This paper reports on the quantitative assessment of the oxygen reduction reaction (ORR) electrocatalytic activity of electrodeposited Mn/polypyrrole (PPy) nanocomposites for alkaline aqueous solutions, based on the Rotating Disk Electrode (RDE) method and accompanied by structural characterizations relevant to the establishment of structure-function relationships. The characterization of Mn/PPy films is addressed to the following: (i) morphology, as assessed by Field-Emission Scanning Electron Microscopy (FE-SEM) and Atomic Force Microscope (AFM); (ii) local electrical conductivity, as measured by Scanning Probe Microscopy (SPM); and (iii) molecular structure, accessed by Raman Spectroscopy; these data provide the background against which the electrocatalytic activity can be rationalised. For comparison, the properties of Mn/PPy are gauged against those of graphite, PPy, and polycrystalline-Pt (poly-Pt). Due to the literature lack of accepted protocols for precise catalytic activity measurement at poly-Pt electrode in alkaline solution using the RDE methodology, we have also worked on the obtainment of an intralaboratory benchmark by evidencing some of the time-consuming parameters which drastically affect the reliability and repeatability of the measurement.

This paper reports an in situ study of the anodic behavior of a model solid oxide electrolysis cell (SOEC) by means of near-ambient pressure X-ray Photoelectron Spectroscopy (XPS) combined with near edge X-ray absorption fine structure (NEXAFS) measurements. The focus is on the anodic surface chemistry of MnOx, a model anodic material already considered in cognate SOFC-related studies, during electrochemical operation in CO2, CO2/H2O and H2O ambients. The XPS and NEXAFS results we obtained, complemented by electrochemical measurements and SEM characterisation, reveal the chemical evolution of Mn under electrochemical control. MnO is the stable chemical form at open-circuit potential (OCP), while Mn3O4 forms under anodic polarisation in all the investigated gas ambients. Carbon deposits are present on the Mn electrode at OCP, but they are readily oxidised under anodic conditions. Prolonged operation of the MnOx anode leads to pitting of the Mn films, damaging of the triple-phase boundary region and also to formation of discontinuities in the Mn patch. This is accompanied by chemical transformations of the electrolyte and formation of ZrC without impact on the surface chemistry of the Mn-based anode.

CeO2 and Co containing CeO2 thin films were deposited on indium tin oxide and stainless steel by anodic electrodeposition. Scanning electron microscopy showed that the films are flat and show globular morphology and cracks resulting from volume shrinking. According to XRD and Raman Spectroscopy pure ceria layers are crystalline, while the presence of Co induces the formation of amorphous films. The good adhesion and the compactness allowed the photoelectrochemical characterization of the films. A band gap value of 2.9 eV was estimated for CeO2, while slightly higher values (̃3.0 eV) were estimated for Co containing films. A mechanism for ceria anodic electrodeposition is proposed and discussed.

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.

Free-standing Chitosan/phosphotungstic acid polyelectrolyte membranes were prepared by an easy and fast in-situ ionotropic gelation process performed at room temperature. Scanning electron microscopy was employed to study their morphological features and their thickness as a function of the chitosan concentration. The membrane was tested as proton conductor in low temperature H2–O2 fuel cell allowing to get peak power densities up to 350 mW cm−2. Electrochemical impedance measurements allowed to estimate a polyelectrolyte conductivity of 18 mS cm−1.

Low energy X-ray fluorescence (XRF) and soft X-ray absorption (XAS) microspectroscopies at high space-resolution are employed for the investigation of the coelectrodeposition of composites consisting of a polypyrrole(PPy)-matrix and Mn-based ternary dispersoids, that have been proposed as promising electrocatalysts for oxygen-reduction electrodes. Specifically, we studied Mn–Co–Cu/PP, Mn–Co–Mg/PPy and Mn–Ni–Mg/PPy co-electrodeposits. The Mn–Co–Cu system features the best ORR electrocatalytic activity in terms of electron transfer number, onset potential, half-wave potential and current density. XRF maps and micro-XAS spectra yield compositional and chemical state distributions, contributing unique molecular-level information on the pulse-plating processes. Mn, Ni, Co and Mg exhibit a bimodal distribution consisting of mesoscopic aggregates of micrometric globuli, separated by polymer-rich ridges. Within this common qualitative scenario, the individual systems exhibit quantitatively different chemical distribution patterns, resulting from specific electrokinetic and electrosorption properties of the single components. The electrodeposits consist of Mn3+,4+-oxide particles, accompanied by combinations of Co0/Co2+, Ni0/Ni2+ and Cu0,+/Cu2+ resulting from the alternance of cathodic and anodic pulses. The formation of highly electroactive Mn3+,4+ in the as-fabricated material is a specific feature of the ternary systems, deriving from synergistic stabilisation brought about by two types of bivalent dopants as well as by galvanic contact to elemental metal; this result represents a considerable improvement in material quality with respect to previously studied Mn/PPy and Mn-based/PPy binaries.

New experimental evidence concerning the formation of La(OH)3 nanowires on anodic alumina membranes by cathodic polarization in 0.05M lanthanum nitrate solution is provided to further support the conclusions previously reached in our work (Bocchetta et al 2007 Electrochem. Commun. 9 683-8) and recently criticized by Gonzlez-Rovira et al (Nanotechnology 2008 19 495305). Some unconvincing aspects of the paper of Gonzlez-Rovira et al, according to which the same electrochemical process should lead to the formation of hydroxycarbonate nanotubes, are also discussed.

Cs0.86(NH4)1.14SO4Te(OH) 6 supported by anodic alumina membranes (AAMs) has been characterized for the first time in H2/O2 fuel cell. The fabricated membrane electrode assemblies are able to produce peak power densities in the range 15-30 mW cm-2 under mild conditions (room temperature, low humidity and low Pt loading) and show an increased durability with cycling with respect to previous results obtained with AAM-based fuel cell. The physico-chemical characterization of the electrolytes has been carried out through X-ray diffractometry, scanning electron microscopy and micro-raman analysis. An estimation of the composite membranes conductance under fuel cell operation has been carried out from I-V characteristics and EIS measurements at room temperature.

The electrochemical fabrication of a hybrid inorganic-organic field effect transistor (IOFET) is described. Ti-Zr mixed oxide (dielectric permittivity ∼45) grown by anodizing has been used as a dielectric, while 3,4-polyethylenedioxythiophene has been employed as a semiconducting polymer. The polymerization of 3,4-ethylenedioxythiophene on the oxide has been realized by a photoelectrochemical process. The metal/oxide/polymer junctions have been investigated by photocurrent spectroscopy and scanning electron microscopy. The output transistor characteristics have been recorded in order to test the performance of the junctions in the IOFET structure.

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.

Electrodeposition of manganese/polypyrrole (Mn/PPy) nanocomposites has been recently shown to be a technologically relevant synthesis method for the fabrication of Oxygen Reduction Reaction (ORR) electrocatalysts. In this study we have grown such composites with a potentiostatic anodic/cathodic pulse-plating procedure and characterised them by a multi-technique approach, combining a suite of in situ and ex situ spectroscopic methods with electrochemical measurements. We have thus achieved a sound degree of molecular-level understanding of the hybrid co-electrodeposition process consisting of electropolymerisation of polypyrrole with incorporation of Mn. By in situ Raman spectroscopy we followed the formation of MnOx and the polymer by monitoring the build-up and development of the relevant vibrational bands. The compositional and chemical-state distribution of the as-deposited material has been investigated ex situ by soft X-ray fluorescence (XRF) mapping and micro-absorption spectroscopy (micro-XAS). XRF shows that the spatial distribution of Mn is consistent in a rather wide range of current densities (c.d.s), while micro-XAS reveals a mixture of Mn valencies, with higher oxidation states prevailing at higher c.d.s. Pyrolysis of electrodeposits, desirable for obtaining more durable and active catalysts, has been followed in situ by photoelectron microspectroscopy, allowing to assess the evolution of: (i) the electrodeposit morphology, resulting in a uniform distribution of nanoparticles; (ii) the chemical state of manganese, changing from a mixture of valences to a final state consisting of Mn(III) and Mn(IV) oxides and (iii) the bonding nature of nitrogen, from initially N-pyrrolic to a combination of pyridinic and Mn–N/graphitic.

An anodic electrodeposition process is proposed to prepare CeO2 and Co-doped CeO2 nanotubes. Anodic alumina membrane is used as template and linear sweep voltammetry is employed to allow the formation of nanotubes without alumina dissolution. SEM micrographs showed large arrays of well defined and aligned NTs, which resulted to be crystalline soon after deposition according to XRD diffraction patterns and Raman Spectroscopy.

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.

Understanding the lateral variations in the elemental and chemical state of constituents induced by electrochemical reactions at nanoscales is crucial for the advancement of electrochemical materials science. This requires in situ studies to provide observables that contribute to both modeling beyond the phenomenological level and exactly transducing the functionally relevant quantities. A range of X-ray coherent diffraction imaging (CDI) approaches have recently been proposed for imaging beyond the diffraction limit with potentially dramatic improvements in time resolution with chemical sensitivity. In this paper, we report a selection of ptychography results obtained in situ during the electrodeposition of a metal–polymer nanocomposite. Our selection includes dynamic imaging during electrochemically driven growth complemented with absorption and phase spectroscopy with high lateral resolution. We demonstrate the onset of morphological instability feature formation and correlate the chemical state of Mn with the local growth rate controlled by the current density distribution resulting from morphological evolution.

Gadolinium-ceria solid solution nanowires with tunable composition have been prepared through template cathodic electrodeposition from solutions containing Ce 3+Gd 3+ in a variable ratio. The employed template is Porous Anodic Alumina because it can function as thermal resistant separator supporting the nanowires if used as ionic conductor in Solid Oxide Fuel Cell (SOFC). Scanning Electron Microscopy of the deposited nanostructures revealed that the use of ethanol as solvent and metal chloride as electrolyte allowed to prepare continuous, compact and well defined nanowires with morphological features stable even after thermal treatment. EDX compositional analysis confirms the presence of both Ce and Gd in the nanowires with an atomic ratio very close to the Ce/Gd in the electrodeposition bath. X-ray diffraction analysis and Raman Spectroscopy revealed the formation of a solid solution of Gd-Ce oxide nanowires.

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 study, at the first an alumina substrates with oriented nanochannels were prepared via controlled anodizing process. Then structurally modified chitosan macromolecules with binary cross-link agents at optimum composition (12 and 2 wt. % of sulfosuccinic acid and glutaraldehyde) was introduced in the nanopores of inorganic substrate. Scanning electron microscope approved the uniform presence of a chitosan based nanorods inside the nanochannels of alumina substrate.

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.

The photoelectrochemical polymerization of poly(3,4-ethylenedioxythiophene) , PEDOT, was successfully realized on anodic film grown to 50 V on magnetron sputtered niobium. Photocurrent Spectroscopy was employed to study the optical properties of Nb/Nb2O5/PEDOT/electrolyte interface in a large range of potential, and to get an estimate of the band gap and flat band potential of both the oxide and the polymer. Scanning Electron Microscopy was used to study the morphology of PEDOT. Both the optical and morphological features of the photoelectrochemically grown polymer were compared with those showed by PEDOT electropolymerized on gold conducting substrate.

This study dealswith themorphological and chemical-state changes caused by the degradation of nanocomposite electrocatalysts – fabricated by pulsed potentiostatic co-electrodeposition and subsequently pyrolysed – under oxygen reduction reaction (ORR) conditions in aqueous alkaline solution. Variations in shape, dimensions and chemical state of theMn-centres were followed by quasi-in situ synchrotron-based scanning photoelectron microscopy with submicron lateral resolution, combined with ex situ Raman measurements, in correspondence of different cyclovoltammetric ageing stages. The decline of the electrocatalytic performance is accompanied by size variations of theMnOx particles that are initially ~30nmin diameter, then shrink to ~10nmand subsequently grow to ~45 nmafter prolonged ORR. Concerning chemical state, the pristine Mn0,II nanoparticles are converted to MnIII,IV oxy-hydroxides as a result of a dissolution/redeposition process favoured by the oxygen environment.

Stoichiometric CdSe nanotubes (NTs) with a length of ∼ 700 nm have been successfully grown by one-step electrochemical technique into Anodic Alumina Membranes. Ciclovoltammetric method has been performed using porous anodic alumina as template electrode and an electrochemical bath containing Cd2+ ions and SeO2. The as-prepared NTs have been identified as face-centred-cubic CdSe by XRD, while Micro-Raman analysis reveals the typical peaks of nanostructured CdSe. The stoichiometric deposition of CdSe NTs formation is suggested by EDX analysis, with an average atomic percentage of Cd:Se of ∼ 0.93. Photoelectrochemical measurements reveal that CdSe NTs are photoactive materials with direct band gap of 1.75 eV and n-type semiconducting behaviour.

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.

an electrochemical reactor for the preparation of self-supported comparatively thin (up to 10 μm) and large area (up to 50 cm2) anodic alumina membranes is described allowing growth of porous alumina at high applied potential (up to 150 V) without burning. Residual Al and barrier oxide beneath the porous film are dissolved through a vessel equipped with a gaskets system, which allows to expose to the dissolving solution an Al area lower than the anodised surface on the front leading to self-supported alumina membranes. According to scanning electron microscopy inspection and Hg-porosity measurements, the anodizing cell and conditions lead to the production of 25 and 50 cm2 Al2O3 porous layers with structural and morphological features very similar to those shown by commercial membranes (pore diameters 200 nm and pore densities 1012 pores/m2). The application of such large area membranes as support of inorganic proton conductors in thin film fuel cell proves their performance scalability. In the last decade, a significant

Hydrous films were grown on high purity and cubicity Al foils for electrolytic capacitors in deionized water, ethylene glycol - deionized water and in glycerol - deionized water for different immersion times. According to the X-ray diffraction patterns the hydration treatment allowed to grow a pseudo boehmite layer on Al surface whose morphology is appreciably affected by the bath composition. Capacitance measurements and photoelectrochemical findings suggest that a more compact barrier layer forms during the immersion in alcohol containing solutions. The hydration in water allowed to save energy and to prepare more blocking oxide films. The beneficial effect of hydration in hot water on the specific capacitance was evidenced only for films formed at 300 V due to the crystallization of amorphous alumina in y’-Al2O3.