Four stainless steels and alloys (17-4 PH, X4CrNiMo 16-5-1, F6NM and UNS N09935) were evaluated in relation to their application in the oil and gas industry. These materials were tested in solutions exhibiting a range of chloride concentrations, pH values and temperatures of interest for the oil and gas producing environments. The pitting sensitivity was investigated by means of potentiodynamic polarisation measurements, based on the ASTM G61 standard, in conjunction with a morphological study performed by scanning electron and optical microscopy. The resistance to stress corrosion cracking (SCC) was evaluated in compliance with the ASTM G123 standard. Erosion–corrosion was assessed by exposing the materials under electrochemical control to a flux of erodent glass microspheres in a rotating disc electrode device. A ranking of the materials resistance was derived, based on appropriate parameters, devised to effectively and synthetically represent the complex sets of environments of interest for the relevant application. Our results showed, as expected, that UNS N09935 displays the best performance with respect to pitting resistance and susceptibility to SCC as well as a very good resistance to erosion–corrosion. Among the other investigated materials, 17-4 PH showed higher resistance to pitting, X4CrNiMo 16-5-1 and F6NM longer time to SCC failure while 17-4 PH and X4CrNiMo 16-5-1 exhibited superior ability to withstand erosion–corrosion damaging.

A detailed description of the preparation and management of reliable and safe corrosion laboratory experiments requiring the presence of hydrogen sulphide (H2S) is reported in this work. The adopted method is based on a modified Kipp’s apparatus allowing to produce on demand just the amount of H2S required for electrolyte saturation. Two benchmark corrosion cases were studied: electrochemical corrosion, monitored by means of potentiodynamic measurements, and sulphide stress corrosion cracking tests, both in H2S-saturated acidic aqueous chloride solutions. The sensitivity to H2S corrosion of a few classical materials of interest in the oil and gas sector, corrosion-resistant alloys, was then examined, proving as the presence of H2S leads to a denobling effect, increases the passive current density and influences significantly the time of cracking in the sulphide stress corrosion cracking tests.

The cathodic behavior of a model solid oxide electrolysis cell (SOEC) has been studied by means of near-ambient pressure (NAP) X-ray Photoelectron Spectroscopy (XPS) and Near Edge X-ray Absorption Fine Structure Spectroscopy (NEXAFS), aiming at shedding light on the specific role of the metallic component in a class of cermets used as electrodes. The focus is on the surface chemistry and catalytic role of Cu, the increasingly popular metallic component in electrodes used in CO2 electrolysis and CO2/H2O co-electrolysis. The NAP-XPS and NEXAFS results, obtained in situ and operando conditions and under electrochemical control, have provided important insights about the evolution of the chemical composition of the Cu surface. We have found that in dry CO2 ambient carbon deposits are scavenged at low cathodic potential by the oxidising action of nascent O, while at high cathodic polarisations C grows due to activation of CO reduction. Instead, in CO2/H2O mixtures, surface deposit of C is steady over the whole investigated potential range. The presence of adsorbed CO has also been detected during electrolysis of CO2/H2O mixtures, while no CO is found in pure CO2 ambient.

In this paper we report an SFG/DFG investigation of the adsorption of CN¯ –used as a probe molecule to study the electrochemical double-layer structure – at a polycrystalline Au electrode in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) amide ([BMP][TFSA]) room-temperature ionic liquid (RTIL). The adsorption of CN¯ yielded single SFG and DFG bands in the range from ca. 2125 to 2135 cm-1, exhibiting a Stark tuning of ca. 3 cm-1 V-1. Vibrational resonances – corresponding to modes of the RTIL coadsorbed with CN¯, were found in the range from ca. 1200 to 1500 cm-1. The study of the double-layer structure was complemented by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements, from which the differential double-layer capacity (CDL) was estimated.

A tapered-end flow Zn–air fuel cell (ZAFC), mechanically refuelable with Zn microspheres, was employed to study the effect of aging of KOH electrolyte on the Zn anode. A complete description of the architecture of the adopted cell is reported. The electrochemical characterization of the ZAFC was performed by long-term current discharge tests in galvanostatic mode. An insightful investigation on the particulate Zn anode consisting of spheres of diameter 0.4 mm was performed by means of X-ray diffraction (XRD), scanning electron microscope (SEM), and Raman spectroscopy in order to characterize the crystallographic structure, surface morphology, and chemical nature of residual metal and solid corrosion products. Electrochemical impedance spectroscopy (EIS) allowed to obtain information on the charge-transfer mechanism of zinc anode reaction and on the thickness, compactness, and blocking features of the passive film as a function of the aging of the electrolyte. The results of our analysis revealed the formation of a passive layer of zinc consisting of a white and porous film of ZnO precipitate (type I) and a light-gray to black compact film (type II). The failure of the particulate anode was chiefly caused by the increase in zincate concentration in the electrolyte, but it was enhanced by the nonuniform spatial current distribution due to the instability of the passive film at high pH.

Owing to their unique combination of wear resistance and toughness, cemented carbides are developing relevance in a systematically increasing number of applications, many of which involve notably corrosive environments. Petrochemical offshore extraction is one of the most appealing prospective fields of use of cemented carbides for critical general-purpose components (e.g. pumps and valves), as well as specialised devices, such as drilling mud circulation systems, as they undergo extremely severe erosion-corrosion related to the handling of tetraphasic flows comprising condensed and gas-phase hydrocarbons in addition to sand or other solid components of slurries. Moreover, oilfields of current interest bear high concentrations of strongly corrosive impurities. The present study is aimed at contributing to the knowledge of the corrosion and corrosion inhibition processes of a range of alloyed Co- and Ni-based cemented carbide grades in solutions containing cyanide (CN¯) and thiocyanate (SCN¯) - typical corrosive contaminants found in crude oil - and 2-mercaptobenzothiazole (MBT), a prospective corrosion inhibitor in the petrochemical field. To this aim, we employed: (i) linear sweep voltammetry (LSV) to assess the cathodic and anodic activity of the hardmetal grades; (ii) in situ Sum- Frequency Generation (SFG) spectroscopy as a sensitive probe of the potential-dependent interfacial chemistry and corrosion behaviour in terms of both adsorption and interaction of adsorbates with the electronic structure of the substrate; (iii) ex situ spectro-ellipsometry to characterise the films formed on the different grades in the investigated environments.We have found that: (i) the grade with Co‐Ru binder exhibits a generally better corrosion resistance in all investigated ambients; (ii) Ni affords protective action provided the oxidising power is below a given threshold and CN¯ is absent, and (iii) MBT improves the pseudopassivation of all the investigated cemented carbides. Typical potential-dependent SFG spectral scenarios have been pinpointed for the different electrode/electrolyte combinations, accurately matching the electrochemical behaviour assessed by LSV and the optical properties of the corroded surfaces investigated by spectro-ellipsometry. This multi-method study offers a comprehensive and insightful understanding of the corrosion of cemented carbides in contact with additive-containing solutions.

In this paper we study the corrosion of AISI 304 austenitic stainless steel PEMFC bipolar plates in aqueous and room-temperature ionic-liquid electrolytes. The anodic potential thresholds and dynamics have been investigated by electrochemical (potentiodynamic and potentiostatic) and in situ spectroelectrochemical methods (visible electroreflectance and VIS-UV spectroellipsometry). We measured the values of damage potentials and we followed the time evolution of corrosion current and reflectivity above and below the pitting potential, obtaining an accurate characterisation of the surface conditions under oxidative attack. The ability of AISI 304 to repassivate in Cl --containing aqueous solution as well as the amount of residual surface damage have been assessed quantitatively by following electrode reflectivity under applied potential. Outstanding inertness of AISI 304 in [BMP][TFSA] was proved. The results of this work show that low-cost AISI 304 is a promising interconnect material for both Nafion- and RTIL-based PEMFCs.

Fabrication and testing of fuel-cells based on nanofilm electrodes and interconnects is a hot technological challenge for three key reasons: (i) miniaturisation and integration into electronic devices as well as implementation of on-chip logics, (ii) testing of the performance of nano-materials on their real scale and (iii) use of cuttingedge material characterisation techniques. The principal interest of a nanotechnological approach to material problems in electrochemical energetics is particularly related to long-term durability issues of critically degradable components. Among the degradation modes, mechanical failure by cracking of the functional thin films is being recognised as a crucial one, impairing the implementation of laboratory systems into real-life devices. In this paper we report on corrosion-induced local thinning and correlated cracking of electrode components in a RTIL-based Proton Exchange Membrane Fuel Cell with Pt micro-particles as catalyst, Au feeder electrodes and Fe interconnects. In situ imaging of the multi-material system in electrochemical environment, based on X-ray scanning and optical microscopies, has disclosed the formation of complex cracking patterns, including spiral cracks. A simple mechanical explanation of the peculiar cracking pattern is proposed.

In a previous paper, we demonstrated the possibility of growing high-capacitance hybrid materials consisting of nanoporous gold (NPG)-supported MnO2 nanowires (NW) for supercapacitors, by electrochemical etching of electrodeposited single-phase Au-Mn alloys. The present paper concentrates on the electrodeposition of Au-Mn alloys from urea/choline-chloride ionic liquid solutions: the precursors of the high-capacitance hybrid material. The electrodeposition process, giving rise to alloys with 4-26% Mn content, was followed by space-resolved soft X-ray fluorescence (XRF) and absorption (XAS) microspectroscopy, complemented with electrochemical (cyclic voltammetry), structural (X-ray diffraction) and morphological (scanning electron microscopy) characterisations. The purposely developed electrochemical cells, exhibiting a specifically designed current density distribution, have allowed the quasi-in situ mapping of the local morphology-composition changes at the electrodes. Supersaturated Au-Mn solid solutions were obtained in the whole investigated compositional range under mass transport control of Mn. Variations in the Mn oxidation state were evidenced comparing low- and high-Mn content regions. It was found that, notwithstanding the heterogeneity of the current density, the morphologically compact high-Mn regions of the particular alloys with 20-26% Mn show a notable compositional homogeneity, rendering this material ideally suited for the fabrication of the target hybrid.

In two previous papers (C. Mele, M. Catalano, A. Taurino, B. Bozzini. Electrochim. Acta 87 (2013) 918; B. Bozzini, A. Gianoncelli, C. Mele, M. Kiskinova. Electrochim. Acta 114 (2013) 889), we have: (i) fabricated high-capacitance materials consisting of nanoporous gold (NPG)-supported MnO2 nanowires (NW), by electrochemical etching of single-phase Au-Mn alloys electrodeposited from a deep eutectic solvent (DES) electrolyte and (ii) investigated some aspects of the precursor Au-Mn alloy electrodeposition process by following it in situ with space-resolved soft X-ray fluorescence (XRF) and absorption (XAS) microspectroscopies: this study has allowed to single-out the peculiarities of elemental and chemical-state distribution that contribute to the nanostructure fabrication. The present paper completes the electrodeposition study by investigating the potential-dependent interfacial composition of the growing Au-Mn alloys by complementary in situ linear (Raman) and non-linear (Sum-Frequency Generation - SFG) vibrational spectroscopies. The results regarding alloy electrodeposition are compared to those obtained with a pure Au bath. In situ spectroscopy during electrodeposition reveals that both choline cation and urea are present at the growing metal/DES interface, coadsorbed with CN resulting from the decomposition of the Au complex. Electrostatic adsorption controls the surface coverage scenario at the Au/DES interface, while Mn favours the relative surface coverage with urea. Moreover, the interaction of urea with the metal film is modified by the addition of Mn, switching from solid-like to liquid-like at the Mn-alloying potential threshold. Also the CN adsorption scenario is sensitive to surface alloying: the Mn-containing interface shows two adsorption sites with lower degree of metal-adsorbate charge transfer. Finally, the degree of surface enhancement correlates well on the one hand with the applied potential and the interfacial chemistry, and on the other hand with the crystallite morphology induced by alloying Au with Mn. The correlation among the spectroelectrochemical scenario, the potential-dependent alloy composition and the crystallite shape expressed by this investigation fits within the framework set by recent modelling of dynamic electrodeposition morphochemistry and opens up novel opportunities for improving the control over the functional properties of net-shape electrodeposited materials

In this paper we report on the electrochemical reconstruction of a Tarentum hemiobolus Ag coin, severely corroded in marine environment. As assessed by conventional analytical tools, most of the initially metallic Ag coin had been converted to AgCl by exposure to the aggressive coastal burial conditions. X-ray computed microtomography proved that only small portions of the artefact had preserved their metallic nature. Since the engraving was preserved partly in the corrosion product bulk and partly in the metallic rests, electrodeposition of Ag from the AgCl layer, under controlled conditions ensuring shape preservation, resulted in the reconstruction of the coin surface with full recovery of the original engraving. Such optimal electrodeposition conditions were identified by a combination of electrochemical and quasi-in situ X-ray microtomography experiments, carried out with artificially corrored engraved Ag wires. Microtomography of the reconstructed coin confirmed the compaction of the external Ag layer and disclosed that the central core of the coin still contains unconverted AgCl. The presence of such a mineralised core does not however impact the numismatic use of the coin and the safeguard of the original engraving.

In this study an electrochemical approach is proposed for the fabrication of nanoporous gold (NPG)- supported manganese oxide nanowires. This method consists in: (i) electrodepositing an Au–Mn alloy, (ii) selectively corroding Mn under electrochemical control, forming simultaneously the NPG support and the functional Mn-oxide decorating the nanopores. The electrodeposition process is carried out from a bath based on eutectic urea/choline chloride ionic liquid. The electrochemical dealloying/oxidation step is performed in an aqueous solution. The oxidation process, performed by cyclic voltammetry (CV) in aqueous solution, has been monitored in situ by visible reflectivity measurements. The crystal structure and the morphology of the electrodeposited Au–Mn alloy have been examined by XRD and SEM, respectively. The 3D morphology of the nanostructure has been characterised by FIB/FEG-SEM. The specific capacity of NPG-supported nanostructured Mn-oxide has been measured by CV and found to be notably better than that of unsupported electrodeposited Mn-oxide nanowires.

Electrodeposition and ageing under oxygen reduction reaction (ORR) of Mn-X/PPy (X=Co, Mg, Ni; PPy=polypyrrole) and Mn-Ag/G (G=graphene) composite electrocatalysts have been studied by quasi-in-situ soft X-ray absorption and fluorescence microspectroscopy. The fabricated materials exhibit micro-grained morphologies in which Mn is present mainly as Mn2+, accompanied by combinations of Co0/Co2+ and Ni0/Ni2+. Ageing leads to the formation of progressively larger mesoscopic aggregates. Initial ageing yields more active Mn3+ and Mn4+, in agreement with an improved ORR behaviour. Prolonged ageing causes the loss of Mn3+ and Mn4+ from the surface, in correlation with a degradation of the ORR response. In the investigated ageing period, Mn-Mg/PPy exhibits the best durability, with about half of the catalyst grains still showing the presence of Mn3+/Mn4+, while the others consist mainly of Mn2+. In Mn-Ni/PPy, the Ni2+ content tends to increase with ageing whereas Co3+ forms in the Mn-Co/PPy composites.

In this research we have fabricated and tested Au/Dy2O3 composites for applications as Solid Oxide Fuel Cell (SOFC) electrocatalysts. The material was obtained by a process involving electrodeposition of a Au-Dy alloy from a urea/choline chloride ionic liquid electrolyte, followed by selective oxidation of Dy to Dy2O3 in air at high temperature. The electrochemical kinetics of the electrodeposition bath were studied by cyclic voltammetry, whence optimal electrodeposition conditions were identified. The heat-treated material was characterised from the morphological (scanning electron microscopy), compositional (X-ray fluorescence spectroscopy) and structural (X-ray diffractometry) points of view. The electrocatalytic activity towards H2 oxidation and O2 reduction was tested at 650 °C by electrochemical impedance spectrometry. Our composite electrodes exhibit an anodic activity that compares favourably with the only literature result available at the time of this writing for Dy2O3 and an even better cathodic performance.

In this paper we describe the one-pot fabrication of hydroxyapatite (HA)-heparin composites by electrodeposition onto Ti substrates and their characterisation in terms of structure, morphology, heparin content and bioactivity. HA coatings are well known and widely applied osteointegration enhancers, but post-implant healing rate in dental applications is still suboptimal: e.g. coagulation control plays a key role and the incorporation of an anticoagulant is considered a highly desirable option. In this study, we have developed an improved, simple and robust growth procedure for single-phase, pure HA-heparin films of thickness 1/3 l m. HA-heparin, forming nanowires, has the ideal morphology for bone mineralisation. Staining assays revealed homogeneous incorporation of sizable amounts of heparin in the composite films. The bioactivities of the HA and HA-heparin coatings on Ti were compared by HeLa cell proliferation/viability tests and found to be enhanced by the presence of the anticoagulant.

Electrodeposition of graphene-supported Co for ORR electrocatalysts from an acetonitrile solution has been studied by a multi-technique approach, combining a suite of spectroscopic methods with electrochemical measurements, allowing a molecular-level understanding of potentiostatic and pulsed-potential plating processes from the organic solvent onto a freestanding graphene film. The formation of the graphene film by the light-scribe approach has been monitored by Raman spectroscopy; the electrodeposition process has been clarified by cyclic voltammetry and the compositional and chemical-state distribution of Co have been investigated ex situ by soft X-ray absorption spectroscopy and fluorescence mapping, showing that both spatial distribution and valence state are homogeneous and independent of the local current density. The deposit consists in micrometric aggregates of Co/CoO nanoparticles with diameter ca. 30 nm (pulsed) and 200 nm (potentiostatic deposition). Potentiostatic deposition allows to obtain better ORR electrocatalytic perfomance in terms of nnumber of transferred electrons, onset/ half-wave potential and current density.

In this paper the electrodeposition of DLC films on carbon steel from aqueous acetic acid solutions and their structural and mechanical characterization are reported. The process is performed at room temperature at relatively low cell voltages (from 28 to 220 V) with entirely environmentally friendly chemicals. Qualitative and quantitative evaluation of C hybridisation type have been performed by Raman spectroscopy. Microhardness and adhesion of the supported electrodeposited films have been measured by micro-indentation and scratch-testing. Notably, ductile failure was found to correspondence to a wide range of film growth conditions. The corrosion resistance of DLC-coated steel has been assessed by electrochemical impedance spectrometry in a neutral chloride solution. Optimal electrodeposition conditions were identified for the formation of high-quality DLC films ca. 270 nm thick with a high content of diamondcoordinated carbon and an ideal combination of hardness and adhesion; films formed under these conditions also confer some degree of corrosion protection to the steel substrate.

Synchrotron-based soft-X-ray imaging and microspectroscopy with sub-micrometer spatial resolution are used to investigate the electrodeposition of Mn-Cu-ZnO, a prospective active material for supercapacitors. This study is focused on the correlation of the local current density and the spatial distribution of the composition and chemical-state in electrodeposits grown potentiostatically at -0.7V (vs a saturated calomel electrode), as well as the optimal potential for the achievement of high specific capacitance and cycling stability. The morphology, elemental distribution, and the local chemical state of both the electrode deposits and the grown dendrite structures are followed by using X-ray imaging, X-ray fluorescence mapping, and X-ray absorption microspectroscopy. For transmission soft-X-ray measurements, a thin-layer Hull-type microcell is developed and fabricated by using electron-beam lithography. The information obtained for the spatial distribution of the deposit is complemented by using electrochemical measurements and numerical simulations.

Ni-cerium oxide coatings were electrodeposited from particle-free aqueous baths containing NiCl2.6H2O and CeCl3.7H2O. The mechanism of deposition was studied systematically by a combination of voltammetric, in situ spectoelectrochemical (visible reflectivity VRS, surface Raman spectroscopy SRS), ex situ spectroscopic (spectroscopic ellipsometry SE) methods, as well as by SEM imaging; yielding details on the steps of the composite formation process. Time- and potential-dependent ERS data were interpreted on the basis of an optical model, accounting for the formation of metal and ceramic phases and corresponding relative distribution and morphology. In the ERS curves measured with the pure Ni and Ce-containing solutions, the value of reflectivity drops sharply when the potential is lower than ca. -0.9 V. The ERS curves measured in the Ce-containing solutions exhibit a second drop when the potential is lower than ca. -1.1V while, instead, for pure Ni solution an increase in reflectivity is observed. According to the proposed optical model, the drop found in the reflectivity transient can be explained with the nucleation of Ni on the Cu substrate, while the second one measured with Ce-containing solutions is due to secondary nucleation of Ni. The results showed that the deposition processes of Ni and Ni-cerium oxide can be divided into 2 and 4 stages respectively. (i) In the case on Ni: nucleation and 3D growth, accompanied by roughening; (ii) as far as Ni-cerium oxide is concerned: nucleation, formation of cerium oxide, secondary nucleation and 3D growth and roughening.

Cobalt/polypyrrole ORR electrocatalysts has been electrochemically synthesized by a potentiostatic anodic/cathodic pulse-plating procedure. The deposition electrochemistry has been studied by cyclic voltammetry and in-situ Micro Raman Spectroscopy complemented with scanning X-ray microscopy and micro-spot X-ray absorption spectroscopy (mu-XAS). Linear sweep voltammetry (LSV) under oxygen reduction has been used to assess the electrocatalytic effect of as-electrodeposited Co/PPy. The obtained results have provided new information about the concomitant electropolymerisation and metal incorporation processes occurring under different pulsed co-electrodeposition conditions, important for optimising the electrosynthesis procedure. The colocation of O and Co, evidenced by the O and Co XRF maps indicates that the Co in the formed composite is in oxidized state and for composites formed at low currents using shorter Co pulses coexistence of both CoO and Co3O4 is evidenced by the Co L-3 XAS spectra. Bimodal Co distribution as micro-grains on a background of nano-grains and co-nulcleation of PPy and Co is evidenced by correlation of Co and N XRF maps.

In this work glucose (G), α-cyclodextrin (α-CD) and sodium salt of carboxymethyl cellulose (CMCNa) are used as dispersing agents for graphene oxide (GO), exploring the influence of both saccharide units and geometric/steric hindrance on the rheological, thermal, wettability and electrochemical properties of a GO/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) nanocomposite. By acting on the saccharide-based additives, we can modulate the rheological, thermal, and wettability properties of the GO/PEDOT:PSS nanocomposite. Firstly, the influence of all the additives on the rheological behaviour of GO and PEDOT:PSS was investigated separately in order to understand the effect of the dispersing agent on both the components of the ternary nanocomposite, individually. Subsequently, steady shear and dynamic frequency tests were conducted on all the nanocomposite solutions, characterized by thermal, wettability and morphological analysis. Finally, the electrochemical properties of the GO/ PEDOT composites with different dispersing agents for supercapacitors were investigated using cyclic voltammetry (CV). The CV results revealed that GO/PEDOT with glucose exhibited the highest specific capacitance among the systems investigated.

Electrical energy storage based on Zn-air concepts is experiencing increasing interest for applications ranging from consumer electronics to automotive and grid storage, owing to their high energy density, intrinsic safety, environmental friendliness and low cost. Their implementation is nevertheless daunted by veral materials-science riddles, affecting the actually available power density and durability. In this scenario, in operando dynamic physico-chemical information at lengthscales between mesoscopic and nanometric is highly desirable for knowledge-based advancements. This overview summarises recent contributions of in situ and quasi-in situ X-ray methods - absorption and fluorescence microspectroscopies, microtomography - to studies of cathodes, anodes and model cells.

This paper reports the first in-situ synchrotron-based scanning photoelectron microscopy study of an operating YSZ-supported single-chamber SOFCwith Au–MnO2 composite cathode and NiO anode, fedwith 10−5 mbar 1:1 mixture of CH4 fuel and O2 at 650 °C.We employed a YSZ-supported cell with Au–MnO2 composite cathode and NiO anode. The chemical imaging and micro-XPS results were complemented with simultaneous electrochemical measurements, open circuit potential, potentiostatic and impedance spectrometry. The cell was operated under two conditions: (i) with fully oxidized electrodes and (ii) after in-situ reductive activation of the anode. The current delivered by the cell after in-situ reduction was about one order of magnitude higher. The chemical states of Ni and Mn were affected by the in-situ reduction process but they were not modified by the fuel-cell operation. Notwithstanding the absence of chemical state transformations of the electrode materials during the prolonged fuel-cell operation, cell aging brings about morphological change, accompanied by a decrease of the extracted current.

This paper reports a pioneering application of soft X-ray imaging and spectromicroscopy to a hot material stability issue in fuel-cell (FC) technology: the corrosion of metallic bipolar plates in ionic-liquid-based nano polymer electrolyte membrane (PEM) FCs. Using the potential of the X-ray scanning microscopy for in situ characterisation of complex multi-material systems in electrochemical environments with sub-micrometer lateral resolution, we study the electrochemical behaviour of Fe electrodes in contact with the room-temperature ionic liquid (RTIL)1-butyl-1-methyl-pyrrolidinium bis (trifluoromethylsulfonyl) amide ([BMP][TFSA]) in a nano fuel-cell fabricated by lithography. Thanks to the properties of this RTIL, an open electrochemical cell could be used in vacuum (10-6 mbar). The possibility of imaging electrochemically induced morphological features in conjunction with local spectroscopic analysis, yields details of the space distribution and chemical correlations of the corrosion products.

This research addresses the problem of localised corrosion of stainless steel PEMFC bipolar plates. The susceptibility to pitting and crevice corrosion of austenitic AISI 304 stainless steel has been investigated both by post-mortem microscopic analysis of the end-plates of a laboratory single-cell and by studies of electrochemically corroded stainless steels, in the presence of specially-designed crevice-formers simulating the operating conditions of a PEMFC. This work is based on optical and scanning-electron microscopies as well as potentiostatic and potentiodynamic measurements. The crevice-formers we considered were: Teflon, graphite and AISI 304. The samples, coupled to the crevice-formers have been tested in aqueous solutions containing Cl−, SO4 2− and F−. From the E–log i plot, the values of corrosion, pitting, crevice and protection potential have been obtained and perfect and imperfect passivity conditions have been identified.

This paper offers an overview of morphogenetic processes going on in metal electrodeposition processes and provides a systematisation of the morphology classes identified experimentally in terms of an electrokinetic theory accounting for charge-transfer and masstransport rates. In addition, it provides a review of the modelling work by the authors, based on a reaction-diffusion system coupling morphology with surface chemistry of the growing metal and briefly describes the experimental validation of the model.

The stability of pyrolyzedMn–Co/polypyrrole (PPy) nanocomposites towards theOxygen Reduction Reaction (ORR) in alkaline solution,was studiedwith a close-knit group of complementarymicroscopic and space-resolved spectroscopic approaches: Atomic Force Microscopy (AFM), Scanning and High-Resolution Transmission Electron Microscopy (SEM, HRTEM) and identical-location Scanning PhotoElectron Microscopy (SPEM). Tracking quasi-in situ the morphochemical evolution of the Mn–Co/PPy catalyst upon electrochemical aging under ORR conditions by this multi-technique approach, has allowed to clarify the key physico-chemical processes underlying the dramatic impact of Co additions to stability improvement.

In this paper we present an extension of a mathematical model for the morphological evolution of metal electrodeposits – recently developed by some of the authors – accounting for mass-transport of electroactive species from the bulk of the bath to the cathode surface. The implementation of mass-transport effects is specially necessary for the quantitative rationalisation of electrodeposition processes from ionic liquids, since these electrolytes exhibit a viscosity that is notably higher than that of cognate aqueous solutions and consequently mass-transport control is active at all practically relevant plating rates. In this work we show that, if mass-transport is coupled to cathodic adsorption of ionic liquid species and surface diffusion of adatoms, it can lead to electrodeposit smoothing. This seemingly paradoxical theoretical result has been validated by a series of Mn electrodeposition experiments from aqueous baths and eutectic ionic liquids. The latter solutions have been shown to be able to form remarkably smoother coatings than the former ones. Mn electroplates have been proposed for Cd replacement and their corrosion protection performance seems comparable, but so far the required surface finish quality has not been achieved with aqueous electrolytes. Ionic liquids thus seem to provide a viable approach to aeronautic-grade Mn electroplating.

This paper reports on the electrodeposition of Mn-Cu-ZnO for hybrid supercapacitors. This material exhibits a dual structure consisting of Mn-rich highly active, but poorly electronically conducting, grains, which are locked by a Cu-rich highly conductive network that also possesses some degree of charge-storage capacity. This work focuses on morphological, compositional, and chemical-state distributions with submicrometer lateral resolution. This information, which is crucial because doping distribution controls supercapacitor performance, has been obtained by combining electrochemical and in situ Raman measurements with synchrotron-based X-ray fluorescence and absorption microspectroscopy. Using a microfabricated thin-layer three-electrode microcell, we followed the morphochemical changes at different electrodeposition stages and found that pulse-plating allows the growth of Mn-and Cu-doped ZnO as self-organized structures with a consistent spatially stable composition distribution.

A corrosion and electrodeposition study of a Zn electrode in 5.3 M KOH, used as a model system for the anode of a secondary Zn–air battery, was performed by means of electrochemical and spectroelectrochemical techniques. The formation of a zinc oxide passive film and its cathodic removal were monitored by electroreflectance spectroscopy, spectroellipsometry and optical second harmonic generation. A dynamic optical model of the growth pathway, morphology and failure modes of the interfacial Zn oxide films was proposed to rationalise the electrokinetics of the secondary battery anode. Some experiments were performed in the absence and in the presence of polyethylene glycol. In situ spectroscopy confirmed and placed on a molecular basis the well-known formation of more compact and uniform electrodeposits crucial for secondary batteries. Keywords Zn–air batteri

In view of improved durability, the study of electrocatalyst supports for PEMFCs alternative to carbon is raising notable research interest. In this paper we investigated the oxidation of ethanol onWC-supported electrodeposited Pt, in pristine and aged conditions by: (i) electrochemical measurements, (ii) in situ spectroscopy (FTIR and sum-frequency generation spectroscopy (SFG)) carried out during the electrooxidation of ethanol and (iii) ex situ synchrotron-based space-resolved photoelectron spectroscopy (SPEM). The complementarity of FTIR and SFG allows an insightful understanding of the electrochemical interface as a function of applied potential and catalyst ageing. In situ FTIR and SFG revealed adsorbed acetate and ethanol, in addition to linearly and bridge-bonded CO and solution-phase CO2. The Stark tuning of CO indicates that it is less strongly bonded to aged electrodes. Quantitative analysis of potential-dependent FTIR and SFG spectra reveals that the population of adsorption sites for CO, acetate and ethanol changes with ageing and correlates with loss of catalytic activity. Changes in catalyst morphology as well as Pt and WC chemical state have been pinpointed by SPEM: electrodeposited Pt nanoparticles tend to agglomerate and the distribution of oxidised and reduced forms of Pt and W correlates with the attack of the catalyst support.

The mechanical and electrochemical behavior of ultrasonic spot welded hybrid joints, made of AA5754 aluminum and carbon fiber reinforced epoxy with a co-cured thermoplastic surface layer, was studied. The effect of the welding parameters (energy and force) and the thickness of a thermoplastic film, applied as an upper ply in the composite lay-up, on the development of adhesion strength, was investigated. The best mechanical results were obtained when the welding parameters were able to achieve a large bonding area of mechanical interlocking between naked carbon fibers and aluminum and a better load distribution. The electrochemical results excluded the possibility of galvanic corrosion between aluminum and composite adherends thanks to the insulating action provided by the thermoplastic film