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• The corrosion of multiphase al-zr-fe alloys containing intermetallics was studied in aqueous solutions of 3.5 % NaCl, H 3 BO 3 and 3.5 % nacl + H 3 BO 3. • 8-week immersion corrosion tests in 3.5 % nacl at 40 °C confirmed different corrosion mechanisms between Al 71 Zr 24 Fe 5 and Al 65 Zr 20 Fe 15 alloys. • High volta potential differences between al-zr and al-fe-zr phases were registered using SKPFM. • The Al 65 Zr 20 Fe 15 alloy was characterized by greater wear resistance in dry conditions and corrosive solutions. • Severe delamination and brittle fracture mechanism was identified for the Al 71 Zr 24 Fe 5 alloy after tribological tests. In this study, the structure of Al 65 Zr 20 Fe 15 and Al 71 Zr 24 Fe 5 alloys was studied using neutron diffraction and SEM with EDX maps. This paper presents the electrochemical measurement results performed in 3.5 % NaCl, H 3 BO 3 , and 3.5 % NaCl+H 3 BO 3 solutions at 40 °C. The Al 71 Zr 24 Fe 5 alloy showed higher corrosion resistance in acidic solution, whereas the Al 65 Zr 20 Fe 15 alloy was more resistant in 3.5 % NaCl+H 3 BO 3. Moreover, the corrosion behavior was described for the samples immersed for 8 weeks in 3.5 % NaCl at 40 °C. SKPFM indicated high Volta potential differences between Al-Zr and Al-Fe-Zr phases. Moreover, the higher wear resistance for Al 65 Zr 20 Fe 15 compared to the Al 71 Zr 24 Fe 5 alloy was demonstrated. [ABSTRACT FROM AUTHOR]

• [Mn(H 2 O) 6 ]2+ can accumulate in oriented sulfonate-functionalized silica thin films. • Their reaction with Na 2 WO 4 ●2H 2 O enables in situ' synthesis of a polyoxometalate. • The immobilized [Mn(H 2 O) 3) 2 (H 2 W 12 O 42)] n 6n- polyoxometalate is electroactive. • [Mn(H 2 O) 3) 2 (H 2 W 12 O 42)] n 6n- in silica exhibits good voltammetric operational stability. We present in this paper the 'in situ' preparation of manganese-containing polyoxotungstate [Mn(H 2 O) 3) 2 (H 2 W 12 O 42)] n 6n- (1) chains in vertically-oriented mesoporous silica thin films on indium-tin oxide (ITO) electrodes. Taking advantage of a soft sequential method allowing the formation of 1 inside the mesoporous matrix, we succeed in its 'in situ' formation according to two main steps: (i) a first one consisting of the immobilization of [Mn(H 2 O) 6 ]2+ in sulfonate-functionalized silica thin films; and (ii) a second one involving the reaction of the [Mn(H 2 O) 6 ]2+ moieties with Na 2 WO 4 2H 2 O. The electrochemical characterization of the functionalized materials obtained clearly demonstrates that the content of sulfonate groups in the starting films is a critical parameter to get the expected electroactive [Mn(H 2 O) 3) 2 (H 2 W 12 O 42)] n 6n- compound inside the silica nanochannels. The experimentally determined chemical composition of the films performed by X-ray Photoelectron spectroscopy (XPS) is in good agreement with the expected composition of 1 in the case of films obtained with the optimal content of sulfonate functions (i.e. , 5–6.5 % sulfonate with respect to silica). Energy Dispersive analysis of X-rays coupled with Transmission Electron Microscopy (TEM-EDX) carried out on the cross section of the films show that a uniform composition in terms of Mn/W ratio is obtained after the functionalization process. This confirms the formation of [Mn(H 2 O) 3) 2 (H 2 W 12 O 42)] n 6n- uniformly within the whole thickness of the silica film (i.e. , 80 nm), explaining also the long-range charge transfer reactions occurring through such insulating silica membrane. Using sulfonated silica films as template, we develop a robust 'in situ' synthesis strategy to assemble 1D linear polyoxotungstates onto ITO electrodes, exhibiting a stable electrochemical response once confined within the silica nanochannels. [ABSTRACT FROM AUTHOR]

An investigation of the solid electrolyte interphase (SEI) on hard carbon (HC) anodes in aprotic sodium batteries was carried out by post-mortem analyses. Electrodes cycled in 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIFSI), and N-trimethyl-N-butylammonium bis(fluorosulfonyl)imide (N 1114 FSI) ionic liquid electrolytes have been collected and studied: benchmark electrodes cycled in commercial organic solutions were examined for comparison purpose. The SEI composition and morphology of post-mortem HC electrodes were analyzed by X-ray Photoelectron Spectroscopy (XPS) and focused ion beam scanning electron microscopy (FIB-SEM) analysis. Overall, the HC electrodes cycled in carbonate-based electrolyte have shown thicker SEI mainly composed of organic compounds, whereas in ILs electrolytes they have shown thinner layer richer in inorganic species, such as NaF, Na 2 CO 3 , N-containing species, and "small" sulfide-based compounds, these improving the SEI interfacial properties towards the Na+ migration kinetics. Focusing on ILs based cell formulations, anodes cycled in the EMIFSI-based electrolyte shows several cracks on its surface. [ABSTRACT FROM AUTHOR]

A passive film serves as a first defense of any material against the attack of a corrosive environment for any material. So, it is essential to understand the parameters affecting the characteristics of the passive film. The present work focused on investigating the effect of tensile load during stress corrosion cracking (SCC) condition on the characteristics of the passive film developed on a TRIP Fe 39 Mn 20 Co 20 Cr 15 Si 5 Al 1 high entropy alloy (HEA) in a 3.5 wt.% NaCl solution at room temperature. A constant load of ∼25% of the yield strength was applied to a flat dog-bone-shaped tensile specimen for 24 h in a 3.5 wt.% NaCl salt environment. For comparison purposes, a specimen with no-load was kept in a salt solution under similar conditions. Electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) techniques were used for passive film characterization. EIS results revealed that the passive film deposited on the no-load and load conditions exhibited a dense and stable structure. However, the passive film deposited on the no-load specimen showed relatively better resistance to corrosion ions. XPS results indicated that the passive film deposited on the no-load and load specimens consisted of Cr rich oxide and hydroxide, forming a monolayer type of passivation film. Nonetheless, the passive film on the no-load specimen exhibited higher concentrations of Cr than the passive film on the loaded specimen. XPS depth profile results showed that the film thickness was relatively greater for the no-load specimen than for the loaded specimen. This study underscores the critical influence of tensile load on the degradation of passive film properties of the HEA. [ABSTRACT FROM AUTHOR]

Heteroatom doping of graphene oxide (GO) with phosphorous (P), and sulfur (S) was studied. In-situ grown binder-free electrodes of these doped and un-doped GO systems were developed via hydrothermal process. S-GO, P-GO, PS-GO, and un-doped hydrothermally treated GO (H-GO) electrodes were thoroughly investigated through physical and electrochemical characterization. The PS-GO electrode, comprising P (10.90 at%), S (0.3 at%), C (45.54 at%), O (36.36 at%), and Ni (2.38 at%) atoms, exhibited a mixed morphology of a few hundred nanometers doped GO flakes and dissolved Ni foam nanorods. Electrochemical analysis showed, this mixed morphology stimulates the charge storage ability of the PS-GO electrode and achieved a high specific capacity of 1218 C/g, compared to 647 C/g for H-GO at 1 mV/s. Electrochemical analysis revealed, charge was primarily stored through the capacitive charge storage mechanism, where only surface atoms are solely responsible for developing a double layer or facilitating redox reactions between electrode atoms and electrolyte ions. Additionally, the PS-GO electrode demonstrated an energy density of 76.94 Wh/kg at 1 A/g, which is much closer to that of batteries. We anticipate that PS-GO has the potential to be utilized as electrode material in modern energy storage devices. [ABSTRACT FROM AUTHOR]

• The MoS 2 /V 2 O 5 composite cathode is successfully constructed by one-step ball milling. • The unique in-situ conversion mechanism allows the obtained MoO 3 /V 2 O 5 cathode to achieve superior electrochemical performance. • The potentiality of rapidly constructing composite cathodes by ball milling is confirmed. Aqueous zinc-ion batteries have advantages of high safety, friendly environment, low cost, and can be applied to large-scale energy storage. To prepare high-performance cathode materials easily and quickly is still one of the development directions. Based on the principle that two-dimensional layered materials can be thinned layer-by-layer via mechanical force, the molybdenum disulfide (MoS 2)-based cathodes are prepared by one-step ball milling. The shear force and shockwave generated during ball milling effectively promote the preparation of MoS 2 /V 2 O 5 cathode materials. X-ray diffraction, Raman, and infrared tests confirm the presence of both MoS 2 and V 2 O 5 components in the prepared MoS 2 /V 2 O 5. The presence of metallic phase 1T-MoS 2 in the MoS 2 /V 2 O 5 is confirmed by X-ray photoelectron spectroscopy and transmission electron microscopy. Via a charging conversion mechanism, the obtained MoO 3 /V 2 O 5 cathode has a high capacity of 417.4 mAh g −1, good rate performance (83.6 mAh g −1 at 10 A g −1), high energy and power densities (83.6 Wh kg−1 at 10,032 W kg−1). This study provides a new idea for constructing two-dimensional material-based cathodes by ball milling. [Display omitted] [ABSTRACT FROM AUTHOR]

Composite materials with properties aimed at the additive manufacturing of affordable electrochemical sensors have received special attention in the scientific scenario. For this reason, we proposed a new composite material based on alumina oxide (Al 2 O 3) and graphite (Gpt) dispersed in polylactic acid (PLA) biopolymer. Various proportions between the materials were studied, and a better compromise between printability and electrochemical performance was obtained using Gpt/Al 2 O 3 /PLA (30:10:60% w/w). The electrodes were manufactured using a 3D pen, a portable, user-friendly, and low-cost tool. Characterizations by Raman and infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy indicated that Gpt and Al 2 O 3 were successfully incorporated into the PLA matrix. Preliminary studies using species with well-known electrochemical behavior revealed that Al 2 O 3 positively impacts the electrochemical response of the sensor. As a proof of concept, sulfamethoxazole (SMZ), a low-cost antibiotic widely used in beekeeping practices, was selected as the target analyte, and a simple, fast, and selective method using square wave voltammetry was proposed. Using the 3D-printed Gpt/Al 2 O 3 /PLA electrode, a wider linear range (2.0 to 40.0 μmol L−1), a 6.5-fold increase in sensitivity, limits of detection (LOD = 0.4 μmol L−1) and quantification (LOQ = 1.2 μmol L−1) were achieved compared to the Al 2 O 3 -free electrode (Gpt/PLA). In addition, the proposed sensor was selective against other antibiotics commonly used in beekeeping practices. Three honey samples were analyzed after simple dilution in 0.12 mol L−1 Britton-Robinson buffer, pH 7.0 (background electrolyte), and recoveries close to 100% as well as statistically comparable results from chromatographic analysis certified the accuracy and reliability of the analysis. The proposed approach is innovative and valuable in contributing to the advancement of additive manufacturing in electrochemical sensing, especially in the on-site analysis of antibiotic species in food, a public health challenge. [Display omitted] [ABSTRACT FROM AUTHOR]

• Materials studied lie in the Na 3/4 (Mn-Al-Ni)O 2 pseudo-ternary system. • P3/P2 phase fraction was manipulated by adjusting the calcination temperature. • Superior electrochemical performance of P3/P2 biphasic cathodes. • Absence of the P3 to O3 phase in the Al-substituted P3-type compounds. Layered oxide cathodes, a promising avenue for Na-ion batteries, hold the highest potential for commercialization. Herein, we delve into the structural and electrochemical properties of Al-substituted layered oxides in our quest to pinpoint the optimal cathode composition in the Na 3/4 (Mn-Al-Ni)O 2 pseudo-ternary system. The cathode materials investigated were synthesized in three distinct phase configurations, which include two monophasic configurations with P3 and P2-type structures and a third biphasic cathode with equal proportions of P3 and P2 phases. The fractions of the P3 and P2 type phases in the cathode materials were manipulated by adjusting the calcination temperature. The varying concentration of Mn3+ and Mn4+, confirmed by X-ray photoelectron spectroscopy, was found to impact the cyclic stability of these materials significantly. During electrochemical testing, the P3 cathodes showed impressive rate performance and exhibited an excellent specific capacity of 195 mAh g−1 at 0.1C. Regarding cyclic performance, the biphasic cathodes consistently outperformed their monophasic counterparts, with P3/P2-Na 0.75 Mn 0.50 Ni 0.25 Al 0.25 O 2 exhibiting 82 % capacity retention after 300 cycles. Analysis of operando Synchrotron XRD data revealed an absence of P3 to O3 type phase transition in the cathodes even at low voltages where large structural variations to the unit cell structure were observed. The absence of P3 to O3 transformations and the superior electrochemical performance of Na 0.75 Mn 0.50 Ni 0.25 Al 0.25 O 2 underlines the importance of Al substitution and P3/P2 biphasic structure in enhancing the electrochemical performance of layered oxides. [ABSTRACT FROM AUTHOR]

Laser-induced graphene (LIG) electrodes have become popular for electrochemical sensor fabrication due to their simplicity for batch production without the use of reagents. The high surface area and favorable electrocatalytic properties also enable the design of small electrochemical devices while retaining the desired electrochemical performance. In this work, we systematically investigated the effect of LIG working electrode size, from 0.8 mm to 4.0 mm diameter, on their electrochemical properties, since it has been widely assumed that the electrochemistry of LIG electrodes is independent of size above the microelectrode size regime. The background and faradaic current from cyclic voltammetry (CV) of an outer-sphere redox probe [Ru(NH 3) 6 ]3+ showed that smaller LIG electrodes had a higher electrode roughness factor and electroactive surface ratio than those of the larger electrodes. Moreover, CV of the surface-sensitive redox probes [Fe(CN) 6 ]3– and dopamine revealed that smaller electrodes exhibited better electrocatalytic properties, with enhanced electron transfer kinetics. Scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy showed that the physical and chemical surface structure were different at the electrode center versus the edges, so the electrochemical properties of the smaller electrodes were improved by having rougher surface, more density of the graphitic edge planes, and more oxide-containing groups. The difference could be explained by the different photothermal reaction time from the laser scribing process that causes different stable carbon morphology to form on the polymer surface. Our results give a new insight on relationships between surface structure and electrochemistry of LIG electrodes and are useful for designing miniaturized electrochemical devices. [Display omitted] [ABSTRACT FROM AUTHOR]

• The N and S heteroatom doping can adjust the O vacancy percentage of Ti-WO 3 and Nb-h-WO 3. • Doped transition metal oxides greatly enhance the actual electrochemical activity of graphite felt. • Doped transition metal oxides are advantageous in reducing the capacity decay of AORFBs. In this study, a graphite felt (GF) electrode was modified with N and S heteroatoms before being loaded with Ti-doped or Nb-doped WO 3 to produce Ti-WO 3 /GF-N-S and Nb-WO 3 /GF-N-S electrodes. X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy were used to analyze the crystal structure, morphology, and elemental state of the modified GF electrodes and investigate the impact of nonmetallic and metallic element doping. The influence of metal doping on the electronic distribution of the oxide was determined using first-principle calculations. The electrochemical properties of the modified GF were studied using cyclic voltammetry, electrochemical impedance spectroscopy, and single-cell tests. The results showed that Ti or Nb doping changed the energy band structure, bond length, and bond angle in the WO 3 crystal and formed O vacancies. The chemical properties of Ti and Nb resulted in different numbers of O vacancies for the two doped-WO 3.The doping of N and S heteroatoms on the carbon fibres altered the O vacancy concentration of WO 3. The synergism between the two doping methods accelerated electron transfer in the anthraquinone redox reaction. In addition, the N-containing functional groups provide lone-pair electrons, which accelerate electron transfer and anthraquinone adsorption. Therefore, compared to the pristine GF, the discharge capacities of the Ti-WO 3 /GF-N-S and Nb-h-WO 3 /GF-N-S graphite GF electrodes increased by 58 % and 41 %, respectively, and the Nb-h-WO 3 /GF-N-S graphite GF electrodes exhibited a good capacity retention rate. This study broadens the practical applications of aqueous anthraquinone redox flow batteries. [ABSTRACT FROM AUTHOR]

• Electrochemistry of Cu (II) & As (III) with Au(111) nanofilm. • Linear stripping voltammetry in Cu & As solutions results in Cu-As alloy formation. • Cu-As alloy formation likely during voltage step deposition. • Sequential deposition of Cu then As during cyclic voltammetry impedes As deposition. • Formation of Cu-As alloy severely impacts ability to detect As at Au(111) surface. The ability to detect trace concentrations of arsenite, As (III), in real water solutions is impacted by co-contamination of other metals and co-occurring ions. The presence of copper (II) ions are the most likely co-contaminant in natural waters to interfere with electrochemical As (III) detection, due to the close oxidation potentials of Cu (II) and As (III). The use of well-oriented ultraflat Au(111) thin film electrodes provided increased peak separation and sensitivity for electrochemical deposition and oxidation of Cu (II) and As (III) in 0.5 M sulfuric acid compared to an Au wire electrode. However, mixtures of Cu (II) and As (III) altered the oxidation peak positions during both cyclic voltammetry (CV) and linear stripping voltammetry (LSV) analysis. Calibration curves using the standard additions method in trace concentrations were conducted for Cu, As, and Cu & As solutions. Sweeping the potential at 10 mV s−1 during CV in Cu & As mixtures resulted in a sequential deposition condition where a layer of Cu inhibited co-deposition of As to the electrode. In contrast, the rapid potential stepping of LSV to a potential where Cu and As reduction simultaneously occurs produced a peak profile different from Cu or As alone. A larger oxidation peak during LSV was also observed when both Cu and As were present. X-ray photoelectron spectroscopy indicates a Cu-As alloy is formed on the surface after LSV deposition. SYNOPSIS: Analysis of Cu (II), As (III) and Cu (II) & As (III) mixtures suggests that a Cu 3 As intermetallic phase is formed during LSV which impacts trace As detection even in trace Cu conditions. This has important implications for the ability to determine As concentrations near the MCL of 10 µg L−1 in natural water systems which may contain Cu (II) and other co-contaminants. [ABSTRACT FROM AUTHOR]

Most Zr conversion coatings are prepared on Al alloys, with Al3+ from the substrate contributing significantly to the film growth process. Thus, the effect of Al3+ on the electrochemical characteristics, surface microstructure and film-formation mechanism of Zr-based conversion coatings on old- rolled steel (CRS) substrates was investigated by growing the coatings with and without Al3+ as an additive. Electrochemical tests indicated that the anticorrosion performance of the Zr-Al coatings prepared in the presence of Al3+ was greatly superior to that of Zr conversion coatings obtained in the absence of Al3+. Field-emission scanning electron microscopy and X-ray photoelectron spectroscopy analysis indicated that adding of Al3+ in the conversion bath changed the surface microstructure of the Zr coating, greatly promoted the deposition of Zr and F on the CRS substrate and increased the film thickness and density. Both coatings were embedded into the etched CRS substrates. The presence of Al3+ additive induced the formation of different coating components. The Zr coating mainly consisted of ZrO 2 and some FeF x , whereas the Zr-Al coatings comprised of ZrO 2 , ZrO x F y , Al 2 O 3 , AlF x and some FeF x. The present study results confirm the key role of Al3+ as an additive in the film formation and growth process of Zr coatings and its effect on enhancing the anticorrosion performance of CRS substrates in NaCl solutions. [ABSTRACT FROM AUTHOR]

• An expected SnO 2 @CuO/CF heterostructure material is synthesized. • p-n heterojunction enhances the adsorption of H 2 O 2 and benefits sensing properties. • Cost-effective H 2 O 2 electrochemical sensor with excellent performance is obtained. • The developed sensor has good biocompatibility for real-time detection of H 2 O 2 released by living cells. Hydrogen peroxide (H 2 O 2) is a major messenger molecule in cellular signal transduction. It is critical to detect cellular secreted H 2 O 2 in situ for clinical diagnosis and biomedical research. Therefore a simple, fast, sensitive, and cost-effective hydrogen peroxide detection method is needed. In this study, copper foam (CF) was used as copper source and conductive substrate, the electrochemical sensor SnO 2 @CuO/CF is prepared to detect H 2 O 2 secreted by living cells. High resolution transmission electron microscopy (HRTEM), X-ray diffraction, Mott Schottky curves and X-ray photoelectron spectroscopy demonstrate the successful formation of SnO 2 @CuO heterostructure. Theoretical calculations confirm that SnO 2 @CuO heterostructure facilitates the adsorption of H 2 O 2. The designed SnO 2 @CuO/CF sensor shows good sensing performance for H 2 O 2. Under optimal conditions, the designed sensor shows a relatively wide linear range to H 2 O 2 concentration from 1 μM to 13.88 mM, with high sensitivity (5100 μA·mM−1·cm−2) and low detection limit (0.13 μM). Cytotoxicity experiments prove that the sensor has good biocompatibility and the prepared sensor is successfully used to detect H 2 O 2 released by HeLa cells. With superior sensitivity, anti-interference ability, and reproducibility, SnO 2 @CuO /CF shows the potential application of H 2 O 2 monitoring in the field of biomedical and clinical diagnosis. This study provides a new platform for the development of highly sensitive H 2 O 2 electrochemical sensors in practical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

In this research, we introduce a pioneering approach for enhancing the electrocatalytic performance of counter electrodes (CEs) in dye-sensitized solar cells (DSSCs) by synthesizing Pt/CeO x hybrid nanocatalysts through a refined polyol reduction technique. This method facilitates the accurate production of Pt nanoparticles supported on ceria, leveraging their strong metal-oxide interactions. X-ray photoelectron spectroscopy (XPS) was employed to confirm the co-presence of both metallic and oxidized states of Pt, as well as the mixed valence states of ceria within these nanostructures. The electrocatalytic behavior of these nanocatalysts was rigorously evaluated using cyclic voltammetry (CV), Tafel polarization analyses, and electrochemical impedance spectroscopy (EIS). We identified an optimal Pt/Ce ratio of 1:0.1, which significantly enhanced the kinetics of the iodine reduction reaction (IRR), a crucial factor for efficient DSSC operation. Photovoltaic testing under one-sun AM 1.5 G conditions demonstrated that DSSCs with the optimized Pt/CeO x CEs exhibited a 10 % increase in power conversion efficiency (PCE) comparted to control cells. This study highlights the effectiveness of Pt/CeO x hybrid nanocatalysts in improving bifacial DSSC performance, combining the catalytic strengths of platinum with the unique properties of ceria. [ABSTRACT FROM AUTHOR]

Microfiber electrodes derived from graphite felt were used for the evaluation of charge transfer kinetic constants in a ferrocyanide-based electrolyte, which is a model system for redox flow batteries. Cyclic voltammetry experiments were performed in the presence of 10−2 M or 0.5 M Fe(CN) 6 4−. Within this framework, microfiber electroanalysis allowed for the quantitative assessment of four distinct activation protocols for graphite felt: thermal treatment under CO 2 at 850 °C, nitric acid immersion at 70 °C, exposure to Fenton's reagent at ambient temperature, and treatment with urea under atmospheric conditions at 550 °C. This analytical method enabled a hierarchical categorization of the various activation techniques, aiding in the identification of optimal conditions that yield the highest charge transfer kinetics for the ferrocyanide electrolyte. Additionally, the methodology provided insights into the temporal degradation or aging of these activated materials. These empirical observations are discussed alongside characterization data obtained from X-ray Photoelectron Spectroscopy (XPS), Raman spectrometry, and capacitive current measurements. [ABSTRACT FROM AUTHOR]

• Formation of bi-layered films with physisorbed outer and chemisorbed inner layers. • 2-MBI bonding by N to metallic and oxidized Cu, S also involved on metallic Cu. • Formation of Cu(I)−2-MBI complex promoted by cathodic conversion of native Cu oxide. • Increased complex formation owing to Cu(I) ions generated by anodic oxidation. • Cu dissolution inhibited depending on pre-treatment used for interface formation. The interfacial bonding and the layered structure of 2-mercaptobenzimidazole (2-MBI) organic films adsorbed on electrochemically controlled copper surfaces and their corrosion inhibition effects in acidic chloride aqueous solution were investigated using an integrated approach of electrochemical methods and advanced surface analyses by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. It is shown that organic films formed on the copper surfaces are bi-layered with a chemisorbed inner layer and a physisorbed outer layer. In the chemisorbed inner layer, 2-MBI is bonded primarily by its nitrogen atoms with metallic and oxidized copper surfaces. Sulphur atoms are also involved in the bonding mechanism when metallic copper is directly accessible to the 2-MBI molecules. The initial presence of native copper oxides at the interface promotes the formation of Cu(I)-2-MBI metal-organic complexes in the chemisorbed inner layer using cathodic reduction to dissociate the oxide. Metal-organic complexes also form upon anodic polarisation due to Cu(I) ions generated by oxidation of the copper metal. 2-MBI effectively inhibits copper anodic dissolution in varying degrees, between 84% and 93%, depending on the pre-treatment used for the formation of the organic bi-layers. An enhanced protection of the substrate is obtained by adsorbing the 2-MBI inhibitor on an initially oxide-free surface, which is achieved by cathodic pre-treatment in absence of the inhibitor followed by 1 hour exposure to the inhibitor. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the effects of electrochemically generated hydrogen on the passivation behaviour of Ni–Ti alloy surfaces. Hydrogen charging via galvanostatic polarisation increased the passive current density during cyclic potentiodynamic polarisation experiments. Electrochemical impedance spectroscopy and Mott–Schottky analyses revealed an increase in the electrochemical conductivity of the film, indicating that hydrogen charging increased the donor density. Changes in the compositions were detected by Auger electron spectroscopy and X-ray photoelectron spectroscopy. Scanning transmission electron microscopy revealed film degradation after hydrogen charging. These results demonstrate that the electrochemical conductivity of the passive film increased owing to hydrogen absorption. [ABSTRACT FROM AUTHOR]

Alkaline oxygen reduction reaction (ORR) presents an important role for energy conversion technologies and requires the development of an efficient electrocatalyst. Pt-based catalysts provide suitable activity; however, Pt production accessibility and high costs create hurdles to their commercial implementation. Fe coordinated within N-doped carbon materials (Fe N C) are a promising alternative due to their high ORR catalytic activity, although the currently commercially available Fe N C materials rely on harsh synthetic protocols which can lead to increased environmental impacts. In this work we target this issue by taking advantage of an oily sludge waste currently generated in refineries to synthesize Fe N C materials, thus, avoiding the environmental impact caused by the management of this waste. The solid particles within oily sludge, which present a high concentration of C and Fe, were combined by different nitrogen sources and pyrolyzed at high temperatures. The prepared materials present a hierarchical pore structure with surface areas up to 547 m2 g−1. X-ray photoelectron spectroscopy analysis found that the impregnation of N using phenanthroline promotes the formation of pyridinic-N structures, which enhances the ORR performance compared to melamine doping. Additional doping of Fe with phenanthroline results in an ORR mass activity of 1.23 ± 0.04 A g FeNC −1 at 0.9 V RHE, iR-free in a rotating disc electrode (0.1 M KOH). This catalyst also shows a lower relative loss in activity at 0.9 V RHE after 8000 cycles in O 2 -saturated conditions compared to a commercial FeNC catalyst, PMF D14401, (−63.5 vs −69 %, respectively), demonstrating promise as a cheap and simple route to Fe N C catalysts for alkaline ORR. [Display omitted] [ABSTRACT FROM AUTHOR]

• Efficient method to immobilize biomolecules to prepare several impedimetric biosensor. • Triglyceride biosensor with low detection limit and high sensitivity. • Biosensor prepared by sol-gel method and dip coating designed using a sequence of films. • Silica-zirconia, gold nanoparticles and silica-lipase films deposited on FTO glass. • The enzyme stays entrapped in silica film maintaining operational stability. A novel electrochemical sensing platform was created using the formation of a sequence of films, over a conductive fluorine-doped tin oxide glass (FTO), obtained using the sol-gel method and the dip coating technique. Firstly, thin films of silica-zirconia mixed oxides were deposited, in sequence an ionic silsesquioxane film stabilizing and controlling the size of gold nanoparticles (6.5 ± 2.4 nm) was settled, and after the lipase enzyme, obtained from Candida rugosa, was entrapped into a silica film maintaining its operational stability. The films were characterized by scanning electron microscopy (SEM) with EDX, UV–Vis spectroscopy and X-ray photoelectron spectroscopy (XPS). The thickness of each film on the FTO glass was evaluated by optical profilometry. The presence of the enzyme on the platform was confirmed by cyclic voltammetry with the ρ-nitrophenyl palmitate method. This platform was applied successfully as a biosensor for tributyrin (TB) determination by electrochemical impedance spectroscopy EIS, showing low limit of detection (LD) of 1.86 μmol L−1 and high sensitivity of 5.37 μΩ μmol−1 L. The biosensor presented a low K M app value of 22.69 μmol L − 1 and the V max app value of 85.57 μmol L−1 min−1 suggesting that the enzyme, immobilized with this method retained activity promoting a fast enzymatic reaction with the TB. [ABSTRACT FROM AUTHOR]

In pursuit of sustainable hydrogen production, alkaline water electrolysis offers fossil-free technology for generating hydrogen. Exploring new non-precious metal electrocatalysts plays a crucial role in this endeavor. Herein, we investigate a trimetallic NiFeMo material on a nickel foam support, serving as a bifunctional electrocatalyst for catalyzing both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Scanning electron microscopy reveals a nanosheet array structure with a uniform distribution of Ni, Fe, and Mo compounds on the electrode surface. Furthermore, the chemical surface composition of the pristine and spent electrodes is elucidated via x-ray photoelectron spectroscopy, displaying primarily oxidized species on the electrocatalyst surface. Bifunctional performance is assessed in a three-electrode setup, unveiling overpotentials of 70 mV for the HER and 140 mV for the OER, in a 30 wt% KOH electrolyte at 90 °C. Additionally, in an industrial electrolysis cell, the activated electrode is evaluated as cathode and anode for 28 days, which decreased the overpotential of 330–350 mV at 200 mA cm geo −2 compared with pristine nickel foam. The performance increase of the electroplated coating is attributed to the increased surface area and enhanced intrinsic activity. The electrolysis cell experiences a ∼6 % voltage loss during the experiment, indicating its robustness and suitability for industrial alkaline electrolysis applications. [ABSTRACT FROM AUTHOR]

• Electrodeposited Ti and Ti foils were anodized to obtain TiO 2 nanotube (TNT) layers. • Two different thicknesses of TNT layers were prepared and extensively compared. • No morphological differences were found between layers on the two substrates. • Preferential (101) orientation of anatase revealed for layers on electrodeposited Ti. • Enhanced photo-electrochemical behavior for TNT layers on electrodeposited Ti. This study conducted a deep investigation of TiO 2 nanotube (TNT) layers of two different thicknesses anodically grown on electrodeposited Ti films. The Ti films were grown from molten salts on Ni foils. The structure of the starting metals was compared by XRD (X-Ray Diffraction) and EBSD (Electron Backscatter Diffraction analyses), which showed a strong orientation towards the titanium (101) for the electrodeposited substrate, compared to the rather polycrystalline structure of the rolled Ti. The photoelectrochemical and electrochemical properties of 1 μm and 5 μm thick TNT layers anodically grown on these substrates were examined and compared with TNT layers of the same thickness. No significant morphological and compositional differences were found using SEM (Scanning Electron Microscopy) and XPS (X-ray Photoelectron Spectroscopy) between the TNT layers grown on the two substrates. However, higher photocurrent densities and ICPE values were observed for TNT layers grown on electrodeposited Ti. An in-depth investigation using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) analyses showed increased conductivity of the TNT layers produced on electrodeposited Ti compared to their counterparts. The carrier density (N D) for the TNT layers on electrodeposited Ti, calculated from Mott-Schottky measurements, showed a higher doping level than the TNT layers grown on Ti foils. This increase in N D results in more optimal photoelectrochemical performance of the TNT layers grown on electrodeposited Ti. All in all, the results presented herein pave the way for the use of electrodeposited Ti, with all its inherent benefits, and allow the further study of its promising properties in a wide range of applications. [ABSTRACT FROM AUTHOR]

Silicon monoxide (SiO), which has been verified as a potential anode material, can improve the energy density of Li-ion batteries (LIBs). These LIBs are crucial for the advancement of electric vehicles. However, the commercial application of SiO is severely limited due to poor initial Coulombic efficiency (ICE). In this study, we present a novel concept to enhance the ICE of silicon oxide-based anodes by collaboratively leveraging two distinct reaction theories: disproportionation reaction and the reaction between acidic oxide and alkali. Based on this concept, we utilize a chemical disproportionation-driven Li metal-free prelithiation method, enabling the in-situ growth of microcrystalline silicon and lithium silicate within amorphous silicon oxide, which bears a striking resemblance to pitaya seeds. This reaction yields unique lithium silicate and nano/micro-structured silicon surrounded by SiO (Si–SiO–Li x SiO y multicomponents, PD-SiO). This can be demonstrated via transmission electron microscopy (TEM), Electron energy loss spectroscopy (EELS) or X-ray photoelectron spectroscopy (XPS). The reaction product, PD-SiO, exhibits remarkable properties, including high ICE (82.5 %), high charging capacity (1419 mAh g–1), and highly stable cycling performance (94.6 % capacity retention after 200 cycles at 0.5 A g–1). This study offers a new approach to enhance the initial Coulombic efficiency of silicon monoxide. [ABSTRACT FROM AUTHOR]

Zirconium oxide-based conversion coatings (CCs) were prepared from hexafluorozirconic acid, H 2 ZrF 6 , with and without CuII as an additive. The CCs were prepared on primary and recycled AA6060. The deposition mechanism, structure, electrochemical properties and effectiveness in protection against filiform corrosion (FFC) have been explored. In presence of CuII additives, a two step deposition mechanism is observed, evidenced by open circuit potential measurements and in situ dynamic electrochemical impedance spectroscopy. Copper deposits predominantly as copper(II) hydroxyfluoride on the top surface, and metallic Cu 0 at the metal/CC interface, as evidenced by x-ray photoelectron spectroscopy and glow-discharge optical emission spectroscopy. The presence of a CuII additive induces a different distribution of the ZrO 2 -based products. After deposition of a weak organic model coating, aluminium pretreated with the CuII-containing system shows a 10%–30% lower maximum filament length compared to the CuII-free system in FFC tests, despite a ca. one order of magnitude higher cathodic activity of the former. [Display omitted] • Deposition of ZrO 2 based conversion coatings is assisted by CuII additives. • Copper hydroxide deposits in the top regions of such conversion coatings. • Presence of CuII in the conversion bath influences the distribution of ZrO 2 • Higher cathodic activity does not induce faster filiform corrosion. • Comparable filiform corrosion performance between primary and recycled alloys. [ABSTRACT FROM AUTHOR]

• Anodic pretreatment increases the HER efficiency of hydrothermally synthesized MoS 2. • Increased HER efficiency is determined by the bridging S 2 2− in the crystallite edges. • Electrochemical behaviour of the MoS 2 crystallite edge is analogous to amorphous MoS x. This work presents the effect of anodic pretreatment of 2D-MoS 2 nanoplatelet-shaped films hydrothermally synthesized on the anodized Ti substrate for electrocatalytic H 2 evolution from water. Structural and compositional changes in MoS 2 species assembly were studied by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The electrochemical performance of designed catalysts was studied in 0.5 mol L−1 H 2 SO 4 solution by cyclic voltammetry and chronopotentiometry for 12 h. The growing hydrogen evolution reaction efficiency upon anodic pretreatment was ascribed to increased sulfur content in the MoS 2 nanoplatelet edges in the form of more active bridging S 2 2− and apical S2− groups. [ABSTRACT FROM AUTHOR]

• NASICON-type Na 3 (VO) 2 (PO 4) 2 F is used as cathode material for AZIBs. • Na 3 (VO) 2 (PO 4) 2 F@CNT cathode material exhibits a high specific capacity of 143 mAh‧g−1 at 0.2 C • Na 3 (VO) 2 (PO 4) 2 F@CNT shows a good low-temperature electrochemical performance. • The electrochemiscal reaction mechanism is studied by ex-situ XRD and XPS. Aqueous zinc-ion batteries (AZIBs) are one of the candidate technologies for large-scale energy storage systems due to their environmental friendliness, safety and resourcefulness. However, designing and synthesizing high-performance cathode materials with practical application value is currently a great challenge. Herein, we synthesize a carbon-nanotube-coated Na 3 (VO) 2 (PO 4) 2 F (Na 3 (VO) 2 (PO 4) 2 F@CNT) cathode material for AZIBs, which has a continuous and interconnected ion transport channel structure. A Zn2+/H+ co-intercalation mechanism is revealed by ex-situ X-ray diffraction (XRD) and ex-situ X-ray photoelectron spectroscopy (XPS) characterizations. The Na 3 (VO) 2 (PO 4) 2 F@CNT cathode material exhibits a high specific capacity of 143 mAh‧g Wan et al. (2019). at 0.2 C in the electrolyte of 3 M Zn(OTf) 2 aqueous solution. In addition, Na 3 (VO) 2 (PO 4) 2 F@CNT shows a good low-temperature electrochemical performance in the electrolyte of 2 M Zn(OTf) 2 deionized water/ethylene glycol (DIW/EG) mixed solution with a different ion storage mechanism. This study provides a new polyanionic cathode material for AZIBs and an idea to modulate the electrolyte polarity to enhance the zinc storage capacity of the cathode material. [Display omitted] [ABSTRACT FROM AUTHOR]

• Passive film of M13Cr becomes more defective after 75 °C in CO 2 -Cl brines. • Cr and Mo enrichment in the passive film contribute to corrosion resistance. • Ti(C,N) serves as pit initiation sites from Cr/Mo depletion and SKPFM results. • Ti(C,N) are anodic which contradicts previous claims of cathodic behavior. • Temperature increases soluble CrO 3 , reducing film repassivation capabilities. The influence of temperature (25, 75, and 150 °C) on the passivation behavior of Modified Martensitic 13Cr Stainless Steel (M13Cr) in CO 2 saturated acidic salt brine environments was investigated. The material was found to contain Ti(C,N) inclusions and Volta potential maps obtained through scanning Kelvin probe force microscopy (SKPFM) identified them to be more anodic (60 mV lower) than the matrix. Cyclic polarization (CP) showed a shift in pitting and repassivation potentials to more negative values at higher temperatures. Electrochemical impedance spectroscopy (EIS) and Mott–Schottky tests showed that the passive film formed was more defective with increasing temperature. X-ray photoelectron spectroscopy (XPS) confirmed the presence of a defective passive film with reduced repassivation capabilities due to higher contents of soluble CrO 3 /Cr6+ species at temperatures exceeding 75 °C. These results offer valuable insights into understanding the pit initiation mechanisms and performance of M13Cr. [Display omitted] [ABSTRACT FROM AUTHOR]

Ti is used as a construction material in many applications including electrodes in various electrochemical technologies due to its high corrosion stability provided by the stable oxide layer on the surface. However, this oxide layer is also the reason for its resistivity causing high interfacial resistance between components and energy losses. This problem can be solved by various surface modifications such as acid etching or coating with a layer of precious metals. In this study, we present a novel method for controlled hydridation of Ti materials based on a combination of acid etching and cathodic hydridation aimed primarily for surface modification of Ti components for proton exchange membrane water electrolyser. Cathodic polarisation represents the means to increase the amount of Ti hydride and to tune its properties to obtain a Ti surface with low interfacial resistance and preserved corrosion stability. The study investigated the effects of concentration, temperature, time, and current density on cathodic polarization in H 2 SO 4 electrolytes. The resulting samples were characterized by X-ray diffractometry, X-ray photoelectron spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, Kelvin probe and temperature-programmed desorption. This allowed finding interesting correlations between the surface composition of the Ti samples and their electrochemical properties. [Display omitted] [ABSTRACT FROM AUTHOR]

Pencil leads can be considered well-defined and cheap graphite electrodes for a wide range of electrochemistry applications. These electrodes display many intriguing properties; however, the origin of these properties is not clear. Using various analytical approaches applied to two different commercially available Tombow (TO) and Staedtler (ST) pencils we reveal a causal relationship between the unique properties of pencils and their graphite/polysiloxane composite. We explore the impact of chloroform etching on chemical composition changes, thermal stability and electrochemical parameters of pencils. Using a combination of X-ray photoelectron spectroscopy (XPS) and gas chromatography-mass spectrometry (GC-MS/MS) various polydimethylsiloxanes in composites are revealed. The polysiloxane species leave into the chloroform solvent during the etching resulting in a significant decrease of their content within the electrodes. Differential scanning calorimetry (DSC) data, corroborated by gravimetric measurements, provide additional proof of the presence of composite structures in ST and TO pencils, showing glass transition temperatures at around 76 °C and 81 °C. The main difference between the TO and ST electrodes is the content and composition of the polysiloxanes within the graphite matrix. ST composites have significantly higher polymer content (∼ 30 %) with traces of Na and S impurities compared to TO ones (∼ 14 %) free of contaminations. Furthermore, mainly cyclic nanostructures appear in chloroform extracts of ST composites whereas rather chain-like clusters are liberated out of the TO counterparts. Complementary electrochemical experiments using cyclic voltammetry (CV), impedance spectroscopy (EIS) and the less known elimination voltammetry with linear scan (EVLS) reflect the performance superiority of TO electrodes with much lower polysiloxane content and free of impurities. High conductivity, low capacitive current along with favoured charge carrier transfer all promise a wide range of technological applications for the TO pencil material. [Display omitted] [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries have emerged as one of the most promising energy storage solutions. However, its commercial application still faces a significant challenge: the sluggish redox reaction kinetics of the reversible lithium polysulfide (LiPS) conversion process. The strategic design of cathode structures and electrocatalysts can help accelerate polysulfide conversion. In this study, systematic density functional theory (DFT) calculations predict that the incorporation of platinum (Pt) nanoparticles, as a model electrocatalyst, into biomass carbon materials can effectively promote the bidirectional conversion of polysulfides. Detailed kinetic analyses reveal that Pt-doped biomass carbon materials possess exceptional electrocatalytic abilities for Li 2 S nucleation and dissociation. These findings are further elucidated by ex situ X–ray photoelectron spectroscopy measurements, elucidating the bidirectional mechanism of Pt. The sulfur cathode delivers a remarkable specific discharge capacity of 1386.9 mAh g–1 at 0.1 C. Even more impressive is its potential for practical applications, exemplified by a high initial capacity of 1218.7/1015.3 mAh g−1 and excellent cycling stability under a high sulfur loading of 4.5/7.5 mg cm−2, which achieved substantial capacity retention (83.9/81.1%) after 100 cycles. This bidirectional electrocatalysis, achieved through the synergy of metal with biomass carbon materials, presents an attractive approach for advancing Li–S systems. [ABSTRACT FROM AUTHOR]

• ZnCo 2 O 4 /N-doped rGO CE was prepared using the simple low-temperature hydrothermal method for dye-sensitized solar cell application (DSSCs). • The DSSC device assembled with znco 2 o 4 /N-doped rGO CE exhibits improved surface area and gained the highest PCE of 5.84 ± 0.06 %. • DSSC performance of the counter electrode improves via the introduction of N-rGO in the ZnCo 2 O 4 material. • ZnCo 2 O 4 /N-doped rGO CE materials are a viable substitute for platinum-free CEs in DSSCs. Diverse varieties of organic and inorganic materials have been employed as counter electrodes (CEs) in dye-sensitized solar cell applications (DSSCs) to replace platinum (Pt). Interestingly, the influence of N-doped reduced graphene oxide on ZnCo 2 O 4 with high surface area, superior electrical activity, and chemical stability has been addressed in this work. Pure ZnCo 2 O 4 (ZCO), ZnCo 2 O 4 /reduced graphene oxide (rGO) (ZCOG), and ZnCo 2 O 4 /nitrogen-doped reduced graphene oxide (N-rGO) (ZCONG) had synthesized using a facile hydrothermal technique, and their performance as a CE material in DSSC application was further investigated. The formation of the material free of impurities is depicted by X-Ray Diffraction (XRD) and Raman analysis. The analysis utilizing Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) confirmed the existence of ZnCo 2 O 4 micro flowers made of rods and sheets as well as the thin sheet-like shape of graphene oxide (GO) and N-rGO. The X-ray photoelectron spectroscopy (XPS) analysis technique was employed to determine the chemical composition and purity of the prepared samples. Further, the BET analysis confirms the higher specific surface area (1198.431 m2/g) of the ZCONG sample. The electrochemical property of the coated CEs was investigated using cyclic voltammetry (CV) analysis with the iodine-based electrolyte in a three-electrode system showing superior catalytic properties of the ZCONG CE than the other ZCO and ZCOG CEs. The as-fabricated CEs were utilized to assemble the DSSC device, and the ZCONG CE reached a photovoltaic power conversion efficiency (PCE) of 5.84 ± 0.06%, surpassing ZCO (3.51 ± 0.15 %) and ZCOG (4.81 ± 0.08 %) CEs. [Display omitted] [ABSTRACT FROM AUTHOR]

Laser drilling is always accompanied by recast layers, micro-cracks, and heat-affected zones, which limit its application in engineering. Due to its unique advantages, such as no heat-affected zones, no residual stresses, and no dependence on the mechanical properties of the materials, electrochemical dissolution has been adopted to remove the laser drilling-induced surface defects. The electrochemical dissolution characteristics and surface evolution of the laser-drilled Ni-based superalloys were studied. The polarization curves and electrochemical impedance spectroscopy (EIS) of the laser-drilled materials and the substrate were measured, indicating that the laser-drilled surface had a smaller corrosion resistance than the original substrate. X-ray photoelectron spectroscopy (XPS) results showed that the laser-drilled surface had a much higher oxygen content than the substrate. Additionally, electric current efficiency curves were obtained to study the anodic dissolution behavior of Ni-based superalloys. An electric current density in the 5–40 A/cm2 range was preferred to enhance the electrochemical dissolution rate. Moreover, the effects of electric current densities and post-processing time on the surface roughness and the recast layer thickness of the laser-processed Ni-based superalloys were investigated using a NaCl and NaNO 3 solution electrolyte. The evolution of the surface quality and recast layer thickness were clarified. Furthermore, an anodic dissolution model of the laser-processed surface was established to illustrate the electrochemical post-processing mechanisms. Results revealed that electrochemical dissolution could completely remove the laser drilling-induced surface defects in 20 s using a 12.5 wt.% NaNO 3 solution electrolyte and a 40 A/cm2 electric current density. Finally, an electrochemical post-processed surface with surface roughness (Ra) of 1.7 µm and without a recast layer was achieved. Micro holes without recast layers and Ra of 0.69 µm were obtained with high efficiency using laser processing and electrochemical post-processing. [ABSTRACT FROM AUTHOR]

A potential-responsive 2-2′-dithiodibenzoic acid (DTSA)/Polyaniline (PANI) hybrid film with high ion-exchange capability and selectivity to cadmium ions was successfully fabricated on electrode by a one-step cyclic voltammetry (CV) method. S–S bonds in the DTSA serve as a gate that can be controllably opened and closed to let cadmium ions get in and out of the hybrid film when changing its redox state, and the PANI mainly enhanced the conductivity of the hybrid film. The working mechanism of the film is proposed and identified via the electrochemical quartz crystal microbalance (EQCM) technique, X-ray photoelectron spectroscopy (XPS), Raman and density functional theory (DFT) computations. As a result, the obtained hybrid film exhibited high selectivity towards cadmium ions even in the presences of other cations. More interestingly, over 240% of its initial capacity was retained after 25 consecutive cycles and maintained in the following cycles. Furthermore, the regeneration rate of the hybrid film retains 99% of its initial value even after 30 cycles. It is expected that such a potential-responsive film can be applied for the removal and recovery of cadmium ions from wastewater in various industrial processes. Image 1 • S–S bonds can be controllably to let Cd2+ get in and out of the hybrid film. • The obtained hybrid film exhibited a high selectivity towards Cd2+ ions. • The regeneration rate of film retains 99% of its initial value after 30 cycles. • It is function as the ion-probe which accelerates the uptaking rate of cadmium. [ABSTRACT FROM AUTHOR]

In this study we investigate how electronic properties of buried semiconductor/ionic liquid interfaces may influence on charging effects observed by X-ray photoelectron spectroscopy (XPS). Droplets of the ionic liquid 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl)imide ([EMIM][Tf 2 N]) were deposited on silicon and germanium semiconductor surfaces with different doping states. Core level spectra were recorded from the ionic liquid/ultra-high vacuum interface with and without irradiation of the droplets using low energy electrons from a flood gun. Changing electron intensity results in shifts of the binding energy of all XPS signals to lower values. Magnitude of shifts is found to directly depend on the intensity of the electron beam and to correlate with the nominal resistivity of the substrates. The observations are qualitatively explained by flood gun induced changes of the electronic properties of the [EMIM][Tf 2 N]/substrate interface and suggested to refer to space charge layer effects. [ABSTRACT FROM AUTHOR]

Herein, we report the surface treatment on Zr4+/Al3+ codoped α-Fe 2 O 3 photoanode for high-performance photoelectrochemical water splitting. A high-temperature quenching exhibits the Zr4+/Al3+ codoping in α-Fe 2 O 3 photoanode without damaging morphology. The presence of Zr4+/Al3+ codoping shows a cathodic shift in onset potential, but lack of increment in photocurrent reveals the major role of passivation and the minimum doping effect of aluminum. Additionally, CoO x cocatalyst exhibits increment in photocurrent with the greater cathodic shift in onset potential than the pristine α-Fe 2 O 3 nanorods. The CoO x surface-reworked Zr4+/Al3+ codoped α-Fe 2 O 3 photoanode displays the highest photocurrent of 1.5 mA/cm2 at 1.23 V vs. RHE (76% increment over the pristine α-Fe 2 O 3) and 0.7 mA/cm2 at 1.0 V vs. RHE (102% increment over the pristine α-Fe 2 O 3). The systematic characterization carried out using x-ray diffraction and scanning electron microscopy confirms that after Zr4+/Al3+ codoping, and surface treatment, the crystalline structure, and morphology of the photoanodes remains unchanged. X-ray photoelectron spectroscopy confirmed the existence of Zr4+/Al3+ codopants in the hematite nanostructure. The electrochemical properties of the photoanode suggest that Al3+ and Zr4+ codoping, as well as surface treatment with CoO x , cocatalyst lowers charge transfer resistance across the FTO/hematite interface, and hematite/electrolyte interface. This designs not only lowers onset potential but also offers the blueprint for the development of an efficient catalyst for solar water oxidation. CoO x surface-reworked Zr4+/Al3+ codoped α-Fe 2 O 3 photoanode displays the 102% increment in PEC performance than pristine α-Fe 2 O 3 at 1.0 V vs. RHE. Image 1 • Zr4+/Al3+-codoped Fe 2 O 3 photoanode synthesized by hydrothermal method. • CoO x co-catalyst improves the OER kinetics via surface reworking. • Optimum photoanode exhibits 102% increase in photocurrent density than Fe 2 O 3. • The charge transfer mechanism in 6% Zr + 6% Al + 15 mM Co is also proposed. [ABSTRACT FROM AUTHOR]

In order to investigate stability of oxygen reduction reaction (ORR) on a Pt 3 Y thin film under relevant fuel cell conditions, we performed an accelerated stress test (AST) consisting of 3600 potential cycles between 0.4 and 1.4 V at 1 V s−1 in a single proton exchange membrane fuel cell (PEMFC). The ORR activities were evaluated via polarization curves before and after the AST. Electrochemical active surface area (ECSA) was obtained by CO-stripping voltammetry whereas the morphological changes were monitored by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Variations in surface composition and electronic structures were evaluated by energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). After AST, the polarization curves show loss of ORR activity in all voltages for both Pt and Pt 3 Y. Except at very high voltages (E > 0.85 V RHE), the ORR activity of Pt 3 Y after AST is very close to that of Pt before AST. This correlates well with the results from the deconvolution of Pt-4f XPS spectra where the binding energy of metallic Pt in Pt 3 Y is comparable to pure Pt (71.22 eV). SEM and TEM images demonstrate that the morphologies of the aged Pt 3 Y and as-sputtered Pt are similar, whereas EDX results confirm a steady bulk composition of Pt 3 Y thin films throughout the entire electrochemical test. By correlating all these results, we conclude that the loss of ORR activity for Pt 3 Y is due to an increase in the thickness of the Pt overlayer which induces a relaxation of the Pt overlayer decreasing the compressive strain effect. For pure Pt, the loss of ORR activity is associated with a growth of the Pt domains associated with Ostwald ripening process. [ABSTRACT FROM AUTHOR]

• AuNPs incorporated Zr-MOFs with different pore size to determination of CH 3 Hg+. • The pore characteristics of MOFs displayed variable effects on the CH 3 Hg+ sensing. • The synergistic effects of pore confinement and gold catalysis are beneficial for CH 3 Hg+ sensing. • Au/UiO-67 GCE presents excellent sensitivity, stability and reproducibility. Catalytic redox reactions and size matching effect between the target molecule and sensing material are reliable methods for highly efficient determination of heavy metal ions. In this work, the electrochemical determination of methylmercury (CH 3 Hg+) was carried out gold nanoparticles (AuNPs) incorporated into four zirconium-based metal organic frameworks (MOF) with different pore diameters, namely MOF-801, (University of Oslo) UiO-66, UiO-67, UiO-68. The work relates the role of dicarboxylic ligands of different lengths to the AuNPs load capacity and the adsorption and reduction of CH 3 Hg+. The voltammetric properties of CH 3 Hg+ at different modified electrodes were studied by differential pulse anodic stripping voltammetry (DPASV). It was found that the CH 3 Hg+ electrochemical behavior was greatly influenced by the pore confinement effect of MOFs. Under the optimal conditions, the pore sizes of Au/UiO-67 are matched to CH 3 Hg+ molecule and they showed the highest response current. The possible reduction process of CH 3 Hg+ at the sensitive interface was explored by X-ray photoelectron spectroscopy (XPS) and chronoamperometry (CA). These four Au/MOFs modified GCE can also be used in detection of CH 3 Hg+ spiked in river water, confirming their potential application in the rapid detection of methylmercury in environmental samples. [Display omitted] Effect of ligand length on electrochemical behavior of CH 3 Hg+ [ABSTRACT FROM AUTHOR]

Oxygen reduction reaction (ORR) is a crucial process for energy conversion and storage devices. Despite platinum (Pt) being the state-of-the-art material for ORR, the limited performance of Pt-based catalyst, Pt scarcity, and vulnerability of global supply chains for critical minerals, have made it imperative to develop alternative electrocatalysts that either contain no precious metals at all or require only a very low loading of these valuable resources. In this study, we demonstrate that the incorporation of co-dopants, nitrogen (N) and boron (B), with a dissimilar electronegativity is a promising approach to develop metal-free electrocatalysts for ORR. We discovered that the interaction between N and B plays a vital role in both (i) incorporating the dopants in high-curvature carbon nano-onions (CNOs) and (ii) promoting ORR performance. Tuning the annealing temperature was crucial to achieve a desirable N-B chemical configuration and synergistic effects of N and B on ORR catalysis. Our investigation revealed that N,B-doped CNOs prepared at 700 °C exhibit the best ORR performance in 0.1 M KOH with a dominant 4-electron pathway and excellent durability. Based on X-ray photoelectron spectroscopy (XPS), Raman analysis, and high-resolution scanning transmission electron microscopy (HR-STEM), we conclude that abundant N and B sites, especially N-C-B (isolated) sites, at the edges in conjunction with high surface activity of CNOs are responsible for such outstanding performances. This study provide insights into the design of metal-free catalysts for efficient ORR catalysis, and the importance of alternative electrocatalysts in the current global supply chain disrutipn scenario. [ABSTRACT FROM AUTHOR]

The water splitting reaction to produce hydrogen is one of the most promising and cleanest ways to resolve the energy crisis. However, the preparation of efficient and stable electrocatalysts with low-cost remains challenging. In this work, the noble-metal free N-doped carbon (NC) incorporated V-doped cobalt phosphide (CoP) nanosheets on nickel foam (NF) (denoted as V-CoP-NC/NF) are prepared by using two-dimension zeolitic imidazolate framework (ZIF-67) as precursor followed by NaVO 3 etching/doping and phosphorization. The V doping is found to be essential to enhance the electrochemical performance of CoP for water splitting. In particular, V 5 -CoP-NC/NF (V 5 represents the concentration of NaVO 3 for etching/doping is 5 mM) exhibits the highest hydrogen evolution performance in alkaline electrolyte, to achieve a current density of 10 mA cm−2, an overpotential of 119 mV (vs reversible hydrogen electrode) is required. X-ray photoelectron spectroscopy results show that the V doping significantly altered the binding energies of Co 2p, P 2p and N 1 s in V 5 -CoP-NC/NF, which is believed to facilitate the adsorption and dissociation of intermediates and accelerate interfacial charge transfer during hydrogen evolution reaction process. This work provides a simple route to prepare heteroatom doped CoP self-standing electrocatalysts for water splitting. [Display omitted] [ABSTRACT FROM AUTHOR]

Binary and ternary cobalt-based spinel oxides have been shown to possess enhanced electrocatalytic activity and stability towards the oxygen evolution reaction (OER), however their performance is inconsistent. In this work, copper and nickel-copper substituted cobalt spinel oxides, Cu x Co 3-x O 4 (x = 0, 0.25, 0.5, 0.75 and 1) and Ni x Cu 1-x Co 2 O 4 (x = 0.25, 0.5, 0.75, 0.9 and 1), were prepared by the thermal decomposition method to re-examine their properties. We used several physical and chemical characterization methods to understand their behavior. The formation of spinel structure was confirmed by X-ray diffraction analysis, however, Cu x Co 3-x O 4 remains monophasic only up to x = 0.75. CuCo 2 O 4 was found to contain an additional CuO phase. The lattice parameters were determined as a function of the composition and found to increase with increased Cu and Ni content in the cobalt spinel lattice, which supports Cu and Ni incorporation in the spinel structure. For Cu x Co 3-x O 4 electrodes, the lattice parameter gradually increased when cobalt is replaced by copper in the composition. Ni x Cu 1-x Co 2 O 4 lattice parameters are higher than those of Cu x Co 3-x O 4 but do not display a particular trend with replacement of Cu by Ni. The XPS analysis indicates the existence of various chemical species on the surface of the electrodes with a significant amount of NiO being detected on the surface of Ni-containing samples. The core-level spectra of all metal cations indicate the presence of mixed-valence states in the spinel structure. The roughness factor was determined by measuring the double layer capacitance of the electrodes using cyclic voltammetry and the data obtained was verified by performing electrochemical impedance spectroscopy (EIS) in a region of low faradaic current. The incorporation of Cu and Ni significantly increased the surface area of cobalt oxide. The current density obtained from cyclic voltammetry (CV) data is reported as a function of the geometric and the real surface areas for each sample, which revealed that Co 3 O 4 possesses the highest current density than other Cu or Cu and Ni-containing cobalt spinel oxides towards OER when corrected for differences in surface area. However, the addition of Cu could be viewed as beneficial as it provides a lower onset potential for OER and results in a relatively high current density compared to Co 3 O 4. Ni x Cu 1-x Co 2 O 4 materials have a similar current density per unit geometric area, however, when corrected for real surface area these electrodes display lower catalytic activity for OER than Cu x Co 3-x O 4 (x = 0 to 1). The presence of a significant surface NiO species may have affected the catalytic activity of Ni-containing samples. The data will be discussed in the context of variable material performance found in the literature. [ABSTRACT FROM AUTHOR]

• CuO Co 3 O 4 micro-sphere composed of smaller nano-particles prepared by a solvothermal method. • CuO leads to lattice distortion of Co 3 O 4. • CuO Co 3 O 4 /NF rich in oxygen vacancies are induced by lattice distortion. • CuO Co 3 O 4 /NF is directly used as anode electrode for GEOR. • The potential of CuO Co 3 O 4 /NF for GEOR is 1.13 V vs RHE at 10 mA cm−2. The replacement of the anodic oxygen evolution reaction in water electrolysis with the glycerol electro-oxidation reaction not only lowers the anodic potential and enhances hydrogen production efficiency at the cathode, but also yields valuable chemicals at the anode, thereby improving overall economic viability. The development of efficient and cost-effective catalysts for the electro-oxidation reaction of glycerol remains a significant challenge. Here, CuO Co 3 O 4 loaded on nickel foam (CuO Co 3 O 4 /NF) is in situ prepared by solvothermal methods. The analysis of scanning electron microscopy reveals that CuO Co 3 O 4 consists of micrometer-scale spherical particles, which are further assembled by even smaller nano-scale particles. The combination of Cu and Co in the catalyst induces lattice strain, as characterized by Raman and X-ray photoelectron spectroscopy, leading to an increased generation of oxygen vacancies. The electrochemical tests demonstrate that CuO Co 3 O 4 /NF exhibits superior electrocatalytic activity at a Cu:Co molar ratio of 1:1, requiring only 1.13 V vs RHE to achieve a current density of 10 mA cm−2. This performance surpasses other ratios as well as monometallic CuO and Co 3 O 4. The CuO Co 3 O 4 /NF║CuO Co 3 O 4 /NF two-electrode system requires 1.46 V to achieve a current density of 50 mA cm −2 and exhibits excellent stability during a 12 h testing period. The electrolysis products consist of formic acid, glycolic acid, and glyceric acid, with the highest selectivity recorded at 90.3 % for formic acid. The high electrocatalytic performance of the CuO Co 3 O 4 /NF catalyst can be attributed to its spherical structure and the presence of oxygen vacancies. [ABSTRACT FROM AUTHOR]

In the present research, the performance of three commercial graphite felts (a 6 mm thick Rayon-based Sigracell®, a 4.6 mm thick PAN-based Sigracell®, and a 6 mm thick PAN-based AvCarb®) used as electrodes in vanadium redox flow batteries (VRFBs) is analyzed before and after thermal activation. The thermal treatment of the electrodes at 500 °C for 1 h in a self-designed industrial furnace under a synthetic air atmosphere. XPS confirms that thermal activation provides with different C=O/C O and sp2/sp3 ratios to the graphite electrodes depending on their carbon precursors, providing different catalitic behavior. T-GFD4.6-EA felt electrode was also oxidized by cycling in H 2 SO 4 and in 0.4 M VOSO 4 + 2 M H 2 SO 4 solution. In the first case, the graphite electrode increased the current density 24.27 mA cm−2 for the VO2+ electrooxidation, however the cathodic current density (VO 2 + reduction reaction) was decreased 36 mA cm−2. In the second case, the increase was of 21.27 mA cm−2, whereas the current density for the VO 2 + reduction hardly changed. Thermally treated GFD4.6-EA graphite felt chemical composition also changed differently when exposed to different laboratory experiments which mimic the electrode behavior in a VRFB. XPS analysis confirmed that the chemical modification of the graphite surfaces can either improve or decrease the electrocatalytic activity of the electrodes depending on their carbon precursors. [ABSTRACT FROM AUTHOR]

• Pt, Ni, Co-oxides were deposited on different support materials in multistep method. • The electrochemical deposition method affected surface morphology and electroactive area. • Electrode morphology affected chlorine generation rate. • Electrode support materials play a role in chlorine generation. • Graphite exhibited better chlorine production than other electrode supports. Platinum, nickel, and cobalt oxides were coated on different electrode supports (graphite, stainless steel mesh, Ti foil and Ni form) by multistep electrode deposition method. Scanning electron microscopy, X-Ray diffraction, X-ray photoelectron spectroscopy, cyclic voltammetry and linear sweep voltammetry were used to characterize electrodes. Results showed that the deposition process, such as applied current and deposition time, and the substrates influenced electrode morphology and electrochemical chlorine generation capability. Porous structure and Co 3 O 4 crystalline could promote chloride oxidation on electrode surface. Graphite substrate exhibited the benefit of chloride oxidation and 0.6A × 20 s × 30 is the optimal deposition condition for electrode fabrication. The 0.6A × 20 s × 30-G electrode has the lowest chlorine evolution potential, largest difference in water oxidation and chloride oxidation potential, and the smallest transfer coefficient (α), meaning that this electrode is more favorable to chloride oxidation than other electrodes. Moreover, a mechanism of chlorine generation has been proposed in this study, indicating that chlorine radicals were formed on electrode surface. The high chlorine generation capability and good durability of Pt-Ni-Co-G electrode has the potential for application in water treatment process, such as disinfection and inorganic or organic pollutants decontamination. [Display omitted] [ABSTRACT FROM AUTHOR]

Diverse microstructure and complex application environments increases the uncertainty of the corrosion resistance of lightweight steels. The effect of solution treatment on the corrosion behavior of Fe–16Mn – 10Al – 1.5C – 0.1Ti lightweight steel in Cl−, HSO 3 − and Cl−–HSO 3 − environments was investigated using electrochemical measurement, scanning electron microscope (SEM) and X–ray photoelectron spectroscopy (XPS). The lightweight steels are dominated by austenite and contain a small amount of ferrite. The increase in solution treatment temperature leads to more ferrite formation, but it has less effect on grain size. The decrease in austenite content results in more corrosion microcells and a porous oxide film; therefore, the corrosion resistance of the steel deteriorates with increasing temperature. In addition, in the Cl−–HSO 3 − environment, the synergistic effect of Cl− and HSO 3 − leads to the formation of a weak protective oxide film, resulting in a significant increase in corrosion rate compared to the Cl−and HSO 3 − environment. [ABSTRACT FROM AUTHOR]

• Hall measurements: hole concentration increases with vicinal angle, {118}<{115}<{113}. • HET kinetics, double layer capacitance and charge transfer resistance evaluated. • These characteristics are reversible for surface conversion: as-deposited → O- → H-. • Most pronounced changes obvious for SC-BDD electrodes with lower [B]. • Dopamine very sensitive even to a minor oxygen content on SC-BDD surfaces. In this study, the effect of vicinal crystal orientation ({113}, {115}, and {118}), boron doping level, and surface termination induced by various pre-treatments on electrical and electrochemical properties of single crystal boron-doped diamond (SC-BDD) electrodes was carefully investigated. van de Pauw measurements confirmed Hall concentration to increase with increasing vicinal angle, {118} < {115} < {113}. As-deposited H-terminated surfaces were converted to predominantly O-terminated surfaces (confirmed by X-ray photoelectron spectroscopy) using hot acid, ozone and anodic pre-treatments, or by spontaneous oxidation in air. This conversion was recognized by inhibited heterogeneous electron transfer kinetics of inner-sphere redox markers ([Fe(CN) 6 ]3−/4− and dopamine), by an increase in double layer capacitance and charge transfer resistance values. The most pronounced surface oxidation was recognized for electrodes with the lowest boron content as a result of blocked boron atoms by oxygen functionalities and loss of superficial hydrogen on the surface. Reverse conversion from oxidized to H-terminated surfaces using cathodic pre-treatment led mainly to restoration of electrochemical parameters. Moreover, spontaneous oxidation of electrode surfaces in ambient atmosphere was confirmed, with the fastest being within the first five days. The results show the key role of boron content, and hence the crystal orientation and superficial hydrogen in affecting conductivity and performance of SC-BDD electrodes, which is demonstrated by changes in heterogenous electron transfer kinetics of surface sensitive redox systems. [Display omitted] [ABSTRACT FROM AUTHOR]

Na-ion batteries have gained significant attention as a cost-effective and efficient energy storage option for large scale applications, serving as an alternative to the Li-ion batteries. However, commercialization of these batteries is still many steps away since most cathode materials suffer from significant capacity loss and more full-cell studies are required. In this work, we report the electrochemical properties of half- and full-cells of P2-type Na 0.67 Mn 0.85 Cu 0.15 O 2 synthesized by solid state technique. X-ray diffraction, FT-IR, and Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy techniques are used to determine the structural properties. Surface properties are studied by X-ray photoelectron spectroscopy and Brunauer–Emmett–Teller techniques. Half cells and full cells were constructed with Na-metal and hard carbon, respectively. Na-ion diffusion kinetics at 10 °C, room temperature, and 50 °C were determined experimentally. Galvanostatic cycling tests on half-cells show capacity values of 165/124 mAh/g for the 1./100. cycles with 24.8 % capacity fade. Operando x-ray absorption spectroscopy measurements were utilized to study local structural modification around transition metal ions during charge/discharge. In the full-cell studies, electrode mass ratio (p/n) and parameters for presodiation of hard carbon were optimized. Using 30 mA/g current density, the unprocessed and the pre-sodiated full-cells reach capacity values of 48 mAh/g (p/ n = 2.5) and 150 mAh/g (p/ n = 0.75 and 1.15), respectively. [ABSTRACT FROM AUTHOR]

The poor electrical conductivity of sulfur, large volume expansion, shuttle effect, and sluggish redox reactions in Li–S battery limit their practical application. Mo 2 C nanoparticles encapsulated in N-doped carbon nanotubes (Mo 2 C/NC NTs) were synthesized using MoO 3 nanorods as templates through a polypyrrole coating, heating, ammonia washing, and high-temperature carbonization. The Mo 2 C/NC NTs had a hollow structure with high specific surface area that can alleviate the volume expansion of cathode and the shuttle effect of polysulfides. The encapsulated Mo 2 C nanoparticles could anchor the lithium polysulfides and increase electrochemical reaction kinetics. Mo 2 C/NC NTs combined with sulfur (Mo 2 C/S/NC NTs) exhibited 400.2 mAh g−1 over 500 cycles at 1.0 A g−1 with a capacity decay rate of 0.068% per cycle. Density-functional theory calculations and X-ray photoelectron spectroscopy confirmed that Mo 2 C/NC NTs could anchor polysulfides and alleviate the shuttle effect by chemical interactions. This study supplies a novel route to prepare nanoparticle-encapsulated in N-doped carbon nanotubes for advanced Li-S battery. [Display omitted] [ABSTRACT FROM AUTHOR]

The surfaces of titanium grade 5 (Ti6Al4V) samples were altered on a micro and nano scale by femtosecond laser irradiation and subsequent electrochemical anodization. The produced micro-cones and nano-ripples covered by the additional oxide layer were characterised and their influence on osteoblast-like Saos-2 cell growth was studied. Surface topography and morphology were studied by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). From the wettability experiments, it was found that the contact angle vs. roughness follows the Wenzel equation and that the wettability increases after the anodization. The composition of the formed oxide layer was determined by X-ray photoelectron spectroscopy (XPS) and oxide incorporation of phosphate ions could be confirmed. Moreover, estimated electrochemical surface area (ECSA) of the femtosecond laser treated sample was 14 times larger compared to a polished sample. The anodic oxide film formation factors for different electrolytes were determined and were in the range of 1.3 nm V−1–2.0 nm V−1. Finally, the samples anodized with 0.1 M H 2 SO 4 and 3 M H 3 PO 4 showed decreased Saos-2 cell growth. [ABSTRACT FROM AUTHOR]

• High sulfur content (9.3%) of SDHC was obtained by adjusting annealing temperature. • Ex situ XPS was used to study the reaction mechanism of covalent sulfur. • In situ EIS revealed that diffusion of K 2 S X is the likely cause of SDHC degradation. Potassium-ion storage devices have gained increasing interest in applications such as large-scale energy storage and smart grids due to the advantages of high abundance, low cost, high working voltage, and fast charge transport in electrolytes. However, obtaining high-performance anodes with excellent rate performance and cycling stability remains a challenge due to the much larger size of K + ions. In this contribution, heteroatom S doped dumbbell-like hard carbon (SDHC) are synthesized using sucrose as the carbon source. SDHC-700, which is carbonized at 700 °C, exhibits the highest sulfur doping degree (9.3 at.%), remarkable reversible capacity (416 mAh g-1 at 0.05 A g-1), and superb rate performance (174 mAh g-1 at 5.0 A g-1). Ex situ X-ray photoelectron spectroscopy (XPS) tests reveal that covalent C-S bonds can undergo a reversible reaction with K to form K 2 S x. In situ electrochemical impedance spectroscopy (EIS) results suggest that the diffusion of long-chain potassium polysulfides may be the main reason for the degradation of SDHC during long-term cycling. Moreover, using SDHC-700 as the anode and commercial activated carbon as the cathode, a dual-carbon potassium-ion hybrid capacitor has been successfully constructed, which can deliver a high energy/power density of 96.5 Wh kg-1/160.3 W kg-1. This study provides a straightforward and practical approach for developing sulfur-doped hard carbons as high-performance anode materials for alkali metal ion storage. [ABSTRACT FROM AUTHOR]

Mesoporous carbon was synthesized to be employed as support in PtRe anodic electrocatalysts. The catalysts were prepared by the polyol method with the following Re loadings: 1, 3, 5, and 10 wt.%. The N 2 adsorption-desorption isotherms, thermogravimetric measurements, temperature programmed desorption and temperature programmed reduction of the support were performed and the catalysts were structurally characterized by temperature programmed reduction, H 2 chemisorption, X-ray diffraction, X-ray photoelectron spectroscopy, benzene hydrogenation reaction, and transmission electron microscopy. Furthermore, the electrochemical characterization of the catalysts was carried out by cyclic voltammetry, chronoamperometry, and CO stripping techniques. The addition of Re leads to a decrease in the CO oxidation onset potential value. The PtRe(3)/MC catalyst exhibited the best electrocatalytic activity, showing an electrochemical active surface area value of 82.5 m2 gPt−1. Moreover, the potential and anodic current values for ethanol oxidation reaction were 889 mV vs Ag/AgCl and 648 mA mgPt−1, respectively. This result is consistent with electronic effects and the smallest particle size found for this catalyst. [ABSTRACT FROM AUTHOR]

We developed a green and facile approach for synthesizing Ag@PP6@SWCNT nano-material via in-situ loading silver nanoparticles on the surface of phosphate pillar [6]arene (PP6) functionalized single-walled carbon nanotubes (SWCNT) at room temperature and without using either toxic or organic solvents. Ag nanoparticles (with an average size of 3–4 nm) were uniformly dispersed on the surface of SWCNT via the anchoring effect of PP6. PP6 provided a coordination environment between Ag and –PO 3 2– groups in PP6, and there were the π-π interactions between SWCNT and benzene rings of PP6. The obtained hybrid nano-material Ag@PP6@SWCNT was characterized using UV-vis absorption spectrum, transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Compared to commercial Pd/C and Ag@SWCNT catalysts, Ag@PP6@SWCNT exhibited higher catalytic activity for 4-nitrophenol (4-NP) reduction and methylene blue (MB) degradation, respectively. Moreover, because of the excellent supramolecular host-guest recognition capability of PP6, a sensitive and convenient electrochemical sensing platform for detecting paraquat (PQ) was constructed, and had potential applications in sensing highly toxic herbicides. Image 1 [ABSTRACT FROM AUTHOR]