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This study aims to assess the performance of cold bitumen emulsion mixtures modified with a one-part geopolymer based on blast furnace slag and an alkaline activator. This material is generally prepared in a liquid solution, from an aluminosilicate source and an alkaline compound, and is dedicated to the precast sector. In this study, it was obtained by mechanosynthesis, a solvent-free process consisting of high-energy ball milling. The powder was incorporated as a filler in the formulation of 0/10 asphalt mixes. Other cold mixtures with limestone and blast furnace slag filler were manufactured to evaluate the influence of the additive nature on the cohesive strength at different curing times, compressive strength, water sensitivity, rutting resistance and resilient modulus. The potential chemical reactivity between each filler and each emulsion was monitored by in situ Fourier transform infrared spectroscopy. The results pointed out that the cohesive strength of the mixes containing one-part geopolymer is two to three times higher than that of the other formulations after 24 h curing. High compressive strength of the one-part geopolymer-based mixes is noticed; however, their compressive strength ratio is slightly lower, in comparison with the other mixes. The rutting percentage of the one-part geopolymer-based mixes reaches 4% at 30,000 cycles and their resilient modulus above 6,000 MPa at 15 °C. These results are attributed to the geopolymerisation reaction occurring between the filler and the emulsion, traduced by a shift in infrared spectroscopy. Therefore, the addition of one-part geopolymer filler, produced according to a non-solvent process, is a promising solution to enhance the implementation and durability of cold mixtures. [ABSTRACT FROM AUTHOR]

Adsorption and reaction site heterogeneity of titania-supported (10%Co + 0.5%Pd) catalysts in CO hydrogenation was studied by chemisorption, temperature-programmed desorption, and diffuse reflectance infrared Fourier transform spectroscopy techniques. Precursor material was treated in various media as reductive, inert, or oxidative. Cobalt metal sites and TiO2 support heterogeneity were proved. Upon H2 chemisorption, a pre-reduced sample exposed mostly homogeneous metal surface. Surface heterogeneity toward CO chemisorption depended on preliminary treatment. A catalyst prepared in inert medium revealed moderate activity dynamics of adsorption and reaction sites. Weak to medium strength sites toward hydrogen adsorption were relatively strong in terms of CO adsorption. Carbonate-(like) species occupied medium and strong sites on the support. Sites of weak strength for CO adsorption were active in hydrogenation but very strong in terms of CHx intermediates adsorption. [ABSTRACT FROM AUTHOR]

Dehydrogenation of formic acid (FA) via photocatalytic technology is an attractive strategy to meet the enhanced demand of hydrogen. Regarding the existing complex modification strategies and unclear mechanism of visible-light response CdS-based photocatalytic materials for dehydrogenation of FA, a simple surface nickel-modified CdS nanocrystals has been constructed for boosting the hydrogen production from FA. In situ infrared spectroscopy and electron spin resonance technology were utilized to study the entire photocatalytic decomposition process of FA, which have limited study in previous work. The surface nickel-modification promoted the adsorption of formic acid on the material surface and the generation of key intermediate hydroxyl radicals, leading to faster hydrogen production and enhanced stability. Consequently, the photocatalytic activity was 12.8 times higher than that of unmodified CdS materials after 48 h irradiation. This work provides a new approach for constructing simple and efficient visible-light response CdS-based photocatalysts for hydrogen production from FA under mild condition. Surface nickel modification promotes the adsorption of formic acid on the surface of photocatalysts and the generation of key reaction intermediates hydroxyl radicals, in addition to enhancement of photo-response and separation of photogenerated carrier, thereby improving dehydrogenation from formic acid. [Display omitted] • A simple Ni-modification of CdS enhances photocatalytic dehydrogenation of FA. • Ni modification promotes adsorption of FA and favors the dehydrogenation pathway. • Ni modification facilitates the generation of key species hydroxyl radicals. • Ni modification accelerates the consumption of formate. [ABSTRACT FROM AUTHOR]

Epoxy asphalt has emerged as a high-performance pavement material. However, research on its curing mechanism and kinetics remains limited. This study aimed to investigate the kinetic equation of the epoxy asphalt curing system using non-isothermal differential scanning calorimetry for better understanding and prediction of the curing reaction. The results revealed that the epoxy asphalt system in this study is autocatalytic, with the conversion rate increasing as the heating rate rises. Additionally, this research employed Density Function Theory to simulate the surface electrostatic potential distribution of the curing agent and epoxy resin in epoxy asphalt. This approach identified potential active sites for chemical reactions, confirming the likelihood of a cross-linking reaction between carbon–carbon double bonds in the oleylamine curing agent. This cross-linking reaction contributes to the formation of a network structure in the cured epoxy resin system, resulting in superior mechanical properties for the cured epoxy asphalt. The study utilized transition state theory to simulate the ring-opening reaction between the primary amine group in oleylamine and epoxy resin. Finally, the above conclusions were verified using in situ infrared spectroscopy, and the microstructure of the epoxy asphalt at different curing times was observed using in situ fluorescence microscopy. In conclusion, this research provides valuable insights into the curing mechanism and kinetics of epoxy asphalt, offering guidance for future applications and development in the field of pavement materials. [ABSTRACT FROM AUTHOR]

Tetraethylene glycol dimethyl ether (TEGDME) decomposition on the Au electrode surface is studied using in situ attenuated total reflectance surface enhanced infrared absorption spectroscopy (ATR-SEIRAS). Due to the weak solvation of TEGDME, the superoxide intermediate (LiO 2 /O 2 −) of the discharge process rapidly gains electrons on the electrode surface to generate Li 2 O 2. Furthermore, alkyl radical, formed by LiO 2 /O 2 − extracting hydrogen from ether, undergoes oxidative decomposition reactions to form by-products. During the charge process, amorphous film-like Li 2 O 2 obtained from surface-phase mechanism oxidizes in the low potential range of 3–3.4 V, while the oxidation potential of large-sized crystal Li 2 O 2 particles obtained from solution-phase mechanism is above 3.4 V. Besides, TEGDME is intrinsically unstable and can decompose at 3.8 V even the solution is saturated with argon, indicating that the degradation of ether-based electrolyte is inevitable during the cycling process. This work confirms the feasibility of ATR-SEIRAS in probing the reaction mechanism and electrolyte stability of lithium oxygen batteries, and provides direct spectroscopic evidence for subsequent optimization of electrolyte components. • Ether-based electrolyte cannot remain stable at high voltages. • Superoxide intermediates trigger the decomposition of the ether solvent. • Gas production behavior is strongly related to the electrode materials. [ABSTRACT FROM AUTHOR]

• A novel W additive is developed to enhance the CO oxidation activity of Pt/CeO 2. • The optimal Pt-W/CeO 2 achieves 100 % conversion at 150 °C (270 ℃ for Pt/CeO 2). • Tungsten species are atomically dispersed on the CeO 2 surface. • The W species plays a key role in adjusting the local environment of Pt. Ceria-supported atomically dispersed Pt is of great interest in CO oxidation due to their unique catalytic performance and high metal utilization. However, the intrinsic activity of the Pt 1 /CeO 2 single atom catalysts may not be desirable due to the overstabilization of Pt2+ species in the CeO 2 matrix. Herein, the local environment of Pt2+ species was tailored by introducing a tungsten oxide additive into the Pt 1 /CeO 2 catalyst, achieving a dramatic improvement in catalytic performance for CO oxidation at low temperatures. The optimized catalyst with 2.5 wt% W loading achieved 100 % CO conversion at 150 °C, which was 120 °C lower than that of the unmodified Pt/CeO 2 catalyst. Through in situ infrared spectroscopy and temperature-programmed reduction characterizations, as well as theoretical calculations, we concluded that the tungsten additive modulated the interactions between Pt2+ species and CeO 2. Thus, the reducibility of Pt was enhanced, which facilitated the formation of catalytically active metallic Pt0 species during the reaction. [ABSTRACT FROM AUTHOR]

The Mn/bastnaesite concentrate and Mn/Al 2 O 3 catalysts were prepared by impregnation method, and their NH 3 -SCR denitrification performance was tested. The results showed that the Mn/bastnaesite concentrate catalyst achieved up to 95% NO conversion rate at 150 °C, and the Mn/Al 2 O 3 catalyst reached 76% at 300 °C. A series of characterisation results showed that the bastnaesite concentrate can better interact with MnOx species and promote mutual dispersion compared to Al 2 O 3. The Mn/bastnaesite concentrate has a stronger redox capacity, and good NH 3 and NO adsorption capacity at low temperatures. The multi-element coexistence system of bastnaesite concentrate itself is a significant advantage of its use as a carrier. In-situ Fourier transform infrared (FTIR) results showed that the Mn/bastnaesite concentrate catalyst follows an L-H mechanism throughout the reaction, with NH 4 + species in the Brønsted acidic site on the catalyst surface being the main reactant species. Most of NO is converted to monodentate nitrite, which is formed by bonding with Mn3+ provided by the supported Mn species, rare earth elements and transition metal ions contained in the carrier itself to form O–N–O–Mn3+ intermediates, which participate in the reaction together, and then combined with the adsorbed NH 4 +/NH 3 species to produce N 2 and H 2 O. An E-R mechanism was also present on the catalyst surface, NO participates directly in the reaction in gaseous form, and the NO [NH 2 ](ads) intermediate species produced by interaction with NH 4 + species in the acidic position of Brønsted was further decomposed to N 2 and H 2 O. By comparing the reaction mechanism with the commonly used catalyst carrier Al 2 O 3 for NH 3 -SCR, it can be concluded that bastnaesite concentrate as a carrier not only has the performance of conventional carriers, but also has certain catalytic activity and can interact with the active components to give it excellent performance, which provides a theoretical basis for rare earth minerals as denitrification catalysts. • The first use of bastnaesite concentrate from Baiyun Ebo as a carrier for NH 3 -SCR catalysts. • Mn/bastnaesite concentrate Catalyst with Excellent Low Temperature Denitrification Performance. • The Ce 7 O 12 species has a better mutual promotion with Mn. • The Mn3+ will bond with the monodentate nitrate species to form O–N–O–Mn3+ species involved in the reaction. • Mn/bastnaesite concentrate surface was a dual-mechanism coexistence with more reaction pathways. [ABSTRACT FROM AUTHOR]

The relationship between reductive decomposition of anion and the efficiency of magnesium deposition was investigated in magnesium bis(trifluoromethane sulfonyl)imide (Mg(TFSI)2) salt and triglyme (G3) solvent without and with magnesium ethoxy chloride (EtOMgCl) salt. Cyclic voltammetry, energy dispersive X-ray spectroscopy analysis, in situ infrared spectroscopy during deposition–dissolution of magnesium and Raman spectroscopy were conducted. Coulombic efficiency for magnesium deposition was also calculated by chrono amperometry. In Mg(TFSI)2/G3 (molar ratio of 1/15), magnesium was hardly deposited. In EtOMgCl/Mg(TFSI)2/G3 (molar ratio of 2/1/15), magnesium was deposited efficiently. The reduction of TFSI− anion occurred in Mg(TFSI)2/G3 during magnesium deposition, while the reduction was suppressed in EtOMgCl/Mg(TFSI)2/G3. The addition of EtOMgCl salt can suppress the reduction of TFSI− anion, leading to highly efficient magnesium deposition.

The recent mechanistic understanding of active sites, adsorbed intermediate products, and rate‐determining steps (RDS) of nitrogen (N)‐modified carbon catalysts in electrocatalytic oxygen reduction (ORR) and oxygen evolution reaction (OER) are still rife with controversy because of the inevitable coexistence of diverse N configurations and the technical limitations for the observation of formed intermediates. Herein, seven kinds of aromatic molecules with designated single N species are used as model structures to investigate the explicit role of each common N group in both ORR and OER. Specifically, dynamic evolution of active sites and key adsorbed intermediate products including O2 (ads), superoxide anion O2−*, and OOH* are monitored with in situ spectroscopy. We propose that the formation of *OOH species from O2−* (O2−*+H2O→OOH*+OH−) is a possible RDS during the ORR process, whereas the generation of O2 from OOH* species is the most likely RDS during the OER process. [ABSTRACT FROM AUTHOR]

A methanol economy will be favored by the availability of low‐cost catalysts able to selectively oxidize methanol to formate. This selective oxidation would allow extraction of the largest part of the fuel energy while concurrently producing a chemical with even higher commercial value than the fuel itself. Herein, we present a highly active methanol electrooxidation catalyst based on abundant elements and with an optimized structure to simultaneously maximize interaction with the electrolyte and mobility of charge carriers. In situ infrared spectroscopy combined with nuclear magnetic resonance spectroscopy showed that branched nickel carbide particles are the first catalyst determined to have nearly 100 % electrochemical conversion of methanol to formate without generating detectable CO2 as a byproduct. Electrochemical kinetics analysis revealed the optimized reaction conditions and the electrode delivered excellent activities. This work provides a straightforward and cost‐efficient way for the conversion of organic small molecules and the first direct evidence of a selective formate reaction pathway. [ABSTRACT FROM AUTHOR]

The synergistic interaction between the isolated metal sites promoted the electrocatalytic activity of the catalysts. However, the structural heterogeneity of the isolated sites makes it challenging to evaluate this effect accurately. In this work, metal-coordinated polyphthalocyanine molecules (Fe-PPc, Co-PPc, FeCo-PPc) with long-range ordered and precise coordination structures are used as a platform to study the synergies of different isolated metal sites in the electrochemical CO 2 reduction reaction. The combination means of experimental and theoretical calculation clearly reveal that the coexistence of Fe and Co sites in PPc significantly enhances the conjugation effect of the macrocycle. This enhancement subsequently causes the metal sites to lose more electrons, thereby improving their adsorption of CO 2 and facilitating the formation of intermediate *COOH on them. As a result, FeCo-PPc achieves a CO partial current density of about 57.4 mA/cm 2 with a high turnover frequency of over 49000 site -1 h -1 at -0.9 V (vs RHE).

High-quality Pt-based catalysts are highly desirable for ethanol oxidation reaction (EOR), which is of critical importance for the commercial applications of direct ethanol fuel cells (DEFCs). However, most of the Pt-based catalysts have suffered from high cost and low operation durability. Herein a two-step method has been developed to synthesize porous Pt nanoframes decorated with Bi(OH)3, which show excellent catalytic activity and operation durability in both alkaline and acidic media. For example, the nanoframes show a mass activity of 6.87 A·mgPt−1 in alkaline media, which is 13.5-fold higher than that of commercial Pt/C. More importantly, the catalyst can be reactivated simply, which shows negligible activity loss after running for 180,000 s. Further in situ attenuated total reflection-infrared (ATR-IR) absorption spectroscopy and CO-stripping experiments indicate that surface Bi(OH)3 species can greatly facilitate the formation of adsorbed OH species and subsequently remove carbonaceous poison, resulting in a significantly enhanced stability towards EOR. This work may favor the tailoring of desired electrocatalysts with high activity and durability for future commercial application of DEFCs. [ABSTRACT FROM AUTHOR]

• New Co-Al 2 O 3 prepared by SEA method with improved activity for ethanol dehydration. • Co-Al 2 O 3 with higher BET area, fewer acid sites, and more hydrophobic than γ-Al 2 O 3. • Kinetics and modulation excitation-DRIFTS showed less water inhibition on Co-Al 2 O 3. • Adsorbed ethanol, ethoxide, and Al hydroxyls as possible reaction intermediates. Ethanol catalytic dehydration was studied on a γ-Al 2 O 3 and Co-Al 2 O 3 catalyst prepared by the strong electrostatic adsorption (SEA) method. Specific surface area characterization indicated that the Co-Al 2 O 3 catalyst possessed higher surface area because of opening of γ-Al 2 O 3 occluded pores. Acidity and basicity measurements of the catalysts by temperature programmed desorption (TPD) as followed by infrared and mass spectrometry (TPD-FTIR-MS) of adsorbed pyridine and CO 2 , respectively, indicated that the Co-Al 2 O 3 catalyst possessed about half the Lewis acidity (accessible to pyridine) and moderately higher basicity than the parent γ-Al 2 O 3. However, similar acidity measurements by NH 3 -TPD suggested the presence of occluded micropore acidity inaccessible to pyridine. XRD and IR measurements indicated that the support in the Co-Al 2 O 3 catalyst underwent partial nitridation forming aluminum nitride and nitrogen containing Co species due to the SEA synthesis conditions. It was found that the Co-Al 2 O 3 catalyst, under identical reaction conditions, could achieve similar ethanol conversion and ethylene selectivity to ethylene at lower temperatures than the original γ-Al 2 O 3 support. Analysis of apparent activation energies contributions and water co-feeding tests indicated that the Co-Al 2 O 3 was less inhibited by water and that water dimers and trimers were required to explain the experimental data. Furthermore, in situ modulation excitation-phase sensitive detection-diffuse reflectance infrared Fourier transform spectroscopy (ME-PSD-DRIFTS) during ethanol dehydration at reaction conditions confirmed the enhanced hydrophobic properties of the Co-Al 2 O 3 , making this catalyst less propense to water inhibition at low to moderate temperatures. The enhanced surface hydrophobicity in combination with new micropore acidity allowed more active sites for reaction not accessible in the parent γ-Al 2 O 3. Additionally, evidence is also presented from in situ ME-PSD-DRIFTS for the participation of adsorbed ethanol and ethoxide species as well as terminal and bridging hydroxyls bonded to octahedral and tetrahedral Al on Al 2 O 3 (1 0 0) and (1 1 0) facets as likely reaction intermediates in the conversion of ethanol to diethyl ether and ethylene. [ABSTRACT FROM AUTHOR]

The exploration of short peptide-based assembly is vital for understanding protein-misfolding-associated diseases and seeking strategies to attenuate aggregate formation. While, the molecular mechanism of their structural evolution remains poorly studied in view of the dynamic and unpredictable assembly process. Herein, infrared (IR) spectroscopy, which serves as an in situ and real-time analytical technique, was intelligently employed to investigate the mechanism of phase transition and aggregate formation during the dynamic assembly process of diphenylalanine. Combined with other spectroscopy and electron microscopy technologies, three stages of gel formation and the main driving forces in different stages were revealed. A variety of stoichiometric methods such as continuous wavelet transform, principal component analysis, and two-dimensional correlation spectroscopy techniques were conducted to analyze the original time-dependent IR spectra to obtain detailed information on the changes in the amide bands and hydration layer. The microenvironment of hydrogen bonding among amide bands was significantly changed with the addition of pyridine derivatives, resulting in great differences in the properties of co-assembled gels. This work not only provides a universal analytical way to reveal the dynamic assembly process of dipeptide-based supramolecular gel but also expands their applications in supramolecular regulation and high-throughput screens in situ.

Xenon (Xe), the heaviest of the stable noble gases, is missing by a factor of 20 relatively to other noble gases, when comparing the Earth's and Mars's atmospheres with chondrites. In this work, the possibility of Xe retention in quartz, a major mineral of the continental crust, is tested. The Xe‐SiO2 system is investigated from 0.7 to 2.7 GPa and up to 1900 K, by in situ X‐ray powder diffraction and infrared spectroscopy. Experimental data are complemented by ab initio calculations to retrieve Xe incorporation mechanisms. An excess of quartz unit cell volume up to 4.2% is observed, consistent with a Xe for Si substitution in the quartz structure. Xe has a linear oxygen environment composed of two O atoms located at 1.98–2.00 Å from the Xe atom. Moreover, a new phase is evidenced above Xe melting curve at 0.8–1.0 GPa. The new (Xe,Si)O2 phase is orthorhombic and corresponds to an elongation of the quartz unit cell. In this phase, Xe substitutes for Si with a nearly planar oxygen environment composed of four O atoms located at 2.06–2.09 Å from the Xe atom. Xe incorporation in SiO2 proves to be significant, as previously shown for olivine. Xe incorporation is therefore expected to occur in the whole range of lithospheric silicate minerals. These findings emphasize the need to consider Xe incorporation in crust and upper mantle minerals as a process to store and fractionate xenon, in the framework of the "missing xenon" issue. Key Points: The Xe‐SiO2 system is studied by in situ high‐pressure and temperature experiments and ab initio calculationsXe is incorporated in quartz, and a new (Xe,Si)O2 phase is identifiedThese findings emphasize the need to consider Xe storage in crust minerals in the framework of the "missing xenon" issue [ABSTRACT FROM AUTHOR]

Abstract The electrochemical behavior of several structurally related catecholamine molecules has been investigated on different electrode materials with cyclic voltammetry, infrared spectroscopy and scanning tunnelling microscopy. Emphasis was on the identification of subsequent chemical processes that follow the main electron transfer step and complicate the interpretation of the mechanism, including the polymerization reaction and fouling of the electrode surface. Among the materials investigated, gold was found out to be the most active for the oxidation of catechol, 4-methylcatechol and dopamine. At the same time, it was also the electrode least sensitive to fouling after voltammetric cycling, exhibiting the highest reversibility. The effect of pH was also investigated. Increase in pH enhanced the processes of quinone hydroxylation and polymerization. Spectroscopic measurements allowed detection of both solution and adsorbed species participating in the oxidation and polymerization processes. Finally, STM results showed the formation of polydopamine granules on gold surfaces, which grew in size as the number of cycles increased. Measured height of the granules, less than 0.5 nm, suggests a flat orientation of the molecules conforming the polymer. [ABSTRACT FROM AUTHOR]

Studying the effect of oxygen in coal oxidation is very important for understanding and controlling coal spontaneous combustion. However, the oxygen effect is not very easy to determine clearly due to the large effect of heat source on coal oxidation in temperature rising experiments. Here, focused on sub-bituminous coal, the oxygen effect was separated from coal oxidation by continuously measuring FTIR spectra of coal with respect to varying temperatures and under oxygen and nitrogen. The active groups’ real-time changes of coal oxidation, thermal treatment and oxygen effect were measured. The carboxylic ester and carboxyl units are the main functional groups that increase with temperatures increasing under oxygen and nitrogen, while the other functional groups decrease in quantity. The oxygen effect promoted the consumption of aliphatic hydrocarbons and hydroxyl groups and also promoted the formation of oxygen-containing groups (except hydroxyl). Four characteristic temperature stages involved in the oxygen effect and their key functional groups were identified. Simultaneously, the relationship of oxygen consumption and chemisorption in oxygen effect was analyzed. The starting temperature of oxygen chemisorption is between 50 and 60°C. The maximum contribution of oxygen effect was observed in methyl and methylene groups. These results are important for chemical control of coal spontaneous combustion. The oxidation of aliphatic hydrocarbon should be controlled before oxygen chemisorption. The value of oxygen consumption between 70 and 80°C can be measured accurately due to the constant chemisorption rate, which help to identify the tendency for spontaneous combustion. These results will help in better understanding of the reaction mechanism of coal oxidation, especially the oxygen effect. [ABSTRACT FROM AUTHOR]

Tuning surface oxygen vacancies is important for oxide catalysts. Doping elements with different chemical valence states or different atomic radii into host oxides is a common method to create oxygen vacancies. However, the concentration of oxygen vacancies in oxide catalysts is still limited to the amount of foreign dopants that can be tolerated (generally less than 10% atoms). Herein, a principle of engineering the configurational entropy to tune oxygen vacancies was proposed. First, the positive relationship between the configuration entropy and the formation energy of oxygen vacancies ( E ov ) in 16 model oxides was estimated by a DFT calculation. To verify this, single binary oxides and high-entropy quinary oxides (HEOs) were prepared. Indeed, the concentration of oxygen vacancies in HEOs (O β/α = 3.66) was higher compared to those of single or binary oxides (O β/α = 0.22-0.75) by O 1s XPS, O 2 -TPD, and EPR. Interestingly, the reduction temperatures of transition metal ions in HEOs were generally lower than that in single-metal oxides by H 2 -TPR. The lower E ov of HEOs may contribute to this feature, which was confirmed by in situ XPS and in situ XRD. Moreover, with catalytic CO/C 3 H 6 oxidation as a model, the high-entropy (MnCuCo 3 NiFe) x O y catalyst showed higher catalytic activity than single and binary oxides, which experimentally verified the hypothesis of the DFT calculation. This work may inspire more oxide catalysts with preferred oxygen vacancies.

In the context of rare earth element extraction using solid-liquid process, hybrid materials having specific functional group were largely studied. However, there is a lack of in situ characterization method to understand how the functional group behaves when interacts with the rare earth element. Here, we propose a new experimental method to understand the interaction between immobilized functional group and REE in aqueous media using a well-characterized model system coupled to surface analyses. Model system was prepared by grafting diglycolamide functionalized silane on planar silica substrate. In order to have a clear description of the morphology and the structure of the model system, the silane grafting process was characterized using contact angle measurement, X-Ray Reflectivity, peak force measurements by Atomic Force Microscopy and in situ analysis by Fourier Transformed Infrared Spectroscopy in Attenuated Total Reflection. Afterwards, the behavior of the grafted molecules was investigated in neodymium aqueous solution at various pH by in situ infrared spectroscopy and hard X-ray reflectivity characterizations. Here, we highlight that the complexation of Nd3+ by the diglycolamide function is correlated with its dehydration and a modification of the molecule configuration. [Display omitted] • In situ characterization method using model system to understand how functional group behaves when interacts with the rare earth element. • Model system prepared by grafting diglycolamide functionalized silane on planar silica substrate. • Behavior of the grafted molecules was investigated in neodymium aqueous solution at various pH by in situ infrared spectroscopy and hard X-ray reflectivity characterizations. • The complexation of Nd3+ by the diglycolamide function goes with its dehydration and a modification of the molecule configuration. [ABSTRACT FROM AUTHOR]

Carbon dioxide methanation is well known to offer some advantages and be catalyzed by Ru, Rh, Pd, and Ni. In this study, Ni catalysts supported on various metal oxides were fabricated and their catalytic activity for CO 2 methanation was evaluated. The CO 2 conversion for most of catalysts drastically increased at 225–250 °C and reached a maximal value at 300–350 °C. The order of CH 4 yield at 250 °C was as follows: Ni/Y 2 O 3 > Ni/Sm 2 O 3 > Ni/ZrO 2 > Ni/CeO 2 > Ni/Al 2 O 3 > Ni/La 2 O 3 . The catalytic activity could be partly explained by the basic property of the catalysts. Moreover, the chemical species formed on the catalyst surface during CO 2 methanation were examined by in situ infrared spectroscopy. From the obtained results, the difference in the activity depending on the support material of Ni catalysts was discussed. [ABSTRACT FROM AUTHOR]

The aim of this paper is to characterize the distribution of paracetamol conformers which are dissolved in a supercritical CO 2 phase being in equilibrium with their corresponding crystalline form. The quantum calculations and molecular dynamics simulations were used in order to characterize the structure and analyze the vibration spectra of the paracetamol conformers in vacuum and in a mixture with CO 2 at various thermodynamic state parameters ( p , T ). The metadynamics approach was applied to efficiently sample the various conformers of paracetamol. Furthermore, using in situ IR spectroscopy, the conformers that are dissolved in supercritical CO 2 were identified and the evolution of the probability of their presence as a functions of thermodynamic condition was quantified while the change in the crystalline form of paracetamol have been monitored by DSC, micro IR and Raman techniques. The DSC analysis as well as micro IR and Raman spectroscopic studies of the crystalline paracetamol show that the subsequent heating up above the melting temperature of the polymorph I of paracetamol and the cooling down to room temperature in the presence of supercritical CO 2 induces the formation of polymorph II. The in situ IR investigation shows that two conformers (Conf. 1 and Conf. 2) are present in the phase of CO 2 while conformer 3 (Conf. 3) has a high probability to be present after re-crystallization. [ABSTRACT FROM AUTHOR]

In order to investigate the methanol synthesis reaction from CO 2 /H 2 , a comparative study of the reactivity of formate species on different types of catalysts and catalyst supports has been carried out. Formic acid was adsorbed on water–gas shift catalysts, Cu/ZnO/Al 2 O 3 methanol synthesis catalyst and ZnO/Al 2 O 3 support, Cu/ZnO/ZrO 2 and Cu/ZnO/CeO 2 methanol synthesis catalysts as well as their corresponding supports ZnO/ZrO 2 and ZnO/CeO 2 . Superior reactivity and selectivity of dedicated methanol synthesis catalysts was evidenced by their behavior during the subsequent heating ramp, when these samples showed the simultaneous presence of formates and methoxy species and a higher stability of these reaction intermediates in the usual temperature range for the methanol synthesis reaction. [ABSTRACT FROM AUTHOR]

A simple method of producing high quality few-layer graphene (FLG) electrodes (< 5 nm thick) has been described and the in situ infrared measurements of the FLG/1-ethyl-3-methylimidazolium tetrafluoroborate system have been reported. Ideal polarizability of the system has been established and three different spectral modes have been discussed in order to provide a varied understanding of both the electronic and structural effects at the interface. The method of in situ electroreflectance spectroscopy has been extended to the study of FLG ∣ ionic liquid interface, providing new information about the method and possibilities for future studies of specific adsorption and electronic structure of the interface. Plasmonic enhancement of the spectra has been demonstrated, providing excellent opportunities for the study of the electric double layer and infrared sensors. [ABSTRACT FROM AUTHOR]

Highlights: [•] Infrared spectra were obtained for three carbon|ionic liquid interfaces. [•] The carbon electrodes have different electrochemical and infrared spectra. [•] The thin carbon film electrodes have great potential for in situ infrared studies. [•] Supercapacitor cell voltage limiting reactions were solved. [ABSTRACT FROM AUTHOR]

Highlights: [•] Preparation and characterization of cyano-bridged dimeric oxo-centered triruthenium complex. [•] Preparation of self-assembled monolayers (SAMs) on gold surface. [•] Electrochemistry of SAMs. [•] In situ infrared spectroscopy of SAMs. [Copyright &y& Elsevier]

Highlights: [•] Ethanol oxidation mechanism on PtSn-based ternary catalysts by in situ FTIR. [•] High level of CO on Pt/C and PtSnRh/C is indicative of the C C bond cleavage. [•] High acetic acid selectivity by the addition of Ni or Pd to PtSn/C. [ABSTRACT FROM AUTHOR]

Abstract: The adsorption and oxidation of acetaldehyde on carbon supported Pt, Pt90Sn10 and Pt80Sn10M10 (M = Ni, Co, Rh, Pd) catalysts have been investigated by using in situ Fourier transform infrared (FTIR) spectroscopy. The result revealed that Pt90Sn10/C catalyst is not very efficient for the conversion of acetaldehyde to CO2 due to the weak adsorption of acetaldehyde in the presence of Sn. However, the addition of a third metal to Pt–-Sn facilitates the C–C bond cleavage of acetaldehyde. It seems that acetaldehyde is adsorbed dissociatively on the surface of Pt80Sn10Ni10/C, Pt80Sn10Co10/C, Pt80Sn10Rh10/C catalysts, producing CH3 and CHO adsorbate species, which can be further oxidized to CO2. However, the pathway forming CO2 for Pt80Sn10Pd10/C catalyst mainly originates from the oxidation of CH3CO species. Thus, the presence of third metal in the PtSn catalyst has a strong impact upon the acetaldehyde adsorption behaviour and its reaction products. [Copyright &y& Elsevier]

Abstract: Dopamine is the biological molecule responsible, among other functions, of the heart beat and blood pressure regulation. Its loss, in the human body, can result in serious diseases such as Parkinson's, schizophrenia or depression. Structurally, this molecule belongs to the group of catecholamines, together with epinephrine (adrenaline) and norepinephrine (noradrenaline). The hydroquinone moiety of the molecule can be easily oxidized to quinone, rendering the electrochemical methods a convenient approach for the development of dopamine biosensors. The reactivity of similar aromatic molecules, such as catechol and hydroquinone, at well-ordered platinum surfaces, has recently been investigated in our group. In this paper, we extend these studies to the structurally related molecule dopamine. The study has been performed in neutral pH, since this is closer to the natural conditions for these molecules in biological media. Cyclic voltammetry and in situ infra-red spectroscopy have been combined to extract information about the behavior of this molecule on well-defined platinum surfaces. Dopamine appears to be electrochemically active and reveals interesting adsorption phenomena at low potentials (0.15–0.25V vs RHE), sensitive to the single crystal orientation. The adsorption of dopamine on these surfaces is very strong, taking place at much lower potentials than the electron transfer from solution species. Specifically, the voltammetry of Pt(111) and Pt(100) in dopamine solutions shows an oxidation peak at potentials close to the onset of hydrogen evolution, which is related to the desorption of hydrogen and the adsorption of dopamine. On the other hand, adsorption on Pt(110) is irreversible and the surface appears totally blocked. Spectroscopic results indicate that dopamine is adsorbed flat on the surface. At potentials higher than 0.6V vs RHE the three basal planes show a common redox process. The initial formation of the quinone moiety is followed by a chemical step resulting in the formation of 5,6-dihydroxyindoline quinone as final product. This oxidation process has also been investigated by vibrational spectroscopy. [Copyright &y& Elsevier]

Highlights: [•] In situ DRIFT targets CO adsorption on the standard Pt reference catalyst EuroPt-1. [•] The 55-atom Pt cuboctahedra exhibit three different sites: faces, edges and corners. [•] The method to analyze the complex spectrum of CO adsorbed on Pt is detailed. [•] IR frequencies come: face, edge, corner, and multiple adsorptions on a single corner. [•] Three parameters are studied: CO partial pressure, temperature and time. [Copyright &y& Elsevier]

Abstract: The gas phase hydrogenation of nitrobenzene over gold nanoparticles supported on titania and alumina was investigated by in situ infrared spectroscopy. Adsorption and reduction of nitrobenzene readily proceeded on both catalysts, and aniline remained adsorbed on the catalyst. On titania, decreasing amounts of nitrobenzene adsorb in each cycle. Adsorption was found to occur through hydrogen-bonding interactions with surface hydroxyl groups on both supports. In the presence of aniline, nitrobenzene adsorbs on other sites on titania, as it is not able to displace aniline from hydroxyl sites. On alumina, nitrobenzene displaces some aniline from the surface hydroxyl groups. Nitrobenzene and aniline thus compete, at least in part, for the same sites on alumina, but not on titania. [Copyright &y& Elsevier]

Abstract: In situ infrared measurements under potential control were carried out in 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) room-temperature ionic liquid (IL) using magnetron sputtered Bi films as the working electrodes. Unexpectedly, it was found that the spectra measured with s-polarized light were more intensive and the absorption peaks had a different direction compared to the p-polarized spectra. This work gives a description and an explanation of this phenomenon. Imidazolium cation dimerization was detected at potential E <−2V and bismuth oxidation and dissolution at E >+0.6V vs. Ag|AgCl wire in the same IL. [Copyright &y& Elsevier]

Abstract: Effects toward electrocatalytic activity for glycerol oxidation of the modification of carbon supported Pd and Pt-based nanomaterials by bismuth were evaluated in alkaline medium. Pd/C, Pd0.9Bi0.1/C, Pt/C, Pt0.9Bi0.1/C and Pd0.45Pt0.45Bi0.1/C catalysts were synthesized by a colloidal route, and physical and electrochemical methods were used to characterize the structure and the surface of the catalysts (TEM, HRTEM, EDX, XRD, ICP-OES and XPS). It was shown that only a few amount of bismuth was deposited on the Pt and/or Pd surface, and that no alloy was formed between bismuth and the other metals. The onset potential of glycerol oxidation is ca. 0.15V lower on Pt/C than on Pd/C. However, Pt-free Pd0.9Bi0.1/C catalyst presented the same catalytic activity than platinum catalyst. The Pt0.9Bi0.1/C led reaching a higher catalytic activity by shifting the oxidation onset potential by ca. 0.2V toward lower potentials compared with the Pt/C catalyst. But, the replacing of half of the platinum atoms by palladium atoms in the Pd0.45Pt0.45Bi0.1/C material allowed achieving the same catalytic activity as with Pt0.9Bi0.1/C. Electrochemical experiments combined with in situ infrared spectroscopy measurements have shown that glycerol electrooxidation mechanism is independent on the catalyst, but dependent on the electrode potential. Chronoamperometry experiments combined with HPLC measurements showed that the main reaction products were glycerate, dihydroxyacetone and tartronate at low potentials, and that the increase of the electrode potential led to the formation of mesoxalate. For potential higher than 0.8V vs RHE, the C–C bond cleavage occurred and oxalate and formiate were detected. [Copyright &y& Elsevier]

Abstract: The influence of sulfur dioxide on methane oxidation over ceria supported platinum catalysts under lean conditions has been studied by transient flow reactor and in situ Fourier transform infrared spectroscopy experiments. The results show that sulfur dioxide can promote the oxidation of methane, here between 300 and 450°C, although, as a function of time on stream, the promoting effect diminish and instead the methane oxidation becomes inhibited. We suggest that sulfate formation on ceria creates oxygen vacancies in the ceria that govern oxygen spillover leading to a lowering of detrimental oxygen coverage of platinum and/or decomposition of platinum oxide facilitating the dissociative methane adsorption. Eventually the ceria becomes saturated with sulfates and the oxygen dynamics in the platinum–ceria system settles. As a consequence, the system regresses towards highly oxidized platinum and/or otherwise active sites on the ceria or platinum–ceria boundary become blocked, which may explain the long-term inhibiting effect by SO2 exposure. [Copyright &y& Elsevier]

Abstract: Transmission infrared and Attenuated Total Reflection (ATR) in situ infrared spectroscopies were combined for the time-resolved monitoring of both liquid and supercritical phases during extraction of water and other impurities from ionic liquids with supercritical carbon dioxide (scCO2). Cleaning and drying by scCO2 at 100bar and 40°C proved to be efficient for all ionic liquids tested, including 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), and 1-butyl-3-methylimidazolium trifluoromethansulfonate ([bmim][TfO] or [bmim] triflate). Despite the moderate solubility of water in scCO2 compared to other classical solvents, the amount of water decreased continuously during the drying. The extraction could be followed by simple transmission IR spectroscopy of the supercritical phase. During the extraction, organic impurities and water were removed rapidly from the ionic liquid phase as scCO2 improved the transport properties in the ionic liquids. [ABSTRACT FROM AUTHOR]

Abstract: Carbon supported Pd, Pt, Au and bimetallic PdAu and PdNi nano-catalysts with different compositions were synthesized. Their catalytic activity toward glycerol electro-oxidation was evaluated in alkaline medium. Physical and electrochemical methods where used to characterize the structure and the surface of the catalysts. It was shown that the Pd x Au1−x /C catalysts were alloys, which present an increase of crystallite (XRD) and particle (TEM) sizes with increasing Au atomic fraction. Their surfaces were palladium rich whatever the Pd atomic ratio. The structure of the Pd0.5Ni0.5/C catalyst is much more difficult to understand, but it seems to be composed of a palladium phase in interaction with a Ni(OH)2 phase. The onset potential of glycerol oxidation is ca. 0.15V lower on Pt/C than on Pd/C and Au/C. All Pd x Me1−x /C catalysts presented lower onset potential than monometallic Au/C and Pd/C ones, but higher than Pt/C. For bimetallic catalysts, the order of activity at low potentials is: Pd0.3Au0.7/C>Pd0.5Au0.5/C>Pd0.5Ni0.5/C. Electrochemical experiments and in situ infrared spectroscopy measurements have shown that glycerol electro-oxidation mechanism is dependent on the catalyst, leading to different reaction products. Adsorbed CO species are detected on monometallic Pt and on Pd rich catalysts, but not on Au and Pd0.3Au0.7 catalysts, indicating that they are not able to break the C–C bond. The formation of hydroxypyruvate ion, which is a costly chemical product, is detected on pure gold catalyst. [Copyright &y& Elsevier]

Abstract: The oxidation of carbon monoxide over a 6.3% Pt/SiO2 catalyst (EUROPT-1) is studied under conventional and microwave heating and found to display similar activity. The capability of the cell to observe the adsorbed gases spectroscopically is also demonstrated. [Copyright &y& Elsevier]

Abstract: The reaction pathways for the photocatalytic oxidation of ethanol on the TiO2 surface at 30 °C were studied by in situ infrared (IR) spectroscopy. The coverage of ethanol and water was found to play a key role in how the reaction is initiated. The low ethanol coverage on the H2Oad-containing TiO2 surface produced adsorbed formate (HCOO− ad) as a primary intermediate; the high ethanol coverage on the H2Oad-deficient TiO2 surface produced adsorbed acetate (CH3COO− ad) as a major intermediate during the initial period (i.e., 2 min) of the photocatalytic oxidation. The adsorbed species and reaction products observed during in situ IR studies suggest the low-coverage ethanol reaction is initiated by •OH, whereas the high-coverage ethanol reaction is initiated by hole. The hole-initiating ethanol oxidation on the H2Oad-deficient TiO2 surface produced adsorbed acetic acid (CH3COOHad)/CH3COO− ad, and built up photogenerated electrons, giving a parallel increase in the IR intensity of CH3COO− ad and the IR background at 2000 cm−1 (i.e., a measure of photogenerated electrons). As the high-coverage ethanol reaction proceeded toward producing CO2/H2O, adsorbed H2O accumulated and the coverage of CH3CH2OHad/CH3CH2Oad decreased on the TiO2 surface, shifting the reaction from hole-initiating to •OH-initiating. [Copyright &y& Elsevier]

Abstract: We present results of a combined electrochemical and in situ spectroscopy study on kinetic and mechanistic aspects of the reduction of CO2 on Pt model electrodes and compare these with the performance of a Pt/C membrane electrode assembly (MEA) in a polymer electrolyte fuel cell (PEFC) for using pure H2 or H2/CO2(25%) mixtures (synthetic reformate). Based on highly sensitive surface enhanced IR absorption spectrocopy (SEIRAS) measurements on a thin film Pt electrode and on-line differential electrochemical mass spectrometry (DEMS) results obtained on a carbon supported Pt catalyst electrode we conclude that (i) linearly and multiply bonded COad is the only adsorbed reaction product, that (ii) COad formation by CO2 reduction saturates after about 30min at coverages of about 0.45 monolayers (ML) at potentials between 0.06 and 0.2VRHE, and drops down to zero at 0.35VRHE, that (iii) in acidic solution COad formation is independent of the presence of H2 in the electrolyte, and that (iv) even at saturation COad coverage (0.45ML), under steady state conditions, hydrogen oxidation is hardly affected by the presence of CO2 in H2/CO2(20–25%) mixtures. The results indicate that CO2 reduction proceeds by reaction with coadsorbed Had rather than by reaction with dissolved H2 and is therefore favored in the H-upd region, i.e., at fuel cell relevant anode potentials. CO2 reduction is kinetically hindered by self-poisoning and blocking of Pt ensembles at COad coverages, which are still low enough for H2 oxidation. These limitations in CO2 reduction are responsible for the relatively small performance losses for PEFCs operating on H2/CO2 mixtures, compatible with a picture where H2 oxidation proceeds in holes of the CO adlayer, which are too small for CO2 reduction. [Copyright &y& Elsevier]

Abstract: This paper is an overview of the progress recently achieved in our laboratory in the development and application of four in situ methods; namely X-ray diffraction (both synchrotron-based and standard), Raman microscopy, differential electrochemical mass spectrometry (DEMS), and infrared spectroscopy. We show representative results on graphite electrodes for each method as an illustration, in particular (i) the influence of the lithium intercalation and graphite exfoliation on the shift of the (002)-reflection of graphite, (ii) Raman single point and mapping measurements of graphite surface, (iii) gas evolution during solid electrolyte interphase (SEI) formation on graphite electrodes, and (iv) the development of infrared spectra during the SEI formation in γ-butyrolactone based electrolytes. [Copyright &y& Elsevier]

Abstract: This paper deals with the kinetics of the reduction of nitric oxides by CO, which is a major reaction involved in automotive exhaust three-way catalysts. Spectroscopic and steady state kinetic measurements have been compared in order to explain the different selectivity behavior of Pt- and Rh-based catalysts, particularly during the cold start. It was found that in situ spectroscopy can be a useful tool either for stating on the nature of intermediates or checking the validity of a rate equation. Regarding the kinetics, subsequent calculations and comparisons of thermodynamic and kinetic parameters provide relevant information for modeling purposes. Also, it was found that our kinetic results can be correlated to surface modifications in the particular case of supported bimetallic Pt–Rh catalysts. [Copyright &y& Elsevier]

Abstract: Ketonization of acetic acid vapour over polycrystalline MgO was examined both kinetically and spectroscopically from room temperature to 480 °C. The kinetic study was performed with the use of a flow-reactor and gas chromatography, whereby the reaction rate and the catalyst selectivity were determined. The spectroscopic study was carried out by means of in situ infrared (IR) absorption measurement. Nature and products of adsorptive and absorptive interactions with the catalyst not only of the acid, but also of products of the reaction (acetone and CO2) were identified by in situ IR spectroscopy, and quantified by thermogravimetric analysis. Moreover, adsorption and surface reactions of methylbutynol molecules were observed by IR spectroscopy and utilized to probe specifically the availability on MgO surfaces of strong, reactive base (O2−) sites. The results could help to reveal the strong catalyst tendency towards absorption of the acid and CO2 molecules, and consequent formation of magnesium acetate and carbonate bulk phases, respectively. This unexpected behaviour of MgO, which enjoys high lattice (Mgnergy, was considered to be driven by the strong catalyst basicity (ionicity). Accordingly, the ketonization of acetic acid over MgO was found to occur via overlapping catalytic and pyrolytic routes. Reactive species and reaction pathways involved in each route were proposed. [Copyright &y& Elsevier]

The evolution with calcination of chromia samples of catalytic interest, prepared from gels with or without added ammonium nitrate, has been studied by thermogravimetry (TG) and differential thermal analysis (DTA). The low-temperature (77 K) adsorption of oxygen on alumina- and silica-supported samples of the former type has revealed the presence of monolayer and multilayer types of irreversibly adsorbed species. Low-temperature in situ infrared (IR) spectra show that the adsorption of oxygen is associated with the removal of a multiplicity of absorptions between 1100 and 730 cm-1. Probable types of surface species removed are Cr&z.dbnd6;O groups of Cr(VI)–O surface species, dichromates and chromates together with possibly peroxide; (O2)2-, the latter being associated with prominent bands near 800 cm-1. Room-temperature ex situ infrared spectra on an alumina-supported sample shows at lower frequencies the presence of the growth of α-Cr2O3 surface species after oxygen adsorption. [Copyright &y& Elsevier]

Simultaneous IR spectroscopic and catalytic measurements have been performed in order to investigate the nature of adsorbed species involved in the formation of N2O on Rh/Al2O3 in the course of the CO + NO reaction. Only nitrosyl species have been isolated that could be involved in the formation of N2 and N2O in accordance with previous kinetic investigations [Granger et al. J. Catal. 175(1998) 194]. Sequential and simultaneous NO and CO exposures lead to the observation of different nitrosyl species that could act as intermediates in the formation of N2 and N2O. Correlations between the appearance/disappearance of Rh(NO)δ+ species and an extra formation of N2O have been established. [ABSTRACT FROM AUTHOR]

Aspects of the surface pathway of the ethane oxidative dehydrogenation (ODH) were investigated by in situ infrared spectroscopy. Adsorption and surface reactions were studied on MoO3/Al2O3 and Al2O3, in order to investigate contributions of the support as well as selective and unselective routes of the ODH reaction. The interaction of ethane with the oxides was investigated at isothermal conditions (50 °C) in the absence and presence of oxygen by time resolved IR spectroscopy between 50 and 500 °C. Catalytic testing of these materials in ethane oxidative dehydrogenation showed that the molybdena catalyst is highly selective (initial C2H4 selectivity was 96%), while mainly COx was formed with alumina. The strong acid sites on alumina, detected by NH3-TPD, are speculated to be responsible for the unselective conversion of ethane to COx, while the moderate acid strength introduced by molybdena allows selective activation of ethane and inhibits the further oxidation of ethylene produced. The spectroscopic data indicate that the activation of the ethane C&z.sbnd;H bond proceeds through the formation of alkoxides, which decompose to ethylene and a surface OH group or are oxidized to surface bound oxygenates. MoO3/Al2O3 favors the first route, while pure alumina favors formation of oxygenates and full oxidation. [Copyright &y& Elsevier]

Oxalic acid adsorption has been studied at platinum single crystal electrodes belonging to the [0 1¯ 1] zone. Cyclic voltammetry and charge displacement experiments have been combined with in situ external reflection infrared experiments and results compared with those previously reported for the Pt(1 1 1) and Pt(1 0 0) electrodes. The spectroscopic data confirm the potential dependent behaviour of oxalic acid adsorption derived from the electrochemical experiments. At the same time, the infrared spectra show distinct C&z.sbnd;O stretching bands for adsorbates on (1 0 0) and (1 1 1) terraces. As previously concluded for Pt(1 0 0) and Pt(1 1 1) electrodes, oxalate and bioxalate anions are adsorbed, respectively, at the (1 0 0) and (1 1 1) terraces for potentials above 0.30 V. Oxalate and bioxalate anions adsorb at edge and step sites at potentials lower than at terrace sites. For Pt(2n−1,1,1) = Pt(S)[n(1 0 0) × (1 1 1)], bands are observed at potentials higher than 0.20 V that can be assigned to oxalate anions adsorbed at (1 0 0) edge sites and bioxalate adsorbed at (1 1 1) step sites. In the case of Pt(n+1,n−1,n−1) = Pt(S)[n(1 1 1) × (1 0 0)] electrodes, bands for oxalate anions adsorbed at the (1 0 0) step sites appears at potentials lower than bands for bioxalate adsorption at the (1 1 1) terrace sites. For all the stepped surfaces, adsorbed CO is slowly formed at the step sites in the hydrogen adsorption region. The extent of this process can be minimised during the collection of the infrared spectra by taking the reference spectrum at 0.20 V. [Copyright &y& Elsevier]

Oxalic acid adsorption and oxidation processes have been studied at platinum single crystal electrodes with basal orientations. Cyclic voltammetry and charge displacement experiments have been combined with in situ external reflection infrared experiments for the study of oxalic acid adsorption at potentials below 0.70 V. Whereas reversible anion-like adsorption is observed for Pt(100) and Pt(111) electrodes, oxalic acid is reduced at Pt(110) leading to the formation of an irreversibly bonded adsorbate which has been identified as adsorbed CO from the infrared spectra. Spectroscopic data confirm the potential dependent behaviour of oxalic acid adsorption on Pt(111) and Pt(100) electrodes derived from electrochemical data. At the same time, the infrared spectra show distinct C–O stretching bands for adsorbates on Pt(100) and P(111). In acidic solutions (pH = 1), for which oxalic acid and bioxalate anions predominate as solution species, oxalate anions are adsorbed at the Pt(100) electrode surface whereas bioxalate anions seem to be the adsorbed species at Pt(111). In neutral solutions, oxalate anions are adsorbed on both Pt(111) and Pt(100) surfaces. No intermediates coming from oxalic acid other than adsorbed CO for Pt(110) and adsorbed (bi)oxalate anions for Pt(111) and Pt(100) are detected during the oxidation of oxalic acid. Adsorbate bands are observed between 1400 and 1600 cm−1 for the Pt(111) electrode for potentials between 0.85 and 1.0 V. These bands are related to adsorbed carbonate anions formed in the presence of carbon dioxide molecules generated from oxalic acid oxidation. [Copyright &y& Elsevier]

Carbon monoxide oxidation on bare and Pt-modified ruthenium surfaces with the (101¯0) and (0001) orientations was investigated with cyclic voltammetry, scanning-tunneling microscopy and in situ Fourier transform infrared spectroscopy. Facile oxidation kinetics of CO on Ru(101¯0) are observed, in contrast with a slow reaction on Ru(0001). Scanning tunneling microscopy (STM) measurements confirmed that spontaneous deposition of Pt produces island-like structures on both single crystal Ru surfaces. CO oxidation on a bimetallic Pt/Ru(101¯0) surface with a Pt coverage of approximately one monolayer occurs at potentials that are 140 mV more negative than those for bare Pt. This potential is, however, more positive than the potential of the onset of the oxidation on Ru(101¯0). IR spectroscopy shows one peak for linearly adsorbed CO on bare and Pt-modified Ru(101¯0) surfaces, while two peaks are visible for the Pt-modified Ru(0001) structure. A single broad peak for the bimetallic Pt/Ru(101¯0) surface may result from addition of the red-shifted peak for Pt and the peak for the Ru(101¯0) substrate. A large red shift of CO on the Pt/Ru(101¯0) surface requires further work to be explained. A negative shift of CO oxidation on Pt/Ru(101¯0) indicates a decrease of the Pt&z.sbnd;CO bond strength on that surface compared with the bond with bulk Pt. [Copyright &y& Elsevier]

The electrooxidation of 2-methyl-5-amino-1,4-naphthoquinone (MANQ) on platinum or glassy carbon (GC) electrodes in acetonitrile leads to poly(2-methyl-5-amino-1,4-naphthoquinone) (PMANQ) films. Films were characterized by UV–VIS, X-ray photoelectron spectroscopy (XPS), ex situ FT-IR and in situ multiple internal reflection FT-IR spectroscopies (MIRFT-IRS). Results converge to a definition of the polymer structure, which is of the polyaniline type, bearing one methylquinone group per monomer unit. The electrochemical properties of PMANQ film in organic and aqueous media were studied by MIRFT-IRS and in situ d.c. conductivity. The film is conducting in negative as well as in positive potential range. [Copyright &y& Elsevier]