Metal Oxide Nanosheets Research Articles

Highly Active Photoreduction of Atmospheric‐Concentration CO2 into CH3COOH over Palladium Particles on Nb2O5 Nanosheets

AbstractThe endeavor to drive CO2 photoreduction towards the synthesis of C2 products is largely thwarted by the colossal energy hurdle inherent in C−C coupling. Herein, we load active metal particles on metal oxide nanosheets to build the dual metal pair sites for steering C−C coupling to form C2 products. Taking Pd particles anchored on the Nb2O5 nanosheets as an example, the high‐angle annular dark‐field image and X‐ray photoelectron spectroscopy demonstrate the presence of Pd−Nb metal pair sites on the Pd‐Nb2O5 nanosheets. Density functional theory calculations reveal these sites exhibit a low reaction energy barrier of only 1.02 eV for C−C coupling, implying that the introduction of Pd particles effectively tailors the reaction step to form C2 products. Therefore, the Pd‐Nb2O5 nanosheets achieve a CH3COOH evolution rate of 13.5 μmol g−1 h−1 in photoreduction of atmospheric‐concentration CO2, outshining all other single photocatalysts reported to date under analogous conditions.

Facile synthesis and electrochemical properties of FeO/Fe(OH)3 nanosheets

Iron oxides and hydroxides, including Fe(OH)3 and Fe(OH)2, exhibit diverse morphologies and compositions. Nanostructures of Fe(OH)3 such as nanosheets are non-toxic and offer multiple active sites that are advantageous for catalysis. We synthesized iron oxide/iron hydroxide (FeO/Fe(OH)3) nanosheets using a surfactant-assisted method and analyzed their structure and composition. Their phase transition to iron oxyhydroxides/oxides via heat treatment were also analyzed. The formation of FeOOH, which catalyzes the oxygen evolution reaction, significantly affected the electrochemical properties. We report the morphological and crystallographic characteristics of the as-synthesized and annealed FeO/Fe(OH)3 nanosheets, highlighting the influence of specific species on their electrochemical behavior. The proposed approach is simple and efficient for the synthesis of highly crystalline transition metal oxide nanosheets using different cation precursors.

Highly Active Photoreduction of Atmospheric-Concentration CO2 into CH3COOH over Palladium Particles on Nb2O5 Nanosheets.

The endeavor to drive CO2 photoreduction towards the synthesis of C2 products is largely thwarted by the colossal energy hurdle inherent in C-C coupling. Herein, we load active metal particles on metal oxide nanosheets to build the dual metal pair sites for steering C-C coupling to form C2 products. Taking Pd particles anchored on the Nb2O5 nanosheets as an example, the high-angle annular dark-field image and X-ray photoelectron spectroscopy demonstrate the presence of Pd-Nb metal pair sites on the Pd-Nb2O5 nanosheets. Density functional theory calculations reveal these sites exhibit a low reaction energy barrier of only 1.02 eV for C-C coupling, implying that the introduction of Pd particles effectively tailors the reaction step to form C2 products. Therefore, the Pd-Nb2O5 nanosheets achieve a CH3COOH evolution rate of 13.5 μmol g-1 h-1 in photoreduction of atmospheric-concentration CO2, outshining all other single photocatalysts reported to date under analogous conditions.

Enhancing electrical conductivity of RuO2 nanosheet-coated films by enlarging the nanosheet area

This study focused on enhancing the electrical conductivity of metal oxide nanosheet films by increasing the size of the nanosheets to promote the electron flow in the desired in-plane direction. We developed a method for increasing the size of RuO2 metal oxide nanosheets, a 2D material, by controlling the heat-treatment process. The size of the RuO2 nanosheets increased from 0.7 to 3.5 μm by modifying the heat-treatment conditions of KxRuO2, which was used as the precursor material. As a consequence, the electrical conductivity of the large-sized-RuO2 nanosheet-coated films was eight times higher than that of their small-sized counterparts. This lower resistance was attributed to the minimal number of contacts required for electron flow; the contact resistance between the nanosheets being higher than the intrinsic resistance. The proposed approach for enhancing the conductivity of metal oxide 2D materials is very promising and is expected to significantly contribute to the development of advanced flexible electronic devices.

General synthesis of porous metal oxides nanosheets for gas sensing by gradient crystallization induced spatial confinement approach

Inorganic-template synthesis of crystalline porous metal oxides nanosheets with fantastic properties is a powerful approach, but it is limited in the systems with strong interaction between inorganic crystals and guest species. Here, we report a gradient crystallization induced spatial confinement method to achieve a general synthesis of porous metal oxides nanosheets regardless of host–guest interaction. Taking the synthesis of porous SnO2 nanosheets as an example, the freezing of KCl/SnCl2 aqueous solution induces the gradient crystallization of lamellar ice and KCl structure, and subsequently expelled KCl/SnCl2 crystals can be limited in the confined region to form the ice/SnCl2/KCl sandwich structure. Followed by freeze-drying, calcination and water washing, the porous SnO2 nanosheets structure can be obtained. Notably, this general method enables the synthesis of functional porous nanosheet with specific designed component and surface properties, and the obtained porous Pt-SnO2 nanosheets with abundant accessible active sites and lower d-band center exhibit superior gas sensing performance to 3-hydroxy-2-butanone.

2D Metal-Oxide Nanosheets as a Homogeneous Li-Ion Flux Regulator for High-Performance Anodeless Lithium Metal Batteries.

The anodeless battery design has recently gained significant interest by eliminating the direct use of a thick lithium (Li) foil. However, it suffers from inhomogeneous Li+ flux, resulting in dendrite growth and a short cycling life. To address this, the exfoliation of layered-structure titanium oxide to 2D nanosheets (2DTiOx) is proposed to precisely control Li+ flux at the atomic scale by maximizing Li+ affinitive Ti sites. Compared to cells without these nanosheets, the Li|2DTiOx|Cu half-cell demonstrates stable cyclability over 900 cycles, with a Coulombic efficiency (CE) over 99% at 0.5 mA cm-2 and 0.5 mAh cm-2. Similarly, a long stable cycling life over 1500 h at 1.0-3.0 mA cm-2 is observed for a 2DTiOx-based symmetric cell containing a limited Li amount from electrodeposited Li metal (e-Li|2DTiOx|e-Li). The full cells (e-Li|2DTiOx||NCM811 and e-Li|2DTiOx||LFP) coupled with NCM811 and LFP cathodes showed a long cycle life of 400 cycles at 1.0 C and 0.5 C, respectively. The exceptional battery performance is attributed to the uniform Li disposition on the 2DTiOx electrode, emphasizing the crucial role of the exposed basal plane in 2DTiOx as an efficient atomic scale Li+ flux regulator. This strategy is expected to advance next-generation lithium metal batteries (LMBs) by highlighting the significance of Li+ affinity at the Ti sites of 2DTiOx nanosheets.

Human Skin-Mimicking Ionogel-Based Electronic Skin for Intelligent Robotic Sorting.

Creating bionic intelligent robotic systems that emulate human-like skin perception presents a considerable scientific challenge. This study introduces a multifunctional bionic electronic skin (e-skin) made from polyacrylic acid ionogel (PAIG), designed to detect human motion signals and transmit them to robotic systems for recognition and classification. The PAIG is synthesized using a suspension of liquid metal and graphene oxide nanosheets as initiators and cross-linkers. The resulting PAIGs demonstrate excellent mechanical properties, resistance to freezing and drying, and self-healing capabilities. Functionally, the PAIG effectively captures human motion signals through electromechanical sensing. Furthermore, a bionic intelligent sorting robot system is developed by integrating the PAIG-based e-skin with a robotic manipulator. This system leverages its ability to detect frictional electrical signals, enabling precise identification and sorting of materials. The innovations presented in this study hold significant potential for applications in artificial intelligence, rehabilitation training, and intelligent classification systems.

Solution‐Processed Nanocoating of Ca2Nb3O10 and Polydopamine for Anticorrosion on Magnesium Alloy

2D materials have exhibited great potential for applications in anticorrosion nanocoatings. However, the nanocoating of prefocused graphene shows “corrosion‐promoting activity” due to its high conductivity. Metal oxide nanosheets obtained by delaminating layered oxides have been another attractive candidate. This study demonstrates a water‐based Ca2Nb3O10 (CNO) ink spray coated on magnesium alloys to form a continuous coating without complex functionalization and structural control. The composite coating of Ca2Nb3O10 (CNO) and polydopamine (PDA) is fabricated by combining spray‐ and dip‐coating methods. The surface composition and microstructure of the as‐prepared coatings are characterized by X‐ray diffractometry, Fourier transform infrared, X‐ray photoelectron spectroscopy, scanning electron microscopy, and energy‐dispersive spectrometry. The anticorrosion performance of the composite coating is evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy, and salt spray tests. The electrochemical results show that the CNO/PDA heterostructure coating provides an enhanced corrosion inhibition efficiency (99.62%) with a corrosion current density of 5.49 × 10−7 A cm−2, three orders of magnitude lower than bare AZ31. The immersion tests before and after heat treatment and salt spray tests indicate that the composite coating has good stability and long‐term anticorrosion performance. Solution‐processed nanocoating and extensible materials design provide a green and facile route to anticorrosion nanotechnology for industrial demands.

Virtual substrate method: synthesis and growth kinetics of 2D metal oxide nanosheets

We present the experimental decomposition kinetics for the synthesis of metal oxide 2D nanosheets by the virtual substrate method. In this method, acetates of Mg and Cu were used as precursors for the growth of prototype MgO and CuO nanosheets, while the filter paper was utilized as a virtual substrate. The synthesized samples were characterized by X-ray diffraction for the phase analysis of the nanostructures, which confirms the cubic phase of MgO and monoclinic phase of CuO; with a minor Cu2O phase. Field emission scanning electron microscopy was used to determine the surface morphology of the nanosheets. Fourier transform infrared spectroscopy was utilized to identify the vibrational modes of the metal oxides and the functional groups present in the sample. Thermogravimetric analysis revealed the evolution of combustive oxidation of filter paper with the thermal decomposition of acetates situated on its surface.

Universal Synthesis of Amorphous Metal Oxide Nanomeshes.

Constructing the pore structures in amorphous metal oxide nanosheets can enhance their electrocatalytic performance by efficiently increasing specific surface areas and facilitating mass transport in electrocatalysis. However, the accurate synthesis for porous amorphous metal oxide nanosheets remains a challenge. Herein,a facile nitrate-assisted oxidation strategy is reported for synthesizing amorphous mesoporous iridium oxide nanomeshes (a-m IrOx NMs) with a pore size of ∼4nm. X-ray absorption characterizations indicate that a-m IrOx NMs possess stretched Ir─O bonds and weaker Ir-O interaction compared with commercial IrO2. Combining thermogravimetric-fourier transform infrared spectroscopy with differential scanning calorimetry measurements, it is demonstrated that sodium nitrate, acting as an oxidizing agent, is conducive to the formation of amorphous nanosheets, while the NO2 produced by the in situ decomposition of nitrates facilitates the generation of pores within the nanomeshes. As an anode electrocatalyst in proton exchange membrane water electrolyzer, a-m IrOx NMs exhibit superior performance, maintaining a cell voltage of 1.67V at 1Acm-2 for 120h without obvious decay with a low loading (0.4mgcatalyst cm-2). Furthermore, the nitrate-assisted method is demonstrated to be a general approach to prepare various amorphous metal oxide nanomeshes, including amorphous RhOx, TiOx, ZrOx, AlOx, and HfOx nanomeshes.

General Scalable Synthesis of Mesoporous Metal Oxide Nanosheets with High Crystallinity for Ultralong‐Life Li–S Batteries

AbstractMesoporous metal oxide nanosheets (MMONs) are demonstrated great promise for various catalytic applications such as water splitting, CO2 reduction, and metal–sulfur batteries. However, limited by the conventional high‐temperature synthetic routes, the prepared MMONs expose only a small portion of the effective catalytic sites, which greatly restricts their electrocatalytic activity. Herein, a facile and general glycine‐assisted strategy is developed to synthesize a series of MMONs with high crystallinity and remarkable porosity. Impressively, single‐phase perovskite type MMONs containing up to ten metal cations can be synthesized easily using this method without any further purification step. As a proof of concept, the Li–S cell with mesoporous LaFe0.4Co0.2Ni0.2Cu0.2O3 nanosheets as catalyst achieves superior ultralong cycling life over 1500 cycles at 2 C with only 0.041% capacity decay per cycle and a high areal capacity reaching 6.0 mAh cm−2 at a low electrolyte/sulfur ratio of 5.9 µL mg−1. The improved performance is attributed to abundant active sites and synergistic contribution of multicomponent. This work paves a new avenue for the general synthesis of advanced MMONs and will inspire the practical applications in different fields.

Molecularly Confined Topochemical Transformation of MXene Enables Ultrathin Amorphous Metal-Oxide Nanosheets.

Two-dimensional (2D) amorphous nanosheets with ultrathin thicknesses have properties that differ from their crystalline counterparts. However, conventional methods for growing 2D materials often produce either crystalline flakes or amorphous nanosheets with an uncontrollable thickness. Here, we report that ultrathin amorphous metal-oxide nanosheets featuring superior flatness can be realized through the molecularly confined topochemical transformation of MXene. Using MXene Ti2CTx as an example, we show that surface modification of Ti2CTx nanosheets with molecular ligands, such as oleylamine (OAm) and oleic acid (OA), not only imparts notable colloidal dispersity to Ti2CTx nanosheets in nonpolar organic solvents but also confines their subsequent oxidation to in-plane configurations. We demonstrate that unlike the drastic oxidation conventionally observed for pristine MXene, hydrophobizing MXene with OAm and OA ligands enables individual Ti2CTx nanosheets to undergo independent oxidation in a nondestructive manner, resulting in amorphous titanium oxide (am-TiO2) nanosheets that faithfully retain the dimension and flatness of pristine MXene. These am-TiO2 nanosheets exhibit exceptional activity as substrates for surface-enhanced Raman scattering. Importantly, this molecular confinement strategy can be extended to other MXene materials, providing a versatile approach for synthesizing ultrathin amorphous metal-oxide nanosheets with tailored compositions and functionalities.

Nanosheet‐like MoO3 and conductive PANI electrodeposited on flexible carbon cloth for self‐supported solid‐state supercapacitor electrode

AbstractIn this paper, uniformly transition metal oxide (MoO3) nanosheets were electrochemically deposited on flexible carbon cloth (CC), and then conductive polyaniline (PANI) was orderly wrapped around their surface by electrochemical polymerization. The morphology and structure of as‐obtained self‐supported PANI/MoO3/CC electrode were investigated by FTIR, X‐ray diffraction, Raman, scanning electron microscope (SEM), transmission electron microscopy (TEM), and X‐ray photoelectron spectroscopy measurements in detail. Among all PANI/MoO3/CC electrode, the self‐supported PMC‐3 (deposition time of 300 s) has high specific capacitance of 841.6 F g−1 at current density of 0.5 A g−1 in the three‐electrode system, having specific capacitance of 595.7 F g−1 even at 10 A g−1. Novelty, the as‐assembled symmetrical capacitor is flexible and convenient with power density of 199.93 W kg−1 at the energy density of 9.69 Wh kg−1 and the energy density of 3.88 Wh kg−1 at power density of 4000 W kg−1. Thus, the electrochemical properties of the self‐supported PANI/MoO3/CC electrode were significantly improved, and the self‐supported electrodes are more competitive than other materials in practical application of clean energy storage systems.

Printable 2D Materials for Thin Film Batteries and Supercapacitors

Two-dimensional transition metal oxide (TMO) nanosheets are the oxide equivalents of the well-known 2D graphene phase. Compared with graphene, a much wider range of compositions, structures and properties can be realized from TMOs. 2D metal oxides typically have thicknesses of 0.45-2.5 nm, and lateral dimensions between 50 nm and tens of micrometers. Interestingly, although they are oxides, they are very flexible and bendable owing to their thinness. So far, several dozen nanosheet phases have been reported in literature, but many more compositions are possible.Dispersions of TMO nanosheets can be made following one of several solution-phase strategies. Often, they are prepared by chemical delamination of isomorphous layered metal oxide parent phases. In a few cases, the 2D TMO phase can be grown directly bottom-up from an aqueous chemical solution. Either way, the resulting colloidal solutions of 2D single crystal nanosheets can serve in subsequent process step as the basis of a chemical ink suitable for ink jet printing on arbitrary substrates like paper, silicon or flexible polymers. Redox-active nanosheets may also be used as active electrode elements for micro-supercapacitors and flexible thin film batteries.For example, 2D MnO2 nanosheets that are isomorphous to the layered δ-MnO2 (birnessite) phase exhibit high pseudocapacance owing to their beneficial redox properties, relatively high in-plane conductivity and very large specific surface area. Ink-jet printed 2D MnO2 based thin film microsupercapacitors were realized that showed comparable performance with other state of the art systems. However, undoped MnO2 nanosheets exhibit relatively low sheet conductivity. Substitutional doping of 3d metal ions (Co, Fe and Ni) into MnO2 nanosheets improved the volumetric energy density to 1.13 mWh cm−3 at a power density of 0.11 W cm−3. The dopants introduced new electronic states near the Fermi level which enhanced the electronic conductivity within the nanosheets and contributed to the further formation of redox-active 3d surface states. Among these, Fe-doped MnO2 exhibited a significant increase in the carrier density and conductivity, while doping with Ni or Co had a much more limited effect on conductivity. These Fe-doped MnO2 nanosheet-based microsupercapacitors show long cycle life and bendability without performance loss on flexible plastic substrates [1].Following a similar inkjet printing approach, thin film cathodes for Li ion batteries were made using V2O5 nanosheets as charge-storage medium. In this case the conductivity of the electrode was improved by addition of highly conductive 2D MXene (Ti3C2) platelets derived from the parent MAX phase Ti3AlC2. Using LiPF6 in EC/DMC as electrolyte, the hybrid V2O5-MXene electrodes showed a high capacity of 321 mAh g-1 at 1C, 112 mAh g-1 at 10.5C and 92% capacity retention after ~700 cycles [2].As third example, an all inkjet-printed MXene/graphene oxide (GO)/MXene thin film supercapacitor with GO as solid electrolyte phase will be discussed. Here, free water molecules trapped between GO layers enabled proton transport through the electrolyte. The as-made capacitor showed high areal capacitance, good cyclability and power densities comparable with state of the art printed supercapacitors. The specific capacitance could be increased further by addition of liquid electrolyte [3].[1] Y. Wang, Y.-Z. Zhang, Y.-Q. Gao, G. Sheng, J.E. ten Elshof, Nano Energy 68 (2020) 104306.[2] Y. Wang, T. Lubbers, R. Xia, Y.-Z. Zhang, M. Mehrali, M. Huijben, J.E. ten Elshof, J. Electrochem. Soc. 168 (2021) 020507[3] Y. Wang, M. Mehrali, Y.-Z. Zhang, M.A. Timmerman, B.A. Boukamp, P.-Y. Xu, J.E. ten Elshof, Energy Storage Mater. 36 (2021) 318-325.

Redox-active pigeon excreta mediated metal oxides nanosheets for enhancing co-catalyst for photovoltaic performance in dye-sensitized solar cells

Pigeon excreta (PE) contains a significant amount of organic components, which are harmful to the environment and humans. Hence, the proper disposal of PE deals with practical problems. Furthermore, using PE for other energy sources is an efficient innovation. In this study, an innovative technique was implemented for producing agglomeration free and distinct metal oxides using PE as a surfactant and capping agent. The different characterizations and their analysis explain the mechanism involved in forming distinct metal oxide nanosheets utilizing PE. The obtained samples were confirmed by the characteristic peaks of PE mediated metal oxides such as (NiO, Co3O4 and CuO) observed in X-ray diffraction (43.47°, 36.61° and 35.71°), and the UV-DRS band-gap narrowing (2.4, 2.13 and 2.02 eV). In the FTIR spectrum, it is clearly evident that there is a high amine group in the PE which plays a key role in reducing the agglomeration in the metal oxides. The morphology of PE mediated NiO, Co3O4 and CuO revealed nanoflakes and nanosheets like structures identified from FE-SEM analysis. The photovoltaic performance of the PE mediated metal oxides showed improved photocurrent conversion efficiencies of 1.2–1.6 times more than pure metal oxides. Among all, the CuO-PE had the most significant photovoltaic performance, with a photoconversion efficiency of 3.22 %. The reduction of I3− to 3I− along the counter electrode/electrolyte interaction is facilitated by the PE mediated transition metal oxides, as shown by the photocurrent response, Tafel plot and electrical impedance spectroscopy results, which were discussed in detail.

Optimization of oxygen evolution electrocatalytic activity of metal oxide nanosheet via surface modification

AbstractA surface modification route to high‐performance oxygen evolution electrocatalysts was developed by immobilization of highly‐oxidized SeO42− species on the surface of exfoliated MnO2 nanosheets. The enhanced stability of tetragonally‐distorted MnO6 octahedron could be achieved by the weakening of axial Mn–O bond due to competition with highly covalent Se6+–O bonds. The selenate anchoring was found to be quite effective in improving the electrocatalyst functionality of MnO2 nanosheets for oxygen evolution reaction, which could be ascribed to the improvement of charge transfer kinetics and the enhancement of Mn3+ stability. This study emphasized that the fine‐control of bonding nature via surface modification with selenate anchoring can offer useful means to explore efficient electrocatalysts.

Monolithic CoMgAl mixed metal oxide nanosheets on Al2O3 granules for the efficient advanced oxidation process

Cobalt-based catalysts are good candidates for the degradation of organic pollutants in wastewater treatment due to their high activity, while powdered catalysts for practical applications face challenges like difficulty in regeneration. To solve the problem, this work designs a monolithic catalyst by in-situ growth of CoMgAl mixed metal oxide (CoMgAl-MMO) nanosheets on the Al2O3 granules. The obtained catalyst possesses a developed mesoporous structure with highly-dispersed Co on the surface. The catalytic activity of CoMgAl-MMO/AG in the dye degradation is dependent on the Co/Mg molar ratio. All monolithic catalysts show high degradation performance, of which the CoMgAl-MMO/AG catalyst with Co/Mg ratio of 0.8/1.2 exhibited the highest degradation rate, achieving 95 % acid orange (AO7) removal in 10 min testing.

Nanotextured surfaces with iron oxide and titania for antibacterial and water purification applications via supersonic spraying

Microbial infections pose a significant threat to public health worldwide. Antibacterial treatments are required to prevent bacterial contamination and protect public health. Herein we supersonically sprayed iron and titania NPs which are nontoxic earth-abundant and low-cost antibacterial materials to fabricate Fe2O3/TiO2-based antibacterial hybrid films capable of inhibiting E. coli by up to 100% upon ultraviolet (UV) light irradiation. The supersonically sprayed iron and titania NPs were annealed to prepare Fe2O3/TiO2-based metal oxide nanosheets. The photomobilized electrons and holes generated superoxide anions and hydroxyl radicals respectively via reduction and oxidation. The bare Fe2O3-based and hybrid Fe2O3/TiO2-based films were photoactivated via visible and UV lights and exhibited E. coli inhibition rates of 42.1% and 99.9% respectively. In addition the hybrid Fe2O3/TiO2-based films were superhydrophilic which promoted the strong adhesion of bacteria-contaminated aerosols between the surrounding atmosphere and films. The water-purification capability of the films was confirmed by the efficient photodegradation of a methylene blue solution upon UV irradiation.

(Invited) Z-Scheme Water Splitting Using Dye-Sensitized Metal Oxide Nanosheets

Solar water splitting by a heterogeneous photocatalyst, producing H2 and O2, is a potential solution for realizing large-scale H2 production. While dye-sensitized metal oxides are good candidates as H2 evolution photocatalysts for solar-driven Z-scheme water splitting, their solar-to-hydrogen (STH) energy conversion efficiencies remains low because of uncontrolled charge recombination reactions. Here it is shown that modification of Ru dye-sensitized, Pt- intercalated HCa2Nb3O10 nanosheets (Ru/Pt/HCa2Nb3O10) with both amorphous Al2O3 and poly(styrenesulfonate) (PSS) improves the STH efficiency of Z-scheme overall water splitting by a factor of ~100, when the nanosheets are used in combination with a WO3-based O2 evolution photocatalyst and an I3 –/I– redox mediator, relative to an analogous system that uses unmodified Ru/Pt/HCa2Nb3O10. The Al2O3 and PSS modifiers, which have previously been shown to suppress back electron transfer reactions in a dye-sensitized H2 evolution photocatalyst, enabled operation of the Z-scheme system even at low intensity of simulated sunlight without a decrease in the STH values. By using the optimized photocatalyst, PSS/Ru/Al2O3/Pt/HCa2Nb3O10, a maximum STH of 0.12% and an apparent quantum yield of 4.1% at 420 nm were obtained, by far the highest among dye-sensitized water splitting systems and also comparable to conventional semiconductor-based suspended particulate photocatalyst systems.

Flexible g‐C3N4 Enhancing Superior Cycling Stability of ZnFe2O4‐Fe2O3 Nanosheet Composites as High‐Capacity Anode Materials for Lithium‐Ion Batteries

AbstractFor lithium‐ion batteries, iron‐based oxides are expected to be the next generation of anode materials because of their high theoretical capacity, environmental friendliness, and affordability. Although, like most transition metal oxides, iron‐based oxides suffer from poor electrical conductivity and cycling performance, volume expansion during charging and discharging, and easily agglomerated. g‐C3N4 has a graphene‐like layered structure consisting of nitrogen‐linked C6N7 repeating units. The abundant nitrogen content can improve the wettability of the electrode and electrolyte, thus improving the lithium charge transfer process, and secondly g‐C3N4 is less expensive and easier to prepare than graphene. Here, we report composites with metal oxide nanosheets (ZnFe2O4−Fe2O3) attached to softly curved g‐C3N4 nanosheets. When used as an anode material for lithium‐ion batteries, after 300 cycles at the current density of 500 mA g−1, ZFO‐Fe2O3/g‐C3N4 offers the discharge specific capacity (1518.5 mAh g−1) and can still deliver 639.2 mAh g−1 at the high current density (10 A g−1). Due to the introduction of g‐C3N4 alleviated the volume change of the electrode, shortened the diffusion distance of Li+ and provided more reactive sites, resulting in excellent electrochemical performance of ZFO‐Fe2O3/g‐C3N4.