Reduced Graphene Oxide Composites Research Articles

Fabrication of Ag-doped magnesium aluminate/ rGO composite: A highly efficient photocatalyst for visible light-driven photodegradation of crystal violet and phenol

Magnesium aluminate (MgAl2O4, MAO) and silver doped magnesium aluminate (Ag–MgAl2O4, Ag-MAO) nanomaterials were fabricated using the co-precipitation technique. For the photo-catalytically degrading organic effluents such as crystal violet (CV) and phenol, the reduced graphene oxide composite (Ag–MgAl2O4@rGO, Ag-MAO@rGO) was prepared using the ultrasonication method. The formation of doped and bare MgAl2O4 was verified by XRD. Functional groups in synthesized photocatalysts were identified using the FTIR method. SEM analysis was used to look at the morphology. A UV–Visible spectrophotometer was used to perform the optical analysis. The bandgap energies for MAO and Ag-MAO were 2.55 eV and 2.40 eV respectively. Under the sunlight, the photocatalytic effectiveness of the prepared samples was examined. Ag-MAO@rGO displayed 81.89% degradation of CV and 40.51% degradation of phenol in the presence of sunlight. The principal photoactive species in case of the photocatalytic experiment are hydroxyl radicals.

Effects of TiO2-Modified RGO Composites on the Mechanical and Durability Properties of Ordinary Portland Cement Mortars

Various applications of graphene-based materials in construction are an alternative to improve the properties of ordinary Portland cement (OPC)-based binders. This paper used a titanium dioxide in situ intercalation method to enhance the dispersibility of reduced graphene oxide (RGO) and then explored the effects of the incorporation of the obtained TiO2–RGO composite and RGO on the mechanical and durability-related properties of the OPC-based binders. Experimental results showed that TiO2 was successfully intercalated into the RGO layers and could improve the dispersion of RGO in water or synthesized OPC pore solution significantly, probably due to the greater spacing between each RGO layer. Besides, a proper amount of TiO2-modified RGO composite (0.03 wt % in this study) could elevate the mechanical strengths of OPC mortars, evidenced by a large increment of 24.78% and up to 34.94% in the compressive strength and flexural strength, respectively. The TiO2–RGO composite led to higher flexural-to-compressive strength ratios with the given dosages (0.01–0.05 wt %), implying a higher fractural toughness. Moreover, the resistance of the enhanced OPC-based mortars toward chloride attacks and freeze–thaw cycles was significantly improved. Based on the microstructural analyses including scanning electron microscopy and X-ray diffraction results, it is found that the modified RGO could to some extent promote the hydration of OPC and densify the overall microstructure of bulk specimens, leading to enhanced mechanical and durability properties. Compared to normal RGO, the TiO2–RGO composite was more effective in enhancing the properties of OPC mortars, due in large part to its better dispersion state.

Assembly of Core/Shell Nanospheres of Amorphous Hemin/Acetone-Derived Carbonized Polymer with Graphene Nanosheets for Room-Temperature NO Sensing.

Implementing parts per billion-level nitric oxide (NO) sensing at room temperature (RT) is still in extreme demand for monitoring inflammatory respiratory diseases. Herein, we have prepared a kind of core-shell structural Hemin-based nanospheres (Abbr.: Hemin-nanospheres, defined as HNSs) with the core of amorphous Hemin and the shell of acetone-derived carbonized polymer, whose core-shell structure was verified by XPS with argon-ion etching. Then, the HNS-assembled reduced graphene oxide composite (defined as HNS-rGO) was prepared for RT NO sensing. The acetone-derived carbonized polymer shell not only assists the formation of amorphous Hemin core by disrupting their crystallization to release more Fe-N4 active sites, but provides protection to the core. Owing to the unique core-shell structure, the obtained HNS-rGO based sensor exhibited superior RT gas sensing properties toward NO, including a relatively higher response (Ra/Rg = 5.8, 20 ppm), a lower practical limit of detection (100 ppb), relatively reliable repeatability (over 6 cycles), excellent selectivity, and much higher long-term stability (less than a 5% decrease over 120 days). The sensing mechanism has also been proposed based on charge transfer theory. The superior gas sensing properties of HNS-rGO are ascribed to the more Fe-N4 active sites available under the amorphous state of the Hemin core and to the physical protection by the shell of acetone-derived carbonized polymer. This work presents a facile strategy of constructing a high-performance carbon-based core-shell nanostructure for gas sensing.

Titanium Dioxide–Reduced Graphene Oxide Composites for Photocatalytic Degradation of Dyes in Water

Dye wastewater due to industrialization, urbanization and academic activities has become one of the most important environmental issues today. Photocatalytic degradation technology is considered as a promising technology for treating dye wastewater due to its advantages of environmental protection and low energy consumption. Herein, titanium dioxide–reduced graphene oxide composites (TiO2-RGO) were prepared by a one-step hydrothermal method to degrade different dyes (methyl orange, methylene blue and rhodamine B) in water. The structure and morphology of TiO2-RGO were characterized using various technical approaches. The degradation effect of TiO2-RGO on the dye was in accordance with a first-order kinetic reaction. The degradation rate of TiO2-6%RGO for methyl orange at 15 min was 1.67 times higher than that of TiO2, due to the strong electron transport ability and excellent adsorption properties of graphene. TiO2-6%RGO has better degradation performance for fluorescent dyes and anionic azo dyes. Notably, the degradation rate of methyl orange by TiO2-6%RGO photocatalysis for 90 min could reach 96.9%. Meanwhile, the TiO2-6%RGO showed excellent reusability, as the initial degradation rate of 93.2% was maintained after five degradation cycles of methyl orange solution. The present work provides a universal strategy for designing efficient photocatalytic materials.

Engineering a hierarchical carbon supported magnetite nanoparticles composite from metal organic framework and graphene oxide for lithium-ion storage

Fe based metal organic framework (MOF) materials are being extensively investigated as a precursor sample for engineering carbon supported iron containing nanoparticles composites. Rational design and engineering Fe-containing MOFs with optimized structures using economic and eco-friendly methods is a challenging task. In this work, 1,3,5-benzenetricarboxylic acid (C9H6O6, trimesic acid, H3BTC) and metal Fe are employed to synthesize a MOF sample Fe-BTC in a mild hydrothermal condition. Moreover, with the addition of a small quantity of graphene oxide (GO) as dispersant, a redox coprecipitation reaction has taken place where small Fe-BTC domains well dispersed by reduced graphene oxide (RGO). The Fe-BTC/RGO intermediate sample is finally converted to the hierarchical Fe3O4@C/RGO composite, which delivers an ultrahigh specific capacity of 1262.61 mAh·g−1 at 200 mA·g−1 after 150 cycles and a superior reversible capacity of 910.65 mAh·g−1 at 1000 mA·g−1 after 300 cycles in half cells. The full cell performance for the Fe3O4@C/RGO composite have been studied. It is also revealed that the improved structural stability, high pseudocapacitive contribution and enhanced lithium-ion and electron transportation conditions jointly guarantee the outstanding lithium-ion storage performances for the Fe3O4@C/RGO composite over long-time cycling. The synthesized samples have good potential for wider application.

Constructing flexible and conductive carbon matrix on organic potassium terephthalate to enhance the K-storage performance

• A flexible and conductive carbon matrix was coated on organic K 2 TP and reduced graphene oxide composite. • The as-synthesized K 2 TP/rGO/C composite displays impressive cycle stability with a reversible specific capacity of 86 mAh g −1 at 200 mA g −1 over 500 cycles. • The improved K-storage mechanism of K 2 TP/rGO/C composite was systematically investigated. Organic potassium terephthalate (K 2 TP) shows promising applications as an anode material in potassium-ion (K-ion) batteries with flexible crystal structure, suitable work potential, stable capability in organic electrolyte and environmentally friendly. Nevertheless, the inherent poor electronic conductivity has been the bottleneck to construct high-performance organic K-ion batteries. Herein, we initially report a flexible and conductive carbon coating layer on organic K 2 TP and reduced graphene oxide composite via electrospinning methodology and controlling medium–low temperature heat treatment (denoted as K 2 TP/rGO/C). The as-synthesized K 2 TP/rGO/C composite displays impressive cycle stability with a reversible specific capacity of 86 mAh g −1 at 200 mA g −1 after 500 cycles with an average capacity decay rate of only 0.1 % per cycle. It is demonstrated that the flexible conductive carbon coating layer and the continuous conductive network structure can significantly improve the electronic conductivity of organic K 2 TP, and reduce the interface transfer resistance. The rational construction of organic composite can offer a guideline for high-performance organic K-ion batteries.

Flexible Pressure Sensor Decorated with MXene and Reduced Graphene Oxide Composites for Motion Detection, Information Transmission, and Pressure Sensing Performance.

Although fiber-based flexible piezoresistive pressure sensors have received extensive attention because of their simple fabrication and easy integration, the common practice of using a single material as the sensing layer often leads to unsatisfactory sensitivity and a limited sensing range. Herein, we exploit the combination of reduced graphene oxide (rGO) and two-dimensional transition-metal carbides and nitrides (MXene), use a polyester filament (PET) as the fiber matrix, and fabricate an MX/rGO PET-based flexible pressure sensor using the "dipping-drying" method. A systematic study is conducted concerning the effect of the dip-coating sequence and material combination on the sensor's resistance and sensitivity, which reveals that MX/rGO PET has the smallest resistance and the highest sensitivity (1.24 kPa-1). A series of tests are conducted to evaluate the pressure sensing characteristics of the MX/rGO PET-based pressure sensor, confirming its good linearity, fast response speed, low detection limit, and stable performance. In addition, the sensor has been successfully used to monitor various human joint activities and physiological signals such as breathing, demonstrating great application potential in the field of personal health care. To further enhance the practical utility, an APP has been designed to analyze and display the collected signals, and the constructed sensor network also provides an ingenious method for information encryption and transmission via pressure sensing. In all, the MX/rGO PET-based pressure sensor proposed in this work is expected to provide a competitive scheme for wearable flexible electronic devices in information transmission and human-computer interaction in the future.

Preparation and electrical properties of rGO-PtNPs/n-Si Schottky contact

In this paper, platinum nanoparticles loaded on reduced graphene oxide composites (rGO-PtNPs) prepared by the hydrothermal method were deposited on the surface of n-Si substrate for the fabrication of rGO-PtNPs/n-Si Schottky contact, and the electrical properties of the Schottky contact were studied by I–V and C–V tests. Results show that the Schottky barrier height of rGO-PtNPs/n-Si presents a trend of firstly increasing and then decreasing with the rise of PtNPs content. The highest potential barrier is 0.731 eV. This phenomenon can be considered that the PtNPs improve the work function of rGO, leading to the increase of barrier height.

Effect of surfactant type on the magnetic and morphological properties of NiFeO4 / reduced graphene oxide composites

A systematic study of the effect of various types of surfactants (polyethylene glycol, Trinon X-100 and cetyltrimethylammonium bromide) and subsequent annealing on the magnetic ordering and morphology of the nickel ferrite / reduced graphene oxide composite materials has been carried out. Hydrazine hydrate has been used both as an agent to initiate precipitation and as a reducing agent to remove oxygen functionality from the surface of graphene oxide particles. To characterize the material, Mössbauer spectroscopy and nitrogen absorption porosimetry have been used. The obtained result suggests a new way for one-pot synthesis of NiFe2O4/rGO composite materials with controlled magnetic ordering and porous structure.

Metal-organic framework–derived carbon/N-doped three-dimensional reduced graphene oxide composite with high capacitive deionization performance

Capacitive deionization (CDI) is an electrostatic adsorption water treatment technology based on capacitor structure and charge-discharge principle, which has the advantages of pollution free, low energy saving, and high value added. Herein, a novel metal-organic framework (MOF)-derived carbon (PC)/nitrogen-doped three-dimensional reduced graphene oxide composite was prepared for CDI electrode material. In this nanoarchitecture, PC was attached to the N-doped graphene sheet, formed a hierarchical porous structure, and provided more active sites and ion transfer channels, which featured with enhanced the salt adsorption capacity (SAC) and rate. The carbonized products (NHG/PC-700) showed a high nitrogen content of 10.78 at.% and large surface area (432.3 m2/g), which was conducive to improve electric conductivity. Accordingly, the specific capacitance of 370.9 F/g and excellent long charge-discharge cycling stability were obtained at 1 A/g current density. In CDI experiments, the NHG/PC-700 electrodes displayed an outstanding SAC of 28.17 mg/g with an initial concentration NaCl solution of 500 mg/L, and the SAC was reduced 4.6% after six CDI regeneration cycles. It was found that the NHG/PC-700 could be considered as a promising electrode material in the field of water treatment.

Polyethylene glycol functionalized reduced graphene oxide coupled with zinc oxide composite adsorbent for removal of phenolic wastewater

The development of agricultural activities and industrialization recently has various adverse impacts on living organisms. The ever-increasing problem of organic pollution has been an environmental concern to the community. Among these, phenolic pollutants like 2,4–dichlorophenol (2,4–DCP), phenol, 2–chlorophenol (2–CP), and bisphenol–A (BPA) are priority toxic pollutants that are continuously released into environment from many industries. In this work, a biocompatible zinc oxide incorporated polyethylene glycol functionalized reduced graphene oxide composite (RGO-PEG-ZnO) was synthesized and explored for the adsorptive removal of toxic phenolic pollutants from water. The optimized adsorption parameters were solution pH 7, adsorption time 60 min, temperature 25 °C, and dosage 0.25 g/L. The isotherms were well fitted by the Langmuir model for BPA and phenol, whereas for 2–CP, and 2,4–DCP, Freundlich was the best-fitted model, and the maximum uptake of BPA, phenol, 2–CP, and 2,4–DCP were 485.756, 511.248, 531.804, 570.641 mg/g, respectively. The kinetic data for all the phenolic pollutants follow the pseudo-second-order model. The thermodynamic analysis shows that Gibb's free energy (ΔGo) values for all the pollutants were negative, confirming that the process was spontaneous. The positive values of change in enthalpy (ΔHo) 28.261, 37.205, 46.182, and 61.682 kJ/mol for BPA, phenol, 2–CP, and 2,4–DCP, respectively, confirm that the above adsorption process was endothermic. The composite can be used for up to five cycles with a small reduction in the removal percentage. Adsorption performance of the synthesized composite for synthetic industrial effluents shows that up to 86.54% removal occurred in 45 min adsorption time. Based on the remarkably rapid adsorption and high adsorption capacity, RGO-PEG-ZnO composite can be considered an efficient adsorbent for treating phenolic pollutants from wastewater.

Controllable engineering magnetite nanoparticles dispersed in a hierarchical amylose derived carbon and reduced graphene oxide framework for lithium-ion storage

A straightforward and eco-friendly method is demonstrated to engineer magnetite (Fe3O4) nanoparticles well dispersed by an amorphous amylose-derived carbon (AMC) and reduced graphene oxide (RGO) framework. Naturally available amylose (AM) serves as both reducing agent for few-layered graphene oxide (GO) in the first mild redox coprecipitation system and precursor for small-sized pyrolytic AMC in the following thermal treatment. In particular, the presence of the AM molecules effectively limits the crystal growth kinetics for the akaganeite (FeOOH) in the intermediate FeOOH@AM/RGO sample, which contributes to the transformation to Fe3O4 nanoparticles with significantly controlled size in the final Fe3O4@AMC/RGO composite. As a result, both Fe3O4 nanoparticles and AMC domains are adjacently anchored on the larger sized RGO sheets, and a unique hierarchical structure has been engineered in the Fe3O4@AMC/RGO sample. Compared with the controlled Fe3O4@RGO sample, the Fe3O4@AMC/RGO composite exhibits remarkably enhanced initial coulombic efficiency, superior cycling stability and rate performance for lithium-ion storage. The mechanisms of the interaction between GO sheets and AM molecules as well as the inspiring electrochemical behaviors of the Fe3O4@AMC/RGO electrode have been revealed. The Fe3O4@AMC/RGO sample possesses good potential for scaling-up and finding applications in wider fields.

Understanding the Impact of the Morphology, Phase Structure, and Mass Fraction of MnO2 within MnO2/Reduced Graphene Oxide Composites for Supercapacitor Applications

Understanding the Impact of the Morphology, Phase Structure, and Mass Fraction of MnO₂ within MnO₂/Reduced Graphene Oxide Composites for Supercapacitor Applications

Detection of Cd2+ and Pb2+ using amyloid oligomer–reduced graphene oxide composite

Heavy metal ions are toxic to humans and can further interact with amyloid in the human body to produce amyloid plaques, which disrupt neurotransmitter function and are linked to Alzheimer's and Parkinson's diseases. In this study, we developed an amyloid oligomer–reduced graphene oxide composite (AOrGOC) electrochemical sensor for effective heavy metal ion detection based on square-wave anodic stripping voltammetry. The reactivity between amyloids and heavy metal ions was studied by analyzing the stripping current for different amyloids (lysozyme, bovine serum albumin, and β-lactoglobulin) and amyloid growth types (monomers, oligomers, and fibrils). Reduced graphene oxide was used to improve the sensitivity of the sensor. The AOrGOC sensor exhibited the detection limits of 86.0 and 9.5 nM for Cd2+ and Pb2+, respectively, and selectively detected Cd2+ and Pb2+ over other heavy metal ions. The AOrGOC sensor also detected Cd2+ and Pb2+ in human plasma, thus exhibiting its potential as a biosensor. This study not only promoted our fundamental understanding of amyloids and the detection of heavy metal ions using amyloids, but also provided valuable insights into amyloid-based electrochemical sensors.

Simultaneous removal of ibuprofen and bisphenol A from aqueous solution by an enhanced cross-linked activated carbon and reduced graphene oxide composite

Reduced graphene oxide-modified activated carbon (RGO/AC) composites are promising materials for organic micropollutant removal from aqueous systems. However, the complex preparation processes and usage of toxic chemicals limit their applications. Here, several green cross-linking reagents, such as an extract solution (ES) originating from fermented tubers and cereal wastes, are developed to enhance the cross-linking of AC and RGO. The reactivity of RGO/AC composites was evaluated for bisphenol A (BPA) and ibuprofen (IBP) adsorption from an aqueous solution in single and binary systems. The cross-linking speed and degree for AC and RGO by ES originating from fermented cassava (RGO/AC1) and wheat residues (RGO/AC2) are better than those obtained for natural ES. Characterization results show that the specific surface area of the RGO/AC composites increases with the cross-linking phenomenon. The RGO/AC composites show a higher BPA and IBP removal efficiency and capability than pristine AC. Moreover, the adsorption competence of BPA and IPB on the surface of RGO/AC composites in the binary system was low. The adsorption of BPA and IBP by AC/RGO is dominated by pseudo-second-order kinetics and Freundlich isotherms in both single and binary systems. Hydrophobic and electrostatic interactions are dominant between BPA, IBP molecules, and adsorbents.

α-Fe2O3/Reduced Graphene Oxide Composites as Cost-Effective Counter Electrode for Dye-Sensitized Solar Cells

The counter electrode (CE) is an important and vital part of dye-sensitized solar cells (DSSCs). Pt CEs show high-performance in DSSCs using iodide-based electrolytes. However, the high cost of Pt CEs restricts their large-scale application in DSSCs and the development of Pt-free CE is expected. Here, α-Fe2O3/reduced graphene oxide (α-Fe2O3/RGO) composites are prepared as the Pt-free CE materials for DSSCs. A simple hydrothermal technique was used to disseminate the α-Fe2O3 solid nanoparticles uniformly throughout the RGO surface. The presence of the α-Fe2O3 nanoparticles increases the specific surface area of RGO and allows the composites to be porous, which improves the diffusion of liquid electrolyte into the CE material. Then, the electrocatalytic properties of CEs with α-Fe2O3/RGO, α-Fe2O3, RGO, and Pt materials are compared. The α-Fe2O3/RGO CE has a similar electrocatalytic performance to Pt CE, which is superior to those of the pure α-Fe2O3 and RGO CEs. After being fabricated as DSSCs, the current–voltage measurements reveal that the DSSC based on α-Fe2O3/RGO CE has a power conversion efficiency (PCE) of 6.12%, which is 88% that of Pt CE and much higher than that of pure α-Fe2O3 and pure RGO CEs. All the results show that this work describes a promising material for cost-effective, Pt-free CEs for DSSCs.

Cobalt nanocrystals doped on CeO2/RGO nanocomposite for supercapacitor applications

The synthesis of cobalt nanocrystals deposited cerium oxide (Co-CeO2) on reduced graphene oxide (RGO) sheets using a facile hydrothermal technique is described in this paper. The Cobalt deposited CeO2/RGO electrode shows outstanding electrocatalytic activity. The phase, morphology, and elemental composition and oxidation states of Co-CeO2 validated by PXRD, HRTEM-EDX and XPS respectively. The average surface area of the Co-CeO2/RGO composite is shown to be 81.125 m2/g as estimated by N2 adsorption isotherm. The cobalt doped with CeO2 nanoparticles over graphene sheets studied by HRTEM coupled with EDX. The electrochemical behavior of the Co-CeO2/RGO nanocomposite was studied using as an electrode by cyclic voltammetry (CV), Galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) measurements. The specific capacitance of the material Csp was found to be 843.8 Fg−1 at a lower current density of 1.0 Ag−1. Furthermore, with a power density of 230Wkg−1, it has a greater energy density of 93.19 Whkg−1.

NiS1−xSex Nanoparticles Anchored on Nitrogen-Doped Reduced Graphene Oxide as Highly Stable Anode for Sodium-Ion Battery

Nickel sulfides are regarded as one of the promising anode materials for sodium-ion batteries (SIBs), but the sluggish electrodes kinetics and rapid capacity decay, caused by their intrinsic low electrical conductivity and high bulk expansion, greatly limit their practical application. To overcome these obstacles, nano-sized, selenium-doped, nickel sulfide particles, anchored on nitrogen-doped reduced graphene oxide composites (NiS1−xSex@N–rGO), are rationally synthesized. The broad Na+ diffusion channels, resulting from Se doping, as well as the short Na+ transferring path, attributed from nano-size scale of NiS1−xSex particles, endow NiS1−xSex@N–rGO composites with ultrafast storage kinetics. Moreover, strong coupled effect between the NiS1−xSex and N–rGO is beneficial to the uniform dispersion of NiS1−xSex nanoparticles, improving electrical conductivity and suppressing the volume variation in charge/discharge process. Furthermore, the cut-off discharge voltage is modulated to realize the smaller volume change during cycle process. As a result, the fabricated anode of SIBs based on NiS1−xSex@N–rGO composites exhibits a high specific capacity of 300 mAh g−1, at the current density of 1 A g−1, after 1000 cycles with almost no capacity degradation.

Vertically Oriented MXene Bridging the Frequency Response and Capacity Density Gap for AC‐Filtering Pseudocapacitors

AbstractElectrochemical capacitors (ECs) with high‐rate characteristics demonstrate great promise for replacing bulky aluminum electrolytic capacitors with alternate current (AC)‐filtering functions. Currently, the performance of AC‐line filtering ECs is limited by the vast gap between the ionic transport kinetics and capacity density of electrode materials. Herein, vertically oriented MXene and reduced graphene oxide composite (VMG) electrodes are prepared by electrochemical co‐deposition to bridge the performance gap for AC‐line filtering ECs. Benefiting from the unique pseudocapacitive characteristic and vertically interconnected microstructure, the VMG‐based EC exhibits an outstanding areal capacitance of 1.14 mF cm−2 with a phase angle of −80° at 120 Hz. Moreover, by utilizing the advantages of MXene at negative potential, an asymmetric pseudocapacitor is constructed with an energy density up to 805 µF V2 cm−2 at 120 Hz, which can be further incorporated in portable and wearable devices with excellent environmental ripple filtering capability in diverse scenarios.

Highly improved nonlinear optical responses of reduced graphene oxide via the decoration of Ni doped ZnS nanoparticles

The application of graphene and graphene-like materials in photonics has attracted extensive attention in recent years. However, their nonlinear optical (NLO) properties need to be improved urgently. Herein, we demonstrate a method to improve the NLO properties of reduced graphene oxide (RGO) via the decoration of Ni transition element doped ZnS nanoparticles on RGO sheet. The samples of Ni doped ZnS decorated RGO (Ni-ZnS/RGO) composites with different Ni doping concentrations and ZnS particles sizes were synthesized via a facile solvothermal method. The NLO responses of Ni-ZnS/RGO composites were investigated via the Z-scan technique under a picosecond laser at 1064 nm. The results indicated that Ni-ZnS/RGO composites exhibited saturation absorption and positive nonlinear refraction properties, and they could be adjusted by controlling the doping concentration of Ni and the size of ZnS nanoparticles. The maximum saturation absorption coefficient, nonlinear susceptibility and nonlinear refractive index of Ni-ZnS/RGO among all the samples were obtained to be − 2.5 × 10−10 mW−1, 3.2 × 10−13cm2/W and 14.1 × 10−14cm2/W, which were 25, 18 and 23 times of those of RGO, and 3.6, 11.7 and 4.2 times of those of ZnS doped with 2.5%Ni, respectively. They were also much greater than those of the direct sum of the two independent units, RGO and Ni-doped ZnS. These highly improved NLO responses of Ni-ZnS/RGO composites were ascribed to the inhibition of the direct electron-hole recombination due to the introduction of Ni doped impurity energy levels within the band gap of ZnS, as well as the charge transfer and synergism between ZnS and RGO. The results of this investigation may promote the development and applications of Ni-ZnS/RGO materials in photonic devices.