Abstract
Electrospinning is a powerful and versatile technique to produce efficient, specifically tailored and high-added value anodes for lithium ion batteries. Indeed, electrospun carbon nanofibers ...(CNFs) provide faster intercalation kinetics, shorter diffusion paths for ions/electrons transport and a larger number of lithium insertion sites with respect to commonly employed powder materials. With a view to further enhance battery performances, red phosphorous (RP) is considered one of the most promising materials that can be used in association with CNFs. RP/CNFs smart combinations can be exploited to overcome RP low conductivity and large volume expansion during cycling. In this context, we suggest a simple and cost effective double-step procedure to obtain high-capacity CNFs anodes and to enhance their electrochemical performances with the insertion of red phosphorous in the matrix. We propose a simple dropcasting method to confine micro- and nanosized RP particles within electrospun CNFs, thus obtaining a highly efficient, self-standing, binder-free anode. Phosphorous decorated carbon mats are characterized morphologically and tested in lithium ion batteries. Results obtained demonstrate that the reversible specific capacity and the rate capability of the obtained composite anodes is significantly improved with respect to the electrospun carbon mat alone.
Ethylene glycol was studied as solvent for the electrodeposition of iron from both bivalent and trivalent iron chloride solutions. Using cyclic voltammetry (CV) on Pt electrodes, the impossibility to ...directly reduce Fe(III) ions to metallic state Fe(0) was evidenced with the formation of Fe(II) species as intermediate step for iron plating. Linear sweep voltammetries (LSVs) were carried out on copper substrate confirming the results previously obtained on platinum. Potentiostatic depositions were performed from both Fe(II) and Fe(III) solutions in a broad potential interval (from −1.5 to −2.3 V vs Pt) to define the threshold value for iron reduction and film formation: the best results were obtained at −1.7 V vs Pt for Fe(II) solution and at −2.3 V vs Pt for Fe(III) one. Deposits were characterized with field emission scanning electron microscope (FE-SEM) showing a nanostructured morphology with no traces of oxygen in the deposits, resulting in a pure metallic plated iron: films showed a corrosion potential (Ecorr = −0.54 V vs Ag/AgCl ) in 3.5 wt% NaCl aqueous solution similar to high purity metallurgical iron sheet (Ecorr = −0.4 V vs Ag/AgCl ). X-Ray diffraction patterns showed a preferential orientation of the nanocrystalline deposit along the BCC 110 direction. Vibrating sample magnetometer (VSM) analysis showed a good saturation magnetization (1500 ± 100 kA/m) and low coercivity (∼20 Oe) indicative of a high purity iron film.
Ethylene glycol-based solutions containing metal precursor chloride salts were investigated for the electrodeposition of cobalt thin films and nanowires. The electrochemical behavior of 0.5 M Co(II) ...chloride solution at 70 °C was studied by means of cyclic voltammetry (CV) on a Pt substrate. The reduction process was shown to be irreversible, with high faradaic efficiencies (85–90 %). A diffusion coefficient (D0) of 2.29 × 10−6 cm2 s−1 for the Co species was estimated from the electrochemical behavior at different scan rates (from 25 to 125 mV s−1). The electrodeposition process was also studied on a copper substrate at different cathodic potentials (from −0.75 V vs Pt to −0.95 V vs Pt). Field-emission scanning electron microscopy (FE-SEM) and electron dispersive spectroscopy (EDS) revealed high-purity, compact films. Template-assisted electrodeposition resulted in ~16–18 μm long cobalt nanowires with an aspect ratio L/D > 100. X-ray diffraction (XRD) analysis of Co thin films showed a preferential orientation along the HCP 100 direction, which was even more marked for the nanowires. Vibrating sample magnetometry (VSM) highlighted that the fact that Co thin films were magnetized in-plane, while in nanowires a competition between shape and magnetocrystalline anisotropy led to similar magnetic behavior for the in-plane and out-of-plane directions.
•Ethylene glycol is an effective solvent for the electrodeposition of cobalt.•Diffusion coefficient of cobalt ions is measured using the Randles-Sevcik equation.•Diffusivity of cobalt ions is higher than that in other organic solvents.•The magnetization of cobalt thin films preferentially lies in the film plane.•Cobalt nanowires show no magnetic anisotropy.
The integration of multifunctional elements directly embedded in three-dimensional (3D) printed parts is the cutting-edge of additive manufacturing (AM) and it is crucial for enlarging as well as for ...strengthening AM role in industrial applications. Here, a straightforward and low-cost method that synergically combines stereolithography (SLA) and selective electroless metallization (EM) is presented for the fabrication of 3D parts characterized by complex shapes and end-use multifunctionalities (conductive, magnetic, mechanical properties). To this end, a novel photocurable composite based on acrylate resin loaded with nickel (Ni) particles is developed for high-resolution SLA-printing of features with self-catalytic properties for EM. Ni particles are loaded in the resin to trigger metal deposition avoiding time consuming and expensive laser-based surface activation. The effect of Ni content on SLA behavior as well as on the efficiency of EM process is studied. Metallized SLA cured samples show good electrical and magnetic properties as well as improved robustness with respect to their non-loaded counterparts. Then, selective metallization of 3D printed parts is successfully achieved by implementing a multi-material SLA-printing where loaded and non-loaded resins are properly interchanged with strong adhesion at the interface, thus offering a cost-effective approach for rapid prototyping of functional free-form features on 3D structures.
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When graphite is immersed in diluted sulfuric acid (H2SO4) electrolyte and positive potentials are applied to the sample, the surface undergoes an incipient oxidation process that develops gases ...(typically CO, CO2 and O2) both on the surface and in the underneath layers. These gases swell the surface and produce blisters, which damage and degrade the crystal. Some of these mechanisms are still under debate, such as the time interval Δt for blister evolution. Very recently, we studied the required Δt in 1 M H2SO4 electrolyte, finding a critical time for their formation of few seconds. Here, we give evidence that this time interval is almost unchanged if the electrolyte is further diluted until 1 mM, by combining electrochemical-atomic force microscopy, cyclic-voltammetry and normal pulse voltammetry.
A single-use disposable in vitro electrochemical immunosensor for the detection of HbA1c in undiluted human serum using differential pulse voltammetry (DPV) was developed. A three-electrode ...configuration electrochemical biosensor consisted of 10-nm-thin gold film working and counter electrodes and a thick-film printed Ag/AgCl reference electrode was fabricated on a polyethylene terephthalate (PET) substrate. Micro-fabrication techniques including sputtering vapor deposition and thick-film printing were used to fabricate the biosensor. This was a roll-to-roll cost-effective manufacturing process making the single-use disposable in vitro HbA1c biosensor a reality. Self-assembled monolayers of 3-Mercaptopropionic acid (MPA) were employed to covalently immobilize anti-HbA1c on the surface of gold electrodes. Electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) confirmed the excellent coverage of MPA-SAM and the upward orientation of carboxylic groups. The hindering effect of HbA1c on the ferricyanide/ferrocyanide electron transfer reaction was exploited as the HbA1c detection mechanism. The biosensor showed a linear range of 7.5-20 µg/mL of HbA1c in 0.1 M PBS. Using undiluted human serum as the test medium, the biosensor presented an excellent linear behavior (R² = 0.999) in the range of 0.1-0.25 mg/mL of HbA1c. The potential application of this biosensor for in vitro measurement of HbA1c for diabetic management was demonstrated.
In this work, the production of low cost and environment friendly anodes for sodium ion batteries is investigated. Algae are selected as bio-source of non-graphitic Hard Carbon (HC) with open ...structure acting as intercalation active material for Na ions storage. Chlorella vulgaris algae were pyrolyzed at temperatures comprised between 800 and 1100 °C. The decomposition products have been characterized with Scanning Electrode Microscope (SEM) and X-Ray Diffraction (XRD) analyses and their structure compared to one of the synthetic commercial HC. Thermogravimetric analysis (TGA) allowed to assess the decomposition process throughout the selected temperature scan. The obtained algae-derived HC is tested as anodic material for Na-ion battery, investigating the effect of pyrolysis temperature on the electrochemical behaviour. Their performances are compared with respect to a commercial synthetic HC active material. The results allow to consider algae as an environmentally benign and sustainable high added-value material for the production of HC anodes for Na-ion batteries.
Graphic abstract
Chemical vapor deposition (CVD) is regarded as the most promising technique for the mass production of graphene. CVD synthesis under vacuum is the most employed process, because the slower kinetics ...give better control on the graphene quality, but the requirement for high-vacuum equipment heavily affects the overall energy cost. In this work, we explore the possibility of using electroformed Cu substrate as a catalyst for atmospheric-pressure graphene growth. Electrochemical processes can produce high purity, freestanding metallic films, avoiding the surface defects that characterize the rolled foils. It was found that the growth mode of graphene on the electroformed catalyst was related to the surface morphology, which, in turn, was affected by the preliminary treatment of the substrate material. Suitable conditions for growing single layer graphene were identified.
Zinc-ion batteries (ZIBs) are currently being studied as an alternative to lithium-ion batteries (LIBs). The nucleation and growth of the zinc deposition mechanism is a critical field of research in ...ZIBs, as it directly affects the battery efficiency and lifespan. It is of paramount importance in mitigating the formation of porous, dendritic Zn structures that may cause cell inefficiency and, eventually, short-circuiting failures. Interfacial engineering plays a key role in providing reversible plating and stripping of metallic Zn in ZIBs through the proper regulation of the electrode–electrolyte interface. In this work, we investigated the behavior and characteristics of Zn plating on inkjet-printed Ti3C2Tx MXene-coated substrates according to the different electrolyte compositions. Specifically, ZnCl2 and ZnSO4 solutions were employed, evaluating the effect of a relatively low-molecular-weight polyethylene glycol (PEG400) addition to the electrolyte as additive. Electrochemical analyses demonstrated higher deposition kinetics in chloride-based electrolytes rather than sulfate ones, resulting in lower nucleation overpotentials. However, the morphology and microstructure of the plated Zn, investigated via scanning electron microscopy (SEM) and X-ray diffraction (XRD), revealed that the electrolytic solution played a predominant role in the Zn crystallite formation rather than the Ti3C2Tx MXene coating. Specifically, the preferential Zn 002 orientation could be favored when using additive-free ZnSO4 solution, and a PEG addition was found to be an efficient texturing agent only in ZnCl2 solution.
•Copper is electrodeposited onto zinc from a chloride-free organic solution.•Diethanolamine is used to greatly minimize displacement reaction between Zn and Cu.•Overall Zn/Cu/Sn stack is achieved by ...electrodeposition.•All layers show a smooth surface and compact morphology.•Well-formed kesterite is obtained from Zn/Cu/Sn electrochemical precursor stack.
A chloride-free solution based on ethylene glycol was shown to be suitable for the electrodeposition of copper onto zinc, allowing the fabrication of a Mo/Zn/Cu/Sn metallic precursor stack. The addition of diethanolamine (DEA) played an essential role in minimizing displacement reactions by shifting copper reduction towards a more negative potential. The electrochemical behavior of copper species with and without DEA was studied by cyclic voltammetry, and subsequently confirmed by displacement reaction assessment (OCV and ICP-OES measurements). The metallic stack was characterized by SEM and AFM, showing the effectiveness of the copper plating solution. Reactive annealing was carried out in a tubular furnace to obtain the CZTS kesterite semiconductor, as confirmed by XRD and Raman spectroscopy.
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