Sheet Electrode Research Articles

Hybrid Binder Chemistry with Hydrogen-Bond Helix for High-Voltage Cathode of Sodium-Ion Batteries.

Since sodium-ion batteries (SIBs) have become increasingly commercialized in recent years, Na3V2(PO4)2O2F (NVPOF) offers promising economic potential as a cathode for SIBs because of its high operating voltage and energy density. According to reports, NVPOF performs poorly in normal commercial poly(vinylidene fluoride) (PVDF) binder systems and performs best in combination with aqueous binder. Although in line with the concept of green and sustainable development for future electrode preparation, aqueous binders are challenging to achieve high active material loadings at the electrode level, and their relatively high surface tension tends to cause the active material on the electrode sheet to crack or even peel off from the collector. Herein, a cross-linkable and easily commercial hybrid binder constructed by intermolecular hydrogen bonding (named HPP) has been developed and utilized in an NVPOF system, which enables the generation of a stable cathode electrolyte interphase on the surface of active materials. According to theoretical simulations, the HPP binder enhances electronic/ionic conductivity, which greatly lowers the energy barrier for Na+ migration. Additionally, the strong hydrogen-bond interactions between the HPP binder and NVPOF effectively prevent electrolyte corrosion and transition-metal dissolution, lessen the lattice volume effect, and ensure structural stability during cycling. The HPP-based NVPOF offers considerably improved rate capability and cycling performance, benefiting from these benefits. This comprehensive binder can be extended to the development of next-generation energy storage technologies with superior performance.

Development of molybdenum trioxide based modified graphite sheet electrodes for enhancing the electrochemical sensing of dopamine

Electrochemical detection of dopamine is crucial in the early stages of Parkinson's and Alzheimer's disease diagnosis. In this paper, we have developed modified electrodes based on molybdenum oxide (MoO3) grown on graphite sheet (GS), which was investigated for its ability to detect dopamine sensitively and selectively. The MoO3/GS electrodes were prepared by thermal evaporation of MoO3 on GS sheets followed by annealing at different temperatures (RT and annealing temperatures of 100 °C, 200 °C, 300 °C, 400 °C and 500 °C). The electrodes were analysed using XRD, Raman, FESEM and HRTEM. Compared to other electrodes, the modified MoO3/GS electrode annealed at 500 °C showed more significant charge transfer and increased selectivity and sensitivity in the electrochemical detection of dopamine. The findings showed a significant sensitivity of 85.71 μA. μM−1·cm−2 for the linear range of 1–10 nM and the lowest detection limit of 2.71 nM were achieved from the dopamine sensing. The developed electrode successfully detected dopamine in human blood serum and urine samples with respectable recovery rates.

Recurrent Neural Network Enabled Continuous Motion Estimation of Lower Limb Joints From Incomplete sEMG Signals.

Decoding continuous human motion from surface electromyography (sEMG) in advance is crucial for improving the intelligence of exoskeleton robots. However, incomplete sEMG signals are prevalent on account of unstable data transmission, sensor malfunction, and electrode sheet detachment. These non-ideal factors severely compromise the accuracy of continuous motion recognition and the reliability of clinical applications. To tackle this challenge, this paper develops a multi-task parallel learning framework for continuous motion estimation with incomplete sEMG signals. Concretely, a residual network is incorporated into a recurrent neural network to integrate the information flow of hidden states and reconstruct random and consecutive missing sEMG signals. The attention mechanism is applied for redistributing the distribution of weights. A jointly optimized loss function is devised to enable training the model for simultaneously dealing with signal anomalies/absences and multi-joint continuous motion estimation. The proposed model is implemented for estimating hip, knee, and ankle joint angles of physically competent individuals and patients during diverse exercises. Experimental results indicate that the estimation root-mean-square errors with 60% missing sEMG signals steadily converges to below 5 degrees. Even with multi-channel electrode sheet shedding, our model still demonstrates cutting-edge estimation performance, errors only marginally increase 1 degree.

Functionalized Electrode Additive for Simultaneously Reinforcing Chemo‐Mechanical Properties of Millimeter‐Thick Dry‐Electrode for High‐Energy All‐Solid‐State Batteries

AbstractVoids are widely disseminated in a powder when mixed, and hence the typical dry‐electrode preparation method yields a sparse dry‐electrode because the external pressure applied to the surface of the mixed powder is not evenly distributed. Consequently, particle cracking and void remnants appear in the electrode after calendaring. This study introduces a practically applicable bi‐functionalized electrode additive to simultaneously reinforce the chemo‐mechanical properties of millimeter‐thick dry electrodes. The agyrodite Li6PS5Cl solid electrolyte and lithium difluorophosphate (LiPO2F2) additive have different sizes, as demonstrated by their densification from their elaborate bimodal structure, which is densely packed. Because the additive is filled into the interparticle voids in the electrode sheet during electrode fabrication, a decrease in electrode cracking after calendaring is possible because of the uniform distribution of external pressure. Hence, a thin, highly ionic/electronic‐conductive electrode can be constructed by the addition of LiPO2F2 additive. Furthermore, during the formation, the active material surface‐contacted LiPO2F2 promptly produces a surface layer comprising LiF and LixPFy. Thus, the addition of LiPO2F2 further reduces the degradation of Li6PS5Cl solid electrolytes. As a result, the LiPO2F2 additive simultaneously improves the electrochemical and physicochemical properties of millimeter‐thick dry‐electrodes for high‐energy all‐solid‐state battery systems.

Green Chemistry of the Future: Co-Electrosynthesis of Biobased Platform Chemicals and Hydrogen

The European Green Deal sends a strong signal for a climate-friendly and CO2-neutral economy. An important aspect to support this is a sustainable and reduced use of resources as well as efficient and green conversion technologies for renewable value-added products. For this reason, electrosynthetic approaches become increasingly important, as electrochemistry fulfils several criteria of green chemistry and offers the possibility to directly use current from renewable energy sources [3]. However, electrolysis and electrosynthesis currently often require the use of platinum group metals (PGM) and need separators, which are mostly based on perfluorinated and polyfluorinated alkyl substances (PFSA). Classical water electrolysis for production of green hydrogen also requires high overvoltage’s, which is due to the oxygen evolution reaction (OER). This is where coupling systems come in, in which the sluggish OER is replaced by a thermodynamically more efficient reaction, such as the electrooxidation of organic substances (EOO). An example of this is the electrooxidation of biobased 5-HMF or various sugars (xylose, glucose) to platform chemicals. When coupled with the hydrogen evolution reaction (HER), the EOO of 5-HMF to 2,5-furandicarboxylicacid (FDCA) requires a theoretical cell voltage of 0.3 V. In contrast, theoretical cell voltages of 1.23 V are required for the OER/HER [5]. With the focus on sustainable and energy-efficient systems, the simultaneous production of platform chemicals and green H2 via paired electrolysis offers high potential. [1-7]Previous studies have mainly focused on electrode materials, morphology and its electrocatalytic activity in divided batch cells. A strongly alkaline environment is considered advantageous for the electro-organic oxidation reaction, while the HER is reported to be kinetically slower in alkaline than in acidic conditions. Overall, the coupled electrolysis of H2 and platform chemicals is described as a promising technology in the development stage. [5-7]In this context, the present research explores paired electrosynthesis of platform chemicals and H2 to advance sustainable and efficient energy sources. A central goal is the prototype development of an undivided flow reactor in TRL4. Particular attention will be paid to mild operating conditions (such as a mild-alkaline environment, low operating pressures and low temperatures), PGM-free catalysts and the elimination of PFSA materials. To achieve this goal, various milestones have been defined. Among them is the development of 3D electrodes with suitable and selective catalysts. These are to be electrochemically tested in a flow-through test cell on a laboratory scale. In order to create a basis for analysis, the electrode reactions were first investigated electrochemically in a typical divided H-cell and reference measurements were carried out on nickel-based materials. In this work, NiOOH sheet and foam electrodes were electrochemically produced and subsequently investigated by cyclic voltammetry (CV) followed by bulk electrolysis. On this basis, suitable analytics (HPLC, UV-VIS) were also determined to quantify and classify the derivatives of the electrosynthesis process. These pre-experiments form the basis for the ongoing development of initial concept ideas for a modular test cell that allows various materials and structures to be electrochemically investigated.Overall, this research contributes to advancing sustainable and efficient energy sources and enabling the production of platform chemicals from renewable raw materials. Acknowledgments The authors thank the European Union’s Horizon Europe research and innovation programme under grant agreement N° 101070856 ELOBIO (Electrolysis of Biomass) for funding.

Non-enzymatic glucose electrochemical sensor based on nitrogen-doped graphene modified with polyaniline and Fe3O4@MIL-101-NH2 nano framework

In this study, a novel highly sensitive and selective non-enzymatic glucose sensor was fabricated by coating simple and cheap graphite sheet (GS) electrodes with a proper conductive nanocomposite containing nitrogen-doped functionalized graphene (NFG), conductive polyaniline (PANI), and core–shell nanoparticles (Fe3O4@MIL-101-NH2). The results revealed that the core centers of iron oxide nanoparticles shelled by MIL-101-NH2 enhanced the electron transfer and led to more conductivity, also their existence caused the limitation of the MOF’s low conductivity. In addition, using Fe3O4@MIL-101-NH2 in the nanocomposite structure led to more sensitivity and selectivity at glucose monitoring due to its amine groups and unique structure. The results showed that NFG/PANI/Fe3O4@MIL-101-NH2 nanocomposite provided a large surface area besides enhanced electron transfer and catalytic properties that lead to proper oxidation of glucose with two linear ranges of 0.5 – 10 µM and 100 µM – 25 mM and a low detection limit of 0.3 µM (S/N = 3). Furthermore, the relative standard deviation (RSD%) in all detection processes was lower than 9 %. Finally, the performance of fabricated non-enzymatic sensor (GS/NFG/PANI/Fe3O4@MIL-101-NH2) in human fluids real samples including serum and plasma was acceptable which significantly indicates that it is toward monitoring of glucose in clinical applications.

A simple method of fabricating activated carbon-based supercapacitor electrode sheets

Pepper shell waste is a side effect of relatively untapped pepper production. In this research, activated carbon from pepper shell waste was made using the chemical activator ZnCl2 and followed by physical activation using nitrogen gas (N2). The resulting activated carbon is then printed into supercapacitor electrode sheets by adding carbon black, PVDF, and NMP by varying the composition between activated carbon and carbon black. The performance of the fabricated electrode sheets was then tested using the Galvanostatic Charge Discharge (GCD) method. The results show that the addition of carbon black affects the specific capacitance value of the fabricated electrode sheet. The GCD results show that the sample has a specific capacitance value of 13.64 F/g.

Unsymmetric design of self-supported sheet electrode: Breaking the tradeoff between electrical conduction and surface wetting for fast energy storage and excellent cycling stability

Biomass-derived porous carbon materials are suitable candidates for energy storage due to their rich pore structure, high specific area, and tunable surface functionality. Carbon electrodes are often required to have both excellent conductivity and wettability, while one needs to be compromised for optimized outcomes. Herein, we constructed a self-supported Carbonized Wood@Graphene Nanosheets (CW@GNs) composite electrode by growing GNs on one side of the CW surface with a plasma-enhanced chemical vapor deposition technology. Both electrical conductivity and interfacial wettability can be obtained simultaneously in CW@GNs electrodes. The CW@GNs-1h showed a satisfactory specific capacitance of 210.2F g−1, while the value of pure CW was 177.2F g−1. Furthermore, a symmetrical supercapacitor assembled with two CW@GNs-1h monoliths performed an excellent energy density of 7.8 Wh kg−1 at 250.8 W kg−1, retaining attractive cycling stability (99.02%) after 50,000 cycles. These results demonstrated the effectiveness of the unsymmetric design in a double-sided sheet electrode that breakthrough the tradeoff of electrical conductivity and surface wettability, and thus enhanced energy storage capacity and cycling stability were achieved.

Dynamically Cross-Linked, Self-Healable, and Stretchable All-Hydrogel Supercapacitor with Extraordinary Energy Density and Real-Time Pressure Sensing.

Wearable electronics with flexible, integrated, and self-powered multi-functions are becoming increasingly attractive, but their basic energy storage units are challenged in simultaneously high energy density, self-healing, and real-time sensing capability. To achieve this, a fully flexible and omni-healable all-hydrogel, that is dynamically crosslinked PVA@PANI hydrogel, is rationally designed and constructed via aniline/DMSO-emulsion-templated in situ freezing-polymerization strategy. The PVA@PANI sheet, not only possesses a honeycombed porous conductive mesh configuration with superior flexibility that provides numerous channels for unimpeded ions/electron transport and maximizes the utilization efficiency of pseudocapacitive PANI, but also can conform to complicated body surface, enabling effective detection and discrimination of body movements. As a consequence, the fabricated flexible PVA@PANI sheet electrode demonstrates an unprecedented specific capacitance (936.8Fg-1 ) and the assembled symmetric flexible all-solid-state supercapacitor delivers an extraordinary energy density of 40.98Whkg-1 , outperforming the previously highest-reported values of stretchable PVA@PANI hydrogel-based supercapacitors. What is more, such a flexible supercapacitor electrode enables precisely monitoring the full-range human activities in real-time, and fulfilling a quick response and excellent self-recovery. These outstanding flexible sensing and energy storage performances render this emerging PVA@PANI hydrogel highly promising for the next-generation wearable self-powered sensing electronics.

Electrooxidation of amoxicillin in aqueous solution with graphite electrodes: Optimization of degradation and deciphering of byproducts using HRMS

Contaminants of emerging concern (CECs) such as antibiotics have become a matter of worry in aquatic environments worldwide. Their presence in the environment has been increasing due to the inability of conventional wastewater and water treatments to annihilate them. Hence, attempts have been made to remove CECs using electrochemical oxidation (EO). Present study employed the low cost, active carbon based graphite sheet electrodes as anode and cathode to oxidize and degrade Amoxicillin (AMOX)- a β-lactum thiazolidine antibiotic. Optimization studies found pH 9, 45 mA cm−2, 81 cm2 electrode surface area, 6 mM electrolyte concentration and 60 min treatment time to be optimal for AMOX removal. Studies with varying concentrations of AMOX (20 mg L−1, 30 mg L−1 and 40 mg L−1) found that increase in concentrations of AMOX require higher current densities and treatment time for better TOC removal. High performance liquid chromatography photo diode array (HPLC-PDA) studies found 94% removal for 40 mg L−1 of AMOX at optimal conditions with 90% COD and 46% TOC removal. High resolution mass spectrometry (HRMS) studies using Ultra performance liquid chromatography-quadrupole time of flight-mass spectrometry (UPLC-Q-ToF-MS) identified major degradation mechanisms to be hydroxylation, β-lactum ring cleavage, breakage of thiazolidine ring chain from the aromatic ring and piperazinyl ring formation. The final byproducts of AMOX oxidation were carboxylic acids.

Insight into pH-controlled bubble dynamics on a Pt electrode during electrochemical water splitting

Bubbles adhering to the electrode surface are the major factors causing the decreased efficiency of water electrolysis. In this work, the dynamic behaviors of oxygen bubbles on vertical platinum sheet electrodes were investigated by a high-speed camera and their corresponding current densities were measured simultaneously using an electrochemical workstation. The impact of wide range of electrolyte pH values (i.e., 1–13) on both the bubble nucleation number and the dynamics behaviors of bubbles was investigated under different applied voltages. When the applied voltage was increased from 1.6 to 1.7 V vs the saturated calomel electrode, the radius of bubbles upon detachment increased in acidic environments (pH = 1–7) and decreased in alkaline environments (pH = 7–13). In an alkaline environment, the Marangoni force plays an essential role here. Furthermore, the bubble detachment radius predicted by the force balance model is well matched with our experimental results. Our results demonstrate that bubble detachment is not favorable in a strongly acidic environment, whereas oxygen bubbles exhibit rapid detachment from the electrode surface in a strongly alkaline environment.

Highly efficient hydrogen evolution of Ni3S2-MoS2@CoMoO4/NF from in situ reaction of metal-organic framework in alkaline media

BackgroundHydrogen energy, as the most promising renewable resource in the future, is severely limited in its development due to electrocatalysts, so the preparation of highly efficient and low-cost non-precious-metal catalysts is crucial for large-scale hydrogen production via electrolysis of water. MethodsHerein, Ni3S2−MoS2@CoMoO4/NF was successfully synthesized for the first time by in situ ion-exchange reaction and sulfidation reaction using Co-MOF/NF as a template. Significant FindingsThe electrochemical tests revealed that the overpotential was only 62.4 mV at a current density of 10 mA cm−2, which was similar to that of the noble metal Pt sheet electrode, the long-term durability of the catalysts was more than 24 h at a constant potential, which demonstrated that the catalysts possessed excellent HER performance in alkaline media. In addition, XPS, SEM, XRD, and Raman characterization also demonstrated the successful growth and loading of Ni3S2, MoS2, and CoMoO4. In this study, transition metal sulfides and transition metal sulfide complexes with good electrochemical properties were prepared using metal-organic frameworks (MOFs) as precursors, providing a new idea for the preparation of HER catalysts with high activity in alkaline media.

CO2-plasma surface treatment of graphite sheet electrodes for detection of chloramphenicol, ciprofloxacin and sulphanilamide.

Graphite sheet (GS) electrodes are flexible and versatile substrates for sensing electrochemical; however, their use has been limited to incorporate (bio)chemical modifiers. Herein, we demonstrated that a cold (low temperature) CO2 plasma treatment of GS electrodes provides a substantial improvement of the electrochemical activity of these electrodes due to the increased structural defects on the GS surface as revealed by Raman spectroscopy (ID/IG ratio), and scanning electron microscopy images. XPS analyses confirmed the formation of oxygenated functional groups at the GS surface after the plasma treatment that are intrinsically related to the substantial increase in the electron transfer coefficient (K0 values increased from 1.46 × 10-6 to 2.09 × 10-3 cm s-1) and with reduction of the resistance to charge transfer (from 129.8 to 0.251 kΩ). The improved electrochemical activity of CO2-GS electrodes was checked for the detection of emerging contaminant species, such as chloramphenicol (CHL), ciprofloxacin (CIP) and sulphanilamide (SUL) antibiotics, at around + 0.15, + 1.10 and + 0.85 V (versus Ag/AgCl), respectively, by square wave voltammetry. Limit of detection values in the submicromolar range were achieved for CHL (0.08 μmol L-1), CIP (0.01 μmol L-1) and SFL (0.11 μmol L-1), which enabled the sensor to be successfully applied to natural waters and urine samples (recovery values from 85 to 119%). The CO2-GS electrode is highly stable and inexpensive ($0.09 each sensor) and can be easily inserted in portable 3D printed cells for environmental on-site analyses.

Oxygen plasma-treated graphite sheet electrodes: A sensitive and disposable sensor for methamphetamines

3,4-methylenedioxymethamphetamine (MDMA) is a drug of abuse, known as ecstasy, and it is among the most consumed drugs worldwide. The presence of MDMA and new psychoactive substances has been widely reported in seized forensic samples. The development of an elective and sensitive screening method for MDMA detection is very important in the current scenario of illicit drugs. In this paper, we present affordable graphite sheet (GS) electrodes a new sensing platform for MDMA detection. Importantly, a surface treatment protocol for these electrodes using cold plasma improves the electrochemical response of MDMA. The XPS results showed that O2 plasma treatment changed the GS electrode surface, creating oxide groups. GSs were characterized before and after treatment by scanning electron microscopy and electrochemical impedance spectroscopy, and the results suggested a higher surface area and lower resistance to the charge transfer for treated GS electrodes. Using differential pulse voltammetry, it was possible to achieve a linear range from 0.5 to 15.0 µmol L−1 with a low limit of detection (0.09 µmol L−1). Higher interaction of MDMA with the plasma-treated GS surface (in comparison with the pristine surface) was confirmed by computational simulations (molecular dynamics), which may explain the improved sensing properties provided by the plasma treatment. Additionally, the interference study with other drugs usually found in seized ecstasy tablets showed high selectivity which enabled MDMA detection in human saliva (collected in parties and electronic music festivals) and seized samples. Therefore, plasma-treated GS can be used as a simple, fast, low-cost, and portable screening device for application in real-world forensic samples.

Sustainable approach to achieve overall leaching of Li and Co in spent lithium-ion batteries without liberation by overall pyrolysis

Dissociation is generally considered to be a necessary treatment of the electrode sheets before leaching, and the inadequacy dissociation cause the loss of electrode materials. In the present study, the feasibility of overall leaching of the undissociated electrode sheets to achieve satisfactory leaching was verified, which was believed to avoid complex crushing and sieving processes and reduce metal loss. Hence, the enhancement of the overall pyrolysis on the overall leaching of the electrode sheets was also analyzed. The undissociated electrode sheets were pyrolyzed at 480 °C that could remove the PVDF effectively. It was conducive to the infiltration of leaching solution between particles, the complete removal of PVDF was identified by SEM, EDS and XPS. Whereafter, the leaching kinetic behavior of the Li and Co in the pyrolyzed and unpyrolyzed electrode sheets were analyzed by the Aframi model. The morphology and composition of the leaching residue were analyzed by SEM-EDS to verify the characteristics of overall leaching behavior. Leaching results show that the overall leaching is feasible for the undissociated electrode sheets, the leaching rate of Li and Co of the undissociated and unpyrolyzed electrode sheet reaches 80.51% and 74.42% with 50 min leaching at 70 °C. Further, overall pyrolysis can enhance the leaching of the undissociated electrode sheet, the leaching rates of Li and Co can reach 93.25% and 93.31% only with 30 min leaching after pyrolysis at 70 °C. The kinetic results illustrate that the leaching of Li and Co is surface chemical reaction. The SEM analysis reveals that overall leaching process is gradual leaching, and the pores generated by pyrolysis help to penetrate the leaching solution and strengthen the leaching process.

Analysis of the circadian distribution of metal ions in blood samples after knee replacement surgery – Consideration for athletes

SiO2 exhibits impressive theoretical specific capacity (1965 mAh g−1) as the anode of lithium-ion batteries. However, its commercial development is seriously hindered by security risks due to capacity fading and sharp fluctuations. Herein, we apply defect engineering to SiO2/C composites and report a stable preparation method of D‐[email protected]@SiO2 @N-C sandwich nanorods. The sandwich structure effectively alleviates the severe mechanical stress caused by volume expansion. The carbon materials with the structural defects provides abundant lithium storage sites for the electrode. It alleviates the influence of the low capacitance of C in the SiO2/C composite on the overall capacity. Furthermore, the flexibility and sulfur carrying capacity of copper foil are not outstanding, which limits the rate capacity of the battery. Therefore, aramid conductive fibers(AF) with excellent electrical conductivity were prepared to load D[email protected]2 @N-C (D-AF) in this work. The unique flexible skeleton in D-AF could realize the internal encapsulation of the active substances and adapt to the deformation of the electrode sheet under stress. Moreover, the dense CNTs network promotes the improvement of the electrode conductivity. D-AF exhibits more stable service life and stronger rate ability, compared with the copper foil. The reversible capacity of the cell with the D-AF electrode remains 789.55 mAh g−1, after 500 cycles at 1.0 C. It improves the cycle life and actual specific capacity of the battery, effectively. This work provides a new path for the development of flexible self-supported electrodes and the application of Multifunctional Silica in electrode.

Flexible aramid current collector loaded with D-CNTs@SiO2 @N-doped carbon composite for enhanced electrochemical performance

SiO2 exhibits impressive theoretical specific capacity (1965 mAh g−1) as the anode of lithium-ion batteries. However, its commercial development is seriously hindered by security risks due to capacity fading and sharp fluctuations. Herein, we apply defect engineering to SiO2/C composites and report a stable preparation method of D‐CNTs@SiO-CNTs@SiO2 @N-C sandwich nanorods. The sandwich structure effectively alleviates the severe mechanical stress caused by volume expansion. The carbon materials with the structural defects provides abundant lithium storage sites for the electrode. It alleviates the influence of the low capacitance of C in the SiO2/C composite on the overall capacity. Furthermore, the flexibility and sulfur carrying capacity of copper foil are not outstanding, which limits the rate capacity of the battery. Therefore, aramid conductive fibers(AF) with excellent electrical conductivity were prepared to load D-CNTs@SiO2 @N-C (D-AF) in this work. The unique flexible skeleton in D-AF could realize the internal encapsulation of the active substances and adapt to the deformation of the electrode sheet under stress. Moreover, the dense CNTs network promotes the improvement of the electrode conductivity. D-AF exhibits more stable service life and stronger rate ability, compared with the copper foil. The reversible capacity of the cell with the D-AF electrode remains 789.55 mAh g−1, after 500 cycles at 1.0 C. It improves the cycle life and actual specific capacity of the battery, effectively. This work provides a new path for the development of flexible self-supported electrodes and the application of Multifunctional Silica in electrode.

Edge-Site-Free and Topological-Defect-Rich Carbon Cathode for High-Performance Lithium-Oxygen Batteries.

The rational design of a stable and catalytic carbon cathode is crucial for the development of rechargeable lithium-oxygen (LiO2 ) batteries. An edge-site-free and topological-defect-rich graphene-based material is proposed as a pure carbon cathode that drastically improves LiO2 battery performance, even in the absence of extra catalysts and mediators. The proposed graphene-based material is synthesized using the advanced template technique coupled with high-temperature annealing at 1800°C. The material possesses an edge-site-free framework and mesoporosity, which is crucial to achieve excellent electrochemical stability and an ultra-large capacity (>6700 mAh g-1 ). Moreover, both experimental and theoretical structural characterization demonstrates the presence of a significant number of topological defects, which are non-hexagonal carbon rings in the graphene framework. In situ isotopic electrochemical mass spectrometry and theoretical calculations reveal the unique catalysis of topological defects in the formation of amorphous Li2 O2 , which may be decomposed at low potential (∼ 3.6V versus Li/Li+ ) and leads to improved cycle performance. Furthermore, a flexible electrode sheet that excludes organic binders exhibits an extremely long lifetime of up to 307 cycles (>1535h), in the absence of solid or soluble catalysts. These findings may be used to design robust carbon cathodes for LiO2 batteries.

CeO2 Nanoparticles Modified on Graphite Sheet Electrodes for Photoelectrochemical Tobacco Wastewater Detection, Degradation, and Toxicity Measurement

Monitoring and implementation of gutka wastewater treatment using a fast and feasible fabrication method, owing to the clean water environment, have a great socioeconomic impact. A facile approach is promoted for detecting and degrading nicotine and gutka wastewater by the means of a wide range of ultraviolet light absorption and is applied in our current research. In this report, we successfully synthesized cerium oxide nanoparticles (CeO2 NPs) by a co-precipitation method for photoelectrochemical (PEC) detection and degradation of smokeless tobacco from wastewater. X-ray diffraction study confirmed the face-centered cubic structure of CeO2 NPs. Raman analysis and ultraviolet–visible spectroscopy endorsed the formation of CeO2 NPs. The as-fabricated CeO2 NP-modified graphite sheet electrode showed high sensitivity (98.1 μA/μM) and good linear range (10–150 nM) for the detection of tobacco from wastewater. The limit of detection was calculated as 0.15 nM. The catalyst photoelectrochemically degraded 93% of nicotine and 94.21% of gutka wastewater at 120 min. Toxicity studies of gutka with an in vivo nematode model, Caenorhabditis elegans, and Vigna radiata proved that PECO-degraded gutka waste had no deleterious effects on the survival (95.43%) (p < 0.01) of C. elegans when compared to nondegraded gutka waste (11.93%) and did not affect the physiological functions and reactive oxygen species production.

Hierarchical N-Ti3C2TX@NiCo2S4 core-shell nanosheets assembled into 3D porous hydrogel as free-standing electrodes for high-performance supercapacitors

Designing new electrode structures with excellent electrochemical properties and finding facile synthesis methods are challenges for energy storage devices. Herein, we constructed a heterogeneous N-doped 2D structure of Ti3C2TX with tubular NiCo2S4 and formed a 3D hydrogel structure using graphene oxide as a binder, which could prevent the natural packing of Ti3C2TX and increase the specific surface area. This electrode combines the metallic conductivity of Ti3C2TX with the pseudocapacitance property of NiCo2S4 to achieve exceptional electrochemical performance. As a result, the electrode achieves an ultra-high specific capacitance of 517.11 F g−1 at 1 A g−1 and 92.6 % capacitance retention after 10,000 cycles. Moreover, a high energy density of 27.78 Wh kg−1 is obtained at a power density of 596 W kg−1. This new N-Ti3C2TX@NiCo2S4/RGO electrode sheet provides more active sites with higher charge transfer rates and improved charge transfer kinetics, boosting the level of material processing of supercapacitors.