Incorporation Of rGO Research Articles

Reduced graphene oxide-based silver selenide nanocomposite synthesized through hydrothermal method for oxygen evolution reaction

Intensive research is being conducted on electrochemical water splitting to deal with environmental issues and energy concerns. The renewable and environment-friendly energy sectors want to develop inexpensive electrocatalysts with prolonged stability and high electrocatalytic activity and accelerate oxygen evolution reaction (OER). The current study reports the fabrication of Ag2Se nanoparticles on reduced graphene oxide (rGO) to create Ag2Se/rGO nanocomposite through hydrothermal method at 165 ℃. Raman analysis validated the good integration of rGO and Ag2Se, revealing distinctive peaks for both materials. The produced nanocomposite has a Tafel plot (34 mV/dec) and overpotential (η) 192 mV at ideal current density (j) 10 mA/cm2. Chronoamperometric study and cyclic durability of the nanocomposite demonstrate stability over 60 hours. The electrochemical impedance spectra (EIS) showed that the Rct (charge transfer resistance) of Ag2Se/rGO was 0.2 Ω. The electrochemical finding indicates that the incorporation of rGO into Ag2Se provides a large surface area and greater active regions which facilitates the faster adsorption of electrolyte ions and reduced the resistance. The current research reveals a novel methodology to produce highly active rGO-based electrocatalysts that enhance long-term OER performance and open new avenues for their extensive application in the energy sectors.

Synthesis of magnetic NiFe2O4/rGO heterostructure as potential photocatalyst for a breakdown of malachite green (MG) dye under the visible source of light

The development of reactive radical generators, visible-light active photocatalysts with predictable stability, and efficient activity toward the breakdown of organic pollutant continue to be the primary goals of research in the area of photocatalytic environmental restoration. The present concern to on the development of an efficient heterostructure with a band gap operated on a visible region. The rGO incorporation into spinel material also decreases the agglomeration and provides a large surface area. The efficacy of NiFe2O4 (NF) nanoparticles, which are supported by rGO, as a photocatalyst for the breakdown of malachite green (MG) dye. The incorporation of rGO into NFO was investigated with the band gap property of the fabricated material using Tauc's plot profile. The NF/rGO nanocomposite underwent a reduction in magnetic properties determined through Vibrating Sample Magnetometer (VSM) analysis. However, the coercivity of the nanocomposite experienced a significant increase. When subjected to visible light, the degradation rate of malachite green (MG) dyes with NF/rGO was comparatively faster (93.84 %) than that of NF (64.33 %) and rGO (79.41 %). The cyclic photocatalytic degradation process exhibited notable reusability and stability of the magnetic recycling nanocomposite. The photocatalytic results revealed that the developed nanocomposite acts as a potential photocatalyst and it can also be employed in different applications.

Enhanced electrochemical performance of the electrodeposited nickel sulfide on ZIF-67@RGO composite for supercapacitor applications

Zeolitic imidazolate frameworks (ZIF), as a form of metal-organic frameworks (MOFs), are promising materials used as electrodes for energy storage devices. Their high electrical conductivity results from numerous conjugated systems and the collaboration between the ligand and cobalt significantly enhances their redox capacity. The bulk electrical conductivity and specific capacitance of ZIF materials can be enhanced by the incorporation of rGO and metal sulfide, respectively. Herein, ZIF-67@RGO nanocomposite was fabricated and then modified with 20.0 wt% Ni nanoparticles followed by co-electrodeposition of sulfur as a novel electrocatalyst. The prepared composites were analyzed using various techniques, including FT-IR, XRD, XPS, SEM, and EDX mapping. The electrochemical performance of the prepared composite electrodes was measured using different techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD). The S-Ni/ZIF-67@RGO electrode displayed excellent electrochemical behaviour which is evident in the high value of the specific capacitance of 1142.3 F g−1 at a current density of 1 A g−1. On the other hand, an asymmetric supercapacitor (ASC) was assembled by employing the unique composite material in conjunction with conductive carbon black. The power and energy densities of the ASC device were 774 W kg−1 and 88.2 Wh kg−1, respectively. The capacitance of S-Ni/ZIF-67-RGO is retained at 90.8% even after 3000 cycles, suggesting remarkable cycle stability. This study expands the application scope of ZIF-67 and introduces a new method for fabricating novel electrode materials.

Effect of reduced graphene oxide on thermal property of recycled textile polyamide

This study explored the impact of reduced graphene oxide (rGO) addition on the thermal properties of recycled polyamide (PARec) obtained from repurposed textile industry microfibers initially earmarked for landfill disposal. Characterization of PARec involved techniques like differential scanning calorimetry (DSC), thermogravimetric analysis (TG), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). RGO was characterized through Raman spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Mixtures with varying rGO concentrations, such as PARec-1 (0.1% rGO), PARec-5 (0.5% rGO), and PARec-10 (1% rGO), were prepared and processed in a twin-screw extruder. SEM images at PARec show good dispersion of rGO in the polymer matrix. Thermal properties were determined via DSC and TG, revealing the presence of polyamide 6 in PARec-0 and indicating rGO's quality. Notably, PARec-10 exhibited a slight 3.8% increase in melting temperature and a 7.5% rise in crystallization temperature. These results suggest the potential for improved thermal properties with rGO incorporation. The study contributes to understanding polymer blend thermal properties and introduces an innovative, efficient polymer waste recycling method aligned with sustainability principles.

Enhancing Alginate Hydrogels as Possible Wound-Healing Patches: The Synergistic Impact of Reduced Graphene Oxide and Tannins on Mechanical and Adhesive Properties.

Hydrogels are three-dimensional crosslinked materials known for their ability to absorb water, exhibit high flexibility, their biodegradability and biocompatibility, and their ability to mimic properties of different tissues in the body. However, their application is limited by inherent deficiencies in their mechanical properties. To address this issue, reduced graphene oxide (rGO) and tannins (TA) were incorporated into alginate hydrogels (Alg) to evaluate the impact of the concentration of these nanomaterials on mechanical and adhesive, as well as cytotoxicity and wound-healing properties. Tensile mechanical tests demonstrated improvements in tensile strength, elastic modulus, and toughness upon the incorporation of rGO and TA. Additionally, the inclusion of these materials allowed for a greater energy dissipation during continuous charge-discharge cycles. However, the samples did not exhibit self-recovery under environmental conditions. Adhesion was evaluated on pig skin, revealing that higher concentrations of rGO led to enhanced adhesion, while the concentration of TA did not significantly affect this property. Moreover, adhesion remained consistent after 10 adhesion cycles, and the contact time before the separation between the material and the surface did not affect this property. The materials were not cytotoxic and promoted healing in human fibroblast-model cells. Thus, an Alg/rGO/TA hydrogel with enhanced mechanical, adhesive, and wound-healing properties was successfully developed.

Tunable electronic coupling of Fe-doped CoS2/reduced graphene oxide composites for boosting bifunctional water splitting activity

The electrochemical water splitting process is always restrained for its sluggish kinetics and high reaction energy barrier. Therefore, developing outstanding bifunctional catalysts to enhance the reaction kinetics and electron transfer efficiency of water splitting is crucial. In this work, we reported a bifunctional nanohybrid electrocatalyst consisting of Fe-doped CoS2 nanocage-decorated reduced graphene oxide (FCSRGO) with superior water splitting activity. The Fe doping adjusts the density of state (DOS) to increase the conductivity and decreases the adsorption free energy of intermediates, contributing to optimized catalytic activity. Furthermore, the incorporation of RGO reduces the agglomeration of CoS2 and improves the conductivity, thereby amplifying the charge/species transfer efficiency. By optimizing the amount of RGO, FCSRGO shows exceptional electrocatalytic performance, achieving a benchmark current density of 10 mA·cm−2 at remarkably low overpotentials (ƞ10) of 107 mV and 239 mV in 1 M KOH solution for HER and OER, respectively. Moreover, the nanohybrid exhibits remarkable stability with the current density retention of 89.8% for HER and 85.8% for OER after 36000 s test. This work highlights the creating of high-performance electrocatalysts for efficient and sustainable hydrogen and oxygen evolution through heteroatom doping and carbon incorporation.

Ultrasensitive Aptasensing Platform for the Detection of β-Amyloid-42 Peptide Based on MOF Containing Bimetallic Porphyrin Graphene Oxide and Gold Nanoparticles.

The prompt detection of diseases hinges on the accessibility and the capability to identify relevant biomarkers. The integration of aptamers and the incorporation of nanomaterials into signal transducers have not only expedited but also enhanced the development of nanoaptasensors, enabling heightened sensitivity and selectivity. Here, the bimetallic nickel-cobalt-porphyrin metal-organic framework ((Ni + Cu)TPyP MOF) is regarded as an electron mediator, immobilization platform for an Alzheimer aptamer and to increase the electrochemical signal for the detection of the main biomarker of Alzheimer's disease (AD), amyloid β (Aβ-42). Furthermore, the ((Ni + Cu)TPyP MOF) was combined with reduced graphene oxide (rGO) and gold nanoparticles (AuNPs), on a gold electrode (GE) to provide an efficient interface for immobilizing aptamer strands. Concurrently, the incorporation of rGO and AuNPs imparts enhanced electrical conductivity and efficacious catalytic activity, establishing them as adept electrochemical indicators. Owing to the superior excellent electrical conductivity of rGO and AuNPs, coupled with the presence of ample mesoporous channels and numerous Ni and Cu metal sites within (Ni + Cu)TPyP MOF, this nanostructure with abundant functional groups is proficient in immobilizing a substantial quantity of aptamer. These interactions are achieved through robust π-π stacking and electrostatic interactions, alongside the high affinity between the thiol group of the aptamer and AuNPs concurrently. The as-prepared ternary (Au@(Ni + Cu)TPyP MOF/rGO) nanostructure electrode exhibited an enhancement in its electrochemically active surface area of about 7 times, compared with the bare electrode and the Aβ-42 redox process is highly accelerated, so the peak currents are significantly higher than those obtained with bare GE substrate. Under the optimized conditions, the designed aptasensor had the quantitative detection of Aβ-42 with a low detection limit of 48.6 fg mL-1 within the linear range of 0.05 pg mL-1 to 5 ng mL-1 by differential pulse voltammetry (DPV), accompanied by precise reproducibility, satisfactory stability (95.6% of the initial activity after 10 days), and minimal impact of interfering agents. Recorded results in human blood plasma demonstrated the high efficacy of porphyrin MOF system sensing even in the clinical matrix. The great performance of this aptasensor indicates that our new design of Au@(Ni + Cu)TPyP MOF/rGO nanostructure provides more opportunities for the detection of chemical signals in early diagnosis of Alzheimer's disease.

Interface Modulation of CoNi Alloy Decorated with Few-Layer Reduced Graphene Oxide for High-Efficiency Microwave Absorption

Metal-organic frameworks (MOFs)-derived microwave absorbers with tunable components and microstructures show great potential in microwave absorption. Herein, we report a facile thermal reduction approach for synthesizing CoNi alloy/reduced graphene oxide (CoNi/rGO) composites from bimetallic CoNi-MOFs. By tuning the ratio of graphene oxide (GO) in the precursors, the resulting CoNi/rGO-2 composite demonstrates optimal microwave absorption performance with a minimum reflection loss (RLmin) of −66.2 dB at 7.6 GHz in the C band. Moreover, the CoNi/rGO-2 with 50 wt% filler loading achieves a maximum effective absorption bandwidth (EAB) of 6.8 GHz (10.6–17.4 GHz) at a thickness of 2.5 mm, almost spanning the entire Ku band and a portion of the X band. The outstanding performance of CoNi/rGO-2 is ascribed to the high magnetic loss from the CoNi alloy and the incorporation of rGO, which induces interfacial polarization to enhance the dielectric loss and improve the impedance matching of composite. These favorable findings highlight the considerable potential and superiority of the CoNi/rGO-2 composite as an electromagnetic wave absorption material. This work sets forth a viable strategy for designing high-efficiency alloy/rGO absorbers.

Crystal defect engineering to construct oxygen vacancies in MXene-derived TiO2 nanocomposites for boosting photocatalytic degradation of 2,4,6-trichlorophenol

Chlorophenolic pollutants pose serious threats to the aquatic ecosystem. Photocatalysis technology has broad prospects for decontamination. In this work, MXene-derived TiO2 nanocomposites with mixed-crystal characteristics and oxygen vacancies (OVs) (E–TiO2@rGO) were successfully synthesized by atmosphere modulation. Compared with commercial TiO2 and N2–TiO2@rGO (anatase phase), the rate constants of E–TiO2@rGO (0.06874 min−1) over 2,4,6-trichlorophenol (2,4,6-TCP) degradation increased 4 and 1.3 times, respectively. The enhanced photocatalytic performance was attributed to the co-existence of anatase and rutile phases. On the one hand, the mixed-crystal phase narrowed the band gap, broadening the light absorption range. On the other hand, it induced the generation of OVs, which has been demonstrated by DFT calculation. The presence of OVs improved the adsorption and activation of O2 and H2O molecules, beneficial for the formation of active free radicals. In addition, the incorporation of rGO promoted the separation of electron-hole pairs. The Gibbs free energy of 2,4,6-TCP degradation revealed that the OVs and mixed-crystal could reduce the energy barrier of the rate-determining step, thereby boosting the dichlorination efficiency of 2,4,6-TCP. The superoxide free radical (O2−) was determined as the dominant active species. Finally, a possible mechanism of 2,4,6-TCP degradation with E–TiO2@rGO was clarified clearly. The proposed mixed-crystal defect engineering represents a novel strategy in the design and synthesis of photocatalysts.

Reduced graphene oxide–reinforced tricalcium phosphate/gelatin/chitosan light-responsive scaffolds for application in bone regeneration

Bone is a mineralized tissue with the intrinsic capacity for constant remodeling. Rapid prototyping techniques, using biomaterials that mimic the bone native matrix, have been used to develop osteoinductive and osteogenic personalized 3D structures, which can be further combined with drug delivery and phototherapy. Herein, a Fab@Home 3D Plotter printer was used to promote the layer-by-layer deposition of a composite mixture of gelatin, chitosan, tricalcium phosphate, and reduced graphene oxide (rGO). The phototherapeutic potential of the new NIR-responsive 3D_rGO scaffolds was assessed by comparing scaffolds with different rGO concentrations (1, 2, and 4 mg/mL). The data obtained show that the rGO incorporation confers to the scaffolds the capacity to interact with NIR light and induce a hyperthermy effect, with a maximum temperature increase of 16.7 °C after under NIR irradiation (10 min). Also, the increase in the rGO content improved the hydrophilicity and mechanical resistance of the scaffolds, particularly in the 3D_rGO4. Furthermore, the rGO could confer an NIR-triggered antibacterial effect to the 3D scaffolds, without compromising the osteoblasts' proliferation and viability. In general, the obtained data support the development of 3D_rGO for being applied as temporary scaffolds supporting the new bone tissue formation and avoiding the establishment of bacterial infections.

PVDF/rGO/CuO nanocomposites: A robust platform for solar-driven tetracycline photodegradation

Tetracycline, a broad-spectrum antibiotic, poses a significant threat to environmental health due to its widespread usage and persistence in water bodies. Traditional treatment methods often prove inadequate, necessitating the development of efficient and sustainable strategies for tetracycline degradation. This study aimed to synthesize and investigate the photocatalytic performance of PVDF/rGO/CuO nanocomposites for tetracycline degradation under ambient solar irradiation. The integration of reduced graphene oxide (rGO) into the nanocomposite addressed the inherent drawbacks of CuO, such as poor dispersibility and limited light absorption. This novel approach aimed to enhance the photocatalytic activity and efficacy of the system. The study successfully synthesized PVDF/rGO/CuO nanocomposites with improved dispersibility and enhanced light absorption due to rGO's incorporation. It is worthy to note that, the 5% CuO/rGO nanocomposite exhibited an exceptional photodegradation rate of 94.8% for tetracycline under solar irradiation. The photodegradation efficiency was concentration-dependent and significantly higher under acidic conditions. These findings demonstrate the potential of PVDF/rGO/CuO nanocomposites as promising photocatalysts for environmental remediation. Their solar-driven tetracycline degradation capability highlights their potential application in addressing water pollution concerns associated with antibiotic residues.

Tuning thermal stability and fire hazards of hydrophobic silica aerogels via doping reduced graphene oxide

This study synthesizes composites of reduced graphene oxide doped silica aerogel (SA/rGO) and assesses their thermal safety. The introduction of rGO minimally affected SA polymerization, as confirmed by FTIR and XRD. Even with rGO (0.05-0.45 %), SA/rGO maintains low density (∼ 0.10 g/cm³), low thermal conductivity (∼ 23 mW/m/K), and large surface area (863.4–913.1 m²/g). TG-DSC results show enhanced thermal stability in SA/rGO, with onset and peak decomposition temperatures rising by 118 °C and 94 °C, respectively. Additionally, gross calorific values and total heat release rates decrease by 12.4 % and 25.4 %. Thus, this work establishes that the incorporation of rGO enhances thermal stability and flame resistance of hydrophobic SAs without impairing their properties, which provides a new insight for developing thermally safer hydrophobic SA materials.

Facile production of Ag-Co3O4/rGO nanocomposite and its enhanced photocatalytic and electrochemical activities for practical applications

In this study, authors produced Co3O4, Ag-Co3O4 nanoparticles and Ag-Co3O4/rGO nanocomposites through a facile, one-step and cost-effective hydrothermal route; and thoroughly analyzed these materials using a variety of complementary techniques, including XRD, SEM/TEM, XPS, FTIR, VSM, UV–Vis, PL, photocatalytic and electrochemical measurements. The formation of cubic spinel structure in Ag-Co3O4/rGO nanocomposite was investigated by X-ray diffraction. The estimated average crystalline size in case ofCo3O4, Ag-Co3O4, and Ag-Co3O4/rGO samples was found to be 11.2, 14.1 and 17.5 nm, respectively. As a comparison to Co3O4 and Ag-Co3O4 nanoparticles, the absorption edge of Ag-Co3O4/rGO nanocomposite was significantly shifted towards the visible region, and hence the band gap is narrowed due to highly conducting Ag and rGO incorporation. The photo-generated electrons and holes were rapidly transferred from Co3O4 to Ag and rGO, leading to reduced PL intensity ofAg-Co3O4/rGO nanocomposite. Authors evaluated the photocatalytic efficiency of synthesized Ag-Co3O4/rGO nanocomposite, which exhibited an enhanced photodegradation potential against RhB dye. Authors also examined the electrochemical activity of as-obtained Ag-Co3O4/rGO nanocomposite using cyclic voltammetry and galvanostatic charge-discharge cycle analysis, demonstrating its employability in supercapacitors as it possessed excellent specific capacitance.

Surface design and engineering of ZnMn2O4/RGO composites for highly stable supercapacitor devices

The manipulation of phase and morphology of metal oxides by controlled engineering is considered to be a significant approach for enhancing electrochemical characteristics. The development of composite materials that are both highly efficient and cost-effective is crucial in the context of supercapacitors. A hydrothermal route is opted to fabricate ZnMn2O4/RGO microsphere electrodes. The control of process parameters during the synthesis and subsequent annealing allows for the development of microspheres exhibiting unique topographies of the surface. The incorporation of RGO into the composites has the potential to enhance conductivity, hence improving the overall utilization of the material. The ZnMn2O4/RGO composites exhibited the specific capacitances of 628, 545, 488, 446, 380 and 364 F g−1 at current densities of 1, 2,3,5,10 and 20 A g−1, respectively. Furthermore, the results demonstrated exceptional rate capability as the material retained 58 % of its initial capacitance even under a high current density. In addition, it retained a capacitance of 95.2 % even after 10,000 cycles at 1 A g−1. Furthermore, ZnMn2O4/RGO@ASC device displayed a reasonable specific capacitance of 128.7 F g−1 at 1.5 A g−1 and retained a capacitance of 83.9 % for 5000 cycles at 5 A g−1. The ZnMn2O4/RGO@ASC device had the energy density of 40.2 W h kg−1 at a power density of 1125 W/ kg. As a result, developed supercapacitor devices are preferred for use in portable electronics and industrial applications.

Reduced graphene oxide–MgTiO3 hybrid nanomaterial for energy storage, degradation of congo red dye and antimicrobial agent against Staphylococcus aureus and Escherichia coli bacterial strains

One-pot green synthesis was employed to prepare rGO decorated MgTiO3 perovskite. To reduce graphene oxide Solanum trilobatum leaf extract was used. MgTiO3 nanoparticles prepared by chemical precipitation have been compared to rGO decorated MgTiO3 nanoparticles for structural, optical, catalytic, electrochemical, and antibacterial properties. Rhombohedral structure was confirmed from the XRD analysis. Crystallite size of MgTiO3 got reduced from 52 nm to 21 nm with rGO induction. rGO embedded MgTiO3 exhibits grains with well defined boundaries. There's a 2.79 eV band gap for MgTiO3 and 2.71 eV for MgTiO3 embedded with rGO. MgTiO3‘s PL intensities quenched with rGO incorporation. Photodegradation efficiency against Congo red dye of MgTiO3 increased from 76.8 % to 87.6 % with rGO incorporation. Distinctive anodic and cathodic peaks demonstrate the pseudo-capacitive nature of both samples from CV curves. Specific capacitance of MgTiO3 increased from 72.6 to 117.8F/g with rGO incorporation. Adding rGO to MgTiO3 increased its antibacterial activity.

Titanium dioxide/reduced graphene oxide nanocomposites as effective photocatalytic for hazardous 4-nitrophenol

Titanium dioxide/reduced graphene oxide nanocomposite (TiO2/rGO NCs) was prepared using various hydrothermal strategies as a highly efficient photocatalyst. The crystal structure, morphology, elemental distribution, chemical structure, optical properties, and electrical conductivity of TiO2/rGO NCs were studied to investigate the effect of the incorporation of rGO with TiO2NPs on these properties. The TiO2/rGO NCs surface exhibits thin sheets of rGO with TiO2NPs distributed on the sheets. The successful incorporation between rGO and TiO2NPs was confirmed by EDX maps, IR spectrum, and XRD patterns. Compared with TiO2NPs, a tiny reduction in the crystallite size and an increase in the microstrain was found; in addition, the TiO2/rGO NCs exhibit a low direct bandgap energy, a high electrical conductivity, and excellent photoconductivity. On the other hand, different amounts of 4-nitrophenol (4-NP) were used to investigate the photocatalyst degradation efficiency of TiO2NPs and TiO2/rGO NCs under UV irradiation. The higher degradation efficiency after 120 min was for TiO2/rGO NCs with 5 mg/L and 10 mg/L of 4-NP, with 94% and 91% values, respectively. The first-order kinetic constant (k1), the kinetic rate constant of the surface reaction (ks) and the adsorption equilibrium constant (KL) were evaluated. The KL of TiO2NPs and TiO2/rGO NCs is 0.003 and 0.182 (mgL−1)−1, and the ks is 2.53 and 0.21 mgL−1.min−1, respectively.

Fabrication and properties of sustainable material from epoxidized natural rubber/poly(vinyl alcohol)/graphene composites

This work reported the production of epoxidized natural rubber (ENR)/poly (vinyl alcohol) (PVA)/graphene (rGO) composite by latex mixing method. The particle size of rGO was about 740 nm and negative charge value (−29 mV). After the incorporation of the rGO into the 80/20 ENR/PVA blend, the color turns into black. The toluene resistance was also improved owing to its chemical interaction between the ENR/PVA blend and rGO. The swelling ratio of the ENR/PVA blend was 7/7 g/g while the swelling ratio of the ENR/PVA blend containing 1% w/w rGO was 3/3 g/g. The lowest moisture content and moisture absorption were found when using 1 g/g rGO. The maximum moisture and moisture absorption were found at ENR/PVA blend without rGO. After incorporation of rGO in the composite, the mechanical strength was enhanced jumping to the enforcement filler. The maximum tensile strength of ENR/PVA/1rGO was 17 MPa. The composite exhibits good thermal stability and the retention tensile strength of ENR/PVA/1rGO composite was about 80% at 24 h. After use, it easily decomposed in nature and the percentage of biodegradation was about 60%–75%.

Synthesis, structural and electrochemical investigations of reduced graphene oxide loaded zinc vanadate nanoparticles for high performance supercapacitors

In this study, supercapacitor performances of reduced graphene oxide-loaded zinc vanadate (Zn3(VO4)2 - ZV) nanoparticles (NPs) were reported. Reduced graphene oxide (rGO) loaded zinc vanadate (Zn3(VO4)2@rGO - ZVR) nanocomposites (NCs) were synthesized through a simple reflux method and their structural, functional group, and morphological properties were analyzed by X-ray diffraction, FT-IR, and electron microscopic analyses. Working electrodes of ZV NPs and ZVR NCs were fabricated using doctor blade technique and their supercapacitor performances were tested with an aqueous KOH electrolyte. Incorporation of rGO greatly enhanced the specific capacitance value of ZV NPs from 104 F g−1 to 1910 F g−1 at 5 mVs−1 (CV studies). At the same, the highest specific capacitance value from the GCD analysis was found to be 1315 F g−1 for ZVR NCs, which was very much greater than pure ZV NPs (53.7 F g−1). The fabricated asymmetrical supercapacitors using ZVR NCs-based working electrode exhibited the higher power and energy densities of 2050 W kg−1 and 13.13 Wh kg−1, respectively. Furthermore, the fabricated supercapacitors demonstrated an excellent cyclic stability of 95.1 % after 2000 GCD cycles, when compared to ZV NPs (90 %). The electrochemical results proved that the supercapacitor performances of ZV NPs were greatly enhanced by the addition of rGO.

Surfactant-free synthesis of AgGO and subsequent catalytic performance of AgGO and WO3-x/AgrGO composites

Suppressing charge recombination in semiconductors via triggering interfacial polarization and synergism provides an effective way to redeem multifunctionality and achieve environmental sustainability. Herein, we anchor a single-step facile synthesis of AgGO, providing bandgap control through varying oxidation time and subsequent simultaneous incorporation of Ag and rGO via the in situ hydrothermal method in WO3-x. The resulting WO3-x/AgrGO composite demonstrated a broadening of optical absorption and excellent suppression of carrier recombination, thereby improving the catalytic properties. The synergism and excellent conductivity of AgrGO enhance the interfacial polarization to store the carriers for longer times and help carriers carry most of their energy to the catalyst’s surface. When WO3-x/AgrGO was tested against RhB under visible light irradiation, its degradation constant reached 0.034/min, 7.4 times faster than pure WO3-x. It has left no viable bacteria during the photoinactivation of gram-negative E. coli bacteria, and even its inactivation rate is 1.07 times faster than AgGO. So, this study provides a direct method of metal-GO composite synthesis and subsequent introduction into WO3-x to broaden the versatility of environmental semiconductors.

Harvesting visible light for enhanced catalytic degradation of wastewater using TiO2@Fe3O4 embedded on two dimensional reduced graphene oxide nanosheets

Carbon-integrated binary metal oxide semiconductors have gained prominence in the last decade as a better material for photocatalytic wastewater treatment technology. In this regard, this research describes the investigation of the binary metal oxide TiO2@Fe3O4 embedded on reduced graphene oxide (rGO) nanosheets synthesized through a combination of sol-gel, chemical precipitation, and Hummer's processes. Besides, the catalyst is applied for the photocatalytic degradation of organic chlorophenol pollutants. The characterized diffraction results showed the peak broadening of the rGO-TiO2@Fe3O4 composite formed with tetragonal and cubic structures having small crystallite sizes. The TEM observation shows an enormous miniature of TiO2@Fe3O4 nanospheres spread on the folded 2D-rGO nanosheets with a large BET surface area. The XPS result holds the mixed phases of Fe3O4 and Fe2O3. Finally, the catalyst demonstrated a low band gap with extended light absorption towards visible light irradiation. The synergistic interactions between Fe3+ and Fe2+ improved the visible light activity due to the incorporation of rGO, and also possessed good recycling capacity. The increased mobility of electrons at the interfaces of TiO2 and Fe3O4 due to the mixing of rGO results in the separation of charge carriers by elevating the photocatalytic degradation efficiency of chlorophenol.