Graphene Oxide Heterostructure Research Articles

In-situ assembly of 3D VS2/Reduced graphene oxide with superior lithium ion storage performance: The role of heterojunction

VS2 is a potential anode material for lithium-ion batteries (LIBs) due to its advantageous properties. Herein, a novel three-dimensional (3D) VS2/reduced graphene oxide (rGO) heterostructure (VS2-rGO) was fabricated by in-situ assembly of caterpillar-like VS2 nanosheets on rGO. This 3D VS2-rGO with a well-defined heterojunction interface is engineered to mitigate the volumetric expansion of VS2 during Li + intercalation/deintercalation cycles. This optimized design promotes enhanced conductivity across the heterojunction, facilitating efficient electron and ion transport. The VS2-rGO electrode shows higher reversible capacity and better rate performance (644.02 mA h g−1 at 0.1 A g−1 after 140 cycles, 526.66 mA h g−1 at 2 A g−1) as compared to the pure VS2 electrode (433.69 mA h g−1 at 0.1 A g−1 after 140 cycles, 63.91 mA h g−1 at 2 A g−1). Ex-situ XRD analysis suggests that the Li + storage mechanism in the VS2-rGO electrode involves the initial intercalation, followed by intercalation and conversion. The lower Li + diffusion barrier within the VS2-rGO heterojunction (0.183 eV) compared to the VS2 layers (0.225 eV), as predicted by first-principles calculations, resulting the enhanced Li + transport kinetics and improved cycling performance of the VS2-rGO electrode material. This work offers novel perspectives for the influence of heterojunctions on LIBs.

Interface coupling of octahedron Cu2O with reduced graphene oxide for enhanced photocatalytic and photoelectrochemical activity

Graphene oxide (GO) has been recognized as an ideal substrate material of semiconductor photocatalysts to achieve superior properties. Herein, Cu2O/reduced graphene oxide hetero-structures (Cu2O/rGO), featured by octahedron Cu2O with highly exposed {111} facets in-situ anchored on the framework of rGO nanosheets, were constructed via a green wet chemistry route at room temperature. During the reactions, Cu2+ ions that were adsorbed on GO could act as the nucleation sites of Cu2O while GO was further converted into rGO under the reduction of glucose, forming a robust hetero-interface of C–O–Cu bonding. Owning to the improved photon capture ability and carrier separation efficiency, the optimized Cu2O/rGO exhibits about 3.5 and 9.3 times enhancement of photocurrent intensity and photocatalytic activity, respectively, as compared to those of pure Cu2O. Meanwhile, the correlation among rGO content, structure and photocatalytic activity of Cu2O/rGO was demonstrated. This work presents a rational route and deep insight for the interface coupling within metal oxide/carbon material hetero-structures for advanced catalytic applications.

In situ Preparation and Visible-light-driven Photocatalytic Degradation Performance of Nano 3C-SiC@Multilayer Graphene Oxide Heterostructure

In situ Preparation and Visible-light-driven Photocatalytic Degradation Performance of Nano 3C-SiC@Multilayer Graphene Oxide Heterostructure

Facilely prepared Co-based MOF functionalized N, S-doped reduced graphene oxide for electrochemical non-enzymatic glucose sensing

Rational design of modified electrode materials is critical for electrochemical sensors. Metal-organic frameworks (MOFs), a novel sort of substance with porosity, has received widespread attention owing to various superior characteristics such as adjustable pore sizes, great surface area and controllable structures. Nevertheless, the poor charge transfer capability of MOFs leads to a general suppression of their electrochemical sensing performance. To solve this issue, compositing conductive substance with MOFs have been demonstrated to be an effective strategy. Herein, Co-based MOF (ZIF-67) functionalized N, S-doped reduced graphene oxide (N, S-RGO) heterostructure (ZIF-67/N, S-RGO) was fabricated through an in-situ synthesis method. The composite material was used in the modification of an electrode to construct a sensing platform for non-enzymatic glucose testing. The synergistic interaction of ZIF-67 and N, S-RGO not only provided more efficient active sites and larger surface areas, but also improved the electron transport efficiency and electrocatalytic performance. Under optimized conditions, the ZIF-67/N, S-RGO/GCE had a dynamic linear range of 1–3200 μM, with a detection limit of 0.33 μM (S/N = 3) for glucose detection. The sensing platform also provided excellent reproducibility, selectivity, and stability (70 % activity retained after 12 days). Furthermore, the sensor had the potential to apply for glucose determination in human serum. This work presented a novel strategy to the field of non-enzymatic glucose sensing and may provide effective coaching for optimizing the electrochemical sensing performance of other series of MOFs.

Heterostructure assembled by organic-molecule intercalated MoS2 and reduced graphene oxide for enhanced interface energy and supercapacitor performance

Organic molecule intercalation and heterostructure construction can optimize the capacitive storage of MoS2. To begin with, we choose MoO3 as the molybdenum source and polypyrrole (PPy) as the intercalation agent to synthesize the enlarged interlayer spacing MoS2 (MoS2-PPy). On this basis, MoS2-PPy@reduced graphene oxide (rGO) heterostructures are eventually fabricated. The electrochemical merits of rGO and MoS2-PPy can be combined through synergistic effects among the heterostructure. What's more, to examine the kinetics storage mechanisms of MoS2 samples, density functional theory (DFT) calculations have been done. It turns out the introduction of rGO enhanced the polarity of MoS2, which lead to stronger interface energy and additional capacitance. Additionally, for the involvement of rGO, the conductivity has been effectually elevated. Moreover, an AC//MoS2-PPy@rGO asymmetric flexible device is assembled, and it have an excellent energy density of 134.4 µWh cm−2 at a power density of 800 µW cm−2. This work paves the way for constructing organic-molecular intercalated-MoS2 based heterostructures in capacitive energy storage.

Low-crystallinity conductive multivalence iron sulfide-embedded S-doped anode and high-surface area O-doped cathode of 3D porous N-rich graphitic carbon frameworks for high-performance sodium-ion hybrid energy storages

Sodium-ion hybrid energy storages (SIHESs) are promising electrochemical energy storages for many applications, but their low energy and power densities are yet to be overcome. Herein, we report a strategy to realize ultrahigh-energy density and fast-rechargeable SIHESs. Ultrafine iron sulfide-embedded S-doped carbon/graphene (FS/C/G) anode materials are synthesized from iron-based metal-organic framework (MOF)/graphene oxide heterostructures via graphitic carbon formation and sulfidation. Operando and ex-situ analyses reveal that cycled iron sulfides are rescaled into low-crystallinity conductive fragments with Fe vacancies and multivalence Fe2+/Fe3+ states. Size reduction to fragments inside a 3D porous S-doped N-rich graphitic carbon framework induces high-capacity/high-rate FS/C/G performance. Moreover, 3D porous O-doped carbon cathode materials are synthesized from zeolitic imidazolate frameworks (ZIFs) via pyrolysis-assisted micropore and KOH-assisted mesopore formations. This ZIF-derived porous carbon (ZDPC) has a ∼20-fold higher surface area (3972 m2/g) than conventional ZDCs, O-induced micropores/N-rich sites for high capacity, heteroatom-induced ion-accessible defects/mesopores, and N-rich conductive graphitic carbon networks. Additionally, FS/C/G//ZDPC SHHES benefits from diffusion-controlled and capacitive reactions, as demonstrated by its hitherto highest energy density of 247 Wh kg-1 outperforming state-of-the-art SIHESs, fast-rechargeable power density (up to 34,748 W kg-1) exceeding battery-type reactions by more than 100 folds, and cycle stability with ∼100 % Coulombic efficiency over 5000 charge-discharge cycles.

Effective assembling of nickel oxide-reduced graphene oxide heterostructures for ultrahigh capacity supercapattery

Developing new materials to facilitate sustainable and renewable energy storage is the most sought research frontier of the current era. In this regard, supercapacitors have drawn huge research attention in developing efficient electroactive materials. Herein, a nickel oxide/reduced graphene oxide (NiO-rGO) composite has been synthesized using the facile precipitation-aging-calcination and ultrasonication technique for energy storage applications. Due to the composite's enhanced surface area and the synergistic effect of redox-active NiO and highly conductive rGO, the resulting heterostructure exhibits excellent performance as a supercapattery. The electrochemical investigations show that the designed NiO-rGO heterostructure exhibits battery-type electrode features with an ultrahigh specific capacity of 850 Cg-1 at 1 Ag-1 current density with 91 % capacity retention even after 5000 charge-discharge cycles. The efficacy of this composite has also been tested in a symmetrical device assembly (NiO-rGO//NiO-rGO), which shows a very high maximum energy density (56.6 Wh.kg−1) and power density (9.65 kW kg−1) with excellent performance retention for 10000 charge/discharge cycles. Further, the experimental charge storage outcomes of the materials have also been supported by calculating the energetics of OH* adsorption using DFT. This work provides a facile approach to maximize the synergistic interactions within metal oxides-rGO-based 3D/2D heterostructures to derive improved electrochemical features. Moreover, it also offers experimental and theoretical insights into designing efficient and cost-effective materials for energy storage.

Investigation of photodetector performance based on methylammonium lead halide perovskites/reduced graphene oxide heterostructure

Investigation of photodetector performance based on methylammonium lead halide perovskites/reduced graphene oxide heterostructure

Ternary Heterostructure Membranes with Two-Dimensional Tunable Channels for Highly Selective Ion Separation.

Selective ion separation from brines is pivotal for attaining high-purity lithium, a critical nonrenewable resource. Conventional methods encounter substantial challenges, driving the quest for streamlined, efficient, and swift approaches. Here, we present a graphene oxide (GO)-based ternary heterostructure membrane with a unique design. By utilizing Zn2+-induced confinement synthesis in a two-dimensional (2D) space, we incorporated two-dimensional zeolitic imidazolate framework-8 (ZIF-8) and zinc alginate (ZA) polymers precisely within layers of the GO membrane, creating tunable interlayer channels with a ternary heterostructure. The pivotal design lies in ion insertion into the two-dimensional (2D) membrane layers, achieving meticulous modulation of layer spacing based on ion hydration radius. Notably, the ensuing layer spacing within the hybrid ionic intercalation membrane occupies an intermediary realm, positioned astutely between small-sized hydrated ionic intercalation membrane spacing and their more extensive counterparts. This deliberate configuration accelerates the swift passage of diminutive hydrated ions while simultaneously impeding the movement of bulkier ions within the brine medium. The outcome is remarkable selectivity, demonstrated by the partitioning of K+/Li+ = 20.9, Na+/K+ = 31.2, and Li+/Mg2+ = 9.5 ion pairs. The ZIF-8/GO heterostructure significantly contributes to the selectivity, while the mechanical robustness and stability, improved by the ZA/GO heterostructure, further support its practical applicability. This report reports an advanced membrane design, offering promising prospects for lithium extraction and various ion separation processes.

3D Hierarchical Ti3C2TX@PANI-Reduced Graphene Oxide Heterostructure Hydrogel Anode and Defective Reduced Graphene Oxide Hydrogel Cathode for High-Performance Zinc Ion Capacitors.

The practical application of supercapacitors (SCs) has been known to be restricted by low energy density, and zinc ion capacitors (ZICs) with a capacitive cathode and a battery-type anode have emerged as a unique technology that can effectively mitigate the issue. To this end, the design of electrodes with low electrochemical impedance, high specific capacitance, and outstanding reaction stability represents a critical first step. Herein, we report the synthesis of hierarchical Ti3C2TX@PANI heterostructures by uniform deposition of conductive polyaniline (PANI) polymer nanofibers on the exposed surface of the Ti3C2TX nanosheets, which are then assembled into a three-dimensional (3D) cross-linking framework by a graphene oxide (GO)-assisted self-convergence hydrothermal strategy. This resulting 3D Ti3C2TX@PANI-reduced graphene oxide (Ti3C2TX@PANI-RGO) heterostructure hydrogel shows a large surface area (488.75 F g-1 at 0.5 A g-1), outstanding electrical conductivity, and fast reaction kinetics, making it a promising electrode material. Separately, defective RGO (DRGO) hydrogels are prepared by a patterning process, and they exhibit a broad and uniform distribution of mesopores, which is conducive to ion transport with an excellent specific capacitance (223.52 F g-1 at 0.5 A g-1). A ZIC is subsequently constructed by utilizing Ti3C2TX@PANI-RGO as the anode and DRGO as the cathode, which displays an extensive operating voltage (0-3.0 V), prominent energy density (1060.96 Wh kg-1 at 761.32 W kg-1, 439.87 Wh kg-1 at 9786.86 W kg-1), and durable cycle stability (retaining 67.9% of the original capacitance after 4000 cycles at 6 A g-1). This study underscores the immense prospect of the Ti3C2TX-based heterostructure hydrogel and DRGO as a feasible anode and cathode for ZICs, respectively.

Role of Cations in the Cation-Driven Assembly Process and their Effect on the Charge Storage Properties of Bilayered Vanadium Oxide and Reduced Graphene Oxide Heterostructures in Alkali Ion Systems

Role of Cations in the Cation-Driven Assembly Process and their Effect on the Charge Storage Properties of Bilayered Vanadium Oxide and Reduced Graphene Oxide Heterostructures in Alkali Ion Systems

Comprehensive analysis of reaction mechanisms in reduced graphene oxide and hematite heterostructure gas sensors

Exposure to formaldehyde (HCHO) in humans causes various types of diseases, such as asthma, lung cancer, and nasal cancer depending on the exposure, which leads to death in severe cases. Many types of gas sensors are being studied in order to sense HCHO, but the sensors cannot detect below the WHO standard of 0.08 ppm. We present a highly sensitive and inexpensive HCHO gas sensor with a heterostructure of reduced graphene oxide (rGO) and hematite (Fe2O3) in this study. In addition, rGO and Fe2O3-based gas sensors are prepared in order to compare the response characteristics with the proposed heterostructure-based gas sensor. As a result, we observed a high response of 309 % for an HCHO of 100-ppm, which is 10 times higher compared to the reference sensors. We also addressed a neural network analysis to predict the response characteristics of the unmeasured HCHO concentration, and we obtained the highest accuracy, which was above 90 %, when we used the sigmoid model-based neural network model. These results facilitate the realization of ultra-sensitive gas sensors to HCHO gas, which lead to prevent various types of diseases.

Low-cost synthesis of titanium dioxide nanotubes/reduced graphene oxide heterostructure for pH sensor applications

In this work, we deposit Graphene Oxide (GO) films on Titanium Dioxide nanotubes (TiO2NTs); electrochemical characterization of this system shows that this structure has potential applications as a pH sensor. TiO2NTs were obtained by electrochemical anodization technique, the GO was fabricated by modified Hummer's method, and deposited by dip coating technique, at room temperature. The thermally treated TiO2NTs/GO structure shows a reduction of the GO deposited film. The samples were characterized by Raman spectroscopy, X-ray Photoelectron Spectroscopy, and Scanning Electron Microscopy. Depending on the GO oxidation time and thermal treatment, we observe a uniform reduced GO film on the TiO2NTs. A pH electrode characterization shows a linear response of the TiO2NTs/GO of 57 mV/pH with non-hysteresis effect.

Designing of an rGO-based heterostructure for highly efficient microwave absorption performance and flame retardancy

To meet the increasingly serious challenges of electromagnetic pollution and fire hazards, highly efficient electromagnetic absorbing materials with good flame retardancy have been accurately developed. A complex high-performance electromagnetic absorber was designed by doping graphene oxide heterostructures (including zero-dimensional nanoparticles and two-dimensional graphene) containing cobalt, nickel and iron oxyhydroxide through the coordination effect. When 20 wt% CNFO@rGO was incorporated into paraffin, the minimum reflection loss (RL) reached -51.6 dB at a thickness of 3.5 mm, showing a high electromagnetic absorption efficiency. It was concluded that the excellent impedance matching, the best dielectric loss and the higher magnetic loss caused by the heterostructure combined with the electromagnetic parameters, Cole-Cole semicircle, impedance matching (Z) and attenuation coefficient resulted in excellent electromagnetic wave absorption performance. Moreover, the peak heat release (PHRR) and heat release rate (HRC) decreased by 55.5% and 55.1%, respectively, when 10 wt% CNFO@rGO was incorporated into the epoxy resin (EP), indicating enormous potential for the enhancement of flame-retarding electromagnetic absorbing materials.

Synergetic effect of ZnS: SnS2/reduced graphene oxide heterostructures for electrochemical detection of carcinogenic pollutant Maleic hydrazide

To ensure agricultural productivity, food security, and an ever-increasing demand for food safety, herbicides are employed to maintain unrestrained weed growth during crop production. Maleic hydrazide (MD) has become an important commonly consumed herbicide due to its various uses which include inhibition of sprouting in vegetables and stored root crops. But unfortunately, MD has genotoxic and carcinogenic effects, thus monitoring the presence of MD in food samples is of prime importance. Therefore, an electrochemical sensing platform based on heterojunctions of ZnS/SnS2/RGO was used for the electrochemical detection of MD. The composite ZnS:SnS2@RGO was synthesized via the hydrothermal method providing a large specific surface area, superior electrical conductivity, rich electrocatalytic sites, and a fast charge transfer rate. A good synergetic effect between the ZnS:SnS2 and RGO results in a wide linear range of 0.01–2359 µM, low LOD of 0.02 µM, and a good anti-interfering capability towards the detection of MD. In addition, good recovery results were obtained for the potato and water samples. Hence, the detection of MD was successfully demonstrated using ZnS:SnS2@RGO composite with superior stability and can be recommended for food monitoring applications.

Hexagonal Boron Nitride/Reduced Graphene Oxide Heterostructures as Promising Metal‐Free Electrocatalysts for Oxygen Evolution Reaction Driven by Boron Radicals

Developing highly efficient earth‐abundant alternatives to traditional noble metal catalysts is essential for clean and sustainable energy‐conversion and energy‐storage technologies, yet still challenging in limited active sites and weak resistance to electrochemical corrosion. Herein, density‐functional theory calculations demonstrate that hexagonal boron nitride (h‐BN), albeit often being considered inert, can generate boron‐active radicals at defective sites by forming heterogeneous structures with graphene‐containing point vacancies, leading to a substantial electron delocalization and charge transfer, indicating a superior catalytic activity. Experimentally, the van der Waals heterostructure is rationally designed with h‐BN nanosheets (BNNs) anchored on reduced graphene oxide (rGO) as strongly coupled composite catalysts. Despite the poor conductivity in BN and lower catalytic activity in rGO, the created heterostructures demonstrate unexpected, improved oxygen evolution reaction (OER) activity with excellent stability in alkaline electrolyte. Qualitative analysis of the valence band offset and theoretical calculation reveal that the formation of heterostructures can significantly drive the electron transfer between C and B atoms near the vacancies across the interface and cause a half‐metallic property of BN, decreasing the free energy barrier of four‐electron OER kinetics. Herein, the synthetic schemes of h‐BNNs are guided as highly active metal‐free OER electrocatalysts.

Manipulating electromagnetic response for tunable microwave absorption, electromagnetic interference shielding, and device

The essence of realizing tunable electromagnetic (EM) function is to manipulate EM response flexibly. Herein, the contributions of dielectric and magnetic genes to EM loss inside NiO/NiFe2O4/reduced graphene oxide heterostructure are dissected to manipulate the EM response, achieving tunable microwave absorption performance and electromagnetic interference shielding performance. The minimum reflection loss reaches −55.0 dB, the matching thickness decreases to 2.3 mm, the effective absorption bandwidth increases to 6.4 dB, and the electromagnetic interference shielding effectiveness is up to 8.69 dB. In addition, based on the manipulation of EM response, a self-powered EM energy conversion device is designed and demonstrated, which can convert waste EM energy into electric energy and realize the recycling of EM energy. This study will provide a theoretical basis for manipulating EM response and designing next-generation EM attenuation materials, facilitating the development of next-generation smart devices as well as environmental government and protection.

Enhanced electrocatalytic performance of 2D/2D MXene/reduced graphene oxide(RGO) heterostructures for paracetamol (APAP) degradation: The critical contributions of charge transfer and Ti-OH edges for active species generation

To improve electrocatalytic performance, 2D/2D MXene/ reduced graphene oxide (RGO) heterostructures was prepared by constructing of Ti-O-C connection between two layers. A Ti-O-C connection not only facilitates charge transfer from MXene to RGO but also creates active sites for active species generation. Through in-depth mechanism investigation, all 1O2, O2•− and active chlorine were identified as active species for APAP degradation by triggering raw MXene, RGO, and MXene/RGO. Explosive generation of O2•− and active chlorine was responsible for the excellent catalytic activity of MXene/RGO. Experimental and density functional theory calculation results demonstrated the critical contributions of charge transfer and Ti–OH edges for active chlorine generation. At Ti-OH edges, Cl− can seize electron from H in H2O (absorbed on MXene/RGO surface), and the Ti-OH edges withdraw electrons from O in H2O. Then, electrons captured by the Ti-OH edges were transferred from MXene to RGO, resulting in the electrostatic imbalance in the Ti-OH/H2O/Cl− region, electron deficiency in H2O, and ultimately active chlorine generation. The electron-rich properties of RGO simultaneously enhanced the production of O2•− radicals. This study provided deepen mechanism discussion for electrocatalytic performance improvement over stable 2D/2D MXene/RGO heterostructures.

Photothermal-enabled single-atom catalysts for high-efficiency hydrogen peroxide photosynthesis from natural seawater

Hydrogen peroxide (H2O2) is a powerful industrial oxidant and potential carbon-neutral liquid energy carrier. Sunlight-driven synthesis of H2O2 from the most earth-abundant O2 and seawater is highly desirable. However, the solar-to-chemical efficiency of H2O2 synthesis in particulate photocatalysis systems is low. Here, we present a cooperative sunlight-driven photothermal-photocatalytic system based on cobalt single-atom supported on sulfur doped graphitic carbon nitride/reduced graphene oxide heterostructure (Co–CN@G) to boost H2O2 photosynthesis from natural seawater. By virtue of the photothermal effect and synergy between Co single atoms and the heterostructure, Co–CN@G enables a solar-to-chemical efficiency of more than 0.7% under simulated sunlight irradiation. Theoretical calculations verify that the single atoms combined with heterostructure significantly promote the charge separation, facilitate O2 absorption and reduce the energy barriers for O2 reduction and water oxidation, eventually boosting H2O2 photoproduction. The single-atom photothermal-photocatalytic materials may provide possibility of large-scale H2O2 production from inexhaustible seawater in a sustainable way.

Light-Dependent A.C. Transport Properties of Zinc Oxide (ZnO)/Reduced Graphene Oxide (rGO) Heterostructure Device: A Signature of Electrical Memory

Light-Dependent A.C. Transport Properties of Zinc Oxide (ZnO)/Reduced Graphene Oxide (rGO) Heterostructure Device: A Signature of Electrical Memory