Organic-inorganic interactions are at the basis of relevant applications, ranging from biocompatibility and nano(bio)technology to antifouling and hygiene issues. A fundamental understanding of the processes occurring at the interface between molecules of biological interest and inorganic surfaces is a key issue to optimize performance in this field. In the present paper, we report on the self-assembly and thermal evolution of the amino acid (l)-cysteine sublimated on Ag(110) under ultrahigh vacuum conditions. The morphology of the layer is investigated by scanning tunneling microscopy, and the chemistry of the system is determined by X-ray photoemission spectroscopy. The molecules adsorb on the surface at RT in the zwitterionic form, binding to the surface via dehydrogenation of the thiol group and, in part, of the carboxylate. When annealing the surface, they convert into the anionic form, and the morphology of the layer changes, indicating the presence of several local minima in the energy diagram of the Cys/Ag(110) system. Based on experimental evidence, empirical models of some self-assembled structures are proposed.

The electrochemical CO2 reduction reaction (CO2RR) on a Cu-based catalyst has garnered significant attention, primarily due to the ability of copper to produce multi-carbon products. Here, in situ soft X-ray absorption spectroscopy (XAS) characterization is employed to investigate the dynamics of a copper-based catalyst during CO2RR, probing for the first time the impact of the Nafion commonly applied as a proton-conductive binder to ensure mechanical integrity and minimize nanoparticles detachment, on the initial oxidation state of the Cu-catalyst. The results show that Nafion alters the chemical environment of pristine Cu catalyst, leading to the formation of Cu2+ species, likely through partial dissolution induced by the acidic nature of the ionomer, followed by coordination of the dissolved copper species with the sulfonic groups of Nafion. These results are corroborated with ex situ Cu K-edge measurements. The Faradaic efficiency measurements reveal product selectivity differences when Nafion is added by spin-coating or drop-casting: while both approaches favor HCOOH as the primary product, spin-coating enhances CO formation and facilitates ethylene generation. These findings underscore the dual role of Nafion as both a structural binder and an active modifier of first-stage catalytic behavior, demonstrating the importance of in situ XAS for elucidating the catalyst-binder interactions during CO2RR.

The corrosion behavior of metallic copper (Cu) was investigated in the presence and absence of corrosion inhibitors in 33.33 vol.% ethylene glycol and propylene glycol heat transfer solutions under aerated conditions at 75 degrees C. Dipotassium hydrogen phosphate and potassium dichromate were evaluated as inorganic corrosion inhibitors, while benzotriazole, tolyltriazole, indazole and benzimidazole were studied as representative organic corrosion inhibitors using gravimetric and electrochemical techniques. Motivated by increasing regulatory constraints on conventional inhibitors, this work aims to establish robust and efficient screening methodologies for identifying sustainable alternatives that provide comparable or enhanced corrosion protection. Weight-loss measurements, time-resolved electrochemical polarization and impedance techniques, and complementary physicochemical analyses were integrated to elucidate corrosion and inhibition mechanisms in glycol-based systems. Comparative analysis of 112 h medium-term and 336 h long-term gravimetric data with 24 h short-term electrochemical results was conducted to bridge the gap between these approaches. Notable discrepancies between gravimetric and electrochemical outcomes were observed, highlighting the need for careful interpretation of short-term electrochemical metrics when assessing long-term inhibitor performance.

Hydrophobic gold nanoparticles (AuNPs) covalently functionalized with organometallic platinum-containing oligomers (Pt-DEBP n , DEBP = 4,4 '-diethynylbiphenyl) with different chain lengths were synthesized and incorporated into a poly(3-hexylthiophene-2,5-diyl) (P3HT) matrix to obtain inorganic/organic AuNPs/P3HT blends with tuned optoelectronic properties. The Pt-DEBP n (n = 3, 4, 6) chain length was modulated by carefully controlling reaction conditions in a catalyst-free polycondensation reaction and monitored using UV-visible spectroscopy. Spherical AuNPs with a (3.3 +/- 1.1) nm diameter from solid-state microscopies and narrow size distributions, evaluated in colloidal suspension by dynamic light scattering (DLS), were obtained by a two-phase wet chemical reduction in the presence of thiolate organometallic ligands. Structural analyses by FTIR and SR-XPS confirmed the functionalization via Au-S bonds. Platinum-containing ligand introduced additional emissive pathways, including long-wavelength emission, attributed to increased rigidity and reduced nonradiative decay in AuNPs. AuNPs/P3HT blends were obtained with different compositions (from 10 to 90 wt % AuNPs content) by a simple room-temperature mixing approach in organic solvents and spin-coated onto an interdigitated ITO substrate. Homogeneous films with a mean thickness of about 3 nm were revealed by atomic force microscopy (AFM). Electrical I/V measurements (range +/- 10 V) carried out on AuNPs/P3HT blends demonstrated a composition-dependent response. The blend containing 10 wt % AuNPs showed a similar to 30-fold increase in the relative electrical response compared to pristine P3HT and a reduced optical band gap (2.13 -> 2.06 eV). Photoluminescence studies revealed red-shifted and broadened P3HT emission with increasing AuNP content, highlighting strong AuNP plasmon-polymer interactions. Further grazing-incidence wide-angle X-ray scattering (GIWAXS) and nanofocused X-ray scattering measurements (nano-GIWAXS) revealed composition-dependent structural and thermal stability. It is noteworthy that low AuNPs wt % promoted a more effective interconnectivity with P3HT chains, responsible for enhanced electronic coupling in blends compared with pristine counterparts. Results showed that this nanoscale arrangement offers tunable properties for optoelectronic applications.

This work reports a comprehensive study on the morphology, composition, and electronic structure of CoAl layered double hydroxide (CoAl-LDH) during the oxygen evolution reaction (OER). To capture electrochemically induced transformations, operando spectroscopic and microscopic methods are combined. The complementary data provided by operando near-edge X-ray absorption fine structure (NEXAFS), supported by density functional theory (DFT) calculations, and electrochemical atomic force microscopy (AFM), reveal that under OER conditions, CoAl-LDH is fragmented into smaller particles due to Al leaching. This process forms a "resting" phase with an average Co oxidation state of 2.5+, which readily transforms into the OER-active β-CoOOH phase upon further potential increase. This work exemplifies how operando methods enable precise tracking of oxidation state changes, element dissolution, and structural transformations at the nanoscale while the electrocatalyst is active. This approach contrasts with conventional pre- and post-mortem characterization, which would instead suggest Co3O4 formation. These findings extend beyond the specific example of CoAl-LDH, emphasizing the crucial importance of selective cation leaching, recrystallization, and morphological restructuring, since these processes play a key role not only in designing advanced multi-element materials but also in understanding the complex nanoscale mechanisms that govern the activation and durability of practical electrocatalysts.

The development of innovative electrocatalysts for CO2 reduction reaction (CO2RR) is essential for producing high-value chemicals and fuels. Here, we report a simple surfactant- and solvent-free strategy to fabricate Cu-Ag bimetallic gas diffusion electrodes (GDEs) via sputtering of Cu onto a carbon substrate, followed by galvanic replacement with Ag. This method yields highly pure and tunable electrodes with minimal processing steps. The resulting CuAg GDEs exhibit a marked enhancement in CO2RR performance compared to monometallic Cu, particularly in promoting C2 (mainly ethanol and ethylene) product formation. This improvement is most pronounced when the galvanic replacement is carried out at 75 °C, yielding an optimal Ag/Cu ratio that maximizes electrochemical performance. Under these optimized conditions, Faradaic efficiencies (FE) for C2 products reach 73% and 69% at high current densities of 400 and 600 mA cm-2, respectively. Notably, the introduction of Ag markedly improves operational stability, with the system maintaining a FE of 49% for C2 products after 3 h of continuous electrolysis. In situ X-ray absorption spectroscopy (XAS) reveals that Ag plays a key role in stabilizing of Cu+ species under reaction conditions, which correlates with the C-C coupling and long-term selectivity. These findings provide valuable insights for rational design of advanced Cu-based catalysts for high-performance CO2 conversion.

Ni and Ni/Fe metal hydroxide organic frameworks (MHOFs) based on aromatic dicarboxylates are attracting great interest as emerging noble metal‐free catalysts for the oxygen evolution reaction (OER), during H 2 production by water splitting. They show good chemical and electrochemical stability during OER, some of them exhibiting similar catalytic activity compared to state‐of‐the‐art catalysts (e.g., IrO 2 ) when isolated as nanosheets. These MHOFs are actually precatalysts and reconstruct into the active NiOOH‐like phases after leaching of the organic linker under electrocatalytic alkaline conditions. Employing β‐Ni(OH) 2 (herein indicated as NiOH‐ x ) with different crystallinity ( x = 1‐low, 2‐intermediate, and 3‐high), we synthesized “bulk” forms of Ni 2 (OH) 2 (L) MHOFs (NiL‐ x ) based on benzene‐1,4‐dicarboxylate (L = BDC 2− ) and azobenzene‐4,4′‐dicarboxylate (L = AZO 2− ) ligands. We systematically obtained highly crystalline NiBDC‐ x and NiAZO‐ x samples, regardless of NiOH‐ x crystallinity. Therefore, the intercalation of L 2− effectively removes stacking faults disorder even from low crystalline NiOH‐1, especially for BDC 2− , while it is less efficient for AZO 2− . The OER‐activities were evaluated after establishing an activation procedure combining cyclic voltammetry with diffuse‐reflectance UV–vis–NIR. NiAZO‐x samples resulted the most stable and efficient catalysts, NiAZO‐1 being the best among them although containing ∼50% in weight of residual NiOH‐1, which converts superficially into highly efficient NiAZO‐phase during synthesis, while retaining its high‐conductivity in the inorganic bulk.

The development and characterization of nanoporous catalyst layers is critical for enhancing the efficiency of emerging energy technology applications. Accurate quantification of catalyst layer thickness, porosity and surface area is required to establish effective transport properties, structure-performance relationships and catalyst layer models with high fidelity. In this work, we fabricated thin nanoporous catalyst layers on gas diffusion electrodes and silicon nitride membranes (0.5-1.8 µm, 66% porosity) by depositing sub -10-nm Cu 2 O and CuO nanocrystals via a sputter gas aggregation source. Cyclic voltammetry coupled with in-situ soft X-ray absorption spectroscopy at the Cu L-edge as well as Pb underpotential deposition analysis in alkaline media were employed in order to probe dynamic processes at the solid nanocrystal aggregate-liquid interface. More specifically, the change in the nanocrystals' oxidation state as a function of potential and the variation in the electrochemically active surface area as a function of catalyst layer thickness were measured. Importantly, we have calculated that the thickest catalyst layers retained 45.2-48.3% of their as-prepared surface area (94 ± 10 m 2 ·g -1 , as determined by electron tomography) after immersion in the electrolyte and biasing. In addition, the derived roughness factors were found to correlate with the extent of multicarbon product formation and alcohol crossover during carbon monoxide reduction, which is a relevant case study and an additional catalyst layer probe. Compared to nonporous sputtered Cu analogues of equal thickness, the nanoporous catalyst layers exhibited equal acetate partial current densities and a lower share of propanol crossover, which may be rationalized by considering the effective volumetric reaction rate, catalyst layer pH and partial pore saturation. Our work emphasizes the importance of combining several physical and electrochemical in-situ characterization tools for measuring the actual utilization of nanoporosity and surface area in catalyst layers for electrosynthesis.

We investigate the interfacial electronic structure of monolayer iron tetraphenylporphyrin chloride (FeTPP-Cl) adsorbed on graphene (Gr) buffer layers supported by Ni(111) and Pt(111). This study unveils the role of a graphene buffer layer in controlling the charge transfer mechanisms of self-assembled porphyrins on metal surfaces, reshaping interfacial energy level alignment, charge transfer dynamics, interface dipoles, and charge injection barriers. By exploiting the intrinsic n- and p-type doping of graphene on Ni and Pt, we modulate the charge transfer behavior in iron tetraphenylporphyrin monolayers, using these systems as model platforms to probe interfacial electronic processes and the impact of graphene-substrate coupling. Through a comprehensive multi-technique approach, combining X-ray photoemission, ultraviolet photoemission, and X-ray absorption spectroscopies, we demonstrate how substrate-induced doping drives significant changes at the molecule-graphene-metal interface. Core-level binding energies (BEs) and ionization potentials (IPs) indicate weak physisorption in both systems, with opposite charge transfer directions depending on the substrate, despite similar molecular morphologies. On Gr/Ni(111), all core levels shift to higher BE, with a pronounced +0.6 eV shift in Fe 2p and a +0.15 eV IP increase, indicating electron transfer from the substrate to the molecule localized at the Fe center. On Gr/Pt(111), C 1s and N 1s shift to lower BE and the IP decreases by -0.15 eV, consistent with electron donation from the molecule to the substrate, more delocalized on the macrocycle. The small interface dipoles (-0.15 eV for Ni, -0.25 eV for Pt) and the absence of rigid shifts demonstrate that charge redistribution is fractional and site-specific, governed primarily by electrostatics and graphene doping rather than strong hybridization. These findings suggest that the interaction strength and electronic behavior at the interface are governed by the underlying metal, with Gr acting as an effective electronic decoupler or mediator. Our study highlights the importance of the graphene-metal interface in modulating charge transfer and level alignment in porphyrin-based hybrid systems.

The design of cathode/electrolyte interfaces in high-energy density Li-ion batteries is critical to protect the surface against undesirable oxygen release from the cathodes when batteries are charged to high voltage. However, the involvement of the engineered interface in the cationic and anionic redox reactions associated with (de-)lithiation is often ignored, mostly due to the difficulty to separate these processes from chemical/catalytic reactions at the cathode/electrolyte interface. Here, a new electron energy band diagrams concept is developed that includes the examination of the electrochemical- and ionization- potentials evolution upon batteries cycling. The approach enables to forecast the intrinsic stability of the cathodes and discriminate the reaction pathways associated with interfacial electronic charge-transfer mechanisms. Specifically, light is shed on the evolution of cationic and anionic redox in high-energy density lithium-rich 0.33Li2MnO3·0.67LiNi0.4Co0.2Mn0.4O2 (HE-NCM) cathodes, particularly those that undergo surface modification through SO2 and NH3 double-gas treatment to suppress the structural degradation. The chemical composition and energy distribution of the occupied and unoccupied electronic states at the different charging/discharging states are quantitatively estimated by using advanced spectroscopy techniques, including operando Raman spectroscopy. The concept is successfully demonstrated in designing artificial interfaces for high-voltage olivine structure cathodes enabling stable battery operation up to 5.1 V versus Li+/Li.

Abstract NbAs2, a topological semimetal, has stirred considerable interest for its potential usage in magnetic and fault‐tolerant quantum computation superconductor devices, owing to its superconductivity, enormous magnetoresistance, and anisotropic magneto‐transport attributes. Yet, its environmental stability, a crucial factor for practical applications, remains largely unexplored. Herein, a comprehensive examination of the stability and electronic properties of the (001) surface of NbAs2 utilizing density functional theory (DFT) and surface science experiments is conducted. The theoretical deductions reveal that As atoms, organized in a buckled honeycomb configuration, terminate the bare (001) surface, akin to the tensile blue arsenene monolayer along the armchair direction. This study further demonstrates that the oxidation barrier is particularly low (only 0.2 eV), highlighting that the (001) surface is highly prone to oxidation under standard conditions, forming a As2O5+Nb2O5/NbAs2 heterostructure. Additionally, it observes that oxidation adversely affects the electronic characteristics of the topological semimetal NbAs2. The conclusions underscore the need for NbAs2 to be managed under high vacuum conditions or to be encapsulated for any usage in the ambient atmosphere in order to retain its electronic properties for practical purposes.

We report on the spectral photoelectric yields of the surface materials of the lunar rover Rashid 1, built by the Mohammed Bin Rashid Space Centre in Dubai. The materials investigated are magnesium alloy, indium-tin-oxide, titanium, the commercial off-the-shelf solar panel cover-glass, and the graphite coatings on the Langmuir probes, namely Aerodag®G and Graphit 33. The yields of gold and silver plates were also measured for reference and calibration purposes. The photoelectric yield of some of these materials was measured in the past but only with photon energies up to 25 eV. The measurements were performed at the BABE facility (stemming from the BACH and BEAR synchrotron beamlines) within the framework of the European AHEAD2020 project operated by the Italian National Research Council CNR-IOM at the synchrotron light source Elettra, Italy. We scanned the 2.8–1240 eV energy region, covering most of the solar spectrum that can potentially lead to photoelectron emission on the Moon. The total electron emission rate per unit surface was estimated by combining the measured photoelectric yield curves with the solar spectral irradiance data from TIMED-SEE/SORCE experiments. The results of this study are needed as input in numerical simulations of the electron sheath forming around Rashid 1 or any similar lunar rover. Such numerical models help estimate the background signal for in-situ measurements of the density of the electron sheath forming above the Moon’s surface.

X-ray detectors for space astrophysics missions are susceptible to noise caused by photons with energies outside the operating energy range; for this reason, efficient external optical blocking filters are required to shield the detector from the out-of-band radiation. These filters play a crucial role in meeting the scientific requirements of the X-ray detectors, and their proper operation over the life of the mission is essential for the success of the experimental activity. We studied thin sandwich membranes made of silicon nitride and aluminum as optical blocking filters for high-energy detectors in space missions. Here, we report the results of a multi-technique characterization of SiN membranes with thicknesses in the range from 40 nm to 145 nm coated with few tens of nanometers of aluminum on both sides. In particular, we have measured the X-ray transmission at synchrotron radiation beamlines, the rejection of ultraviolet, visible, and near-infrared radiation, the amount of native oxide on the aluminum surfaces by X-ray photoelectron spectroscopy, the morphology of the sample surfaces by atomic force microscopy, and the aging effects under proton irradiation.

Light is a versatile tool to remotely activate molecules adsorbed on a surface, for example, to trigger their polymerization. Here, we explore the spatial distribution of light-induced chemical reactions on a Au(111) surface. Specifically, the covalent on-surface polymerization of an anthracene derivative in the submonolayer coverage range is studied. Using scanning tunneling microscopy and X-ray photoemission spectroscopy, we observe a substantial increase of the local molecular coverage with the sample illumination time at the center of the laser spot. We find that the interplay between thermally induced diffusion and the reduced mobility of reaction products steers the accumulation of material. Moreover, the debromination of the adsorbed species never progresses to completion within the experiment time, despite a long irradiation of many hours.

Chiral materials showing Kramers-Weyl fermions represent a suitable platform for quantum technology, i.e., for engineering quantum solenoids, spin-torque devices, polarization-sensitive photodetectors based on quantized circular photogalvanic effect, etc. Accordingly, the stability of this class of materials in oxidative environments, such as the ambient atmosphere, should be carefully investigated to succeed in technology transfer. Here, taking as case-study example the well-recognized topological chiral system cadmium diarsenide (CdAs2), we assess its chemical reactivity towards ambient gases (oxygen and water) and air by density functional theory and experiments. The surface of CdAs2 evolves into an oxide skin, but its thickness remains nanometric even after one year in air, as directly imaged by high-resolution transmission electron microscopy. Accordingly, it is evident that future quantum devices based on Kramers-Weyl fermions could be stable in air, as the oxide layer formed on chiral quantum materials only represents a native oxide, which actually protects bulk features, including Kramers-Weyl fermions (correlated to bulk band structure), from degradation in air.

Correction for ‘Impact of thermal gas treatment on the surface modification of Li-rich Mn-based cathode materials for Li-ion batteries’ by Maximilian Mellin et al. , Mater. Adv. , 2023, 4 , 3746–3758, https://doi.org/10.1039/D3MA00236E.

Theoxygen evolution reaction (OER) from water, while more stableon transition metal oxide surfaces than others, has nonetheless provedto be concomitant with charge-induced surface degradation. Since heterogeneousand nanostructured electrodes are often used and with a large excitationarea, the degradation can be difficult to quantify. Here, we utilizesingle crystalline SrTiO3, highly efficient photoexcitationof the OER, and a focused laser to spatially define the degradation.A repetitive, ultrafast laser pulse above the band gap energy is employed,which allows for highly varied exposure of the surface using differentscan methods. It also connects the work to the OER and its time-resolvedmechanisms. By characterizing the degradation using optical spectroscopyand electron microscopy, the material dissolution constitutes an upperbound of 6% of the charge passed in a pH 13 electrolyte, while forpH 7, it reaches 23%; the pH dependence is anticorrelated with theultrafast population of trapped charge. Although a minority component,the remarkable consistency of the 6% upper bound in the pH 13 electrolyteacross a large range of linearly increasing degradation volumes andchanging electrode composition defines a dominant lattice dissolutionreaction as thermodynamically concomitant with the OER. Along withthe pH dependence, the elemental composition of the degraded layerquantified by energy-dispersive and photoelectron and absorption X-rayspectroscopy suggests the relevance of certain chemical cation redepositionreactions. Altogether, using spatially and temporally defined photoexcitationof a crystalline surface provides a means to quantify semiconductingtransition metal oxide degradation during the OER and constricts itsmechanisms.