Mitigating Interfacial Capacity Fading in Vanadium Pentoxide by Sacrificial Vanadium Sulfide Encapsulation for Rechargeable Mg-Ion Batteries.

Rechargeable Mg-ion Batteries (RMB) containing a Mg metal anode offer the promise of higher specific volumetric capacity, energy density, safety, and economic viability than lithium-ion battery technology, but their realization is challenging. The limited availability of suitable inorganic cathodes compatible with electrolytes relevant to Mg metal anode restricts the development of RMBs. Despite the promising capability of some oxides to reversibly intercalate Mg+2 ions at high potential, its lack of stability in chloride-containing ethereal electrolytes, relevant to Mg metal anode hinders the realization of a full practical RMB. Here the successful in situ encapsulation of monodispersed spherical V2O5 (≈200 nm) is demonstrated by a thin layer of VS2 (≈12 nm) through a facile surface reduction route. The VS2 layer protects the surface of V2O5 particles in RMB electrolyte solution (MgCl2 + MgTFSI in DME). Both V2O5 and V2O5@VS2 particles demonstrate high initial discharge capacity. However, only the V2O5@VS2 material demonstrates superior rate performance, Coulombic efficiency (100%), and stability (138 mA h g-1 discharge capacity after 100 cycles), signifying the ability of the thin VS2 layer to protect the V2O5 cathode and facilitate the Mg+2 ion intercalation/deintercalation into V2O5.

Fluorinated Co-Solvents Enable Excellent Performances of Practical Cells Comprising LixSiO-Graphite Composite Anodes and LiNi0.89Co0.05Mn0.05Al0.01O2 (NCMA) Cathodes.

Li-ion batteries based on high specific capacity LixSiO-Graphite anodes and LiNi0.89Co0.05 Mn0.05Al0.01O2 (NCMA) cathodes may have numerous practical applications owing to high energy density without a necessary compromise on safety. SiO, which is an attractive Li insertion anode material, offers more cycling stability than Si and a higher capacity than graphite. Therefore, a new trend has emerged for developing composite C-Si anodes, possessing the excellent cyclability of graphite coupled with high capacity SiO. The composite structure described herein prevents the volume expansion of SiO and maintains the structural integrity during prolonged cycling. However, graphite electrodes suffer from exfoliation in propylene carbonate (PC) based electrolyte solutions, which avoids well known safety benefits related to a possible use of PC based electrolyte solutions in all kinds of Li batteries. Herein, it is reported that trifluoro propylene carbonate (TFPC) is compatible with graphite anodes. New electrolyte formulations are developed and tested containing fluorinated co-solvents and compared the performance of several electrolyte solutions, including conventional alkyl carbonates-based solutions in full Li-ion cells, which included LixSiO-Graphite anodes and LiNi0.89Co0.05Mn0.05Al0.01O2 (NCMA) cathodes. Cells with new electrolyte solutions developed herein demonstrated nearly twice capacity retention in prolonged cycling experiments compared to similar reference cells containing conventional electrolyte solutions.

Improved Cycling Stability of LiNi0.8 Co0.1 Mn0.1 O2 Cathode Material via Variable Temperature Atomic Surface Reduction with Diethyl Zinc.

High-Ni-rich layered oxides [e.g., LiNix Coy Mnz O2 ; x > 0.5, x + y + z = 1] are considered one of the most promising cathodes for high-energy-density lithium-ion batteries (LIB). However, extreme electrode-electrolyte reactions, several interfacial issues, and structural instability restrict their practical applicability. Here, a shortened unconventional atomic surface reduction (ASR) technique is demonstrated on the cathode surface as a derivative of the conventional atomic layer deposition (ALD) process, which brings superior cell performances. The atomic surface reaction (reduction process) between diethyl-zinc (as a single precursor) and Ni-rich NMC cathode [LiNi0.8 Co0.1 Mn0.1 O2 ; NCM811] material is carried out using the ALD reactor at different temperatures. The temperature dependency of the process through advanced spectroscopy and microscopy studies is demonstrated and it is shown that thin surface film is formed at 100 °C, whereas at 200 °C a gradual atomic diffusion of Zn ions from the surface to the near-surface regions is taking place. This unique near-surface penetration of Zn ions significantly improves the electrochemical performance of the NCM811 cathode. This approach paves the way for utilizing vapor phase deposition processes to achieve both surface coatings and near-surface doping in a single reactor to stabilize high-energy cathode materials.

Mussel-Inspired Polynorepinephrine/MXene-Based Magnetic Nanohybrid for Electromagnetic Interference Shielding in X-Band and Strain-Sensing Performance.

The current work delivers preparation of MXene-based magnetic nanohybrid coating for flexible electronic applications. Herein, we report carbon dot-triggered photopolymerized polynorepinepherene (PNE)-coated MXene and iron oxide hybrid deposited on the cellulose microporous membrane via a vacuum-assisted filtration strategy. The surface morphologies have been monitored by scanning electron microscopy analysis, and the coating thickness was evaluated by the gallium-ion-based focused ion beam method. Coated membranes have been tested against uniaxial tensile stretching and assessed by their fracture edges in order to assure flexibility and mechanical strength. Strain sensors and electromagnetic interference (EMI) shielding have both been tested on the material because of its electrical conductivity. The bending strain sensitivity has been stringent because of their fast 'rupture and reform' percolation network formation on the coated surface. Increased mechanical strength, solvent tolerance, cyclic deformation tolerance, and EMI shielding performance were achieved by decreasing interstitial membrane porosity. Considering a possible application, the membrane also has been tested against simulated static and dynamic water flow conditions that could infer its excellent robustness which also has been confirmed by elemental analysis via ICP-MS. Thus, as of nurturing the works of the literature, it could be believed that the developed material will be an ideal alternative of flexible lightweight cellulose for versatile electronic applications.

Lithium-Oxygen Batteries and Related Systems: Potential, Status, and Future.

The goal of limiting global warming to 1.5 °C requires a drastic reduction in CO2 emissions across many sectors of the world economy. Batteries are vital to this endeavor, whether used in electric vehicles, to store renewable electricity, or in aviation. Present lithium-ion technologies are preparing the public for this inevitable change, but their maximum theoretical specific capacity presents a limitation. Their high cost is another concern for commercial viability. Metal-air batteries have the highest theoretical energy density of all possible secondary battery technologies and could yield step changes in energy storage, if their practical difficulties could be overcome. The scope of this review is to provide an objective, comprehensive, and authoritative assessment of the intensive work invested in nonaqueous rechargeable metal-air batteries over the past few years, which identified the key problems and guides directions to solve them. We focus primarily on the challenges and outlook for Li-O2 cells but include Na-O2, K-O2, and Mg-O2 cells for comparison. Our review highlights the interdisciplinary nature of this field that involves a combination of materials chemistry, electrochemistry, computation, microscopy, spectroscopy, and surface science. The mechanisms of O2 reduction and evolution are considered in the light of recent findings, along with developments in positive and negative electrodes, electrolytes, electrocatalysis on surfaces and in solution, and the degradative effect of singlet oxygen, which is typically formed in Li-O2 cells.

Structure and Functionality of an Alkylated LixSiyOz Interphase for High-Energy Cathodes from DNP-ssNMR Spectroscopy.

Degradation processes at the cathode-electrolyte interface are a major limitation in the development of high-energy lithium-ion rechargeable batteries. Deposition of protective thin coating layers on the surface of high-energy cathodes is a promising approach to control interfacial reactions. However, rational design of effective protection layers is limited by the scarcity of analytical tools that can probe thin, disordered, and heterogeneous phases. Here we propose a new structural approach based on solid-state nuclear magnetic resonance spectroscopy coupled with dynamic nuclear polarization (DNP) for characterizing thin coating layers. We demonstrate the approach on an efficient alkylated LixSiyOz coating layer. By utilizing different sources for DNP, exogenous from nitroxide biradicals and endogenous from paramagnetic metal ion dopants, we reveal the outer and inner surface layers of the deposited artificial interphase and construct a structural model for the coating. In addition, lithium isotope exchange experiments provide direct evidence for the function of the surface layer, shedding light on its role in the enhanced rate performance of coated cathodes. The presented methodology and results advance us in identifying the key properties of effective coatings and may enable rational design of protective and ion-conducting surface layers.

Interfacial Engineering of Na3 V2 (PO4 )2 F3 Hollow Spheres through Atomic Layer Deposition of TiO2 : Boosting Capacity and Mitigating Structural Instability.

To mitigate the associated challenges of instability and capacity improvement in Na3 V2 (PO4 )2 F3  (NVPF), rationally designed uniformly distributed hollow spherical NVPF and coating the surface of NVPF with ultrathin (≈2 nm) amorphous TiO2  by atomic layer deposition is demonstrated. The coating facilitates higher mobility of the ion through the cathode electrolyte interphase (CEI) and enables higher capacity during cycling. The TiO2 @NVPF exhibit discharge capacity of >120 mAhg-1 , even at 1C rates, and show lower irreversible capacity in the first cycle. Further, nearly 100% capacity retention after rate performance in high current densities and 99.9% coulombic efficiency after prolonged cycling in high current density is reported. The improved performance in TiO2 @NVPF is ascribed to the passivation behavior of TiO2  coating which protects the surface of NVPF from volume expansion, significantly less formation of carbonates, and decomposition of electrolyte, which is also validated through post cycling analysis. The study shows the importance of ultrathin surface protection artificial CEI for advanced sodium-ion battery cathodes. The protection layer is diminishing parasitic reaction, which eventually enhances the Na ion participation in reaction and stabilizes the cathode structure.

Improving Amorphous Carbon Anodes for Na Ion Batteries by Surface Treatment of a Presodiated Electrode with Al2O3.

Disordered carbons are promising anode materials for sodium ion batteries. However, a major drawback of these materials is their low coulombic efficiency in the first cycles, which indicates parasitic reactions. Such reactions can be suppressed by alumina coating on the surface of the anodic materials; more ions are then available for electrochemical activity, and less electrolyte solution is lost. On the other hand, some pores and surface edge sites are passivated by the coating and are no longer available for reversible reaction with sodium ions; hence, their contribution is eliminated, leading to reduction in specific capacity. We show herein that electrochemical insertion of sodium ions into carbon anodes prior to alumina coating has a double positive effect on anode perfomances, meaning preventing passivation and maintaining high specific capacity. We show that the artificial layer still prevented parasitic reactions, while the pores and surface edge sites retained electrochemical activity. The capacity values were thus restored and even became higher as a result of preventing the development of a surface layer. Ultraviolet photoelectron spectroscopy measurements assessed the energetic states of the electrodes and confirmed that the alumina coating forms a barrier for interfacial electron transfer from the electrode to the solution at any polarization stage.

Anodic decomposition of surface films on high voltage spinel surfaces-Density function theory and experimental study.

Oxidative decomposition of organic-solvent-based liquid electrolytes at cathode material interfaces has been identified as the main reason for rapid capacity fade in high-voltage lithium ion batteries. The evolution of "cathode electrolyte interphase" (CEI) films, partly or completely consisting of electrolyte decomposition products, has also recently been demonstrated to correlate with battery cycling behavior at high potentials. Using density functional theory calculations, the hybrid PBE0 functional, and the (001) surfaces of spinel oxides as models, we examine these two interrelated processes. Consistent with previous calculations, ethylene carbonate (EC) solvent molecules are predicted to be readily oxidized on the LixMn2O4 (001) surface at modest operational voltages, forming adsorbed organic fragments. Further oxidative decomposition of such CEI fragments to release CO2 gas is however predicted to require higher voltages consistent with LixNi0.5Mn1.5O4 (LNMO) at smaller x values. We argue that multistep reactions, involving first formation of CEI films and then further oxidization of CEI at higher potentials, are most relevant to capacity fade. Mechanisms associated with dissolution or oxidation of native Li2CO3 films, which are removed before the electrolyte is in contact with oxide surfaces, are also explored.

Electrochemical Thin Layers in Nanostructures for Energy Storage.

Conventional electrical energy storage (EES) electrodes, such as rechargeable batteries, are mostly based on composites of monolithic micrometer sized particles bound together with polymeric and conductive carbon additives and binders. The kinetic limitations of these monolithic chunks of material are inherently linked to their electrical properties, the kinetics of ion insertion through their interface and ion migration in and through the composite phase. Redox chemistry of nanostructured materials in EES systems offer vast gains in power and energy. Furthermore, due to their thin nature, ion and electron transport is dramatically increased, especially when thin heterogeneous conducting layers are employed synergistically. However, since the stability of the electrode material is dictated by the nature of the electrochemical reaction and the accompanying volumetric and interfacial changes from the perspective of overall system lifetime, research with nanostructured materials has shown often indefinite conclusions: in some cases, an increase in unwanted side-reactions due to the high surface area (bad). In other cases, results have shown significantly better handling of mechanical stress that results from lithiation/delithiation (good). Despite these mixed results, scientifically informed design of thin electrode materials, with carefully chosen architectures, is considered a promising route to address many limitations witnessed in EES systems by reducing and protecting electrodes from parasitic reactions, accommodating mechanical stress due to volumetric changes from electrochemical reactions, and optimizing charge carrier mobilities from both the "ionic" and "electronic" points of view. Furthermore, precise nanoscale control over the electrode structure can enable accurate measurement through advanced spectroscopy and microscopy techniques. This Account summarizes recent findings related to thin electrode materials synthesized by atomic layer deposition (ALD) and electrochemical deposition (ECD), including nanowires, nanotubes, and thin films. Throughout the Account, we will show how these techniques enabled us to synthesize electrodes of interest with precise control over the structure and composition of the material. We will illustrate and discuss how the electrochemical response of thin electrodes made by these techniques can facilitate new mechanisms for ion storage, mediate the interfacial electrochemical response of the electrode, and address issues related to electrode degradation over time. The effects of nanosizing materials and their electrochemical response will be mechanistically reviewed through two categories of ion storage: (1) pseudocapacitance and (2) ion insertion. Additionally, we will show how electrochemical processes that are more complicated because of accompanying volumetric changes and electrode degradation pathways can be mediated and controlled by application of thin functional materials on the electrochemically active interface; examples include conversion electrodes, reactive lithium metal anodes, and complex reactions in a Li/O2 cathode system. The goal of this Account is to illustrate how careful design of thin materials either as active electrodes or as mediating layers can facilitate desirable interfacial electrochemical activity and resolve or shed light on mechanistic limitations of electrochemical processes related to micrometer size particles currently used in energy storage electrodes.

A Rechargeable Al/S Battery with an Ionic-Liquid Electrolyte.

Aluminum metal is a promising anode material for next generation rechargeable batteries owing to its abundance, potentially dendrite-free deposition, and high capacity. The rechargeable aluminum/sulfur (Al/S) battery is of great interest owing to its high energy density (1340 Wh kg(-1) ) and low cost. However, Al/S chemistry suffers poor reversibility owing to the difficulty of oxidizing AlSx . Herein, we demonstrate the first reversible Al/S battery in ionic-liquid electrolyte with an activated carbon cloth/sulfur composite cathode. Electrochemical, spectroscopic, and microscopic results suggest that sulfur undergoes a solid-state conversion reaction in the electrolyte. Kinetics analysis identifies that the slow solid-state sulfur conversion reaction causes large voltage hysteresis and limits the energy efficiency of the system.

Enhancing the reversibility of Mg/S battery chemistry through Li(+) mediation.

Mg metal is a promising anode material for next generation rechargeable battery due to its dendrite-free deposition and high capacity. However, the best cathode for rechargeable Mg battery was based on high molecular weight MgxMo3S4, thus rendering full cell energetically uncompetitive. To increase energy density, high capacity cathode material like sulfur is proposed. However, to date, only limited work has been reported on Mg/S system, all plagued by poor reversibility attributed to the formation of electrochemically inactive MgSx species. Here, we report a new strategy, based on the effect of Li(+) in activating MgSx species, to conjugate a dendrite-free Mg anode with a reversible polysulfide cathode and present a truly reversible Mg/S battery with capacity up to 1000 mAh/gs for more than 30 cycles. Mechanistic insights supported by spectroscopic and microscopic characterization strongly suggest that the reversibility arises from chemical reactivation of MgSx by Li(+).

Chiral Molecular Coating of a LiNiCoMnO2 Cathode for High-Rate Capability Lithium-Ion Batteries.

The growing demand for energy has increased the need for battery storage, with lithium-ion batteries being widely used. Among those, nickel-rich layered lithium transition metal oxides [LiNi1-x-yCoxMnyO2 NCM (1 - x - y > 0.5)] are some of the promising cathode materials due to their high specific capacities and working voltages. In this study, we demonstrate that a thin, simple coating of polyalanine chiral molecules improves the performance of Ni-rich cathodes. The chiral organic coating of the active material enhances the discharge capacity and rate capability. Specifically, NCM811 and NCM622 electrodes coated with chiral molecules exhibit lower voltage hysteresis and better rate performance, with a capacity improvement of >10% at a 4 C discharge rate and an average improvement of 6%. We relate these results to the chirally induced spin selectivity effect that enables us to reduce the resistance of the electrode interface and to reduce dramatically the overpotential needed for the chemical process by aligning the electron spins.

High-energy all-solid-state lithium batteries enabled by Co-free LiNiO2 cathodes with robust outside-in structures.

A critical current challenge in the development of all-solid-state lithium batteries (ASSLBs) is reducing the cost of fabrication without compromising the performance. Here we report a sulfide ASSLB based on a high-energy, Co-free LiNiO2 cathode with a robust outside-in structure. This promising cathode is enabled by the high-pressure O2 synthesis and subsequent atomic layer deposition of a unique ultrathin LixAlyZnzOδ protective layer comprising a LixAlyZnzOδ surface coating region and an Al and Zn near-surface doping region. This high-quality artificial interphase enhances the structural stability and interfacial dynamics of the cathode as it mitigates the contact loss and continuous side reactions at the cathode/solid electrolyte interface. As a result, our ASSLBs exhibit a high areal capacity (4.65 mAh cm-2), a high specific cathode capacity (203 mAh g-1), superior cycling stability (92% capacity retention after 200 cycles) and a good rate capability (93 mAh g-1 at 2C). This work also offers mechanistic insights into how to break through the limitation of using expensive cathodes (for example, Co-based) and coatings (for example, Nb-, Ta-, La- or Zr-based) while still achieving a high-energy ASSLB performance.

Anodic instability of carbon in non-alkaline Zn-air batteries.

Although non-alkaline rechargeable Zn-air batteries (RZABs) are promising for energy storage, their chemistry is still underdeveloped and unclear. It was suggested that using Zn(OAc)2 or Zn(OTf)2 aqueous solutions as electrolytes enables reversible, corrosion-free charge-discharge processes, but the anodic stability of carbon in these cells has remained poorly studied. We report that CO2 evolution is manifested during the oxygen evolution reaction in non-alkaline RZABs, which is associated with the corrosion of carbon scaffolds. This corrosion is observed for different electrolyte compositions, such as Zn(OAc)2, ZnSO4 and Zn(OTf)2 solutions of various concentrations. The corrosion rate decreases when the overpotentials during the oxygen evolution reaction are lower. This study underlines the importance of addressing the anodic instability of carbon in non-alkaline RZABs.

High-Entropy Co-Free O3-Type Layered Oxyfluoride: A Promising Air-Stable Cathode for Sodium-Ion Batteries.

Sodium-ion batteries have recently emerged as a promising alternative to lithium-based batteries, driven by an ever-growing demand for electricity storage systems. The present workproposes a cobalt-free high-capacity cathode for sodium-ion batteries, synthesized using a high-entropy approach. The high-entropy approach entails mixing more than five elements in a single phase; hence, obtaining the desired properties is a challenge since this involves the interplay between different elements. Here, instead of oxide, oxyfluoride is chosen to suppress oxygen loss during long-term cycling. Supplement to this, lithium is introduced in the composition to obtain high configurational entropy and sodium vacant sites, thus stabilizing the crystal structure, accelerating the kinetics of intercalation/deintercalation, and improving the air stability of the material. With the optimization of the cathode composition, a reversible capacity of 109 mAh g-1 (2-4 V) and 144 mAh g-1 (2-4.3 V) is observed in the first few cycles, along with a significant improvement in stability during prolonged cycling. Furthermore, in situ and ex situ diffraction studies during charging/discharging reveal that the high-entropy strategy successfully suppresses the complex phase transition. The impressive outcomes of the present work strongly motivate the pursuit of the high-entropy approach to develop efficient cathodes for sodium-ion batteries.

Multifunctional solvent molecule design enables high-voltage Li-ion batteries.

Elevating the charging cut-off voltage is one of the efficient approaches to boost the energy density of Li-ion batteries (LIBs). However, this method is limited by the occurrence of severe parasitic reactions at the electrolyte/electrode interfaces. Herein, to address this issue, we design a non-flammable fluorinated sulfonate electrolyte by multifunctional solvent molecule design, which enables the formation of an inorganic-rich cathode electrolyte interphase (CEI) on high-voltage cathodes and a hybrid organic/inorganic solid electrolyte interphase (SEI) on the graphite anode. The electrolyte, consisting of 1.9 M LiFSI in a 1:2 v/v mixture of 2,2,2-trifluoroethyl trifluoromethanesulfonate and 2,2,2-trifluoroethyl methanesulfonate, endows 4.55 V-charged graphite||LiCoO2 and 4.6 V-charged graphite||NCM811 batteries with capacity retentions of 89% over 5329 cycles and 85% over 2002 cycles, respectively, thus resulting in energy density increases of 33% and 16% compared to those charged to 4.3 V. This work demonstrates a practical strategy for upgrading the commercial LIBs.

Diethylzinc-Assisted Atomic Surface Reduction to Stabilize Li and Mn-Rich NCM.

Li and Mn-rich nickel cobalt manganese oxide (LMR-NCM) is one of the most promising cathode materials for realizing next-generation Li-ion batteries due to its high specific capacity of >250 mA h g-1 and operating potential > 4.5 V. Nevertheless, being plagued by severe capacity fading and voltage decay, the commercialization of LMR-NCM appears to be a distant goal. The anionic activity of oxygen and associated phase transformations are the reasons behind the unstable electrochemical performance. The tendency of LMR-NCM to react with CO2 and moisture further makes it prone to interfacial instability and degradation. Here, we report a neoteric method to mitigate the stability issues and improve the electrochemical performance of LMR-NCM by changing the electronic configuration of constituting O and transition metals via diethylzinc-assisted atomic surface reduction (Zn-ASR) using an extremely facile protocol. With the proposed Zn-ASR, a 2-3 nm thin layer of a reduced surface enriched with complex ZnOx or ZnOxRy was obtained on the LMR-NCM particles. X-ray photoelectron spectroscopy suggested the transfer of ethyl groups of diethylzinc to O atoms on the LMR-NCM surface, which ultimately led to the reduction of near-surface Mn and Ni atoms and impeded irreversible anionic activity. The presence of ZnOx/ZnOxRy also resulted in superior charge transfer and resistance against HF. As a result, in contrast to LMR-NCM, the Zn-ASR-treated sample exhibited substantially improved rate capabilities, facilitated charge transfer, enhanced capacity retention, reduced parasitic reactions, and long-term stability as reflected from in-depth electrochemical analysis, in operando gaseous evolution studies, and post-mortem microscopic analysis.

Carbon-Dots-Initiated Photopolymerization: An In Situ Synthetic Approach for MXene/Poly(norepinephrine)/Copper Hybrid and its Application for Mitigating Water Pollution.

The current work presents a facile and green synthesis of carbon quantum dots (C-dots), which could serve as initiators for polymerization. Herein, C-dots have been synthesized from an easily available green herb, dill leaves, by a single-step hydrothermal method. These C-dots were efficiently utilized as initiators for the photopolymerization of the polymer poly(norepinephrine) (PNE) for the first time. The photopolymerization is discussed by a factorial design, and the optimized synthesis conditions were evaluated by a third-order regression model of three reaction parameters: monomer concentration, C-dots concentration, and UV exposure time. The sign convention of the factorial design mode indicated that monomer concentration and time of exposure are the most important factors for polymerization. The photopolymerized poly(norepinephrine) was extensively studied using Fourier transform infrared (FTIR) analysis, X-ray photoelectron spectroscopy (XPS), mass spectra, scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle measurement, and thermogravimetric analysis (TGA). UV-assisted deposition of PNE on six different types of substrates was performed, and their water contact angle and surface morphology were studied to evaluate the coating. This UV-triggered polymerization technique was further applied to fabricate sandwich-like composite catalyst MXene/poly(norepinephrine)/copper nanoparticles. This catalyst displayed good performance in the reduction of 4-NP (4-nitrophenol) at ambient temperature, and the first-order rate constant of the catalysis was 9.39 × 10-3 s-1. The reusability of the catalyst was evaluated in terms of the conversion factor. After 10 catalytic cycles, the conversion to catalyze 4-NP was still greater than 91%. The catalytic performance was also evaluated in the continuous flow condition through a membrane, fabricated from a cellulose filter paper coated with MXene/poly(norepinephrine)/copper nanoparticles. This composite catalyst not only offers a practical mode for the catalytic reaction of MXene-based materials but also lays down the foundation for the development of new catalysts.

Selective Catalyst Surface Access through Atomic Layer Deposition.

Catalyst poisoning is a prominent issue, reducing the lifetime of catalysts and increasing the costs of the processes that rely on them. The electrocatalysts that enable green energy conversion and storage, such as proton exchange membrane fuel cells and hydrogen bromine redox flow batteries, also suffer from this issue, hindering their utilization. Current solutions to protect electrocatalysts from harmful species fall short of effective selectivity without inhibiting the required reactions. This article describes the protection of a standard 50% Pt/C catalyst with a V2O5 coating through atomic layer deposition (ALD). The ALD selectively deposited V2O5 on the Pt, which enhanced hydrogen transport to the Pt surface and resulted in a higher mass activity in alkaline electrolytes. Cyclic voltammetry and X-ray photoelectron spectroscopy showed that the Pt was protected by the coating in the HBr/Br2 electrolyte which dissolved the uncoated 50% Pt/C in under 3 min.