Nanostructured Electrodes Research Articles

Recent progress in nanostructured electrodes for solid oxide fuel cells deposited by spray pyrolysis

Low-temperature solid oxide fuel cells (LT-SOFCs), operating below 650 °C, are attracting a great interest due to their long-term stability and potential application for stationary and portable power generation. Much effort is being devoted to investigating new electrode materials because the electrode polarization resistance remains a serious limitation to the performance. Nanostructured electrodes offer the possibility of increasing the SOFC efficiency at low temperatures. Among the different electrode preparation techniques, spray pyrolysis deposition is a versatile, economic and industrially scalable method to grow electrodes directly on the electrolyte, reducing preparation steps and time. Recent progresses in this field are summarized here, especially highlighting the wide variety of different microstructural strategies used to improve the electrode performance, i.e. nanocomposite cathodes graded cathodes, infiltrated cathodes and cathodes with active/functional layers. Finally, the current existing challenges and the future working directions for further enhancing the properties of new nanostructured electrodes are discussed. • Microstructural strategies for SOFC electrodes based on spray-pyrolysis are presented. • Microstructural optimization greatly improves the efficiency of the electrodes. • Both cathode and anode prepared for spray deposition are reviewed. • This review will be helpful for the development of new nanostructured electrodes.

In Situ Probing Potassium-Ion Intercalation-Induced Amorphization in Crystalline Iron Phosphate Cathode Materials.

Na-ion and K-ion batteries are promising alternatives for large-scale energy storage due to their abundance and low cost. Intercalation of these large ions could cause irreversible structural deformation and partial to complete amorphization in the crystalline electrodes. A lack of understanding of the dynamic changes in the amorphous nanostructure during battery operation is the bottleneck for further developments. Here, we report the utilization of in-operando digital image correlation and XRD techniques to probe dynamic changes in the amorphous phase of iron phosphate during potassium ion intercalation. In-operando XRD demonstrates amorphization in the electrode's nanostructure during the first charge and discharge cycle. Additionally, ex situ HR-TEM further confirms the amorphization after potassium-ion intercalation. An in situ strain analysis detects reversible deformations associated with redox reactions in the amorphous phases. Our approach offers new insights into the mechanism of ion intercalation in the amorphous nanostructure which are highly potent for the development of next-generation batteries.

Water structure at the multilayers of palladium deposited at nanostructured Au electrodes

In situ ATR-SEIRAS experiments were carried out to describe water structure at the surface of multilayers of Pd modified nanopatterned gold film electrodes in contact with aqueous 0.1 M HClO 4 solution. The results show that the surface water becomes more ordered when the thickness of the Pd film increases. The “ice-like water” band becomes stronger and for the electrode with 5 ML Pd@Au, the ratio of “ice-like water” to “liquid-like water” becomes larger than that in bulk water. Concomitantly, the population of “monomers” or small water clusters diminishes. All surface water bands increase when hydrogen adsorption takes place. The bending band corresponding to “monomers” or “multimers” water is observed chiefly at the potentials of hydrogen adsorption.

Facile self-assembly of carbon-free vanadium sulfide nanosheet for stable and high-rate lithium-ion storage

Metal sulfides are recognized as potential candidates for the anode materials of lithium ion batteries (LIBs) because of their high theoretical capacity. However, the low reaction kinetics of metal sulfides leads to their poor cycle life and rate performance, which limits their practical application in the field of energy storage. In this work, we synthesized a self-assembled carbon-free vanadium sulfide (V3S4) nanosheet via a facile and efficient method. The unique mesoporous nanostructure of V3S4 can not only accelerate the migration of ions/electrons, but also alleviate the volume expansion during the lithium ion insertion/extraction process. When used as the anode material of LIBs, the carbon-free V3S4 electrode exhibits remarkable electrochemical performance with ultra-high charge capacity (1099.3 mAh g−1 at 0.1 A g−1), superior rate capability (668.8 mAh g−1 at 2 A g−1 and 588.8 mAh g−1 at 5 A g−1) and impressive cycling ability (369.6 mAh g−1 after 200 cycles at 10 A g -1), which is very competitive compared with those of most metal sulfides-based anode materials reported so far. The strategy in this work provides inspiration for the rational design of advanced nanostructured electrode materials for energy storage devices.

Highly active methanol oxidation electrocatalyst based on 2D NiO porous nanosheets:a combined computational and experimental study

Two-dimensional (2D) nanostructures are attractive candidates for electrocatalytic applications owing to their excellent mechanical flexibility and large exposed surfaces. In this work, we present ultra-thin 2D NiO porous nanosheets prepared by a simple, economical and green experimental method (hydrothermal, freeze-drying, and sintering) as efficient electrocatalysts for direct methanol fuel cell (DMFC) application. Benefiting from the ultra-thin 2D framework and porous nanostructure, the 550-NiO catalyst (annealed at 550 °C) exhibit higher current density (12.54mA cm−2) and faster charge transfer in the catalytic process, due to its abundant solid state redox couples (Ni2+/Ni3+= 0.991), suitable oxygen defects and surface coverage of redox species (2.90 × 10−7mol cm−2). First-principles density functional theory calculations were employed to provide mechanistic insights into the methanol oxidation reaction over the NiO catalyst via methanol dehydrogenation to CO involving O–H and C–H bond scissions, and subsequently, CHO oxidation with OH. The most plausible reaction pathway of methanol oxidation on NiO (100) is predicted to be CH3OH → CH3O → CH2O → CHO → CHOOH → COOH → CO2. The reported facile, simple, low-cost and method provides an avenue for the rational design and synthesis of 2D NiO porous nanostructured electrode materials for DMFC and beyond.

A single-molecule blueprint for synthesis.

Chemical reactions that occur at nanostructured electrodes have garnered widespread interest because of their potential applications in fields including nanotechnology, green chemistry and fundamental physical organic chemistry. Much of our present understanding of these reactions comes from probes that interrogate ensembles of molecules undergoing various stages of the transformation concurrently. Exquisite control over single-molecule reactivity lets us construct new molecules and further our understanding of nanoscale chemical phenomena. We can study single molecules using instruments such as the scanning tunnelling microscope, which can additionally be part of a mechanically controlled break junction. These are unique tools that can offer a high level of detail. They probe the electronic conductance of individual molecules and catalyse chemical reactions by establishing environments with reactive metal sites on nanoscale electrodes. This Review describes how chemical reactions involving bond cleavage and formation can be triggered at nanoscale electrodes and studied one molecule at a time.

Electrospun MOF-based ZnSe nanocrystals confined in N-doped mesoporous carbon fibers as anode materials for potassium ion batteries with long-term cycling stability

Potassium ion batteries (KIBs) are promising energy storage systems for large-scale applications. However, owing to the large diameter of K+, these batteries show limited electrochemical performance, particularly in terms of cycling stability. Thus, it is essential to design novel electrode materials for practical applications of KIBs. In this study, novel N-doped porous carbon nanofibers embedded with ultrafine ZnSe nanocrystals were successfully prepared as an advanced anode material for KIBs via electrospinning of a Zn-based zeolitic imidazolate framework (ZIF-8) and subsequent thermal treatment. Numerous mesopores were generated within the nanofibers by the transformation of ZIF-8 nanoparticles into a hollow carbon frame during thermal treatment. The unique 1D structure provided sufficient active sites for K+ storage, shortened the diffusion path for ions, and enhanced the structural robustness of the electrode. The N-doped carbon matrix also effectively alleviated the mechanical stress in the ZnSe nanocrystals and improved the electrical conductivity. Consequently, the 1D porous nanostructured electrodes exhibited excellent long-term cycling stability for 1000 cycles when tested as anodes for KIBs, with a reversible capacity of 270 mA h g−1 at 0.5 A g−1 and a high-rate capacity of 139 mA h g−1 at 2.0 A g−1.

Monoclinic Cu3(OH)2V2O7·2H2O nanobelts/reduced graphene oxide: A novel high-capacity and long-life composite for potassium-ion battery anodes

Developing suitable anode materials for potassium-ion batteries (PIBs) remains a great challenge owing to the limited theoretical capacity of active materials and large radius of K+ ion (1.38 Å). To solve these obstacles, by integrating the principles of multielectron transfer and rational porous crystal framework, we creatively propose the monoclinic Cu3(OH)2V2O7·2H2O (CVO) as a novel anode for PIBs. Furthermore, inspired by the metastable nature of CVO under high temperature/pressure, we skillfully design a facile hydrothermal recrystallization strategy without the phase change and surfactants addition. Thus, for the first time, the porous composite of Cu3(OH)2V2O7·2H2O nanobelts covered in situ by reduced graphene oxide (CVO NBs/rGO) was assembled, greatly improving the deficiencies of CVO. When used as a novel anode for PIBs, CVO NBs/rGO delivers large specific capacity (up to 551.4 mAh g−1 at 50 mA g−1), high-rate capability (215.3 mAh g−1 at 2.5 A g−1) and super durability (203.6 mAh g−1 at 500 mA g−1 even after 1000 cycles). The outstanding performance can be ascribed to the synergistic merits of desirable structural features of monoclinic CVO nanobelts and the highly conductive graphene 3D network, thus promoting the composite material stability and electrical/ionic conductivity. This work reveals a novel metal vanadate-based anode material for PIBs, would further motivate the subsequent batteries research on M3(OH)2V2O7·nH2O (M; Co, Ni, Cu, Zn), and ultimately expands valuable fundamental understanding on designing other high-performance electrode materials, including the combined strategies of multielectron transfer with rational porous crystal framework, and the composite fabrication of 1D electrode nanostructure with conductive carbon matrix.

Studies on electrochemical mechanism of nanostructured cobalt vanadate electrode material for pseudocapacitors

The supercapacitive behaviour of chemically synthesized cobalt vanadate nanostructures was reported in this work. Various analytical techniques along with optical studies were utilized to investigate the crystallographic information's and optical response. Crystallographic information of the prepared nanostructures was revealed by the XRD analysis and it's formation was confirmed by the FTIR and XPS techniques. The nano-layered structural and surface morphology was observed through scanning electron microscopy and high-resolution transmission electron microscopy. Electrochemical performances in aqueous electrolytic medium were examined for supercapacitive behaviour of prepared Co3V2O8. Specific capacitance value of about 790 F/g was achieved at 1 A/g current density and the superior capacitive retention of 90.1 % after 10000 cycles had been imparted by the prepared Co3V2O8. Based on the results, it was confirmed that the prepared cobalt vanadate nanostructures can be used as an electrode material for future energy storage devices.

Confining invasion directions of Li+ to achieve efficient Si anode material for lithium-ion batteries

Tremendous volume expansion of silicon anode during cycling limits its further application. Here, a novel silicon nano-ribbon (SiNR) with (110) crystal plane is proposed as anode for the Lithium-ion batteries. The SiNRs with (110) crystal plane have been synthesized by a simple electrochemical micromachining method. Both invasion direction of the lithium-ions and expansion directions of the lithiated silicon are limited to the <110> crystal direction. Recrystallization of SiNR induced by the retention of silicon atomic chains after delithiation is verified experimentally and theoretically. Such SiNR, without necessary surface coating treatment, exhibits high ionic conductivity, high stable solid electrolyte interphase (SEI) and long cycling stability, retaining a specific capacity of 1721.3 mAh g−1 (∼80% capacity retention) after 2000 cycles with an initial coulombic efficiency (CE) of 83%. The rational design of nanostructured battery materials and electrodes in this work also opens a new dimension in material design for other batteries.

Characterization of two-way fabricated hybrid metal-oxide nanostructured electrode materials for photovoltaic and miniaturized supercapacitor applications

Portable electronic devices require a small volume self-powered energy system that can combine fabrication of energy harvesting and storage devices in one plane. This study focuses on fabricating novel all-oxide photovoltaic and supercapacitor devices based on MoO3, V2O5, and CoxOy thin electrodes prepared by a two-electrode cell arrangement. The fabricated devices were tested using solar simulator and potentiostat at ambient temperature. The power conversion efficiencies of the fabricated photovoltaic devices were found in the range of 0.17–0.39% depending on buffer layer characteristics. It therefore suggests that V2O5 and MoO3 can buffer photovoltaic processes by lowering the conduction band offset in the proximate CoxOy absorber. Pseudocapacitive behavior of MoO3/CoxOy||MoO3/CoxOy and V2O5/CoxOy||V2O5/CoxOy planar devices showed that they delivered maximum specific areal capacity values of 0.694 and 0.778 μAhcm−2 respectively at discharge current density of 0.1 mAcm−2. They also showed considerably low reduction in energy density (about 38.7%) even at a remarkable increase in power density of about 450% (at a high current density of 1.0 mAcm−2). In addition, the symmetric microsupercapacitors showed excellent retention of capacity even after 5000 cycles. These results generally indicate the reliability of the fabricated devices in the development of portable electronic components for energy application.

Preparation of lithium titanate nanoparticles assisted by an ion-exchange process and their electrochemical performance as anode materials for Li-ion batteries

Spinel-structured lithium titanate (Li4Ti5O12, LTO) has received broad attention as a next-generation anode material for Li+-ion batteries because of its excellent safety and long cycle life. However, calcination at the high temperatures (>800 °C) is necessary to obtain spinel-phase LTO. This interferes the synthesis of LTO particles as nano-sized material which is advantageous for electrochemical performance. In this study, spinel-structured LTO nanoparticles were synthesized via an ion-exchange process in conjunction with a mild calcination temperature (600 °C). First, Li2TiO3 was prepared by calcination of a LiOH∙H2O/TiO2 (atomic ratio Li/Ti = 2) mixture at 600 °C. Second, the Li+ ions of the layered Li2TiO3 were partially exchanged with H+ ions in HCl solution, resulting in the synthesis of HxLi2−xTiO3 (0 <x<2). We investigated the effects of the H/Li ratio in the ion-exchange process of Li2TiO3 particles and the calcination temperature on the phase composition of the final product. The phases in the final product are sensitively determined by the conditions used in the ion-exchange reaction and subsequent calcination. Under the optimized conditions, spinel phase dominant LTO particles are synthesized by calcination at a low temperature (600 °C). Because of the mild calcination temperature, the crystal size and secondary particle size of the spinel-structured LTO are 23.9 nm and<1 µm, respectively. These particles show a high initial discharge capacity of 165.3 mAh g−1 at 1 C, excellent cyclic stability, and superior rate performance when used as an anode material in a Li+-ion battery. Therefore, the suggested synthetic process is advantageous for the production of nanostructured LTO electrode materials.

Direct Amperometric Sensing of Fish Nodavirus RNA Using Gold Nanoparticle/DNA-Based Bioconjugates.

We describe the design of a simple and highly sensitive electrochemical bioanalytical method enabling the direct detection of a conserved RNA region within the capsid protein gene of a fish nodavirus, making use of nanostructured disposable electrodes. To achieve this goal, we select a conserved region within the nodavirus RNA2 segment to design a DNA probe that is tethered to the surface of nanostructured disposable screen-printed electrodes. In a proof-of-principle test, a synthetic RNA sequence is detected based on competitive hybridization between two oligonucleotides (biotinylated reporter DNA and target RNA) complimentary to a thiolated DNA capture probe. The method is further validated using extracted RNA samples obtained from healthy carrier Sparus aurata and clinically infected Dicentrarchus labrax fish specimens. In parallel, the sensitivity of the newly described biosensor is compared with a new real-time RT-PCR protocol. The current differences measured in the negative control and in presence of each concentration of target RNA are used to determine the dynamic range of the assay. We obtain a linear response (R2 = 0.995) over a range of RNA concentrations from 0.1 to 25 pM with a detection limit of 20 fM. The results are in good agreement with the results found by the RT-qPCR. This method provides a promising approach toward a more effective diagnosis and risk assessment of viral diseases in aquaculture.

Tunable Electrode Architectures for La0.8Sr0.2Fe1-XTixO3- δ Based Symmetrical Solid Oxide Fuel Cells

The efficiency of SOCF electrodes can be improved by optimizing the microstructure from alternative preparation methods, such as infiltration and nanostructured electrodes deposited at low temperature. Recent studies have demonstrated that spray-pyrolysis deposition is a versatile method to obtain nanostructured electrodes with improved performance in comparison with conventional electrodesprepared at high sintering temperatures. Among the different electrodes studied in the last few year, titanium-doped ferrites are one of the most promising because of their high redox stability and great electrochemical performance in both oxidizing and reducing conditions2,3. In this work, (La0.8Sr0.2)0.95Fe1-xTixO3- δ (x=0.2, 0.4) perovskites, hereafter labelled as LSFT02 and LSFT04, respectively, with different architectures were obtained by spray-pyrolysis deposition and they were tested as symmetrical electrodes for solid oxide fuel cell (SSOFC). The electrodes were deposited on as-prepared YSZ pellets and porous Ce0.9Gd0.1O1.95, preciously fixed on the electrolyte. A nanocomposite electrode was also prepared in a single step onto YSZ. The precursor solution containing the corresponding nitrates and etilendiaminetetraacetic acid (EDTA) as a complexing agent in a 25% molar ratio in Milli-Q water with a concentration of 0.025 M, was sprayed directly onto the electrolyte. The temperature deposition, time and flow rate was optimized to 325 ºC, 1 h and 20 mL min-1, respectively. After the deposition, the samples were calcined at 800 ºC for 1h to achieve crystallization. The structural characterization by XRD revealed that both LSFT02 and LSFT04 are nanocrystalline compounds without any secondary phases after annealing in air and reducing conditions. Figure 1 shows SEM images of the different electrode architectures cross-section at different magnifications. The electrodes deposited into the CGO backbone consists of a porous backbone (10 µm) coated with a layer of LSFT nanoparticles (∼50 nm of diameter) at 800 ºC (Fig. 1a). The HAADF-STEM images of the nanocomposite material showed a high homogeneity and particle size as low as 50 nm at 1000 ºC The electrochemical properties of the symmetrical cells were tested by impedance spectroscopy. The polarization resistance (Rp) in air of LSFT0.2 and LSFT0.4 impregnated CGO backbone by spray pyrolysis (SP) decrease from 1.19 and 8.84 Ω·cm2 to 0.23 and 0.67 Ω·cm2 at 700 ºC, respectively, when compared with the powders obtained by freeze drying precursor method. The similar behavior observed for both compositions confirmed that the increase of the TPB length, highly improves the electrochemical performance. Same results were obtained for the nanocomposite architecture. On the other hand, the Rp values in H2 for LSFT04 are slightly lower when compared with LSFT02, 0.21 and 0.35 Ω·cm2 at 700 ºC, respectively, fact that could be explained by the great efficiency of Ti-doped electrodes in reducing conditions at high temperature. In other to further improving the electrochemical performance, LSFT02 was doped with Ni and Ru, infiltrated into the CGO backbone and tested as SSOFC. The electrochemical performance in H2 improves substantially for the Ni-doped sample, achieving 0.09 Ω·cm2 at 750 ºC, which is one of the lowest ASR values for related materials, mainly attributed to the Ni0 nanoparticle exsolution combined with an advance microstructure configuration. The influence of d.c. bias in a 3-probe configuration was studied under cathodic and anodic polarization in symmetrical cells in both oxidizing and reducing conditions. The results revealed a considerable decrease on the LF process, attributed to surface diffusion and/or charge transfer in the electrode. The study of performance of the different architectures electrodes in real SOFC conditions are currently in process, but high maximum power densities are expected due to the low ASR values achieved.

Nanostructuring and Electrochemical Performance of Nb Doped La0.7Sr0.3Co1.XNbxO3- δ (LCSN) Perovskites for Solid Oxide Fuel Cells

For solid oxide fuel cells (SOFCs), the electrode fabrication with the electrolyte showing a good thermal expansion coefficient (TEC) match at high temperatures is considered a key element in deciding upon the potential of a candidate electrode material. Here, in this work a Nb doped perovskite La0.7Sr0.3Co0.95Nb0.05O3- δ (LCSN) material is tested for the desired properties of a SOFC cathode. The results are showing improved (TEC) by about 28% for the temperature range of 200 - 2100 K and an increase in ionic conductivity by 19% at 873 K as compared to the base material, La0.7Sr0.3CoO3-- δ (LSC). The material is further fabricated in the form of a nanostructured thin-film electrode using a pulse laser disposition system with thickness varying from 50 nm to 100 nm on a GDC electrolyte. The impedance of the electrode in a symmetric cell is observed to vary with the thickness, suggesting oxygen anion transport, limiting the electrode performance.

Examine Operando Generated Ni-Based Alloy Nanomaterials as Fuel Electrode in Solid Oxide Cells

Solid oxide cells are highly efficient electrochemical device for energy conversion. They can convert chemical energy to electrical energy in solid oxide fuel cells (SOFCs) mode and vice versa in solid oxide electrolysis cells (SOECs) mode. Constructing nanostructured electrodes have been demonstrated as an effective approach to enhance performance and durability for solid oxide cells, primarily due to significantly extended triple phase boundaries, where the active sites for electrochemical reactions locate. [1, 2] Exsolution, an innovative method of generating uniformly distributed fine particles through redox treatment, is of particular interest in recent years, as it offers well embedded nanoparticles bringing greatly boosted catalytic properties, thermal stability, and coking resistance. A wide range of nanomaterials have been fabricated by this manner, including metals [3, 4] , alloys [5, 6] and oxides [7, 8] .Through exsolution processing, catalytically active materials can be produced either in-situ by exposing to a H2-containing atmosphere in which nanoparticles form on the surface upon reduction, or operando in an SOEC through electrochemical reduction when a high potential is applied. It was reported that exsolution happened almost instantly at 2.0 V in steam electrolysis operation, generating sufficiently high amount of nanocatalysts pinned on the surface of perovskite. [9] In contrast, it takes hours even days by chemical reduction, yet with less impressive performance. This indicates that electrochemical reduction by applying suitable potential or current can serve as an efficient method to produce electrocatalysts in nanoscale. However, potential-driven exsolution has not been extensively studied, especially in CO2 electrolysis via SOEC.In this work, we have been focusing on examine titanate perovskites with exsolved Ni-based alloy nanocatalysts as fuel electrode of solid oxide cells, particularly on generating nanocatalysts via electrochemical reduction in CO2 electrolysis conditions. A series of titanate perovskites were prepared, including La0.43Ca0.37Ni0.06Ti0.94O3-δ, La0.43Ca0.37Ni0.03Fe0.03Ti0.94O3-δ, and La0.43Ca0.37Ni0.03Co0.03Ti0.94O3-δ. These compositions represent metallic Ni, Ni-Fe alloy, and Ni-Co alloy as nanocatalysts to be exsolved respectively. X-ray diffraction (XRD) and DC conductivity measurement were conducted to determine material crystal structure and conductivity properties, respectively. SOCs with scandium stabilized zirconia (ScSZ) electrolyte, standard (La, Sr)MnO3 (LSM)/ScSZ air electrode and the above prepared titanates fuel electrodes were fabricated for electrochemical characterisation. The fuel electrodes were firstly activated by applying varying potential/current in pure CO2 gas, prior to performance evaluation. In-situ impedance spectroscopy and polarization curves were recorded, and post-mortem microstructure analysis was carried out to investigate the exsolution behaviour on different electrodes. Results obtained so far showed that nanoparticles induced by electrochemical reduction formed at potentials higher than 2V in CO2 electrolysis conditions, leading to improved cell performance towards CO2 reduction as well as H2 oxidation. Higher performance was observed on the cells with alloy nanocatalysts compared to that with sole Ni nanoparticles. P. A. Connor, X. Yue, C. D. Savaniu, R. Price, G. Triantafyllou, M. Cassidy, G. Kerherve, D. J. Payne, R. C. Maher, L. F. Cohen, R. I. Tomov, B. A. Glowacki, R. V. Kumar, J. T. S. Irvine, Adv. Energy Mater., 8, 1800120 (2018).J. T. S. Irvine, D. Neagu, M. C. Verbraeken, C. Chatzichristodoulou, C. Graves, M. B. Mogensen, Nat. Energy, 1, 15014 (2016).D. Neagu, G. Tsekouras, D. N. Miller, H. Menard, J. T. S. Irvine, Nat. Chem., 6, 916 (2013).D. Neagu, T. S. Ou, D. N. Miller, H. Me ́nard, S. M. Bukhari, S. R. Gamble, R. J. Gorte, J. M. Vohs, J. T. S. Irvine, Nat. Comm., 6, 8120 (2015).T. Zhu, H. E. Troiani, L. V. Mogni, M. Han, S. A. Barnett, Joule, 2, 478 (2018).D. Neagu, E. I. Papaioannou, W. K. W. Ramli, D. N. Miller, B. J. Murdoch, H. Ménard, A. Umar, A. J. Barlow, P. J. Cumpson, J. T. S. Irvine, I. S. Metcalfe, Nat. Comm., 8, 1855 (2017).J. Wang, J. Zhou, J. Yang, D. Neagu, L. Fu, Z. Lian, T. Shin, K. Wu, Adv. Mater. Interfaces, 7, 2000828 (2020).L. Ye, M. Zhang, P. Huang, G. Guo, M. Hong, C. Li, J. T. S. Irvine, K. Xie, Nat. Comm., 8, 14785 (2017).J. Myung, D. Neagu, D. N. Miller, J. T. S. Irvine, Nature, 537, 528 (2016).

High-Performance Lead-Acid Batteries Enabled by Pb and PbO2 Nanostructured Electrodes: Effect of Operating Temperature

Lead-acid batteries are now widely used for energy storage, as result of an established and reliable technology. In the last decade, several studies have been carried out to improve the performance of this type of batteries, with the main objective to replace the conventional plates with innovative electrodes with improved stability, increased capacity and a larger active surface. Such studies ultimately aim to improve the kinetics of electrochemical conversion reactions at the electrode-solution interface and to guarantee a good electrical continuity during the repeated charge/discharge cycles. To achieve these objectives, our contribution focuses on the employment of nanostructured electrodes. In particular, we have obtained nanostructured electrodes in Pb and PbO2 through electrosynthesis in a template consisting of a nanoporous polycarbonate membrane. These electrodes are characterized by a wider active surface area, which allows for a better use of the active material, and for a consequent increased specific energy compared to traditional batteries. In this research, the performance of lead-acid batteries with nanostructured electrodes was studied at 10 C at temperatures of 25, −20 and 40 °C in order to evaluate the efficiency and the effect of temperature on electrode morphology. The batteries were assembled using both nanostructured electrodes and an AGM-type separator used in commercial batteries.

Nanostructure-based electrochemical sensor: Glyphosate detection and the analysis of genetic changes in rye DNA

Glyphosate, commonly known by its original trade name Roundup™, is the world's most widely used herbicide. Glyphosate and its metabolites have a profound negative environmental impact and long-term toxicity risk, including carcinogenicity, genotoxicity, and endocrine disruption, even at concentration levels too low to have a herbicidal effect. Therefore, the detection of these pollutants at low concentrations is an important task.To increase the sensitivity of the sensor, nanostructures were used.To analyze the presence of glyphosate and its metabolites in rye juice, two groups of samples were selected. In the first case, glyphosate at different concentrations was added to the water for irrigation on the first day, and then the rye samples were watered with pure water for 7 days. In the second case, the samples were watered with pure water for all 8 days, and glyphosate was artificially added just before the measurement. The obtained samples were studied by the Different Pulse Voltammetry (DPV) employing nanostructured working electrodes. To analyze changes in the DNA sequence, a Polymerase chain reaction (PCR) product obtained from samples of the first group was electrochemically studied. To confirm the results obtained, an electrophoresis method was also applied. The results indicate that the DPV signal obtained from samples with artificially added glyphosate has significant differences compared to the signal obtained from the juice of plants absorbing glyphosate in a natural way during growth. However, in both cases, the CuO nanostructure based sensor detects the presence of glyphosate or its metabolites compared to the control sample. The experiment also found significant changes in the DNA caused by exposure with glyphosate during the growth process of rye sprouts.A nanostructured electrochemical sensor was used for the detection of glyphosate residuals and genetic changes caused by glyphosate in untreated rye juice.

Tunable Electrode Architectures for La0.8Sr0.2Fe1-XTixO3- δ Based Symmetrical Solid Oxide Fuel Cells

New strategies are necessary to enhance the efficiency of the electrodes for solid oxide fuel cells (SOFC) applications. Most of the preparation techniques require high sintering temperatures that drastically increases the grain size, leading to a very poor electrochemical activity. On this way, titanium doped ferrites have demonstrated to be promising electrodes, showing high redox stability and acceptable performance. In this study, spray-pyrolysis has been used to prepare nanostructured electrodes of La0.8Sr0.2Fe1- xTixO3-δ (x= 0.2 and 0.4) in a single deposition step. An infiltrated electrode architecture was obtained by depositing the electrodes directly on a porous Ce0.9Gd0.1O1.95 (CGO) backbone previously screen-printed onto a Zr0.84Y0.16O1.92 (YSZ) electrolyte. The properties of this electrode, in comparison with the traditional electrode, are investigated in both oxidizing and reducing conditions for the implementation of these electrodes in Symmetrical Solid Oxide Fuel Cells (SSOFC).

Gradient-based impedance synthesis for breast and lung cancer cell screening deploying planar and nano-structured electrodes.

World Health Organization articulated 9.8 million casualties globally in 2018 due to cancer. Cancer, as the world's second most fatal disease, can be recuperated well if diagnosed at an early stage. In this work, a gradient-based impedance synthesis of normal and cancerous cells of breast and lungs, is demonstrated numerically for early-stage cancer detection. Low-voltage single-cell level examination is employed for indomitable diagnosis. MCF-7 and MCF-10A are utilized as breast cancer and breastnormal cells, respectively; likewise, SK-MES and NL-20 are utilized as lung cancer and lung normal cell. Pre-examination numerical setup validity ensured with multiple test regimes. Micro-scaled planar and nano-structured electrodes are employed individually to witness the effect of the electrode's structure during electrical impedance examination of cancer and non-cancer cell. Frequency range, at which differential impedance effect is found detectable, for breast and lung cancer cell pairs is determined to be 107Hz and 108Hz, respectively. By surpassing the conventional impedance spectroscopy with tedious data fitting formalities, the gradient synthesis technique for cancer detection is introduced. The gradient synthesis for cancer detection is found independent of electrode shape effect. Gradient for breast cancer cell is found to be 2 times greater than the normal breast cell while for lung cancer cell it is found to be 1.5 times greater than the normal lung cell. Our results suggest that as the frequency of applied electrical stimulus increases, impedance of cancerous cell falls at the rate almost double than its counterpart normal cell. This work provides a theoretical basis for further experimental exploration of gradient-based impedance synthesis in cancer therapy and serves as a design tool for performance optimization. Figure 1 (a) Represents electrical Impedance analysis of breast normal cell MCF-10A and breast cancer cell MCF-7 using micro-scaled planar and nano-structured electrodes. (b) Gradient impedance synthesis performed, for breast normal cell (MCF-10A) and breast cancer cell (MCF-7) likewise for lungs normal cell (NL-20) and lungs cancer cell (SK-MES), which assures clear differential effect for cancer screening. Surpassing the conventional and tedious data fitting impedance spectroscopies, a novel gradient-based impedance spectroscopy for early cancer detection is introduced. It clearly detects cancer without any data fitting formalities to find parameter of identification. Planar and nano structure electrodes are used to witness the impact of electrode shape on cell impedance. Breast normal MCF-10A and cancer cell MCF-7 as well as lungs normal NL-20 and cancer cell SK-MES are examined to reflect the efficacy of our work. Single cell level examination is performed for authenticated results.