unless the growth starts onto a crystalized surface, a thick TiO2 layer in our case. Here we propose and show the efficiency of 2-dimensional (2D) [Ca2Nb3O10]- and [Ti0.865O2]0.54-nanosheets as seeds at the surface for the crystallization and epitaxy of ultra-thin films of TiO2 below the critical thickness. Furthermore, we show that the structure of the 2D nanosheets determines the growth orientation of the epitaxial anatase, namely (010) for [Ti0.865O2]0.54-, and (100) for [Ca2Nb3O10]-. These results, based on the tailoring of crystal anisotropy via adapted 2D seed nanosheets and low temperature ALD, opens the way for opto-electronics applications of titanium oxide layers of a few unit cells.

Alkali metal doping and grain boundaries (GB) have been at the center of attention within the Cu(In,Ga)(S,Se) 2 photovoltaics community for years. This study provides the first experimental evidence that the GB of sodium‐doped CuInSe 2 thin films may undertake reversible oxidation even at room temperature, whereas undoped films may not. The findings are corroborated by cathodoluminescence imaging, secondary ion mass spectrometry, and Kelvin probe force microscopy on air‐exposed films subsequently subject to vacuum. A thermochemical assessment identifies the likely solid–gas equilibria involved. These reactions open new research questions with respect to the beneficial role played by alkali metal dopants in chalcopyrite solar cells and may steer the community toward new breakthroughs.

A trend in the synthesis of Boron Doped Diamond (BDD) materials resides in increasing surface areas to exalt reactivity at the BDD/electrolyte interface. This can be achieved either by surface structuration of BDD films or conformal growth on 3D substrates. Another strategy considers isolated BDD particles, mainly obtained by milling of BDD layers that can be further deposited on surfaces or embedded in a conductive matrix. Here, we propose an alternative method to obtain boron doped diamond particles using a core-shell approach, which consists in growing diamond coatings on spherical silica templates seeded with nanodiamonds. We investigated the effects of the nature and the density of diamond seeds as well as growth parameters on the crystalline quality of the coatings. The microstructure and the boron incorporation in the diamond shell was investigated by combining Scanning Electron Microscopy (SEM), UV Raman and X-ray Photoemission Spectroscopy (XPS) investigations. Such characterizations were compared to Scanning TEM (STEM) imaging, Energy Dispersive Spectroscopy (EDS) and Electron energy loss spectroscopy (EELS) performed on thin cross-sections of core shells prepared by focused ion beam (FIB) milling.

Due to its high purity (99.9995%) liquid ammonia (NH3 liq.) has found a distinguished place in electrochemical studies of III-V semiconductors (III-Vsc) at low temperature (-55°C and atmospheric preasure). NH3 liq. provides interfacial electrochemistry in an original environment strongly different from the aqueous medium. However, in both solvents, the concepts of interfacial electrochemistry are the same onto III-Vsc. The contribution of NH3 liq. is significant in the understanding of fundamental electrochemical reactions such as hydrogen evolution and oxygen photo-reduction mechanism on III-Vsc (InP and GaAs). The aim of this article is to describe why NH3 liq. is a powerful solvent to understand charge transfer mechanisms at the interface III-Vsc/electrolyte.