Electrochemical Systems Research Articles

State‐of‐the‐art CO2 reduction in electrochemical microfluidic systems: A short review and new perspectives

The need to mitigate carbon dioxide has motivated an influx of interest in innovative technologies, and microfluidic systems have emerged as a promising forefront in this endeavor. This short review analyzes CO2 reduction within microfluidic platforms, thoroughly investigating existing methodologies, challenges, and novel perspectives. This work commences with a detailed exposition of the fundamental principles governing microfluidic electrolyzers, elucidating the interaction of microchannels and electrodes. We show the electrochemical reactions supporting CO2 reduction, detailing the processes at the cathode. The use of microfluidic systems encompasses precise control over reaction conditions, efficient mass transport, reduced energy consumption, high throughput screening capabilities, integration with analytical tools, and portability. Catalyst selection for optimal CO2 reduction products, technical complexities, integration of renewable energy sources, and cost‐effectiveness are notable challenges on the horizon. A perspective on potential pathways to resolution is delineated, with each impediment succinctly but insightfully addressed. Moreover, this review extends beyond a looking‐back analysis, propounding innovative perspectives. It posits the concept of microfluidic fuel cells directly fueled by CO2. This work seeks to inspire new researchers and innovation in the field by comparing the present state‐of‐the‐art with prospective avenues of exploration

Probing Electronic Structure Changes in Cobalt Oxalate Anode for Lithium‐Ion Batteries

AbstractTransition metal‐based materials exhibit a broad range of catalytic activities in numerous electrochemical processes. Their displayed catalytic functions rely essentially on their distinctive electronic structures, changes of which play pivotal roles in dictating reaction dynamics within many electrochemical devices. Nevertheless, accurately probing electronic structure changes, especially in real‐time, of active materials remains a formidable challenge. In this work, a viable approach to achieve it within a CoC2O4/Li model system by employing a combined microscopic is demonstrated, spectroscopic analysis, plus a unique operando magnetometry technique. The findings reveal that upon completion of the conventional conversion of CoC2O4, a surface‐dominated capacitance emerges at the Co/Li2C2O4 interface owing to the injection of spin‐polarized electrons. Subsequently, the decomposition of Li2C2O4 proceeds through the releasing of the spin‐polarized electrons from Co, which, therefore serve as a catalyst leading to further discharge products. Such real‐time monitoring of electron transfer is realized by in situ monitoring electronic structure changes of Co, manifested by its intriguing magnetization alterations during the process. This work highlights a novel characterization tool that provides a solid explanation for the commonly observed large capacities in this type of materials and sheds light on design rules and selection guidance of materials for high‐performance electrochemical energy storage systems.

Redox-Modified Nanostructured Electrochemical Surfaces for Continuous Glucose Monitoring in Complex Biological Fluids

Continuous glucose monitoring is valuable for people with diabetes but faces limitations due to enzyme–electrode interactions and biofouling from biological samples that reduce sensor sensitivity and the monitoring performance. We created an enzyme-based electrochemical system with a unique nanocomposite coating that incorporates the redox molecule, aminoferrocene (NH2-Fc). This coating enhances stability via electroactivity and reduces nonspecific binding, as demonstrated through cyclic voltammetry. Our approach enables real-time glucose detection via chronoamperometry with a calculated linear range of 0.5 to 20 mM and a 1 mM detection limit. Validated with plasma and saliva, this platform shows promise for robust metabolite detection in clinical and research contexts. This versatile platform can be applied to accurately monitor a wide range of metabolites in various biological matrices, improving patient outcomes.

Differential Impact of Surface Conduction and Electroosmotic Flow on Ion Transport Enhancement by Microscale Auxiliary Structures.

Our research investigates the impact of auxiliary structures on ion transport in electrochemical systems such as batteries and microscale desalination units, whose importance for sustainable development has increased dramatically in recent decades. The electrochemical systems typically feature ion-selective surfaces, such as electrodes and ion exchange membranes, where ion depletion can cause performance issues including metal dendrite formation and flow instability. Recent research has shown that auxiliary structures in these electrochemical systems can enhance ion transfer near ion-selective surfaces, thereby resolving the instability problem and improving the energy conversion efficiency of the system. Our study leverages recent advancements in nanoscale electrokinetics to model these auxiliary structures as pillar arrays near an ion exchange membrane in a microchannel. We examine how these structures enhance ion transports relative to the characteristic length scale of microchannel depth and pillars' proximity to the ion-selective surface. Results show that the effect of the pillars varies significantly with their placement. Specifically, in deeper microchannels, where electrokinetic convection is stronger, the closer the auxiliary structure is to the ion-selective membrane, the better the ion transfer. However, in the thinner microchannel, the proximity of the auxiliary structure to the ion selective membrane has a less significant correlation with the ion transfer. Therefore, this finding highlights the importance of spatial arrangement of the auxiliary structures in improving the performance of electrochemical devices. Conclusively, this study can help to better understand energy conversion systems such as fuel cells, salinity gradient power generation systems, and electrochemical desalination systems, where auxiliary structures can be used in the vicinity of ion-selective surfaces. Especially, our fundamental electrokinetic study provides an effective means for designing the efficient electrochemical platforms utilizing micro/nanofluidics.

Surface Reconstruction for Selective Oxidation of Tetrahydroisoquinoline.

Integration of hydrogen evolution with the oxidation of organic substances in one electrochemical system is highly desirable. However, achieving selective oxidation of organic substances in the integrated system is still highly challenging. In this study, a phosphorylated NiMoO4 nanoneedle-like array was designed as the catalytic active electrode for the integration of highly selective electrochemical dehydrogenation of tetrahydroisoquinolines (THIQs) with hydrogen production. The leaching of anions, including MoO42- and PO43-, facilitates the reconstruction of the catalyst. As a result, nickel oxyhydroxides with the doping of PO43- and richness of defects are in situ formed. In situ Raman and density functional theory calculations have shown that the high catalytic activity is attributed to the in situ formed PO43- involved NiOOH substance. In the dehydrogenation process, the involved C-H bond but not the N-H bond is first destroyed. A two-electrode system was then fabricated with the optimized electrode that shows a benchmark current density of 10 mA cm-2 at 1.783 V, providing a yield of 70% for dihydroisoquinolines. A robust stability was also shown for this integrated electrochemical system. The understanding of the reconstruction behavior and the achievement of selective dehydrogenation will provide some hints for electrochemical synthesis.

Water splitting via electrocatalysis and photocatalysis: Engineering stumbling blocks and advancements

Renewable green hydrogen is produced using solar or wind-powered photocatalysis and electrocatalysis of water. In today's world, more than a third of nations have national plans for widespread green hydrogen generation. A variety of electrocatalytic water splitting methods exist such as alkaline water electrolyzer (AWE), proton exchange membrane (PEM), anion exchange membrane (AEM), solid oxide water electrolyzer (SOWE), and proton conducting ceramic electrolyzer (PCCEL). Nowadays, the high cost of producing hydrogen is a major barrier to the broad adoption of PEC and PEM, even though these processes are more efficient than conventional water-splitting technologies. A variety of carbon dopants, including graphene oxide, graphitic-carbon nitride, nanosheets, nitrogen, and other non-noble metals, are discussed in the present work and their applications in PEC and PEM catalysts. Based on the literature review, it is noticed that the hydrogen's levelized production cost (LCOH) for PEC is 8.43 USD/kg, whereas that for electrochemical water splitting systems is just 6.22 USD/kg. As a result, scientists are still looking for better, cheaper ways to produce green hydrogen. When combined with carbon dopants in catalysts, green hydrogen shows promise way as a sustainable energy source that can help bring the world closer to climate neutrality.

Toward Quantitative Electrodeposition via In Situ Liquid Phase Transmission Electron Microscopy: Studying Electroplated Zinc Using Basic Image Processing and 4D STEM.

High energy density electrochemical systems such as metal batteries suffer from uncontrollable dendrite growth on cycling, which can severely compromise battery safety and longevity. This originates from the thermodynamic preference of metal nucleation on electrode surfaces, where obtaining the crucial information on metal deposits in terms of crystal orientation, plated volume, and growth rate is very challenging. In situ liquid phase transmission electron microscopy (LPTEM) is a promising technique to visualize and understand electrodeposition processes, however a detailed quantification of which presents significant difficulties. Here by performing Zn electroplating and analyzing the data via basic image processing, this work not only sheds new light on the dendrite growth mechanism but also demonstrates a workflow showcasing how dendritic deposition can be visualized with volumetric and growth rate information. These results along with additionally corroborated 4D STEM analysis take steps to access information on the crystallographic orientation of the grown Zn nucleates and toward live quantification of in situ electrodeposition processes.

Electrocatalysis‐driven sustainable plastic waste upcycling

AbstractWith large quantities and natural resistance to degradation, plastic waste raises growing environmental concerns in the world. To achieve the upcycling of plastic waste into value‐added products, the electrocatalytic‐driven process is emerging as an attractive option due to the mild operation conditions, high reaction selectivity, and low carbon emission. Herein, this review provides a comprehensive overview of the upgrading of plastic waste via electrocatalysis. Specifically, key electrooxidation processes including the target products, intermediates and reaction pathways in the plastic electro‐reforming process are discussed. Subsequently, advanced electrochemical systems, including the integration of anodic plastic monomer oxidation and value‐added cathodic reduction and photo‐involved electrolysis processes, are summarized. The design strategies of electrocatalysts with enhanced activity are highlighted and catalytic mechanisms in the electrocatalytic oxidation of plastic waste are elucidated. To promote the electrochemistry‐driven sustainable upcycling of plastic waste, challenges and opportunities are further put forward.

Applicability of Single-Layer Graphene as a Hydrogen-Blocking Interlayer in Low-Temperature PEMFCs.

Gas crossover is critical in proton exchange membrane (PEM)-based electrochemical systems. Recently, single-layer graphene (SLG) has gained great research interest due to its outstanding properties as a barrier layer for small molecules like hydrogen. However, the applicability of SLG as a gas-blocking interlayer in PEMs has yet to be fully understood. In this work, two different approaches for transferring SLG from a copper or a polymeric substrate onto PEMs are compared regarding their application in low-temperature PEM fuel cells. The SLG is sandwiched between two Nafion XL membranes to form a stable composite membrane. The successful transfer is confirmed by Raman spectroscopy and in ex situ hydrogen permeation experiments in the dry state, where a reduction of 50% upon SLG incorporation is achieved. The SLG composite membranes are characterized by their performance and hydrogen-blocking ability in a fuel cell setup at typical operating conditions of 80 °C and with fully humidified gases. The performance of the fuel cell incorporating an SLG composite membrane is equal to that of the reference cell when avoiding the direct etching process from a copper substrate, as remnants from copper etching deteriorate the performance of the fuel cell. For both transfer processes, the hydrogen crossover reduction of SLG composite membranes is only 15-19% (1.5 barabs) in the operating fuel cell. Further, hydrogen pumping experiments suggest that the barrier function of SLG impairs the water transport through the membrane, which may affect water management in electrochemical applications. In summary, this work shows the successful transfer of SLG into a PEM and confirms the effective hydrogen-blocking capability of the SLG interlayer. However, the hydrogen-blocking ability is significantly reduced when running the cell at the typical humidified operating conditions of PEM fuel cells, which follows from a combination of reversible interlayer alteration upon humidification and irreversible defect formation upon PEM fuel cell operation.

Tailoring atomically local electric field of NiFe layered double hydroxides with Ag dopants to boost oxygen evolution kinetics

The demand for clean energy sources has driven focus towards advanced electrochemical systems. However, the sluggish kinetics of the oxygen evolution reaction (OER) constrain the energy conversion efficiency of relevant devices. Herein, a one-step method is reported to grow oxygen vacancies (Vo) rich NiFeAg layered double hydroxides nanoclusters on carbon cloth (Vo-NiFeAg-LDH/CC) for serving as the self-supporting electrode to catalyze OER. The OER performance of Vo-NiFeAg-LDH/CC has been remarkably enhanced through Ag and Vo co-modification compared with pristine NiFe-LDH, achieving a low Tafel slope of 49.7 mV dec−1 in 1 m KOH solution. Additionally, the current density of Vo-NiFeAg-LDH/CC is 3.23 times higher than that of the state-of-art IrO2 at 2 V under an alkaline flow electrolyzer setup. Theoretical calculations and experimental results collectively demonstrate that Ag dopant and Vo strengthen the O* adsorption with active sites, further promoting the deprotonation step from OH* to O* and accelerating the catalytic reaction. In a word, this work clarifies the structural correlation and synergistic mechanism of Ag dopant and Vo, providing valuable insights for the rational design of catalyst for renewable energy applications.

High‐rate Dissolution Mechanism of Ti‐48Al‐2Cr‐2Nb Alloy in Electrochemical Machining from a Nonlinear Dynamic PeWen Yuan Lirspective

The high‐rate dissolution process of Ti‐48Al‐2Cr‐2Nb alloy in electrochemical machining exhibits strong nonlinear dynamic characteristics, but the quantitative relationship between these nonlinear characteristics and surface topography, as well as the electro‐dissolution mechanism, is unknown. Therefore, the fractal and recursive features of dissolution behavior was investigated, and the dissolved surface topography was quantitatively characterized. Additionally, an electro‐dissolution mechanism model in electrochemical machining process was presented. Applying a moderate extraction potential of 8 V instead of 11 V can enhance the stability of the electrochemical system, resulting in a smoother and uniform surface. At 11 V, the saturation correlation dimension, surface roughness, and integral area of lacunarity initially decrease before increasing with higher electrolytic pressure, while laminarity (𝐿𝐴𝑀) and determinism (𝐷𝐸𝑇) show an initial increase followed by a decrease. These five characteristic parameters reach their optimal values at an electrolyte pressure of 0.4 MPa, indicating that achieving a stable and deterministic electrochemical system is crucial for obtaining a uniform smooth surface. These nonlinear dynamic characteristic parameters can be considered as in‐situ monitoring parameters for surface quality in ECM. The anodic dissolution process comprises three stages: initial passive film dissolution and breakdown, rapid dissolving with surface coarsening, and stable dissolving with polishing.This article is protected by copyright. All rights reserved.

Photosynthetic microalgae microbial fuel cells for bioelectricity generation and microalgae lipid recovery using Gd-Co@N-CSs/NF as cathode

Photosynthetic microalgae microbial fuel cells (PMMFCs) have an enormous potential for wastewater treatment and bioenergy recovery. However, to overcome low power generation problem, it is crucial to understand how the operational parameters influence the pathways and mechanisms of PMMFCs performance. In this study, microalgae (Chlorella vulgaris, Chlorella sp., Tetradesmus obliquus and Microcystis aeruginosa), light intensity (1400, 2100 and 3200 lx) and light/dark cycle (12/12, 18/6 and 24/0) were screened to promote the bioenergy recovery of PMMFCs. The highest power generation and electrochemical activity were obtained for Chlorella vulgaris under 3200 lx and cycle 18/6, with the maximum power density of 2.0 W m−3, and the lowest charge transfer resistance of 26.60 Ω and Tafel slope of 44.74 mV dec−1. Correlation analysis showed a significant negative correlation between NH4+-N concentration in the cathode chamber and output voltage. Structural equation model further elucidated that NH4+-N indirectly regulated the output voltage via the negative association with dissolved oxygen. In addition, the by-product lipid reached 145 mg g−1 dry mass. Furthermore, the specific gravity, iodine value, and cetane number of the fatty acids met the production standards for biodiesel. The electroactive bacteria Propionibacteriaceae (24.45%) were the dominant genera. This study provided suitable microalgae species and crucial operating conditions for bioenergy recovery from electrochemical systems with high catalytic activity.

Highly Exothermic and Fast Mechanochemical Redox and Intercalation Reactions of V2O5 with Sodium Hydride.

Vanadium oxides exhibit promising characteristics for electrochemical energy storage, owing to their capability to switch between different oxidation states, in combination with the incorporation of alkali metals. Here, we report on a systematic investigation of the mechanochemical reduction of V2O5 with NaH. In contrast to conventional high-temperature synthesis methods, the mechanochemical reaction occurs already after a few minutes. We observed a mixture of different (sodium) vanadium oxides with vanadium oxidation states ranging from +III to +V. Remarkably, these highly exothermic self-propagating reactions occur even within a rudimentary pistil-mortar setup. Hereby, the hydride concentration has a greater effect on the final sample composition than the milling time. In general, higher percentages of sodium vanadates are formed instead of vanadium oxides, and the lower oxidation states of vanadium are accessible with increasing amounts of NaH. Theoretical calculations confirm these experimental observations and emphasize the central role of sodium vanadates, especially with vanadium in the +V oxidation state, in carrying out the observed exothermic reactions. This comprehensive study sheds light on the mechanochemical reduction of vanadium oxides and underlines their potential for further development of electrochemical energy storage systems.

Fabrication of 0D/2D CoFe2O4/CoFe LDH composite intruded within CNTs network as a high-performance electrocatalyst for oxygen evolution and hydrogen evolution reactions

Designing highly efficient and durable multicomponent heterostructured composites as catalytic materials for concomitant hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is highly desirable. Researchers all over the world are continuously working to develop such materials. Herein, CNTs wrapped CoFe2O4/CoFe LDH (CoF/CoFe LDH@CNTs) ternary composite is synthesized by hydrothermal and ultra-sonication routes. Numerous methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrical Mott-Schottky, and electrochemical impedance spectroscopy (EIS) are employed to study structure, morphology, flat band potential, and electrochemical properties of prepared samples. In terms of water splitting performance, CoF/CoFe LDH@CNTs composite showed predominant performance for both HER and OER activities, as compared to its analogs (CoF and CoF/CoFe LDH). Faster electron transfer is also exhibited by CoF/CoFe LDH@CNTs, as it possesses a lower Tafel slope. For OER, CoF/CoFe, LDH@CNTs require a small overpotential of 170 mV to reach a current density of 10 mA cm−2 in 1 M KOH, with a Tafel slope of 42 mV dec-1. Similarly, for HER an overpotential of 218 mV is required to drive 10 mA cm−2 with a small Tafel slope of 31 mV dec-1. Impedance studies show a small value of charge transfer resistance (Rct = 1.11 Ω) for CoF/CoFe, LDH@CNTs. Significant electrochemical performance for CoF/CoFe, LDH@CNTs for both half-reactions (OER and HER) is ascribed to the synergy among electrochemically active CoF and CoFe LDH, and a highly conductive network of CNTs. The present strategy improves the electrochemical performance of electrochemical systems relevant to energy applications.

Enhancing selective ammonium transport in membrane electrochemical systems

Recovering ammonia nitrogen from wastewater is a sustainable strategy that simultaneously addresses both nitrogen removal and fertilizer production. Membrane electrochemical system (MES), which utilizes electrochemical redox reactions to transport ammonium ions through cation exchange membranes, has been considered as an effective technology for ammonia recovery from wastewater. In this study, we develop a mathematical model to systematically investigate the impact of co-existing ions on the transport of ammonium (NH4+) ions in MES. Our analysis elucidates the importance of pH values on both the NH4+ transport and inert ion (Na+) transport. We further comprehensively assess the system performance by varying the concentration of Na+ in the system. We find that while the inert cation in the initial anode compartment competes with NH4+ transport, NH4+ dominates the cation transport in most cases. The transport number of Na+ surpasses NH4+ only if the fraction of Na+ to total cation is extremely high (>88.5%). Importantly, introducing Na+ ions into the cathode compartment significantly enhances the ammonia transport due to the Donnan dialysis. The analysis of selective ion transport provides valuable insights into optimizing both selectivity and efficiency in ammonia recovery from wastewater.

Heteroatom Doping in Pollutant Diesel Soot-Derived Nanocarbon for Enhanced Zn-Ion Storage Performance.

Herein, we have isolated onion-like nanocarbon (ONC) from the exhaust soot of diesel engines and further doped it with nitrogen (N) and sulfur (S) to fabricate N,S-co-doped ONC (N-S-ONC). To explore its application feasibility, we have assembled an aqueous Zn-ion hybrid supercapacitor (ZIHSC) with a N-S-ONC cathode, which attains high specific capacitance with good rate capability. In-depth analyses suggest that the mechanism of charge storage in the ONC is governed by both capacitive-controlled and diffusion-controlled processes, with the capacitive processes leading at all sweep rates. The ZIHSC demonstrated a good energy density of 50 Wh/kg, a maximum power density of 3.6 kW/kg, and an impressive cycle life with 73% capacitance retention after 50,000 charge-discharge cycles. The study suggests the potential possibly for the long-term application of BC derived nanocarbon in electrochemical energy storage systems (EESSs).

Mixed valence Mo2C-MoC/C catalyst enhances polysulfides conversion kinetics in lithium–sulfur batteries

Lithium-sulfur batteries have received extensive attention in the field of electrochemical energy storage systems due to their extremely high theoretical energy density (2600 Wh·kg−1) and low cost. However, poor electrical conductivity, shuttle effect, and volume expansion effect still need to be addressed. Here, we controllably synthesized hollow spherical Mo2C-MoC/C structure as the cathode material for lithium-sulfur batteries. Through high-temperature calcination, the synthesis of graphitized reticular carbon matrix and the loading of Mo2C and MoC nanoparticles with mixed valence of Mo2+ and Mo3+ were simultaneously achieved. The two synergistically improved the electronic conductivity and ensured excellent battery performance. From the experimental results, Mo2C-MoC/C structure strongly adsorbed polysulfides and promoted the conversion of polysulfides to lithium sulfide, accelerating the reaction kinetics and enhancing the battery performance. The initial discharge specific capacity of Mo2C-MoC/C electrode with 57.12 wt% sulfur content was 870.4 mAh·g−1 at 0.2 C, and remained at 770.7 mAh·g−1 at 0.5 C, which was significantly better than that of Mo2C/C/S. The rational design of the Mo2C-MoC/C structure in this study can be generalized to the advanced electrode materials of other Mo-based nanomaterials.

AC-Modulated XPS Enables to Externally Control the Electrical Field Distributions on Metal Electrode/Ionic Liquid Devices.

X-Ray Photoelectron Spectroscopy (XPS) has been utilized to extract local electrical potential profiles by recording core-level binding energy shifts upon application of the AC [square-wave (SQW)] bias with different frequencies. An electrochemical system consisting of a coplanar capacitor with a polyethylene membrane (PEM) coated with the Ionic Liquid (IL) N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis(trifluoromethanesulfonyl)imide (DEME-TFSI) as the electrolyte is investigated. Analyses are carried out in operando, such that XPS measurements are recorded simultaneously with current measurements. ILs have complex charging/discharging processes, in addition to the formation of Electrical Double Layers (EDL) at the interfaces, and certain properties of these processes can be captured using AC modulation within appropriate time windows of observation. Herein, we select two frequencies, namely, 10 kHz and 0.1 Hz, to separate effects of the fast polarization and slow migratory motions, respectively. Moreover, the local potential developments after adding two equivalent series resistors at three different physical positions of the device have been carefully evaluated from the binding energy shifts in the F 1s peak representing the anion of the IL. This circuit modification allows us to quantify the AC currents passing through the device, as well as the system's impedance, in addition to revealing the potential variations due the IR drops. The complex AC-modulated local XPS data recorded can also be faithfully reproduced using the unmodulated F 1s spectrum and by convoluting it with electrical circuit output provided by the LT-Spice software. The outcome of these efforts is a more realistic equivalent circuit model, which can be related to chemical/physical makeup of the electrochemical system. An important finding of this methodology emerges as the possibility to induce additional local electrical field developments within the device, the directions of which can be reversed controllably.

Ethylenediamine-functionalized metal-organic frameworks for applications of electrochemical supercapacitors as an additive

In this study, the impact of incorporating ethylenediamine (ED)-functionalized metal-organic frameworks (MOFs) on enhancing the electrochemical performance of polypyrrole(PPy)-based conducting polymers as supercapacitor electrode materials was investigated. The stability of terephthalic acid-containing MOFs in different environments, including exposure to acids, relies on the specific metal ions and ligands utilized in their construction. In this research, ED treatment was chosen for its resistance to acid attack. Unlike the post-synthetic modifications observed in previous literature regarding ED-modified MOF5, this study introduces a unique approach where ED is directly integrated into the framework in a single step. The resulting materials, referred to as ED-MOF, were employed in creating a novel composite material concurrently with polypyrrole, designed for use as electrode materials in supercapacitor applications. The optimal loading in the electrochemical preparation of polypyrrole-based conducting polymers was determined using cyclic voltammetry and electrochemical impedance spectroscopy techniques. Areal capacitance for the resulting electrodes was evaluated through cyclic charge-discharge experiments. The areal capacitance of the ED-ZnMOF/1@/PPy/PGE electrode was found to be 575.2 mF.cm−2 at a charge/discharge current density of 1 mA.cm−2. This research underscores the potential advantages of combining conducting polymers and metal-organic frameworks in supercapacitors, as well as other electrochemical systems.

Intercalating polypyrrole tuning interlayer space of V2O5 for advanced aqueous zinc ion batteries

Aqueous zinc-ion batteries is considered as a promising system for large scale electrochemical energy storage system owing to their intrinsic safety, and low cost. Nevertheless, the industrialization process is slow due to the constraints of high-performance cathode materials. Adjusting the layered structure of V2O5 through metal ion or polymer intercalation can effectively improve low electron conductivity, vanadium dissolution, and slow ion transport kinetics. Herein, the conductive polymer polypyrrole-intercalated V2O5·H2O (PVOH) was successfully prepared via simple hydrothermal method and following interface polymerization reaction. Getting benefit from the insertion of polypyrrole, the prepared PVOH composite material achieves a V2O5 cathode with a more open structure, rich active sites, and greater stability, allowing for an expanded crystal plane spacing of 14.5 Å. Therefore, the PVOH electrode demonstrates a discharge capacity of 475 mAh g−1 and a cycling stability of 95% capacity retention after 2000 cycles. The intercalating conductive polymers strategy can become a new approach to improve the electrochemical behavior of vanadium oxide cathodes.