Renewable Electrode Research Articles

Acoustic Levitation-Controlled Droplets for Contactless Enrichment and Sensitive Detection of Volatile Organic Substances Integrated with GC-MS.

Analyzing trace-level volatile organic compounds (VOCs) remains challenging due to initial sampling and preconcentration limitations. Inspired by the highly reproducible and constantly renewable electrode surface of dropping mercury electrode (DME), a contactless enrichment process was first reported by using an acoustic levitation device to trap and concentrate VOCs from gas samples onto suspended droplets, which were then directly transferred into gas chromatography-mass spectrometry (GC-MS) for real-time analysis. Compared with traditional methods injection methods, this method achieves a 46-fold increase in nicotine peak area. The detection sensitivity was enhanced significantly, attributed to the high specific surface area of the droplets and the accelerating extraction vibration. Notably, the number of identified VOCs from burning cigarettes significantly increased from 17 to 212, including 22 aromatic compounds with distinct aromas. The remarkable versatility of this method was demonstrated by effectively monitoring the dynamic changes of 16 VOCs in environmental tobacco smoke (ETS) following cigarette burning, revealing the persistence of these compounds, even after 40 min. Moreover, directly analyzing human-exhaled aerosol found that nicotine rapidly decreased while its metabolite cotinine increased, showcasing the potential for tracking human metabolism and behavior in vivo. Furthermore, multivariate data analysis of VOC profiles from six cigarette brands allowed for their visual differentiation. With versatility, sensitivity, and the ability to distinguish trace-level VOCs in realtime, this method offers promising avenues for environmental monitoring, metabolic studies, and various analytical applications.

Covalent Bonding of MXene/COF Heterojunction for Ultralong Cycling Li-Ion Battery Electrodes.

Covalent organic frameworks (COFs) have emerged as promising renewable electrode materials for LIBs and gained significant attention, but their capacity has been limited by the densely packed 2D layer structures, low active site availability, and poor electronic conductivity. Combining COFs with high-conductivity MXenes is an effective strategy to enhance their electrochemical performance. Nevertheless, simply gluing them without conformal growth and covalent linkage restricts the number of redox-active sites and the structural stability of the composite. Therefore, in this study, a covalently assembled 3D COF on Ti3C2 MXenes (Ti3C2@COF) is synthesized and serves as an ultralong cycling electrode material for LIBs. Due to the covalent bonding between the COF and Ti3C2, the Ti3C2@COF composite exhibits excellent stability, good conductivity, and a unique 3D cavity structure that enables stable Li+ storage and rapid ion transport. As a result, the Ti3C2-supported 3D COF nanosheets deliver a high specific capacity of 490 mAh g-1 at 0.1 A g-1, along with an ultralong cyclability of 10,000 cycles at 1 A g-1. This work may inspire a wide range of 3D COF designs for high-performance electrode materials.

Biomass Porous Carbon Derived from Celery Leaves with High Capacitance for Supercapacitor

AbstractTo develop environmentally friendly and high‐performance supercapacitors, the low‐cost, high‐capacitance renewable electrode material is at present viewed as one of the most challenging tasks for obtaining the next‐generation of energy storage devices. Therefore, in this study, Celery leaves, a common biomass vegetable, are used to prepare activated carbon for high voltage and high‐capacity supercapacitors through a simple method. Due to their high surface area and abundant nitrogen and sulfur heteroatoms, hierarchically porous carbon materials can simultaneously realize high capacity and long‐cycling durability. The specific capacitance has been recorded to be up to 753.0 F g−1 at 0.5 A g−1 with capacity retention as high as 96.7 % even after 5,000 cycles. Also, the assembled symmetric cell provided a high energy density of 17.36 Wh kg−1 at 250 W kg−1. The effects of yellow and green colors and different activation temperatures on the properties of electrode materials were systematically studied. The results showed an excellent electrochemical performance in biomass carbon electrode materials, which would facilitate the development of a high‐quality energy system and a green supercapacitor.

One-step strategy of 3D hierarchical porous carbon with self-heteroatom-doped derived bread waste for high-performance supercapacitor

Bio-waste is a promising carbon source that can be used as a basic component in renewable supercapacitors due to its abundant hierarchical pore structure potential, heteroatom self-doping capability, high surface area, as well as well-defined chemical and mechanical stability. This study converted bread bio-waste into rich 3D hierarchical porous carbon through a one-step facile strategy to be used as the main component of a supercapacitor. The porous carbon was obtained through physical activation approach at different temperatures of 750, 800, 850, and 900 °C without being combined with chemical activation. The optimized activated carbon illustrated high porosity behavior with an abundant 3D hierarchical pore structure consisting of 76.98% micropores and 23.02% mesopores and also produced a well-defined wettability of self-doping heteroatoms. Moreover, the electrochemical behavior in a symmetric supercapacitor cell showed a high specific capacitance of 202 F g−1 at 1 A g−1 with a rate capability of 73% at 10 mV s−1 in a 1 M H2SO4 electrolyte. It was also discovered that the activation temperature of 850 produced the highest energy density of 11.61 Wh kg−1 at a power density of 156.71 W kg−1 with a low equivalent series resistance of 0.11 Ω. Finally, the proof-of-concept showed that bread waste has immense potential as a 3D hierarchical porous carbon source after the synthesis through a single-stage facile approach and can be used as a major renewable electrode component for sustainable supercapacitors.

Application of Capacitive Deionization in Water Treatment and Energy Recovery: A Review

Water resources are the basis for human survival and development. However, human beings face severe challenges of water pollution and freshwater shortage. With the critical advantages of low energy consumption, high efficiency, low cost, green and pollution-free, and renewable electrodes, capacitive deionization (CDI) has become an up-and-coming water treatment technology. After decades of development, the application of CDI has expanded from seawater desalination to many fields. However, the existing literature still needs a comprehensive overview of the multi-functional application of CDI technology in water treatment. Therefore, our work critically reviewed the latest research progress of CDI in water treatment to meet the technical requirements of various application fields. This paper first summarizes the various applications of CDI in water treatment, focusing on CDI’s representative research results in heavy metal removal, organic contaminants removal, water softening, phosphate and nitrate removal, and water disinfection. In addition, we also discussed the latest research progress of energy recovery and energy consumption assessment for the CDI process. Finally, this paper discusses the challenges and future opportunities facing CDI technology.

Advanced Electrode Materials in Capacitive Deionization for Lithium Recovery

Demand for lithium batteries and lithium resources is growing because of the fast development of electric vehicles which will reach 900,000 metric tons per year by 2025. But the available lithium supplies are running out, and the future utilization of lithium resources will depend on strong productivity and resource recovery. However, current methods of extracting lithium ion resources still have the disadvantages of slow rates, unstable system outputs, and low purity. These methods can hardly compensate for the huge market demand in the future. The alternative technology, capacitive deionization (CDI) technology based on electrochemical ion pumping, provides a high capacity and rate of lithium resource recovery, which uses renewable electrode materials, reduces system waste generation, and has high lithium ion purity in the extract, which is sufficient to meet the future market demand. This mini-review analyzes the electrode materials used in CDI technology with a particular emphasis on the development of three materials, Olivine LiFePO4/FePO4, Spinel LiMn2O4/λ-MnO2, and Spinel LiNi0.5Mn1.5O4. The advantages and disadvantages of the current advanced materials are evaluated from various perspectives, and the feasibility of different electrodes is analyzed.

In Situ Growth of NiCo Layered Double Hydroxide on Biomass Waste‐Based Substrate: A Novel Material with 3D Interconnected Structure as Electrodes for Supercapacitors

Next‐generation energy storage systems require green and renewable electrodes with a high specific capacity, which combine biomass waste and bimetallic hydroxide synergically to satisfy environmental enhancements and economic benefits. Herein, a novel approach to improving the electrical conductivity of bimetallic materials by in situ growing NiCo layered double hydroxides (LDHs) with pseudocapacitance capability on KMnO4‐activated fungus bran‐derived carbons (FBCs) is reported, achieving improved electrochemical performance in supercapacitors (SCs). The hierarchical porous FBC substrate contributes to the homogeneous growth of the LDHs and high electronic and ionic conductivity. The optimal composite (FBC/NCL‐3) with a 3D interconnected structure provides a specific capacitance of 1938 F g−1 at a current density of 1 A g−1. Correspondingly, the hybrid battery‐SC device composed of FBC/NCL‐3 and FBC provides favorable stability (76% specific capacity retention at 5 A g−1 for 3000 cycles) with an operating voltage of 1.4 V and a high energy density of 37.3 Wh kg−1 at a power density of 695.6 W kg−1. This work demonstrates a promising strategy using FBC as a substrate for growing LDH materials aiming to achieve high‐performance SCs.

Preparation of cerium oxide–MWCNTs nanocomposite bulk modified carbon ceramic electrode: a sensitive sensor for tamoxifen determination in human serum samples

In this study, cerium oxide and multi-walled carbon nanotubes nanocomposite were incorporated into the carbon ceramic electrode (CeO2–MWCNTs/CCE) as a renewable electrode for the electrocatalytic purposes. To demonstrate capability of the fabricated electrode, determination of tamoxifen as an important anticancer drug with differential pulse voltammetry technique was evaluated in details. Linear range, limit of detection and sensitivity of the developed sensor were found to be 0.2–40 nM, 0.132 nM and 1.478 µA nM−1 cm−2, respectively. Ease of production, low cost and high electron transfer rate of the CeO2–MWCNTs/CCE promises it as a novel electro-analytical tool for determination of important species in real samples.

Enhancing the understanding of the redox properties of lithium-inserted anthraquinone derivatives by regulating molecular structure

The reductional potentials of AQ is positive correlation with the number of EWGs, and the overall effect ability of substituents on redox potentials of AQ is -C 2 F 5 >-CF 3 >-F>-Cl >-Br under the condition of the same number of EWGs. • The effect of -CF 3 and -C 2 F 5 on redox properties of AQ are firstly investigated by DFT. • Overall influence ability of substituents on redox potentials of AQ is -C 2 F 5 > -CF 3 > -F > -Cl > -Br. • Full -C 2 F 5 substituted EWGs on AQ exhibits the highest reductional potential in five types EWGs. Organic compounds, such as quinone compounds, are promising renewable electrode materials for lithium ion batteries (LIBs) with redox stability and structural diversity. However, quinone electrode materials (QEMs) have low redox potentials as cathode and high solubility. In particular, low redox potentials result in low energy density and power density of QEMs. In this work, the substituent influence on anthraquinone (AQ) are studied by density-functional theory calculations to predict redox properties of potential positive materials for LIBs. The calculated results indicate a positive correlation between the redox potentials and the number of substituent, and the full substitution groups with electron-withdrawing groups (EWGs) gain the highest redox potentials, which is borne out by lowest unoccupied molecular orbital (LUMO). Mono-substitution, however, bring the highest specific capacity. Also, the different substituent sites on AQ can influence the redox potentials of AQ. Moreover, the calculation of molecular electrostatic potential (MESP) reveal carbonyl groups with local minima of MESP easily tend to bind lithium. AQ with Li binding carbonyl groups is more stable than the bare AQ, which is confirmed by the calculation of nucleus-independent chemical shift. At the same time, lithium atoms also easily bind electronegative atoms of EWGs and form intramolecular lithium bonds, which improve the thermodynamic stabilization of the lithiation AQ. The present study provide the new understanding with guidelines to design potential organic cathode materials with efficiency for LIBs.

Lignin-based monolithic carbon electrode decorating with RuO2 nanospheres for high-performance chlorine evolution reaction

One of the primary challenges of the chlor-alkali industry is the passivation of Ti electrode during the electrolysis process. Therefore, a renewable electrode with abundant active sites but without a passivation layer was necessary to address this issue. In this work, lignin and acetylene black were applied to fabricate a self-standing and low-resistance carbon electrode as a conductive substrate. Then, RuO2 nanospheres were decorated on the surface of the carbon electrode by an electrochemical deposition and electrochemical oxidation process for the high-performance chlorine evolution reaction. The results indicated that the carbon electrode possessed high mechanical strength and desired shape without any binders. More significantly, it was revealed that the RS of the optimized carbon electrode was only 0.91 Ω which was comparable in conductivity to the commercial carbon cloth. The RuO2/CE-10 % had abundant active sites and the current density could reach to 129 mA cm−2 at 1.2 V, which was attributed to the RuO2 nanospheres with huge specific surface area and excellent catalytic activity. Our work demonstrated the successful conversion of biomass waste into the high-performance chlorine evolution electrode, and its promising catalytic activity further suggested the developed approach may provide a positive route to solve the issue of passivation layer.

Waste-Biomass-Derived Carbon As Renewable Electrode Materials for Plant Microbial Fuel Cells

Developing clean and sustainable energy sources is important as it deals directly with energy shortage and environmental pollution problems caused by fossil fuels. Plant microbial fuel cells (PMFCs) is a novel technology that can convert solar energy into electrical energy by the microbes at the region of rhizosphere of the plants. Without producing any harmful byproducts during the energy generation process, PMFCs seems to be a promising choice as a renewable power supply technique. Green carbon materials, utilizing agro-industrial waste as precursors, has attracted lots of interest in research recently on account of them being environmental friendly materials and mitigating bio-wastes.To combine the advantages of PMFCs and green carbon materials, the aim of this study is to optimize the electrochemical performance of our designed PMFCs by utilizing biowaste-derived activated carbon materials as the electrode materials. The biowaste-derived activated carbon materials were characterized by Brunauer-Emmett-Teller (BET) surface area analyzer, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The electrochemical performance of PMFCs devices developed by ourselves were analyzed through linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). This study set out to examine the relationship between the properties of activated carbon and the electrochemical performance of PMFCs, expecting to develop a high power density PMFCs device.

Determination of 8-hydroxy-7-iodo-5-quinoline sulfonic acid (HIQSA) at renewable electrode with Sb2O3/MWCNT-TiO2 nanohybrid

8-hydroxy-7-iodo-5-quinoline sulfonic acid (HIQSA) was determined using square wave anodic stripping voltammetry (SWASV) at the surface of carbon paste electrode modified with Sb2O3 and multi-walled carbon nanotubes-titanium dioxide nanohybrid (Sb2O3/TiO2-MWCNTPE) in aqueous media. To estimate the properties and morphology of the modified electrode, field emission-scanning electron microscopy (FE-SEM) coupled by energy dispersive spectroscopy (EDS) was applied. The linear concentration range was found to be 1.0 to 100 μM by using accumulation potential of −0.8 V and accumulation time of 150 s. Under these conditions, LOD and LOQ were obtained at 1.2 and 3.9 μM, respectively. This newly developed method was successfully applied for the determination of HIQSA in tap water.

Corn Cob Lignin-based Porous Carbon Modified Reduced Graphene Oxide Film For Flexible Supercapacitor Electrode

Flexible supercapacitors (FSCs) have attracted widespread attention of many researchers as a type of portable energy storage devices. However, there are still challenges in preparing renewable and inexpensive electrode materials. Herein, we prepared the porous carbon (PC) by the two-step process involving hydrothermal method and low-temperature heat treatment using corn cob lignin as the carbon source, and different types for PC were obtained by changing the temperature of low temperature heat treatment (100 °C–300 °C). The flexible electrode film was prepared by combining the obtained corn cob lignin-based PC with reduced graphene oxide (RGO), in addition, we investigated the effect of PC obtained by different low-temperature heat treatment (100 °C, 150 °C, 200 °C, 250 °C, and 300 °C) on the electrochemical properties of the composite electrode. The optimal low-temperature heat treatment temperature (250 °C) was determined and the PC250/RGO film electrodes displayed a high area specific capacitance of 636 mF/cm2 with a mass of 2.2 mg/cm2 (specific capacitance of 289 F/g) at 0.2 mA/cm2 and 82% of the capacitance was retained after 10,000 charge and discharge cycles at 5 mA/cm2, at the same time on the electrode film flexibility test, the influence of different bending angle on the electrochemical properties can be ignored. The assembled supercapacitor had the advantages of flexible, lightweight, low price, and environment friendly, which can achieve area specific capacitance of 324.5 mF/cm2 at 0.2 mA/cm2 and 91.8% capacitance retention after 1000 charging/discharging cycles. These good electrochemical properties illustrate the application prospects of composite electrode materials in wearable and portable electronic devices.

Photo-assisted electrochemical detection of bisphenol A in water samples by renewable {001}-exposed TiO2 single crystals

Bisphenol A (BPA) is a semi-persistent environmental endocrine disrupter and widely present in aqueous environments. Electrochemical detection is an effective method to monitor pollutants like BPA in aqueous environments. However, the electrode fouling from anodic polymeric products is one main barrier of electrochemical sensors for their practical applications. In this work, a renewable electrochemical sensor was rationally designed, constructed and tested for efficient BPA detection. The TiO2 anodic material was surface-engineered by inorganic-framework molecular imprinting sites with tailored morphological shape, exposed facet and crystal structure. This electrode could be activated mainly as an electrochemical catalyst and partially as a photochemical catalyst. The developed TiO2-based sensor exhibited a good detection reliability and cyclic stability for determining BPA in water samples, with an electrochemical signal decrease of less than 5.0% in 10-run cyclic tests. By virtue of the bi-functional properties of the tailored TiO2 anodic material, a unique photo-assisted electrochemical sensor was further developed, in which analyte digestion and analytical signal originated mainly from anodic conversion. Such a synergistic digesting mechanism distinguishes it from the reported electro-assisted photochemical TiO2 sensors. Our work provides a robust sensor for monitoring pollutants in aqueous environments and a new opportunity to develop renewable electrode materials with good reusability.

Graphene functionalized bio-carbon xerogel for achieving high-rate and high-stability supercapacitors

Biomass carbons have attracted considerable attention in the pursuit of cheap and renewable electrode materials. However, a low-energy route (like hydrothermal carbonization) is still a challenge for achieving bio-carbon electrodes with high-performance. Herein, a high-rate and high stability supercapacitor was fabricated based on graphene functionalized bio-carbon xerogel. The supercapacitor shows comparable or even higher performance than reported supercapacitors derived from bio-carbons and graphene-based materials, which can be attributed to sandwich-like porous structure that carbon spheres interspersed between porous graphene nanoplatelets. It demonstrates a superior specific capacitance of 139 F g−1 at a superhigh current of 100 A g−1 in an aqueous electrolyte, maintaining 73.5% of that at 1 A g−1 (189 F g−1). More importantly, the device retains 100% of initial specific capacitance, energy density and power density after 10000 cycles at 5 A g−1. This work paves the way to develop renewable supercapacitors based on low-cost biomass resources and low-energy fabrication.

Preparation of Molecularly Imprinted Polymers-Based Electrochemical Renewable Ceramic Electrode as a Sensitive Uranyl Ions Sensor

Preparation of Molecularly Imprinted Polymers-Based Electrochemical Renewable Ceramic Electrode as a Sensitive Uranyl Ions Sensor

The difference between interfaces formed by mechanically renewed gold and silver electrodes with acetonitrile and aqueous solutions

The impedance method and cycling voltammetry were used in studying the structure of interface between mechanically renewable electrodes of Au and Ag and solutions with different concentration of LiClO4 in acetonitrile (AN). The obtained data allowed us to conclude that the considered systems are characterized by the wide potential regions in which these electrodes can be considered as ideally polarizable. These regions are: from −0.5 to 1.0V for Au and from −1.7 to −0.2V (vs. aqueous SCE) for Ag electrodes; the zero charge potentials of Au and Ag electrodes in these systems are: 0.62 and −0.37V, respectively. It was shown that, in the above-noted potential regions, the experimental C vs. E curves can be well described by the classical model of Gouy–Chapman–Stern–Grahame. It was shown, as well, that the difference in experimental zero charge potentials of Au and Ag electrodes correlates with the difference in electron work functions of these metals. These data allow us to conclude that the interaction at the interface between renewable Au and Ag electrodes and AN solutions can be characterized as lyophobic, i.e., close to that observed for Hg/AN and mercury-like metals/AN systems. On the other hand, the interfaces of Au and Ag electrodes with aqueous solutions should be considered as hydrophilic systems being radically different from the interfaces of Hg and mercury-like metals with aqueous solutions. It was demonstrated that the specific features of the interface structure on Au and Ag electrodes in contact with aqueous and AN solutions can be well described on the qualitative level within the framework of phenomenological model of «two limiting states».

Kraft Lignin as Electrode Material for Sustainable Electrochemical Energy Storage

AbstractElectrochemical energy storage using lignin as a renewable electrode material is a cheap and sustainable approach for future organic batteries. Previous reports mainly focus on lignosulfonates (LS) or composites with conductive polymer additives with inherent problems, such as still expensive monomers. Here, composite electrodes are used from more available Kraft lignin and sustainable conductive carbon. Charge storage is evaluated in terms of electrical double layer storage and redox reactions, aiming at a better understanding of desired lignin properties for electrochemical energy storage. Using unmodified, commercial lignin and high surface area conductive carbon, reasonable capacity of ≈80 mAh g−1 is achieved in samples in which a thin layer of lignin covers the interface of high surface area carbon. Non‐faradaic contribution to charge storage is as large as in comparable pure carbon electrodes, and redox reactions in lignin contribute to additional, faradaic charge storage, significantly enhancing capacity in these systems. Resulting electrodes are cheap, reliable, and stable.

Ni–Al/layered double hydroxide/Ag nanoparticle composite modified carbon-paste electrode as a renewable electrode and novel electrochemical sensor for hydrogen peroxide

Cyclic voltammograms of the bare CPE (a and c) and Ni–Al/LDH/Ag NPs/CPE (b and d) respectively in the presence and absence of. Inset is cyclic voltammograms Ni–Al/LDH/CPE in the absence (a) and presence (b) of H2O2.

Kinetics of electroreduction of S2O 8 2− anions on mechanically renewable silver electrode

The kinetics of electroreduction of peroxodisulfate anions on a mechanically renewed silver electrode is studied by voltammetric and impedance methods. Impedance diagrams obtained in the region of negatively charged metal surface are successfully modeled by the equivalent circuit formed by the solution resistance and also the reaction resistance connected in parallel with the constant-phase element substituted for the double layer capacitance. The analysis of experimental data carried out in terms of this circuit and their comparison with the literature data makes it possible to assume that the reduction kinetics of S2O82− anions on this electrode can be adequately described in the framework of the phenomenological theory of slow discharge. The reasons for deviation of the literature data on the kinetics of this reaction on polycrystalline Ag electrode from the relationships following from the slow discharge theory are put forward and substantiated.