Oxide Hybrid Nanosheets Research Articles

Corrigendum: Synthesis of Graphite Oxide/Cobalt Molybdenum Oxide Hybrid Nanosheets for Enhanced Electrochemical Performance in Supercapacitors and the Oxygen Evolution Reaction

Corrigendum: Synthesis of Graphite Oxide/Cobalt Molybdenum Oxide Hybrid Nanosheets for Enhanced Electrochemical Performance in Supercapacitors and the Oxygen Evolution Reaction

Graphene oxide embedded in Bi2S3 nanosheets by hydrothermal method to enhance thermoelectric performance

Bi2S3 is an inexpensive and non-toxic thermoelectric material with high Seebeck coefficient and low thermal conductivity, which makes it have broad development prospects in the field of thermoelectric materials. In this work, we successfully synthesized Bi2S3/graphene oxide (GO) hybrid nanosheets by a simple hydrothermal synthesis method. Due to the unique structure of the two-dimensional nanomaterial GO, it can be uniformly embedded in the Bi2S3nanosheet matrix. The total thermal conductivity of Bi2S3/GO hybrid nanosheets is astonishingly low as 0.32Wm−1K−1 at 619K, which is 13% lower than that of pure Bi2S3. In addition, the thermoelectric performance of Bi2S3/GO hybrid nanostructures were further improved by changing the doping amount of GO. At 300–650K, the maximum thermoelectric figure of merit (ZT) of Bi2S3/GO(0.5 wt%) is 0.17, and its ZT below 550K is higher than that of pure phase Bi2S3. Bi2S3/GO composites were synthesized by an inexpensive and simple experimental method, which provides a new strategy for optimizing the thermoelectric properties of Bi2S3.

Self-Hybrid Transition Metal Oxide Nanosheets Synthesized by a Facile Programmable and Scalable Carbonate-Template Method.

2D transition metal oxides (TMO) nanosheets have attracted considerable attention in both fundamental research and practical applications. Herein, a convenient programmable and scalable carbonate crystals templating synthesis is developed to produce high-quality self-hybrid TMO nanosheets (Si-WO3- x , Tax Oy , Mnx Oy ) and their respective polymetallic oxide hybrid nanosheets with tunable composition, low-cost and high-yield. Taking tungsten oxide nanosheets as example, silicotungstic acid precursor is in situ converted into tungsten oxide nanosheets like scales on the surface of calcium carbonate crystals through the simple soaking-drying-calcination process, and after selectively dissolving calcium carbonate by etching, the dispersive tungsten oxide nanosheets with unique self-hybrid Si-doped h-WO3 /ε-WO3 /WO2 compositions are obtained, which show excellent acetone gas-sensing performances at low temperatures. This carbonate-template method opens up the possibility to economically produce various functional TMO nanosheets with specific compositions for diverse applications.

Spatial confinement and electron transfer moderating Mo[sbnd]N bond strength for superior ammonia decomposition catalysis

Advanced catalysts for ammonia (NH3) decomposition reaction hold great promise in the area of renewable energy. In this work, highly dispersed molybdenum nitride (MoN/Mo2N) nanocrystals anchored on in-situ assembled two-dimensional (2D) mesoporous silica/reduced graphene oxide (rGO) hybrid nanosheets (MoN/SBA-15/rGO and Mo2N/SBA-15/rGO) were designed and synthesized as active and stable catalysts for COx-free H2 generation via NH3 decomposition. Benefiting from well-defined molybdenum nitride nanocrystals and moderate MoN band strength, the nanohybrids exhibited superior catalytic property, especially Mo2N/SBA-15/rGO with the highest NH3 decomposition rate of 30.58 mmol g−1cat min−1 among any Mo-based catalysts reported to date. Density functional theory (DFT) calculations revealed that the superior catalytic activity for Mo2N compared to MoN stemmed from a large reduction of kinetic energy barriers of dehydrogenation and nitrogen desorption. Moreover, the introduction of rGO can effectively weaken the associative desorption of adsorbed N atoms and thus improve NH3 decomposition activity. This study highlights the importance of designing spatially confined metal nitrides for enhancing energy catalysis.

Modification of polyvinylidene fluoride membrane by silver nanoparticles-graphene oxide hybrid nanosheet for effective membrane biofouling mitigation

Membrane biofouling poses severe impacts on the membrane lifespan and performance. In this study, a silver nanoparticles-graphene oxide hybrid nanosheet (AgNPs-GO) was synthesized as a bactericidal agent for effective membrane biofouling mitigation. The surface polymerization between polyvinyl alcohol (PVA) and AgNPs-GO nanosheet improved the stability of inorganic biocidal materials on the membrane surface and had a significant effect on the permeability and rejection performance of membranes. The PVA/AgNPs-GO modified hydrophilic polyvinylidene fluoride (H-PVDF) membrane exhibited an excellent anti-microbial activity in both static contact and filtration modes; nearly 100% inactivation of Pseudomonas aeruginosa in solution and 91% reduction in the membrane surface adhesion were found. The composite membrane with good stability and anti-microbial ability may offer an alternative to alleviate membrane biofouling problem.

TiO2 nanotube/g-C3N4/graphene composite as high performance anode material for Na-ion batteries

To improve the electrochemical kinetics and alleviate the structural collapse of TiO2 in the process of charge/discharge, TiO2 nanotubes (TiO2NT) anchored on a large-area graphitic carbon nitride/reduced graphene oxide (g-C3N4/RGO) hybrid nanosheets have been designed by alkaline hydrothermal method. This unique architecture ensures the uniform distribution of TiO2NT and inhibits the natural tendency to agglomeration of RGO to a large extent. When applied as anode material for Na-ion batteries (NIBs), the resultant sample delivers high reversible capacities of 138.5 mAh g−1 after 244 cycles at 0.1 A g−1 and good rate capability (103.3 mAh g−1 at 0.8 A g−1). These excellent sodium storage behaviors are attributed to the double coating effect of g-C3N4/RGO nanosheets on TiO2 nanotubes, which can reduce the volume change in the cycle. Therefore, TiO2 nanotubes/graphite phase carbon nitride/graphene composite (TiO2NT/g-C3N4/RGO) should be a promising and attractive NIBs anode material.

Reduction-induced surface reconstruction to fabricate cobalt hydroxide/molybdenum oxide hybrid nanosheets for promoted oxygen evolution reaction

Electrocatalysts for oxygen evolution reaction (OER) have received substantial interests owing to its critical role in boosting water electrolysis for hydrogen production, and designing highly efficient and durable OER catalysts based on earth-abundant elements is of great importance in replacing noble metal-based catalysts. Herein, a facile reduction-induced surface reconstruction process was proposed for fabricating cobalt hydroxide/molybdenum oxide hybrid nanosheets with high porosity, rough surface and facile charge transport behavior. Benefitted from the structural merits, the highly porous α-Co(OH)2/Mo9O26 hybrid nanosheets exhibit an ultralow overpotential of 279 mV for achieving a 10 mA cm−2 current density and a high current density of 225.2 mA cm−2 at 1.8 V vs. RHE. In addition, a remarkable normalized current density of 11.9 A F-1 can be identified at η = 400 mV, which is much larger than previously reported Co-based catalysts and even benchmarking RuO2 and IrO2. Moreover, for CoMoO-r displays stable OER activity towards long-term operation with no performance degradation but obvious enhancement even for 72 h. The high OER activity combined with the excellent stability makes the hybrid catalyst a promising candidate for commercial water splitting.

Incorporating silica-coated graphene in bioceramic nanocomposites to simultaneously enhance mechanical and biological performance.

The applications of a variety of bioactive ceramics such as hydroxyapatite (HA) in orthopedics are limited by their insufficient mechanical properties, especially poor fracture toughness. Thus, further extending the clinical applications of these materials warrants the enhancement of their mechanical properties. Although the reinforcement of ceramics by 2D nanomaterials has been well recognized, integrated structural, mechanical, and functional considerations have been neglected in the design and synthesis of such composite materials. Herein, we report the first use of silica-coated reduced graphene oxide (S-rGO) hybrid nanosheets to create bioceramic-based composites with simultaneously enhanced mechanical and biological properties. In the representative HA-based bioceramic systems prepared by spark plasma sintering, S-rGO incorporation was found to be more effective for increasing the Young's modulus, hardness, and fracture toughness than the incorporation of uncoated reduced GO (rGO). Furthermore, when assessed with osteoblast-like MG-63 cells, such novel materials led to faster cell proliferation and higher cell viability and alkaline phosphatase activity than are generally observed with pure HA; additionally, cells demonstrate stronger affinity to S-rGO/HA than to rGO/HA composites. The S-rGO/bioceramic composites are therefore promising for applications in orthopedic tissue engineering, and this research provides valuable insights into the fabrication of silica-coated hybrid nanosheet-reinforced ceramics.

Metal–organic framework derived nitrogen-doped carbon-RhNi alloys anchored on graphene for highly efficient hydrogen evolution reaction

Nitrogen-doped carbon-RhNi alloy nanoparticles anchored on reduced graphene oxide nanosheet hybrid structure (NC-RhNi/rGO) exhibit high HER performance.

Fabrication of Janus graphene oxide hybrid nanosheets by Pickering emulsion template for self-healing nanocomposite hydrogels

Janus nanomaterials can be highlighted to design a series of smart materials with the remarkable characteristic of two different properties or constituents. In this manuscript, functional Janus graphene oxide-type (GO-type) nanomaterials were fabricated by Pickering emulsion template and successfully applied to develop of dual self-healing nanocomposite hydrogels. Asymmetric functionalization of Janus nanosheets were achieved in typical oil-in-water Pickering emulsion by atom transfer radical polymerization (ATRP) and mussel-inspired chemistry. Poly(2-(acryloyloxy)ethyl ferrocenecarboxylate) (PMAEFc) and polydopamine (PDA) were unsymmetrically grafted on the two sides of GO (Janus GO-PMAEF/PDA (JGNs)), which successfully applied in self-healing nanocomposite hydrogels. The collaborative effect of metal-ligand coordination and host-guest interaction make the dual self-healing hydrogels have excellent self-healing properties (self-healing efficiency can reach to 93.4% within 1 h) and mechanical strength (tensile strength of 0.94 MPa and strain of 508.5%). Therefore, these chemical asymmetric JGNs have outstandingly application prospect in the development of smart materials.

Adsorption energy engineering of nickel oxide hybrid nanosheets for high areal capacity flexible lithium-ion batteries

Enriching electrode materials with definite functions is of great influence but highly challenging towards achieving high areal capacity lithium ion batteries (LIBs). Taking transition metal oxides (TMOs) as a case study, several attempts have been employed to demonstrate the large variations in lithium storage performance of TMOs, but explanation of the adsorption capability is rarely reported. Herein, the Li-ion storage chemistry of NiO nanosheets is successfully enhanced by modulating the position of the p-orbital energy level via engineering with porous N-doped carbon fiber and carbon quantum dots (CDs). The as-prepared monolithic NiO hybrid nanosheets (denoted CF/ECF/NiO/CD) exhibit high reversible areal capacity of 3.97 mA h cm−2 at 0.25 mA cm−2, excellent cyclic stability with capacity of 2.91 mA h cm−2 at 3.0 mA cm−2, as well as attractive rate capacity of 2.61 mA h cm−2 at 6.0 mA cm−2. In situ Raman analyses, XPS, and DFT calculations reveal that performance enhancement is related to the electronic modulations between NiO, porous carbon fiber and CDs that triggers the shift of the p-band towards accommodating interfacial electron transfer that helps in promoting the Li storage activity. In addition, an all-flexible lithium ion battery based on CF/ECF/NiO/CD anode is assembled and a volumetric energy density of 619.9 Wh L−1 is achieved (equivalent to an energy density of 201.7 Wh kg−1). This work opens an achievable approach for high-areal-capacity LIBs and provides relevant understanding into designing other LIB electrodes and beyond.

Efficient extraction of uranium in organics-containing wastewater over g-C3N4/GO hybrid nanosheets with type-II band structure

The presence of organics in radioactive wastewater decreased the extraction efficiency in traditional adsorption treatment of nuclide. Herein, we developed g-C3N4/graphene oxide hybrid nanosheets (g-C3N4/GO) with the typical type-Ⅱ band structure for the phtodegradation-extraction treatment of hexavalent uranium (U(VI)) in the tannic acid (TA)-containing wastewater. Due to the staggered band structure, the photoelectron transferred from g-C3N4 to GO under simulated sunlight. Accordingly, g-C3N4/GO hybrid nanosheets exhibited promoted TA degradation and U(VI) extraction compared with the pristine g-C3N4 and GO nanosheets. In light condition, the g-C3N4/GO hybrid nanosheets degraded 92% of the TA and a 352 mg/g of U(VI) extraction capacity in 40 min. Notably, as an adverse factor for the U(VI) extraction in dark condition, the existence of TA increased the extraction capacity under simulated sunlight, which resulted from the consuming of photoinduced holes and promotion of U(VI) reduction.

Electromagnetic interference shielding effectiveness of reinforced composite with graphene oxide-lead oxide hybrid nanosheets

ABSTRACTThe rapid development of telecommunication devices and related technologies improved the distribution of electromagnetic (EM) waves within the environment, which can adversely affect the performance of electronic systems and put the life of living species in serious danger; thus, practical alternatives are required to protect vulnerable sources from them. To address this demand, we developed reinforced composites with graphene oxide (GO)-lead oxide (GO-Pb3O4) hybrid 2D nanosheets at diverse filler loadings by employing the vacuum shock technique. Next, the developed fillers and composites were well characterized by the diverse analysis methods and their electromagnetic interference shielding effectiveness (EMI SE) was evaluated and compared with their X-ray shielding performance. The obtained results showed that the developed composites can perfectly attenuate X-ray waves and weaken the total power of applied EM waves (in X-band frequency (8.2–12.4 GHz)) more than 50%. In this regard, a 6 mm thick specimen containing 10 wt% GO-Pb3O4 attenuated emitted X-ray waves equal to 4.06, 4.83 and 3.91 mmAl at 40, 60 and 80 kVp energies, which shows about 124%, 124% and 121% increase, respectively, in the X-ray attenuation compared with neat epoxy resin. These results indicated that developed composites are perfect candidates to protect vulnerable sources from diverse EM sources, and despite the insulative nature of the GO-Pb3O4, these hybrid nanosheets can act as a potential barrier against EM waves.

Synthesis of Graphite Oxide/Cobalt Molybdenum Oxide Hybrid Nanosheets for Enhanced Electrochemical Performance in Supercapacitors and the Oxygen Evolution Reaction

AbstractReduced graphite oxide (rGO)/cobalt molybdenum oxide (CoMoO4) hybrid nanosheets (NSs) have been prepared by using the hydrothermal method followed by detailed characterization with X‐ray diffraction, electron microscopy, Raman and FTIR spectroscopy. The unusual rGO/CoMoO4 hybrid NSs allow the electrochemical reactions of electrodes for supercapacitors. Therefore, an excellent specific capacitance (ca. 450 F/g at 2 mV/s) and stability performance of the rGO/CoMoO4 hybrid NSs were observed in alkaline medium (i. e. 5 M KOH electrolyte). The rGO/CoMoO4 hybrid NSs show five times higher specific capacitance compared to pure CoMoO4 NSs. The cyclic stability of the rGO/CoMoO4 hybrid NSs reveals retention of approximately 98 % of the initial capacitance after 1500 cycles. Moreover, the rGO/CoMoO4 hybrid electrocatalyst shows higher oxygen evolution activity than CoMoO4 NSs in 0.1 M KOH versus Ag/AgCl. Cyclic voltammetry (CV), galvanostatic charge‐discharge (GCD), linear sweep voltammetry (LSV), and chronoamperometric (CA) measurements strongly support the enhanced electrochemical performance of the rGO/CoMoO4 hybrid NSs.

Ethanol concentration sensor based on TiO2-ZnO composite film enhanced surface plasmon resonance with a molybdenum disulfide-graphene oxide hybrid nano-sheet

A method of ethanol concentration detection based on surface plasmon resonance is proposed. Therefore, a novel prism coupling structure is designed for the ethanol concentration sensor by use of the unique feature of graphene oxide (GO) to act as a sieve for ethanol in water, and a TiO2-ZnO composite film is chosen to enhance the surface plasmon resonance with a molybdenum disulfide–graphene oxide hybrid nano-sheet. The thickness of each layer of the structure is analyzed by the finite element method to obtain the optimal value in order to improve the sensitivity greatly. The optimal thickness of each layer is given, and the sensitivity of the surface plasmon resonance ethanol concentration sensor can reach as high as 0.089°/% within the detection range of ethanol concentration (0%–80%). The relationship between the surface plasmon resonance angle and the ethanol concentration is obtained within the detection range of ethanol concentration.

A novel non-enzymatic dopamine sensors based on NiO-reduced graphene oxide hybrid nanosheets

Ni(OH)2 nanoflakes (NFs) and graphene oxide (GO) nanosheets were prepared by a hydrothermal process and the modified Hummer’s method, respectively. Then, Ni(OH)2 NFs were dispersed in the GO suspension with the assistance of ultrasonic. Finally, the mixed colloidal solution was uniformly sprayed onto the surface of indium tin oxide (ITO) glass and annealed to obtain the NiO-reduced GO (RGO)/ITO electrode, which subsequently used for electrochemical sensing of dopamine (DA) analyte. The NiO-RGO/ITO electrode exhibits enhanced electrochemical response in the aqueous solution of DA analyte, which shows a high sensitivity (1.04 µA µM− 1), the lower measured detection limit (1 µM). The NiO-RGO/ITO electrode also exhibits an excellent selectivity under the interference of uric acid, repeatability and stability. The prepared sensor has been successfully applied in real samples and has a great potential to be used in clinical medicine.

Ethanol concentration sensor based on TiO2-ZnO composite film enhanced surface plasmon resonance with molybdenum disulfide — graphene oxide hybrid nano-sheet

Ethanol concentration sensor based on TiO2-ZnO composite film enhanced surface plasmon resonance with molybdenum disulfide — graphene oxide hybrid nano-sheet

Boron doped graphitic carbon nitride dots dispersed on graphitic carbon nitride/graphene hybrid nanosheets as high performance photocatalysts for hydrogen evolution reaction

Ternary hybrid photocatalysts have been prepared consisting Boron doped graphitic carbon nitride dots (BCNDs) dispersed on high-surface-area graphitic carbon nitride/ reduced graphene oxide (g-C3N4/rGO) hybrid nanosheets. The overall procedure was developed in four stages. First, g-C3N4 nanosheets with positive charge and graphene oxide (GO) nanosheets with negative charge were prepared by treating bulk g-C3N4 in nitric acid and using the modified Hummer’s method, respectively. Second, mixing the two solution with opposite charge, g-C3N4/rGO hybrid nanosheets will form under the driving of electrostatic gravity. Next, the BCNDs were introduced onto the surface of g-C3N4/rGO hybrid nanosheets through hydrothermal process. Finally, the resulting ternary hybrid photocatalysts were tested for photocatalytic hydrogen evolution reaction. The ternary photocatalysts exhibited a high hydrogen evolution rate of 741.4 µmol·h−1·g−1 and an apparent quantum efficiency of 19.0% at 420 nm. Compared with binary hybrid photocatalysts, the experiments results indicate that ternary photocatalysts can efficiently suppress electron-hole pairs recombination and improve the photocatalytic performance.

Facile construction of a molybdenum disulphide/zinc oxide nanosheet hybrid for an advanced photocatalyst

Zinc oxide, an important semiconductor material with good stability, is widely used in photocatalytic degradation of organic pollutants. MoS2 is a two-dimensional semiconductor material. When molybdenum disulfide has more sulfur elements exposed, the photocatalytic activity can be improved. Through the hydrothermal method, zinc oxide nanosheets and molybdenum disulfide nanosheets were successfully supported to form MoS2-ZnO heterojunctions. The surface area of these heterojunctions is large, and they expose more sulfur elements which can effectively promote the separation of photo-generated electrons and holes, and improve the photocatalytic performance of MoS2-ZnO heterojunctions. The photocatalytic degradation of Rhodamine B by MoS2-ZnO heterojunctions was completed in one hour. MoS2-ZnO heterojunctions are environmentally friendly photocatalysts that do not pollute the environment when they degrade organic pollutants in water.

Low diffuse reflection of silver nanowire/ruthenium oxide nanosheet hybrid films for high-performance transparent flexible electrodes

Transparent conducting electrodes (TCEs) based on silver nanowire (AgNW) networks possess high conductance, transmittance, and mechanical flexibility. However, due to the relatively high diffuse reflection of incident light on AgNWs, they cannot be practically implemented in displays requiring low pattern visibility. One promising strategy for solving this problem is to place an optical stack with high refractive index underneath the AgNW layer. In this work, AgNW-RuO2 nanosheet hybrid TCEs with low diffuse reflections are fabricated using metallic RuO2 nanosheets as undercoats. As predicted by theoretical simulations, RuO2 nanosheets with high refractive indices reduce the diffuse reflections of AgNWs by almost 8%. Moreover, after the partial etching of AgNWs, the difference in the diffuse reflections of their etched and non-etched regions becomes equal to about 0.003, leading to the formation of an invisible pattern. The film consisting of micro-sized RuO2 nanosheets is not damaged during etching, but instead forms a current path between different AgNWs broken by cyclic bending, resulting in a tenfold decrease in the resistance of the AgNW TCE after 170 000 cycles. Further, RuO2 nanosheets suppress the diffusion of humid air from the outside, thus improving the environmental stability of the AgNW-RuO2 nanosheet hybrid TCEs.