A Na-Free Surface Enables "Three-In-One" Enhancement of Structural, Interfacial and Air Stability for Sodium-Ion Battery Cathodes.

O3-type layered oxides are regarded as one of the most promising cathode materials for sodium-ion batteries. However, the multistep phase transitions, severe electrode/electrolyte parasitic reactions, and moisture sensitivity are challenging for their practical application because of the highly active Na+. Here, a Na-free layer is built on the surface of NaNi1/3Mn1/3Fe1/3O2 (NMF111) via a leaching treatment and the subsequent surface reconstruction. Accordingly, both the structural degradation from bulk to surface and the overgrowth of the solid electrolyte interface (SEI) are greatly ameliorated, which results in the improved capacity retention of modified NMF111 from 58.3% to 89.6% after 400 cycles at 1 C. Besides, the Na-free surface with rock-salt structure prevents the H+/Na+ exchange and then enables good reversibility and low polarization of the optimal NMF111 when exposed to wet air (50% RH) for 4 days. This work opens a new avenue for the comprehensive cyclability improvement of layered oxides via surface reconstruction.

An Active Strategy to Reduce Residual Alkali for High-Performance Layered Oxide Cathode Materials of Sodium-Ion Batteries.

Residual alkali is one of the biggest challenges for the commercialization of sodium-based layered transition metal oxide cathode materials since it can even inevitably appear during the production process. Herein, taking O3-type Na0.9Ni0.25Mn0.4Fe0.2Mg0.1Ti0.05O2 as an example, an active strategy is proposed to reduce residual alkali by slowing the cooling rate, which can be achieved in one-step preparation method. It is suggested that slow cooling can significantly enhance the internal uniformity of the material, facilitating the reintegration of Na+ into the bulk material during the calcination cooling phase, therefore substantially reducing residual alkali. The strategy can remarkably suppress the slurry gelation and gas evolution and enhance the structural stability. Compared to naturally cooled cathode materials, the capacity retention of the slowly cooled electrode material increases from 76.2% to 85.7% after 300 cycles at 1 C. This work offers a versatile approach to the development of advanced cathode materials toward practical applications.

Tuning the Solvation Structure in Water-Based Solution Enables Surface Reconstruction of Layered Oxide Cathodes toward Long Lifespan Sodium-Ion Batteries.

Layered oxides of sodium-ion batteries suffer from severe side reactions on the electrode/electrolyte interface, leading to fast capacity degradation. Although surface reconstruction strategies are widely used to solve the above issues, the utilization of the low-cost wet chemical method is extremely challenging for moisture-sensitive Na-based oxide materials. Here, the solvation tuning strategy is proposed to overcome the deterioration of NaNi1/3Mn1/3Fe1/3O2 in water-based solution and conduct the surface reconstruction. When capturing the water molecules by the solvation structure of cations, here is Li+, the structural collapse and degradation of layered oxides in water-based solvents are greatly mitigated. Furthermore, Li(H2O)3EA+ promotes the profitable Li+/Na+ exchange to build a robust surface, which hampers the decomposition of electrolytes and the structural evolution upon cycling. Accordingly, the lifespan of Li-reinforced materials is prolonged to three times that of the pristine one. This work represents a step forward in understanding the surface reconstruction operated in a water-based solution for high-performance sodium layered oxide cathodes.

Cu-N Synergism Regulation to Enhance Anionic Redox Reversibility and Activity of Li- and Mn-Rich Layered Oxides Cathode.

Anionic redox chemistry enables extraordinary capacity for Li- and Mn-rich layered oxides (LMROs) cathodes. Unfortunately, irreversible surface oxygen evolution evokes the pernicious phase transition, structural deterioration, and severe electrode-electrolyte interface side reaction with element dissolution, resulting in fast capacity and voltage fading of LMROs during cycling and hindering its commercialization. Herein, a redox couple strategy is proposed by utilizing copper phthalocyanine (CuPc) to address the irreversibility of anionic redox. The Cu-N synergistic effect of CuPc could not only inhibit surface oxygen evolution by reducing the peroxide ion O2 2- back to lattice oxygen O2-, but also enhance the reaction activity and reversibility of anionic redox in bulk to achieve a higher capacity and cycling stability. Moreover, the CuPc strategy suppresses the interface side reaction and induces the forming of a uniform and robust LiF-rich cathode electrolyte, interphase (CEI) to significantly eliminate transition metal dissolution. As a result, the CuPc-enhanced LMRO cathode shows superb cycling performance with a capacity retention of 95.0% after 500 long-term cycles. This study sheds light on the great effect of N-based redox couple to regulate anionic redox behavior and promote the development of high energy density and high stability LMROs cathode.

Ordered planar plating/stripping enables deep cycling zinc metal batteries.

Metal anodes are emerging as culminating solutions for the development of energy-dense batteries in either aprotic, aqueous, or solid battery configurations. However, unlike traditional intercalation electrodes, the low utilization of "hostless" metal anodes due to the intrinsically disordered plating/stripping impedes their practical applications. Herein, we report ordered planar plating/stripping in a bulk zinc (Zn) anode to achieve an extremely high depth of discharge exceeding 90% with negligible thickness fluctuation and long-term stable cycling. The Zn can be plated/stripped with (0001)Zn preferential orientation throughout the consecutive charge/discharge process, assisted by a self-assembled supramolecular bilayer at the Zn anode-electrolyte interface. Through real-time tracking of the Zn atoms migration, we reveal that the ordered planar plating/stripping is driven by the construction of in-plane Zn─N bindings and the gradient energy landscape at the reaction fronts. The breakthrough results provide alternative insights into the ordered plating/stripping of metal anodes toward rechargeable energy-dense batteries.

Se-p Orbitals Induced "Strong d-d Orbitals Interaction" Enable High Reversibility of Se-Rich ZnSe/MnSe@C Electrode as Excellent Host for Sodium-Ion Storage.

The heterostructure of transition-metal chalcogenides is a promising approach to boost alkali ion storage due to fast charge kinetics and reduction of activation energy. However, cycling performance is a paramount challenge that is suffering from poor reversibility. Herein, it is reported that Se-rich particles can chemically interact with local hexagonal ZnSe/MnSe@C heterostructure environment, leading to effective ions insertion/extraction, enabling high reversibility. Enlightened by theoretical understanding, Se-rich particles endow high intrinsic conductivities in term of low energy barriers (1.32 eV) compared with those without Se-rich particles (1.50 eV) toward the sodiation process. Moreover, p orbitals of Se-rich particles may actively participate and further increase the electronegativity that pushes the Mn d orbitals (dxy and dx2-y2) and donate their electrons to dxz and dyz orbitals, manifesting strong d-d orbitals interaction between ZnSe and MnSe. Such fundamental interaction will adopt a well-stable conducive electronic bridge, eventually, charges are easily transferred from ZnSe to MnSe in the heterostructure during sodiation/desodiation. Therefore, the optimized Se-rich ZnSe/MnSe@C electrode delivered high capacity of 576 mAh g-1 at 0.1 A g-1 after 100 cycles and 384 mAh g-1 at 1 A g-1 after 2500 cycles, respectively. In situ and ex situ measurements further indicate the integrity and reversibility of the electrode materials upon charging/discharging.

Polymeric Electronic Shielding Layer Enabling Superior Dendrite Suppression for All-Solid-State Lithium Batteries.

LiBH4 is one of the most promising candidates for use in all-solid-state lithium batteries. However, the main challenges of LiBH4 are the poor Li-ion conductivity at room temperature, excessive dendrite formation, and the narrow voltage window, which hamper practical application. Herein, we fabricate a flexible polymeric electronic shielding layer on the particle surfaces of LiBH4. The electronic conductivity of the primary LiBH4 is reduced by 2 orders of magnitude, to 1.15 × 10-9 S cm-1 at 25 °C, due to the high electron affinity of the electronic shielding layer; this localizes the electrons around the BH4- anions, which eliminates electronic leakage from the anionic framework and leads to a 68-fold higher critical electrical bias for dendrite growth on the particle surfaces. Contrary to the previously reported work, the shielding layer also ensures fast Li-ion conduction due to the fast-rotational dynamics of the BH4- species and the high Li-ion (carrier) concentration on the particle surfaces. In addition, the flexibility of the layer guarantees its structural integrity during Li plating and stripping. Therefore, our LiBH4-based solid-state electrolyte exhibits a high critical current density (11.43 mA cm-2) and long cycling stability of 5000 h (5.70 mA cm-2) at 25 °C. More importantly, the electrolyte had a wide operational temperature window (-30-150 °C). We believe that our findings provide a perspective with which to avoid dendrite formation in hydride solid-state electrolytes and provide high-performance all-solid-state lithium batteries.

Achieving High Initial Coulombic Efficiency and Capacity in a Surface Chemical Grafting Layer of Plateau-type Sodium Titanate.

The plateau-type sodium titanate with suitable sodiation potential is a promising anode candidate for high safe and high energy density of sodium-ion batteries (SIBs). However, the poor initial Coulombic efficiency (ICE) and cyclic instability of sodium titanate are attributed to the unstable interfacial structure along with the decomposition of electrolytes, resulting in the continuous formation of solid electrolyte interface (SEI) film. To address this issue, a chemical grafting method is developed to fabricate a highly stable interface layer of inert Al2O3 on the sodium titanate anode, rendering the high ICE and excellent cycling stability. Based on theoretical calculations, NaPF6 are more likely adsorption on the Al2O3 surface and produce sodium fluoride. The formation of a thin and dense SEI film with rich sodium fluoride achieves the low interfacial resistances and charge-transfer resistances. Benefitting from our design, the obtained sodium titanate exhibits a high ICE from 67.7 % to 79.4 % and an enhanced reversible capacity from 151 mAh g-1 to 181 mAh g-1 at 20 mA g-1, along with an increase in capacity retention from 56.5 % to 80.6 % after 500 cycles. This work heralds a promising paradigm for rational regulation of interfacial stability to achieve high-performance anodes for SIBs.

Critical Review of Emerging Pre-metallization Technologies for Rechargeable Metal-Ion Batteries.

Low Coulombic efficiency, low-capacity retention, and short cycle life are the primary challenges faced by various metal-ion batteries due to the loss of corresponding active metal. Practically, these issues can be significantly ameliorated by compensating for the loss of active metals using pre-metallization techniques. Herein, the state-of-the-art development in various pr-emetallization techniques is summarized. First, the origin of pre-metallization is elaborated and the Coulombic efficiency of different battery materials is compared. Second, different pre-metallization strategies, including direct physical contact, chemical strategies, electrochemical method, overmetallized approach, and the use of electrode additives are summarized. Third, the impact of pre-metallization on batteries, along with its role in improving Coulombic efficiency is discussed. Fourth, the various characterization techniques required for mechanistic studies in this field are outlined, from laboratory-level experiments to large scientific device. Finally, the current challenges and future opportunities of pre-metallization technology in improving Coulombic efficiency and cycle stability for various metal-ion batteries are discussed. In particular, the positive influence of pre-metallization reagents is emphasized in the anode-free battery systems. It is envisioned that this review will inspire the development of high-performance energy storage systems via the effective pre-metallization technologies.

Transient Zwitterions Dynamics Empowered Adaptive Interface for Ultra-Stable Zn Plating/Stripping.

A highly reversible zinc anode is crucial for the commercialization of zinc-ion batteries. However, the change in the microstructure of the electric double layer originated from the dynamic change in charge density on the electrode greatly impacts anode reversibility during charge/discharge, which is rarely considered in previous research. Herein, the zwitterion additive is employed to create an adaptive interface by coupling the transient zwitterion dynamics upon the change of interfacial charge density. Ab initio molecular dynamics simulations suggest the molecular orientation and adsorption groups of zwitterions will be determined by the charging state of the electrode. ZnSO4 electrolyte with zwitterion fulfills a highly reversible Zn anode with an average Coulombic efficiency of up to 99.85%. Zn/Zn symmetric cells achieve greatly enhanced cycling stability for 700 h with extremely small voltage hysteresis of 29 mV under 5 mA cm-2 with 5 mAh cm-2 . This study validates the adaptive interface based on transient dynamics of zwitterions, which sheds new light on developing highly reversible metal anodes with a high utilization rate.

Oxygen-regulated spontaneous solid electrolyte interphase enabling ultra-stable solid-state Na metal batteries.

Solid-state sodium metal batteries utilizing inorganic solid electrolytes (SEs) hold immense potentials such as intrinsical safety, high energy density, and environmental sustainability. However, the interfacial inhomogeneity/instability at the anode-SE interface usually triggers the penetration of sodium dendrites into the electrolyte, leading to short circuit and battery failure. Herein, confronting with the original nonuniform and high-resistance solid electrolyte interphase (SEI) at the Na-Na3Zr2Si2PO12 interface, an oxygen-regulated SEI innovative approach is proposed to enhance the cycling stability of anode-SEs interface, through a spontaneous reaction between the metallic sodium (containing trace amounts of oxygen) and the Na3Zr2Si2PO12 SE. The oxygen-regulated spontaneous SEI is thin, uniform, and kinetically stable to facilitate homogenous interfacial Na+ transportation. Benefitting from the optimized SEI, the assembled symmetric cell exhibits an ultra-stable sodium plating/stripping cycle for over 6600 h under a practical capacity of 3 mAh cm-2. Quasi-solid-state batteries with Na3V2(PO4)3 cathode deliver excellent cyclability over 500 cycles at a rate of 0.5 C (1 C = 117 mA cm-2) with a high capacity retention of 95.4%. This oxygen-regulated SEI strategy may offer a potential avenue for the future development of high-energy-density solid-state metal batteries.

In Situ Fast Construction of Ni3S4/FeS Catalysts on 3D Foam Structure Achieving Stable Large-Current-Density Water Oxidation.

By increasing the content of Ni3+, the catalytic activity of nickel-based catalysts for the oxygen evolution reaction (OER), which is still problematic with current synthesis routes, can be increased. Herein, a Ni3+-rich of Ni3S4/FeS on FeNi Foam (Ni3S4/FeS@FNF) via anodic electrodeposition to direct obtain high valence metal ions for OER catalyst is presented. XPS showed that the introduction of Fe not only further increased the Ni3+ concentration in Ni3S4/FeS to 95.02%, but also inhibited the dissolution of NiOOH by up to seven times. Furthermore, the OER kinetics is enhanced by the combination of the inner Ni3S4/FeS heterostructures and the electrochemically induced surface layers of oxides/hydroxides. Ni3S4/FeS@FNF shows the most excellent OER activity with a low Tafel slope of 11.2 mV dec-1 and overpotentials of 196 and 445 mV at current densities of 10 and 1400 mA cm-2, respectively. Furthermore, the Ni3S4/FeS@FNF catalyst can be operated stably at 1500 mA cm-2 for 200 h without significant performance degradation. In conclusion, this work has significantly increased the high activity Ni3+ content in nickel-based OER electrocatalysts through an anodic electrodeposition strategy. The preparation process is time-saving and mature, which is expected to be applied in large-scale industrialization.

Interfacial Reconstruction Toward Reversible Mg Anode in Conventional Electrolytes.

Rechargeable magnesium batteries are considered with great potential as sustainable, economic-friendly, safe energy storage techniques. Whereas, the Mg metal anode exhibits limited plating/stripping behavior in the conventional electrolytes due to the severe passivation. Herein, a facile LiI solution treatment is reported to reconstruct the interphase between Mg metal anode and electrolytes, converting the original passivation film to I-riched solid electrolyte interphase with the ability of rapid Mg2+ migration, which can reduce the overpotential for Mg anode plating/stripping from 2 to 0.4 V at 0.1 mA cm-2. In addition, Li+ from the LiI precursor can be released and shuttles to the Mo6S8 cathode side, promoting cointercalation of Mg2+. With the simultaneous improvement of the anode and cathode, the Mg//Mo6S8 full cell delivers a decreasing voltage hysteresis (0.1 V) and much enhanced specific capacity (80.8 mAh g-1). This work provides a maneuverable anode treatment for constructing a passivation-against interphase between Mg metal anode and the conventional electrolytes, contributing an insight for the development toward high-performance Mg batteries.

Continuous Amorphous Metal-Organic Frameworks Layer Boosts the Performance of Metal Anodes.

Employing metal anodes can greatly increase the volumetric/gravimetric energy density versus a conventional ion-insertion anode. However, metal anodes are plagued by dendrites, corrosion, and interfacial side reaction issues. Herein, a continuous and flexible amorphous MOF layer was successfully synthesized and used as a protective layer on metal anodes. Compared with the crystalline MOF layer, the continuous amorphous MOF layer can inhibit dendrite growth at the grain boundary and eliminate ion migration near the grain boundary, showing high interfacial adhesion and a large ion migration number (tZn2+ = 0.75). In addition, the continuous amorphous MOF layer can effectively solve several key challenges, e.g., corrosion of the zinc anode, hydrogen evolution reaction, and dendrite growth on the zinc surface. The prepared Zn anode with the continuous amorphous MOF (A-MOF) layer exhibited an ultralong cycling life (around one year, more than 7900 h) and a low overpotential (<40 mV), which is 12 times higher than that of the crystalline MOF protective layer. Even at 10 mA cm-2, it still showed high stability for more than 5500 cycles (1200 h). The enhanced performance is realized for full cells paired with a MnO2 cathode. In addition, a flexible symmetrical battery with the Zn@A-ZIF-8 anode exhibited good cyclability under different bending angles (0°, 90°, and 180°). More importantly, various metal substrates were successfully coated with compact A-ZIF-8. The A-ZIF-8 layer can obviously improve the stability of other metal anodes, including those of Mg and Al. These results not only demonstrate the high potential of amorphous MOF-decorated Zn anodes for AZIBs but also propose a type of protective layer for metal anodes.

Synergistic "Anchor-Capture" Enabled by Amino and Carboxyl for Constructing Robust Interface of Zn Anode.

While the rechargeable aqueous zinc-ion batteries (AZIBs) have been recognized as one of the most viable batteries for scale-up application, the instability on Zn anode-electrolyte interface bottleneck the further development dramatically. Herein, we utilize the amino acid glycine (Gly) as an electrolyte additive to stabilize the Zn anode-electrolyte interface. The unique interfacial chemistry is facilitated by the synergistic "anchor-capture" effect of polar groups in Gly molecule, manifested by simultaneously coupling the amino to anchor on the surface of Zn anode and the carboxyl to capture Zn2+ in the local region. As such, this robust anode-electrolyte interface inhibits the disordered migration of Zn2+, and effectively suppresses both side reactions and dendrite growth. The reversibility of Zn anode achieves a significant improvement with an average Coulombic efficiency of 99.22% at 1 mA cm-2 and 0.5 mAh cm-2 over 500 cycles. Even at a high Zn utilization rate (depth of discharge, DODZn) of 68%, a steady cycle life up to 200 h is obtained for ultrathin Zn foils (20 µm). The superior rate capability and long-term cycle stability of Zn-MnO2 full cells further prove the effectiveness of Gly in stabilizing Zn anode. This work sheds light on additive designing from the specific roles of polar groups for AZIBs.

In-Situ-Generated Electron-Blocking LiH Enabling an Unprecedented Critical Current Density of Over 15 mA cm-2 for Solid-State Hydride Electrolytes.

LiBH4 is a promising solid-state electrolyte (SE) due to its thermodynamic stability to Li. However, poor Li-ion conductivities at room temperature, low oxidative stabilities, and severe dendrite growth hamper its application. In this work, a partial dehydrogenation strategy is adopted to in situ generate an electronic blocking layer dispersed of LiH, addressing the above three issues simultaneously. The electrically insulated LiH reduces the electronic conductivity by two orders of magnitude, leading to a 32.0-times higher critical electrical bias for dendrite growth on the particle surfaces than that of the counterpart. Additionally, this layer not only promotes the Li-ion conductance by stimulating coordinated rotations of BH4 - and B12 H12 2- , contributing to a Li-ion conductivity of 1.38 × 10-3 S cm-1 at 25 °C, but also greatly enhances oxidation stability by localizing the electron density on BH4 - , extending its voltage window to 6.0 V. Consequently, this electrolyte exhibits an unprecedented critical current density (CCD) of 15.12 mA cm-2 at 25 °C, long-term Li plating and stripping stability for 2700 h, and a wide temperature window for dendrite inhibition from -30 to 150 °C. Its Li-LiCoO2 cell displays high reversibility within 3.0-5.0 V. It is believed that this work provides a clear direction for solid-state hydride electrolytes.

Thickness-Controlled Synthesis of Compact and Uniform MOF Protective Layer for Zinc Anode to Achieve 85% Zinc Utilization.

Zinc anode-based aqueous batteries have attracted considerable interest for large-scale energy storage and wearable devices. Unfortunately, the formation of Zn dendrite, parasitic hydrogen evolution reaction (HER), and irreversible by-products, seriously restrict their practical applications. Herein, a series of compact and uniform metal-organic frameworks (MOFs) films with precisely controlled thickness (150-600 nm) are constructed by a pre-oxide gas deposition (POGD) method on Zn foil. Under the protection of MOF layer with optimum thickness, the corrosion of zinc, the side reaction of hydrogen evolution, and the growth of dendrites on the zinc surface are suppressed. The symmetric cell based on Zn@ZIF-8 anode exhibits exceptional cyclicality for over 1100 h with low voltage hysteresis of≈38 mV at 1 mA cm-2 . Even at current densities of 50 mA cm-2 with an area capacity of 50 mAh cm-2 (85% Zn utilization), the electrode can keep cycling for >100 h. Besides, this Zn@ZIF-8 anode also delivers a high average CE of 99.4% at 1 mA cm-2 . Moreover, a rechargeable Zn ion battery is fabricated based on the Zn@ZIF-8 anode and MnO2 cathode, which presents an exceptionally long lifespan with no capacity attenuation for 1000 cycles.

Extraordinary Ionic Conductivity Excited by Hierarchical Ion-Transport Pathways in MOF-Based Quasi-Solid Electrolytes.

Liquid-electrolyte-laden metal-organic frameworks (LE-laden MOFs) are promising quasi-solid electrolytes (QSEs) for metal-anode batteries. To achieve a high ionic conductivity, considerable efforts have been devoted to designing continuous and compact LE-laden MOF layers. Surprisingly, in this work, an extraordinarily high ionic conductivity (1.02 mS cm-1 ) is observed in an LE-laden MOF electrolyte with abundant interstices and cracks. Herein, various macroscopic and mesoscopic pore structures of Li-LE-laden HKUST-1 QSEs are prepared via morphology control and different cold-pressing procedures. Thereinto, Li-LE-laden cuboctahedron HKUST-1 prepared under 150 MPa cold-pressing with an optimal hierarchical pore structure (Li-Cuboct-H) exhibits the highest ambient ionic conductivity (1.02 mS cm-1 ). It is found that interstices and cracks in electrolytes construct a set of interconnected Li-LE networks with innate MOF channels and facilitate Li+ transfer in the hybrid ion-transport pathways. The Li/LiFePO4 cells based on Li-Cuboct-H deliver a splendid capacity retention of 93% over 210 cycles at 1 C. Meanwhile, the high ionic conductivities (higher than 10-4 S cm-1 ) can be achieved in different ion conductor systems (Na, Mg, and Al) under the same guideline. This work redefines the understanding of ion transport in MOF-based QSEs and breaks the bottleneck of MOF-based QSEs.

Quantified versus willful handgrip exercises for the prevention of PICC-related thrombosis: A meta-analysis and systematic review.

BACKGROUND: Thrombosis is a common yet serious complication in patients with peripherally inserted central venous catheter (PICC), the prevention of thrombosis is very important to the prognosis of PICC patients. We aimed to evaluate the effects of quantified versus willful grip exercises for the prevention of PICC-related thrombosis, to provide evidence to the clinical nursing care of PICC patients. METHODS: Two authors searched PubMed et al databases for randomized controlled trials (RCTs) comparing the effects of quantified versus willful grip exercises in PICC patients up to August 31, 2022. Quality assessment and data extraction were independently performed by 2 researchers, and meta-analysis was performed using RevMan 5.3 software. RESULTS: 15 RCTs involving 1741 PICC patients were finally included in this meta-analysis. Synthesized outcomes indicated that compared with willful grip exercises, quantified grip exercises reduced the incidence of PICC-related thrombosis (odds ratio = 0.19, 95% confidence interval [CI]: 0.12-0.31) and infection (odds ratio = 0.30, 95% CI: 0.15-0.60) in PICC patients, increased the maximum venous velocity (mean difference = 3.02, 95% CI: 1.87-4.17) and mean blood flow (mean difference = 3.10, 95%CI: 1.57-4.62) in PICC patients (all P < .05). There were no publication biases amongst the synthesized outcomes (all P > .05). CONCLUSION: Quantified grip exercises can effectively reduce the occurrence of PICC-related thrombosis and infection, improve the venous hemodynamics. Limited by study population and regions, large-sample, and high-quality RCTs are still needed in the future to further evaluate the effects and safety of quantified grip exercises in PICC patients.

Electrostatically directed assembly of two-dimensional ultrathin Co2Ni-MOF/Ti3C2Tx nanosheets for electrocatalytic oxygen evolution.

Hydrogen production from water electrolysis is severely restricted by the poor reaction kinetics of oxygen evolution reaction (OER). In this work, a series of two-dimensional (2D) composites MOF/Ti3C2Tx (the MXene phase) were fabricated by electrostatically directed assembly and used as catalysts for OER. The obtained composite materials exhibit enhanced electrocatalytic properties, thanks to the ultrathin 2D/2D heterostructure with abundant active sites in Co2Ni-MOF and the high electronic conductivity of Ti3C2Tx. Among all the catalysts, Co2Ni-MOF@MX-1 achieved the best oxygen evolution performance with the lowest Tafel slope (51.7 mV dec-1) and the lowest overpotential (265 mV on carbon paper) at the current density of 10 mA cm-2. These results demonstrated that the synthesis of 2D composite materials by electrostatically directed assembly could be a feasible and promising method for the preparation of 2D heterostructure catalysts.