Bicelles form a disc-like planar lipid bilayer surrounded by short-chain lipids at the peripheral rim. Therefore, they are well-suited to study purified transmembrane proteins in a more native-like environment. In this study, we investigated the physico-chemical properties of bicelles using transmission electron microscopy, dynamic light scattering, and fluorescence spectroscopy. The G protein-coupled receptor rhodopsin served as a prototypical membrane protein, which we reconstituted into bicelles having an average diameter of 11.6 ± 0.6 nm that increased to 14.9 ± 0.7 nm upon incorporation of rhodopsin. These results were confirmed by transmission electron microscopy and fluorescence spectroscopy. Comparing the molar concentration of bicelles and rhodopsin, we determined an average of 4 ± 1 bicelles per molecule of rhodopsin based on dynamic light scattering, and 6 ± 3 based on transmission electron microscopy data. Thus, only 14-25% of bicelles contained rhodopsin without evidence of aggregation. Infrared and circular dichroism spectroscopy measurements demonstrated that, in bicelles, rhodopsin forms a more packed structure compared to the detergent-solubilized condition, and exhibits enhanced α-helical packing. Moreover, the bicelle-reconstituted form exhibited increased thermal stability. When immobilized on sensor chip surfaces via concanavalin A anchoring, rhodopsin in bicelles showed at least a 10-fold lower binding efficiency to the G protein transducin than in detergent, although maintaining a 1:1 binding stoichiometry. These results indicate a monolamellar orientation of the bicelles on the sensor chip surface, exposing rhodopsin in native folding.

Effects of iron impurities on the alkaline hydrogen evolution reaction (HER) for nickel-based electrodes are not fully understood. Iron deposits on the Ni surface can either enhance HER kinetics by increasing surface roughness or act as a protective layer against NiH formation. This work systematically evaluates how different iron concentrations in the electrolyte affect HER activity and durability of polycrystalline Ni in 0.1 M KOH. Initial HER activity differences between 0 and 14 ppm Fez+ species are marginal. However, during 24-h chronopotentiometry tests at i = -10 mA cm-2 (0-3 ppm) cause pronounced deactivation, while higher concentrations (6-14 ppm) maintain more stable operation. Combining structural and electrochemical analyses we link HER overpotential changes to accessible Ni sites, instead of surface roughness. This study shows a critical Fez+ impurity threshold (>= 6 ppm) in the electrolyte to exploit the beneficial effects of iron on HER durability of alkaline water electrolysis.

Solid electrolyte interphases (SEIs) are essential for high-performance lithium and lithium-ion batteries. The SEI is formed by the reductive decomposition of electrolyte components. Ideally, it exhibits ion conductivity but blocks unwanted electron transfer (ET) reactions between the negative electrode materials and electrolyte components. Understanding the relation between functional properties of respective electrodes and the complex composition as well as evolution of the SEI over time and cycling is key for further advances in battery technology. Identical location experiments are demonstrated using scanning electrochemical microscopy (SECM) to probe local reactivity for ET reactions and small-area X-ray photoelectron spectroscopy (XPS) for the analysis of the local chemical surface composition of the SEI on lithium electrodes, both having comparable resolution in the micrometer range. This is enabled by a specially designed sample holder facilitating the cycling of electrodes inside the SECM cell and the inert transfer from the SECM instrument inside a glovebox to another glovebox directly attached to the XPS instrument. The relocation of specific regions, identified in SECM images, in the XPS instrument is enabled by a calibration process of the coordinate transform between the internal coordinates of the SECM and XPS instruments using an overlay of SECM and XPS images from the test samples. This transform is shown to be applicable to other samples. Using the optimized procedures for sample transfer and data acquisition, lithium metal electrodes were studied by SECM and XPS after storage at open circuit potential (OCP) as well as before and after metal deposition-dissolution cycles. The blocking properties improved during storage at the OCP in two kinetically different phases, and cycling caused a temporary strong decrease in the ET blocking and an increase in lateral variation of ET kinetics. The methodology is easily transferable to other samples and other localized techniques, where the relation between local reactivity and chemical surface composition is of interest.

Bimetallic platinum-iridium electrocatalysts for oxygen reduction/evolution reactions (ORR/OER) are of great interest for unitized regenerative fuel cells. The potential-dependent formation of catalytically active Pt-Ir species and their resulting electronic structure to accelerate both the ORR and OER are still unknown. Raman spectroscopy is used to monitor in situ the potential-resolved electronic and structural interactions of Pt and Ir in sputtered Pt-Ir thin films as model catalyst systems for the ORR and OER. The low coverage of oxygen-based intermediates on the Pt surface sites for Pt-Ir films correlates with enhanced ORR activity. At potentials before and during the OER, further electrochemical oxidation of the Pt-Ir thin films occurs that clearly differs from that of the monometallic films. DFT calculations indicate the formation of hydrous PtO6-IrO6 edge-sharing chains with & micro;-oxo bond linkages to couple Pt and Ir centers electronically. The theoretical stretching and bending motions of these Pt-O-Ir bonds are the most intense vibrations at 494, 542 and 682 cm-1 and are in very good agreement with the experimental data (similar to 510, similar to 540 and 657 cm-1). Very remarkably, theoretical and experimental data uncover a clear shift to lower energy by similar to 38 cm-1 for symmetric stretching of Ir-O-Pt (657 cm-1) compared to Ir-O-Ir (695 cm-1) under OER conditions. In other words, this change in bond strength can be correlated with lower OER activity and indicates a weakening of the Ir-O-Pt bond by similar to 0.48 kJ mol-1 compared to IrOx. Overall, our comprehensive in situ Raman and DFT investigations provide new mechanistic insights into the potential-resolved formation of catalytically active Pt-Ir sites for both the ORR and OER.

Developing robust and efficient anodes is essential for advancing sodium-ion battery technology. Herein, a systematic investigation of SnSx@C composites prepared at different pyrolysis temperatures to elucidate how their structural, surface, and electrochemical properties govern sodium-ion storage is reported. The study reveals that a lower synthesis temperature traps extra sulfur within the carbon matrix, which hampers the complete SnS conversion reaction and Na+ intercalation processes. In contrast, pyrolysis at 800 °C facilitates more thorough sulfur release, yielding a defect-rich but stable carbon matrix that supports enhanced sodiation/desodiation reversibility. Operando Raman spectroscopy and X-ray photoelectron spectroscopy depth profiling confirm that the pyrolysis temperature strongly affects the formation and stability of the solid electrolyte interphase. The SnSx@C material pyrolyzed at 800 °C not only possesses superior ion transport characteristics but also delivers enhanced electrochemical performance, maintaining a stable capacity of ≈500 mAh g-1 at C/10 and retaining a substantial fraction of its capacity over 100 cycles, in contrast to the rapidly decaying capacity of the material pyrolyzed at 600 °C.

Eumelanin is an interesting functional material for electrochemical applications due to its quinone/hydroquinone redox equilibrium. One major issue in the eumelanin film processing is the lack of solubility in polar solvents. In this study, the influence of functional groups of different polarity and their steric effects (tert-butyloxycarbonyl (Boc) groups giving “Mel-Boc” and nitro groups giving “Mel-NO2”) on the electrochemical properties of eumelanin in Zn coin cell devices is discussed. The derivatives are investigated using structural and surface analysis methods. Mel-Boc gives increased particle size and reduced capacity (0.97 mA h g−1 at 0.4 A g−1) in aqueous electrolyte compared to synthetic eumelanin. This indicates the importance of high surface area and metal ion chelation in the polymers. Mel-NO2 shows improved water-solubility, cycling stability, improved capacity at current densities over 0.1 A g−1 (19.5 mA h g−1 at 0.2 A g−1), and good conductivity in ionic liquid electrolyte devices. Post-density functional theory calculations using a higher-level theoretical approach (meta-GGA level) compared to previous theoretical melanin investigations show the electron withdrawing nitro groups causing a reduced HOMO-LUMO gap potentially being a reason for the improved electrochemical properties. Eumelanin’s potential in electrochemical applications is hindered by its poor solubility in polar solvents. Here, the authors explore functional group modifications, revealing that nitro groups enhance water solubility and electrochemical performance, highlighting the critical role of electron-withdrawing effects in optimizing eumelanin-based devices.

Dealloying of Ag–Au nanoparticles strongly differs from bulk alloys and is controlled by electrochemical conditions and Au surface atom mobility.

As a promising electrocatalyst for the CO2 reduction reaction (CO2RR), Cu/Cu oxide (CuxO) derived materials have been intensively studied in the last few decades. However, it is still poorly understood how the structure of Cu/CuxO precursors and their simultaneous reduction process influence CO2RR product distribution. Using Quick X-ray absorption near edge structure spectroscopy (Quick-XANES), we aim to understand the potential-dependent reduction processes of CuxO foam precursors with different Cu-0 : Cu+ : Cu2+ ratios to pure metallic Cu during the CO2RR. Initially, the CuxO foams were prepared by thermal annealing of electrodeposited Cu foams at 100, 200, 300, and 450 degrees C in air to vary the Cu-0 : Cu+ : Cu2+ ratio and especially the crystallinity of CuO. With these different chemical states and structures, the oxide-metal transition kinetics during the cathodic potential increment (Delta E = 100 mV), step (Delta E >100 mV), and jump (Delta E >500 mV) experiments were comprehensively investigated using multivariate curve resolution-alternating least squares (MCR-ALS) analysis of the Quick-XANES data. This allows in operando monitoring of the changes in the chemical state of Cu species particularly in relation to the effect of the previously applied potential. In principle, two rate determining steps can be involved in the CuO reduction to Cu(0)via intermediate Cu+ formation. First, our results demonstrate that the oxide-metal transition kinetics strongly depend on the initial abundance of Cu2+ species and precursor structure (ordered vs. amorphous) as well as on the type of chronoamperometric experiment. More precisely, compared to amorphous CuO, a high initial population of crystalline CuO species leads to a significant shift of the oxide-metal transition potential towards lower cathodic values, signifying a lower energy barrier to reduction. In addition, our work reveals that the different chronoamperometric experiments strongly influence the electrochemical stability of Cu+ species within the CuxO foams during CO2 electrolysis. Smaller potential steps increase the formation of Cu+ species and lead to a slowdown in the reduction kinetics.

Two bio-inspired variations of the sol-gel technique produced silica-hyperbranched poly (ethylene imine) (PEI) composite nanoparticles (NP) and xerogels (XG). Both methods are performed in ambient conditions and do not require toxic organic solvents or high temperatures. We have investigated the removal efficiency of trivalent europium by these two hybrid species in near-neutral aqueous solutions. The adsorption kinetics and isotherms, including data fitting with the pseudo-first and second order kinetic, and the Langmuir isotherm model are presented and discussed. Thermodynamic parameters indicate exothermic reaction (-180 kJ/mol for NP and -192 kJ/mol for XG, respectively) In addition, spectroscopic (Fourier Transform Infra-Red FTIR, Fluorescence Spectroscopy FS, X-ray Photoelectron Spectroscopy XPS) and microscopic techniques (Scanning Electron Microscopy SEM coupled with Energy Dispersive X-ray analysis EDX), as well as zeta -potential and Dynamic light scattering (DLS) measurements, have been employed to evaluate the interaction mechanism between the surface active moieties and Eu(III). The extremely high and homogeneous dispersion of the amino and silicate groups of the composites has led to the highest capacity value (22 mmol/g or 3343 mg/g and 14 mol/g or 2128 mg/g for the two distinct forms of the nanoparticles and the xerogels, respectively) reported up to today implying a potential application for lanthanide recovery. The adsorption data along with the spectroscopic and microscopic indicate that the adsorption is well described by the Langmuir isotherm model and is based on the formation of inner- and outer-sphere complexes between Eu(III) the amine and -Si-O- moieties.

Pressing environmental challenges require focused research on sustainable solutions in the domains of energy, water, food, land, and climate. The pigment eumelanin has recently been positioned as a promising candidate for solving issues in health, sensors, and energy storage. However, the low solubility of eumelanin in aqueous solvents, difficult film processibility, and high cost have hindered the material from wide deployment. Here, we propose melanin extracted from the black soldier fly, Hermetia illucens (Mel-BSF), as a sustainable alternative for the preparation of organic electrodes in energy storage applications. Mel-BSF displays pseudocapacitive behaviour with a high potential window, good electrochemical stability, and higher maximum capacity (91.8 mAh g−1) compared to synthetic eumelanin (17.3 mAh g−1) as the working electrode material in zinc-ion hybrid capacitors using an ionic liquid electrolyte. Structural and surface investigations reveal that additional aliphatic compounds, potentially lipids present after Mel-BSF refinement, significantly increase the film stability and redox centre availability. Eumelanin is a promising pigment for use in energy storage applications but has limitations hindering its wide usage. Here, melanin extracted from the black soldier fly is used to prepare electrodes with higher performance than synthetic melanin in zinc-ion hybrid capacitor applications.

Electrochemical CO2 reduction reaction (CO2RR) is a promising alternative for large-scale production of hydrocarbons. However, there are still some challenges including poor product selectivity and highly complex multiple-step reaction mechanisms.[1,2] To enhance the electrochemically active surface area and create more active surface sites, one of the promising approaches is the use of partial or complete (surface) oxidation of nanostructured copper materials. These Cu oxide precursor catalyst materials are not stable during the cathodic potentials applied for CO2RR, but still show an enhanced selectivity for the formation of C2+ products.[3,4] Interestingly, few studies proposed that oxygen can be present under CO2RR conditions in a few nm thick amorphous copper layer, while DFT calculations indicate that no subsurface oxygen remains thermodynamically stable at these highly cathodic potentials.[5-7] So far, only Valesco-Vélez et al. studied the Cu oxidation state changes (Cu2+ and Cu+ to metallic Cu) during CO2RR in CO2-saturated 0.1 M KHCO3 probed by operando X-ray absorption spectroscopy (XAS).[8] However, for pure CuO no reduction to metallic copper or Cu2O even at highly cathodic conditions is found, due to the formation of a copper carbonate passivation layer.[8] Thus, it is still poorly understood how the structure of the Cu/CuxO precursor materials and their simultaneous reduction processes to metallic copper influence the CO2RR product distribution and the overpotential required for hydrocarbon formation. Recently, we have shown the critical potential of oxide-metal transition processes for a Cu oxide foam annealed at 300 °C in air probed by operando XAS, X-ray diffraction (XRD), and Raman spectroscopy techniques.[9,10] Using Cu K-edge Quick-XAS technique, we aim to understand the potential-dependent reduction of different Cu2+:Cu+ ratios to Cu0 for nanoporous CuxO foam precursor catalysts under CO2RR conditions. The CuxO foams were prepared by electrodeposition and subsequent thermal annealing between 100 and 450 °C in air to generate the different Cu2+:Cu+:Cu0 ratios. Initially, from ex-situ XANES, XRD, and XPS analyses, we found that a rise in annealing temperature leads to an increase in the proportion of Cu2+ species and their degree of crystallinity within the CuxO foams. After annealing at 100 °C and 200 °C, the CuO phase/species are amorphous and mainly found at the surface of the foam. Once the annealing temperature reaches 300 °C or higher, the CuO phase is entirely crystalline. With these different chemical states of the precursor catalyst, the Cu oxide-metal transition kinetics during cathodic potential increment (ΔE = 100 mV), step (ΔE > 100 mV), and jump (ΔE > 500 mV) experiments in CO2-saturated 0.5 M KHCO3 were comprehensively investigated using Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) and Linear Combination Fit (LCF) analyses of the operando Cu K-edge Quick-XANES data. Our results demonstrate that different oxide-metal transition kinetics were found strongly dependent on the initial abundance of Cu2+ species and precursor structure (ordered vs. amorphous) as well as on the applied potential protocol to the CuxO foam precursor catalysts. More precisely, a high initial population of crystalline CuO, which is found for the CuxO foams annealed at 300 °C and 450 °C, leads to a significant shift of the oxide-metal transition potential towards lower cathodic overpotentials. For example, for the CuxO foam annealed at 450 °C (rich in crystalline CuO phases) the oxide-metal transition potential is shifted to 0 VRHE, while for the foam annealed at 100 °C this transition occurs at – 0.6 VRHE. Furthermore, smaller potential increments increase the formation and accumulation of Cu+ species, thereby slowing down the reduction kinetics. For the CuxO foam annealed at 200 °C, we could observe a full reduction to metallic Cu if jumping from OCP directly to – 0.5 VRHE, whereas no full reduction took place if using incremental potentials before applying – 0.5 VRHE. Overall, we show the substantial influence of crystalline CuOand the applied potential protocol on the reduction of CuxO foam precursor materials to metallic Cu during CO2RR. References: [1] Nitopi, S. et al., Chemical Reviews 2019,119 (12),7610–7672.DOI: 10.1021/acs.chemrev.8b00705.; [2] Li, C. W. et al., Journal of the American Chemical Society 2012,134(17),7231–7234. DOI:10.1021/ja3010978.; [3] Rahaman, M. et al., ACS Catal. 2017,7(11),7946–7956. DOI: 10.1021/acscatal.7b02234.; [4] Kas, R. et al.,, Phys. Chem. Chem. Phys. 2014,16 (24),12194–12201. DOI:10.1039/C4CP01520G.; [5] Zhan, C.; et al., ACS Catal. 2021,11(13),7694–7701. DOI:10.1021/acscatal.1c01478.; [6] Fields, M.; et al., J. Phys. Chem. C 2018,122(28),16209–16215. DOI:10.1021/acs.jpcc.8b04983.; [7] Cavalca, F. et al., J. Phys. Chem. C 2017,121(45),25003–25009.DOI:10.1021/acs.jpcc.7b08278.; [8] Velasco-Vélez, J.-J. et al., ACS Sustainable Chem. Eng. 2019,7(1),1485–1492. DOI:10.1021/acssuschemeng.8b05106.; [9] Dutta, A.; et al., Chimia 2021,75 (9),733–743.DOI:10.2533/chimia.2021.733.; [10] Dutta, A.; et al.,Journal of Catalysis 2020,389,592–603. DOI:10.1016/j.jcat.2020.06.024.

Understanding the mechanism and charge transport functionality of semiconducting photoresponsive materials will allow the designing of smart photoresponsive devices, such as optical memory devices, photodetectors, and NIR imaging sensors. A novel semiconducting photoresponsive material consisting of a gold-nanocluster functionalized with a tetrapyrrolic macrocycle (rhodin G7) has been developed using the Turkevich method, such that the transfer of the singlet state excitation energy of a macrocycle to the Au nanocluster is feasible. Polydentate chromophoric ligands bearing carboxylic acid functional groups to stabilize gold nanoparticles are rare. Chromophore functionalized gold nanoparticles are generally prepared by a ligand replacement strategy or through the two-phase synthesis protocols (Brust's method). We propose a simple one-phase method, and the possible advantage of this synthesis is that one can get rid of surface contaminants from the costabilizer. Detailed structural, morphological, and spectroscopic characterizations were performed to understand the efficacy of this synthesis process. Transport measurements indicated a clean p-type transport wherein the hole mobility of the pristine molecule increases by at least 2 orders of magnitude upon the incorporation of Au nanoparticles. Consequently, the photoresponsivity increases from 1 to 576 mA/W in the best single-component broadband photodetectors, which overtakes commercial Si photodetectors, indicating the efficacy of the molecular design for smart optical devices.

Over the last 15 years, core-shell nanoparticles with a Ptenriched shell have emerged as efficient electrocatalysts for the oxygen reduction reaction (ORR). However, to what extent the chemical state of the cobalt species inside the particle core has influence on the ORR performance and particularly on the long-term durability has not yet fully understood to date. In this study, we investigate the chemical state of the internal cobalt atoms and their stability within the PtxCo1-x core-shell catalysts during the ORR as well as after applying different accelerated stress test (AST) protocols. Remarkably, at the begin-of-life, the activated PtxCo1-x core-shell catalysts exhibit over 3.7-5.3 increase in Pt mass-based activity and over 5.8-10.6 increase in Pt surface area-specific activity at 0.95 VRHE compared to Pt/C. The superior ORR activity originates from the chemical composition of the particle core, where cobalt not only exists in the metallic state but also as 40-60% of Co oxide species detected by X-ray photoelectron spectroscopy. The Co oxide species are very likely relics of the precursor catalyst from the activation process via electrochemical dealloying. Moreover, the PtxCo1-x core-shell catalysts show improved durability and high cobalt retention against electrochemical dissolution during the AST protocols (e.g., >70% of Co after 2000 cycles between 0.5 and 1.5 VRHE). Although the potential cycle-dependent changes in the electrochemically active Pt surface area and particle size are negligible or moderate, the ORR activities of PtxCo1-x core-shell catalysts decrease but still surpass that of Pt/C by a factor of 2-3. The observed loss of ORR performance for PtxCo1-x core-shell catalysts is very likely related to Ostwald ripening as the main degradation process, which leads to increasing thickness of the Ptenriched particle shell. Remarkably, the stability of the internal Co oxide species is barely affected under the aggressive AST conditions. Thus, we suggest that the Co oxide species might have a positive effect and could even be a yet undiscovered alternative to metallic cobalt to boost the ORR activity and the long-term durability of PtxCo1-x core-shell catalysts beyond their expected useful life

The sorption of Eu(III) and U(VI) on microplastics (MP) has been investigated at pH 4 and increased metal ion concentrations ([Eu(III)], [U(VI)] <= 1 mmol). The sorption studies have been carried out in batch type experiments and the characterisation of MP prior and after metal ion sorption was performed by FTIR and Raman, and Fluorescence (FS) and X-ray photoelectron (XPS) spectroscopy, zeta-potential measurements and SEM-EDS. The data clearly indicate that up to a certain concentration the metal ion sorption occurs via electrostatic interaction resulting in a surface charge neutralization and further metal ion concentration results in surface precipitation in the form of microparticles. The uranium microparticles have a well defined crystalline structure whereas in the case of europium amorphous particles are formed. The formation of microparticles on the MP surfaces is of cardinal importance regarding both, the preparation of a new type of microparticles as well as the environmental impact of such microparticle structures. (c) 2022 Elsevier B.V. All rights reserved.

Dealloying process is a powerful and versatile method to fabricate three-dimensional nanoporous (np) materials for applications in electrochemical synthesis, sensors, and catalysis. In the last years, several morphologies of np-copper and their dealloying mechanisms have been reported in alkaline and acidic media.[1-4] For instance, the nature of anions such as chloride and phosphate strongly influence the ligament size of np-Cu. The effects of several experimental parameters to control the structural and chemical properties of np-Cu materials via dealloying are not fully understood to date. In our work, Zn 80 Cu 20 alloy ribbons prepared by melt-spinning were dealloyed by free corrosion in 0.1 M HCl and 1.3 M NaOH solutions. Both the surface and cross-section of the obtained np-Cu ribbons were comprehensively characterized by SEM, EDX, STEM, XRD, and XPS. Our results show a clear relation between dealloying conditions (pH, kind of electrolyte and reaction time) and structural parameters (ligament size and chemical composition) for np-Cu ribbons. The ligament size is strongly coupled with the residual Zn content prepared by dealloying in acidic environment. In contrast, the ligaments produced in alkaline media are much smaller, whereas the residual Zn content can be tuned in a broad range without changes in ligament size. For the first time, we point out the distribution of residual Zn within single ligaments of np-Cu. We suggest that the Cu surface atoms diffuse and capture the Zn atoms which are located in the near-subsurface during dealloying. Therefore, the Zn-rich regions seem to be relicts of the master alloy. We have also evaluated the time-resolved evolution of porosity within the ribbons via cross-section analysis. Despite the relatively thick melt-spun ribbons (35 ± 3 μm), kinetics of a bicontinuous ligament-pore structure are controlled by the interfacial process instead of the diffusion of corrosive electrolyte solution in and out of the porous layers, referred to as long-range mass transport. Surface diffusivities of Cu at 25 °C were determined to be 1.4 × 10 −18 and 9.4 × 10 −21 m 2 s −1 in 0.1 M HCl and 1.3 M NaOH, respectively. Therefore, the high Cu surface diffusion rate in the presence of chloride ions enables an enhanced dealloying front propagation into the ribbons, and also coarsening of the ligaments to form larger ligament. On the contrary, the slow surface diffusion rate of Cu (hydr)oxide in 1.3 M NaOH solution strongly limits the dealloying process and forms smaller ligaments. Moreover, dealloying temperature strongly influences the surface diffusivity of Cu, leading to a strong relationship between dealloying temperature and the np-Cu structure. The electrochemically active surface area of np-Cu ribbons was determined by double layer capacity method. The catalytic properties of the np-Cu ribbons were then evaluated for organic electro-synthesis of cyclic carbonates from CO 2 and epoxide. The yield of cyclic carbonate could be improved by using np-Cu ribbons for the activation of CO 2 . Based on our results, we provide deeper insights to the formation processes of np-Cu ribbons with tunable ligament size and Zn content in various electrolyte environments and its application as electrode material for electro-synthesis of cyclic carbonates formation from CO 2 and epoxide. References: Ibrahim, S.; Dworzak, A.; Crespo, D.; Renner, F. U.; Dosche, C.; Oezaslan, M.; Nanoporous Copper Ribbons Prepared by Chemical Dealloying of a Melt-Spun ZnCu Alloy. J. Phys. Chem. C, 126 (2022) 212-226 Hecker, B.; Dosche, C.; Oezaslan, M. Ligament evolution in nanoporous Cu films prepared by dealloying. J. Phys. Chem. C, 122 (2018) 26378−26384. Li, M.; Zhou, Y.; Geng, H. Fabrication of nanoporous copper ribbons by dealloying of Al-Cu alloys. J. Porous Mater., 19 (2012) 791−796. Liu, W. B.; Zhang, S. C.; Li, N.; Zheng, J. W.; Xing, Y. L. Facile One-Pot Synthesis of Nanoporous Copper Ribbons with Bimodal Pore Size Distributions by Chemical Dealloying. J. Electrochem. Soc., 158 (2011) D611.

Carbon supported Pt based nanoparticles are important electrocatalysts forenergy conversion reactions such as the oxygen reduction reaction (ORR). Althoughthis reaction has been extensively studied, the influence of factors such asthe particle size and inter-particle distance of the nanoparticle-based ornano-sized electrocatalysts on the ORR activity and durability are not yet fullyunderstood and often intertwined. This lack of understanding is mostly based onthe limitation in the synthetic approaches of the electrocatalysts whichusually do not allow an independent variation of particle size and inter-particledistance. In the presented work, we succeeded to disentangle both factors usinga “colloidal toolbox” approach and have demonstrated an effect of the inter-particledistance on the electronic properties of the nanoparticle via operando electrochemicalX-ray absorption spectroscopy (XAS).

Bifunctional mechanism and Pt–Had binding energy can be discriminated by a new descriptor, Q(Hupd) : Q(Coz+) ratio to tailor the HOR activity on a Pt–Co surface in alkaline environment.

Dealloying is a powerful and versatile method to fabricate three-dimensional nanoporous (np) materials with high surface area. In this work, we investigated the dealloying processes of Zn80Cu20 alloy ribbons in acidic and alkaline environments. Our results show that the nanostructure can be controlled by varying the nature of electrolyte solution, pH value, dealloying time, and temperature. In acidic media, the presence of chloride ions enhances the Cu surface mobility, leading to a faster coarsening and growth of ligaments during the dealloying process over time. In contrast, the surface diffusivity of Cu atoms in alkaline media is three orders lower than that in acid and results in a remarkably smaller ligament size due to the formation of Cu (hydr)oxide surface species. Cross-section analysis indicates that the dealloying process is largely controlled by interfacial processes. Interestingly, local Zn-rich regions were found near the surface in np-Cu ribbons dealloyed in 0.1 M HCl. This comprehensive study shows the influence of dealloying conditions on the morphology and residual Zn content of np-Cu ribbons as a model system for fabricating bicontinuous ligament-pore network materials with tailored structural and chemical properties for applications in electrochemical synthesis, sensors, and catalysis.

In the framework of bio-circular economy, miscanthus biomass was valorized through a single-stage, low severity hydrothermal carbonization process. The produced hydrochars were characterized using elemental and spectroscopic methodologies. It was determined that as the temperature increased so did the C content (47.9 and 68.9% for the samples prepared at 180 and 260 degrees C, respectively), whereas the O content decreased (from 44.2 to 25.5%, respectively). The adsorption behaviour of the hydrochars was investigated in the adsorption of Cu2+ and NH4+ and MIS-180 was determined as the optimum sample, achieving qmax values of 310 and 71 mg g-1, respectively. Isotherm and kinetic analysis indicated the higher number of O-containing functional groups of MIS-180 as the main reason for its higher adsorption capacities. Furthermore, Cu2+ adsorption followed the 2ndorder kinetic model, whereas NH4+ adsorption followed the 1st-order kinetic model, due to the different mechanisms involved, inner-sphere and outer-sphere complex formation, respectively.

Recently, Pt-based core-shell nanoparticles (NPs) have emerged as highly active catalyst materials to accelerate the sluggish oxygen reduction reaction (ORR) in acidic media as well as the hydrogen oxidation reaction (HOR) in alkaline. Less attention has been payed to the chemical state of the less noble metal after forming core-shell NPs. Intuitively; a metallic state of the less noble metal inside the particles has been suggested from many research groups. In this talk, we will show a new catalyst concept for Pt-Co nanoparticles by manipulating the surface arrangement and composition induced by the reaction conditions. More precisely, our catalysts exhibit superior Pt surface area-based specific activities (up to 10-fold) and Pt mass-based activities (up to 5-fold) towards the ORR compared to commercial Pt/C at 0.95 VRHE. In addition, we will show the influence of the chemical state and surface enrichment of the cobalt on the HOR activity in alkaline media. Altogether, we will solve the long standing mystery of the chemical state of the cobalt and its distribution for PtxCo1-x nanoparticles and its remarkable effect on the catalytic performance for HOR and ORR.