Partially Reduced Graphene Oxide Research Articles

Graphene-Loaded Aphron Microbubbles for Enhanced Drilling Fluid Performance and Carbon Capture and Storage.

Maintaining the stability of microbubbles is essential for enhancing the longevity of aphronic water-based drilling fluid usage in drilling depleted reservoirs and other under-pressured zones. Here, we introduce the integration of partially reduced graphene oxide (PrGO) nanosheets into the shell of aphron microbubbles (AMBS) to enhance the stability and size distribution, particularly for drilling fluid applications and carbon geological storage. The amphiphilic characteristic of PrGO nanosheets, due to meticulous control of the reduction process of graphene oxide, facilitates their spontaneous adsorption at interfaces, thereby reducing the interfacial energy as a two-dimensional surfactant. The loading of PrGO nanosheets in the polymeric shell of AMBs enhances mechanical strength, stability, and resistance to gas diffusion, prolonging the half-life of the microbubbles to over 120%. According to the results, a more uniform size distribution and reduction of microbubble size up to 60% have been achieved at a concentration of 0.30 wt % PrGO. Rheological studies using various models indicate the optimal PrGO concentration for improved stability in aphronic fluids. Filtration tests indicate the loaded PrGO can reduce filtration loss by up to 45% at 0.50 wt % by forming a cohesive and compressible cake, improving filtration control. Changes in the Fourier-transform infrared spectra and contact angle measurements suggest increased surface hydrophobicity with higher graphene concentrations in aphronic fluid cakes. Moreover, the study elucidates that the stability of microbubbles is influenced by the type of core gas, with N2 gas yielding the highest stability and CO2 the lowest. Ultimately, these results highlight the beneficial effect of incorporation of PrGO nanosheets in aphron microbubbles to boost the drilling fluid performance and efficiency, which will pave the way toward ultralightweight fluids that can even be used as carrier and injection fluids in carbon capture and leak-free geological storage technologies.

Electronegative graphene film based interface-chemistry regulation for stable lithium metal batteries

To achieve practical application of lithium (Li) metal anodes for high-energy–density batteries, the primary challenges of the inhomogeneous solid electrolyte interphase (SEI) and irregular Li electrochemical stripping/depositing behaviors should been surmounted. So as to homogenize Li+ distribution and stabilize the SEI layer, herein, we reported a partially reduced graphene oxide (PrGO) film with a manageable electronegativity as an ideal Li host to construct composite electrode (PrGO@Li). The fabricated PrGO with tunable oxygen amount and negatively charge can achieve controllable Li capacity avoiding excess Li. More importantly, the electronegative PrGO film matrix can cause an electrostatic force and thereby regulate the Li+ distribution pattern and diffusion kinetics, which induces a homogeneous and stable LiF-rich SEI and highly conformal Li+ stripping/deposition behaviors without Li dendrites. As a result, the optimal PrGO@Li electrode delivers long-term reversible Li+ stripping/depositing processes with an extremely low overpotential (7 mV) after 2000 h cycling at 20 mA cm−2 and 10 mAh cm−2. Moreover, the full battery based on this anode paired with LiFePO4 cathode exhibits outstanding cycling stability, high rate capacity and excellent flexibility characters. Meanwhile, the controllable PrGO films can also be loading with sulfur as cathodes for satisfactory Li/sulfur batteries. This research deeply analyzes the intermediation mechanism between the graphene host and Li+ on the electrochemical behaviors, and offers universal guidance for the development of high-performance Li-metal batteries.

Partially reduced graphene oxide as an efficient adsorbent towards ionic dyes and interaction mechanism

Graphene based adsorbent has fascinating perspective in environmental application. Herein, partially reduced graphene oxide (PRGO) was facilely prepared with hydrothermal method. The as prepared PRGO was characterized and utilized as adsorbent to remove Congo red (CR) and malachite green (MG). Moreover, adsorption mechanism was elaborately surveyed via adsorption fitting (isotherm, kinetic and thermodynamic) and spectroscopic analysis (FTIR, UV-Vis). Results show, CR, MG adsorption by PRGO swiftly reaches equilibrium in 8 min and 10 min, with adsorption quantity 121.29 mg g−1 and 198.10 mg g−1 respectively. Both adsorptions are chemically favorable as satisfactorily described by the Freundlich model and pseudo second order model in equilibrium level and non equilibrium level, respectively. With regard to adsorption mechanism, adsorption is associated with both polar and non polar interactions. For CR adsorption, the specific form of polar and non polar interaction is hydrogen bond and π-π interaction, respectively. While for MG adsorption, the specific form of polar and non polar interaction is electrostatic attraction and π-π interaction, respectively. This work may provide insight for exploiting graphene related adsorbent for environmental treatment.

Amplified hybrid surface plasmon polaritons in partially reduced graphene oxide supported on gold

We experimentally investigated the surface plasmon polaritons' (SPPs) localisation, resonance, and propagation in three plasmonic waveguides: graphene oxide (GO), partially reduced graphene oxide (PRGO), and reduced graphene oxide (RGO) in two configurations; as stand-alone structures and when deposited on gold films. Our experiments measuring the nonlinear absorption/refraction and leakage radiation microscopy (LRM) reveal that the intense Lorenz/Fano resonance of surface plasmon polaritons can occur in the PRGO-based waveguide. We also observe an increasing surface plasmon polaritons generation rate in PRGO-supported Au waveguide, a procedure similar to the spaser (surface plasmon nanolaser) mechanism. This, in turn, leads to increasing the propagation length. Furthermore, our analytical simulation results also suggest the suitability of PRGO as a superior optical material for spaser application. Our density functional calculations confirm that oxidised graphene has a more robust absorption spectrum in infrared wavelengths than pure graphene. Additionally, through van der Waals interaction, PRGO forms a more consistent and uniform bond with gold substrate than pristine graphene, reinforcing the suitability of PRGO as plasmonic waveguides.

Nano-flower like CoFe-layered double hydroxide@reduced graphene oxide with efficient oxygen reduction reaction for high-power air-cathode microbial fuel cells

Microbial fuel cells (MFCs) are “self-sufficient” renewable energy sources that utilize the redox processes inherent in microbial metabolism to generate an electrical potential. However, the cathodic region of these fuel cells typically utilizes an oxygen reduction reaction (ORR) operating at high overpotential and slow reaction kinetics significantly, restricting the power generation capacity of MFCs. Herein, to improve the cathodic reduction efficiency, we synthesized CoFe-layered double hydroxides (LDH) on partially-reduced graphene oxide (p-rGO) via electrostatic interaction. In contrast to pure CoFe-LDH, CoFe-LDH@p-rGO composite possessed a three-dimensional uniform porous nanoflower-like morphology, giving the catalyst a high surface area for efficient catalysis. The proportions of CoFe-LDH to p-rGO were optimized to minimize layer stacking through strong π-π bond and van der Waals force, maximizing the overal electron transfer numbers n (3.66), with the lowest charge transfer resistance Rct (38.5 Ω). As a result, this novel catalyst combined the rich Co/Fe metal center catalytic active sites and interlayer structure of CoFe-LDH, with the high electrical conductivity of p-rGO to accelerate the electron transfer rate of ORR. Air-cathode microbial fuel cell (ACMFC) utilizing CoFe-LDH@p-rGO catalyst showed comparable output voltage of 423 mV to Pt/C catalyst, and a comparably high-power density of 204 mW m−2. This work provides a new path towards development of nanostructured non-noble metal catalysts for the optimization of oxygen reduction reaction in high-power ACMFCs.

Gut microbiome interactions with graphene based nanomaterials: Challenges and opportunities

Rapid growth of nanotechnology has accelerated immense possibility of engineered nanomaterials (ENMs) exposure by human and living organisms. In this context, wide range applications of graphene based nanomaterials (GBNMs) may inevitably cause their release into the environment. Consequently, potential risks to the ecological system and human health is consistently increasing due to the probable ingestion of GBNMs by mean of contaminated water or food sources. Further, gut microbiome is known to play a profound impact on the health status of human being and has been recognized as the most exciting advancement in the biomedical science. Recent studies has shown vital role of ENMs to alter gut microbiome and thereby changed pathological status of organisms. Therefore, in this review results of numerous studies dedicated to explore the impact of GBNMs on gut microbiome and thereby various pathological status have been summarized. Dietary exposure of different types of GBNMs [e.g. graphene, graphene oxide (GO), partially reduced graphene oxide (PRGO), graphene quantum dots (GQDs)] have been evaluated on the gut microbiome through numerous in vitro and in vivo models. Moreover, emphasis has been made to evaluate different physiological responses with the short/long-term exposure of GBNMs, particularly in gastrointestinal tract (GIT) and its correlation with gut microbiome and the health status. It is reviewed that exposure of GBNMs can exert significant impact which alter the composition, diversity and function of gut microbiome. This may further appear in terms of enteric disorder along with numerous pathological changes e.g. IEC (intestinal epithelial cells) colitis, lysosomal dysfunction, inflammation, shortened colon, resorbed embryo, retardation in skeletal development, low weight of fetus, early or late dead of fetus and IBD (inflammatory bowel disease) like symptoms. Finally, potential health risks due to the exposure of GBNMs have been discussed with future perspective.

Characterization of the Adsorption of Bisphenol A and Carbamazepine from Aqueous Solution on Graphene Oxide and Partially Reduced Graphene Oxide by High-Performance Liquid Chromatography (HPLC)

Two carbonaceous materials were prepared and characterized for their effectiveness in eliminating bisphenol A (BPA) and carbamazepine (CBZ) from aqueous solution. The adsorption of these pollutants was investigated because these compounds are unregulated in water legislation and their prevalence and toxicity require special attention related to their removal. There is a global concern linked to indirect ingestion of endocrine disrupting compounds (EDCs) and pharmaceuticals due to their deleterious effects on humans and animal health. In order to determine the optimum adsorption parameters, the influence of the contact time and of the initial concentration of pollutant were investigated. According to the Langmuir model, the maximum adsorption capacity (qmax) of partially reduced graphene oxide (PRGrO) for BPA and CBZ (346.07 mg/g respectively 55.13 mg/g) was higher than qmax of graphene oxide (GO) (92.40 mg/g, respectively 32.35 mg/g). Considering these results, we suggest that partially reduced graphene oxide is a promising and effective adsorbent for the removal of bisphenol A and carbamazepine from aqueous solutions. To our knowledge, there are no other studies related to the adsorption of these pollutants on partially reduced graphene oxide.

Robust seawater desalination and sewage purification enabled by the solar-thermal conversion of the Janus-type graphene oxide evaporator

The state-of-the-art structure design of solar-thermal evaporators demonstrating convenient manufacture, high evaporation rate, high energy efficiency and multiple environment evaporation is urgently needed in solar-driven low-energy water purification/harvesting. Herein, a novel Janus-type graphene oxide (GO) evaporator is proposed by chemical crosslinking to form integrated GO hydrogel and sunlight triggered partial reduction of top GO layer. The partially reduced GO (PRGO) nanosheets present an extremely high solar absorbance of 92.97%, leading to an efficient localized solar-thermal conversion. The porous and hydrophilic GO hydrogel facilitates the fast vertical water transport to the top PRGO photothermal layer. Taking advantages of the synergistic effect in the water-energy nexus, the Janus-type solar-thermal evaporator evaporates water with an ultra-high rate of 3.24 kg·m−2·h−1 via 99.98% energy efficiency from 1sun irradiation with a low GO loading of 0.146 wt%. The Janus-type GO evaporator presents robust desalination and purification performances in simulated seawater, sewage and acidic/alkaline water. Furthermore, a portable solar-thermal water purification device equipped with the Janus-type GO evaporator desalts a real seawater far above the drinking water standard with a 99.99% salt rejection rate and removes 90.90% of total carbon in a real sewage, highlighting its potential for high-performance clean water harvesting.

Hydrothermal-Freeze-Casting of Poly(amidoamine)-Modified Graphene Aerogels towards CO2 Adsorption.

This article presents novel poly(amidoamine) (PAMAM) dendrimer-modified with partially-reduced graphene oxide (rGO) aerogels, obtained using the combined solvothermal synthesis-freeze-casting approach. The properties of modified aerogels are investigated with varying synthesis conditions, such as dendrimer generation (G), GO:PAMAM wt. ratio, solvothermal temperature, and freeze-casting rate. Scanning electron microscopy, Fourier Transform Infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy are employed to characterize the aerogels. The results indicate a strong correlation of the synthesis conditions with N content, N/C ratio, and nitrogen contributions in the modified aerogels. Our results show that the best CO2 adsorption performance was exhibited by the aerogels modified with higher generation (G7) dendrimer at low GO:PAMAM ratio as 2:0.1 mg mL−1 and obtained at higher solvothermal temperature and freeze-casting in liquid nitrogen. The enclosed results are indicative of a viable approach to modify graphene aerogels towards improving the CO2 capture.

Lightweight and high-efficiency microwave absorption of reduced graphene oxide loaded with irregular magnetic quantum dots

Due to the excessively high electrical conductivity and single dielectric properties of the graphene material, when used as a wave absorbing material, the imbalance of impedance matching causes strong reflection effects, resulting in poor wave absorbing performance. In this research, we partially reduced graphene oxide (GO) and loaded magnetic quantum dots (MQDs) through a one-step pyrolysis method, and a novel composite material of three MQDs (Fe, Fe3O4, Fe3C) embedded partially reduced graphene oxide (P-rGO) was prepared and the influence of pyrolysis temperature on its electromagnetic performance was systematically studied. The research found that ethylene glycol selectively reduced the CO functional group of the GO component and enhanced its dielectric properties; the loading of MQDs for a single carbon material increased the magnetic loss mechanism and improved the impedance matching and attenuation capabilities. In addition, the flaky structure of GO and the ultra-small nanostructure of MQDs suppress the eddy current effect and promote the occurrence of exchange resonance between magnetic particles. The prepared four sets of samples exhibit excellent absorbing properties in the 2–18 GHz frequency band. Among them, the samples prepared by pyrolysis at 800 °C can obtain 5.59 GHz broadband electromagnetic wave absorption at an ultra-thin thickness of 1.7 mm. The special quantum size effect and enhanced electromagnetic wave attenuation capabilities are the main reasons for the high-efficiency microwave absorption of MQDs/P-rGO composite materials.

Acetamide-assisted hydrothermal growth of NiCo double hydroxide on graphene modified Ni foam for high-performance supercapacitor

The free-standing hierarchical flower-like NiCo-double hydroxide/reduced graphene oxide composite (NiCo-DH/RGO) on Ni foam (NiF) was synthesized with a facile two-step method. First, the growth of partially reduced graphene oxide (PRGO) membrane on NiF was achieved via the direct reduction of graphene oxide (GO) by NiF, which acted as not only the reducing agent but also the current collector. Then, the growth of high mass-loading NiCo-DH on PRGO/NiF was realized with a hydrothermal process, in which acetamide plays a crucial role. The high mass-loading of NiCo-DH is due to the addition of acetamide into the hydrothermal bath, in which PRGO reacted with the solution, containing Ni(II), Co(II), acetamide and urea, to form a thick gelatinous membrane on Ni foam. During the hydrothermal process, PRGO was further reduced to RGO while both Ni(II) and Co(II) reacted with ammonium, released by the hydrolysis of urea, to form NiCo-DH. Used as the positive electrode of supercapacitor, NiCo-DH/RGO/NiF displays an ultrahigh areal capacity of 6.15 C cm−2 at 10 mA cm−2 and 94.6% capacity retention after 1000 GCD cycles at 10 mA cm−2. An asymmetric supercapacitor (ASC) is also assembled with NiCo-DH/rGO/NiF as the positive electrode and activated carbon (AC) as the negative electrode. The ASC exhibits a prominent energy density of 61.81 Wh kg−1 at a high power density of 842.63 W kg−1. It is especially worth noting that the ASC exhibited remarkable capacity retention of 84.53% even after 1000 GCD cycles at a current density of 10 mA cm−2.

Reduced graphene oxide foam templated by nickel foam for organ-on-a-chip engineering of cardiac constructs.

Myocardial tissue engineering has attracted increasing awareness for heart failure, and researchers are committed to developing an appropriate biological material to reconstruct myocardial tissues. Here, we applied a simple and high-throughput method to fabricate a three-dimensional (3D) partially reduced graphene oxide (PRGO) foam chip, whose structure, properties and biocompatibility confirmed that it is a suitable material for myocardial tissue engineering. The PRGO foam was produced based on a reduction reaction that occurred at the interface between the graphene oxide (GO) solution and Ni foam; as the Ni foam scaffold was dissolved in an HCl solution, the PRGO foam was harvested. After the PRGO foam was freeze-dried, its elasticity property was evaluated, and primary cardiomyocytes obtained from 2-day-old SD rats were cultured in the 3D foam. The results demonstrated good cell adherence, spreading, activity, organization and beating function in the PRGO foam during the long-term culturing process, which proved that the PRGO foam obtained by this method had application potential for myocardial tissue engineering.

Protein interactions and conformations on graphene-based materials mapped using a quartz-crystal microbalance with dissipation monitoring (QCM-D)

Graphene-based materials have shown significant potential for biomedical applications including biosensors, cell scaffolds and drug delivery. However, the interaction of complex biomacromolecules like proteins with graphene and its derivatives, graphene oxide (GO) and reduced (r)GO, remains poorly understood. Here, we demonstrate that the quartz-crystal microbalance with dissipation monitoring (QCM-D) technique can be used to systematically study the interaction dynamics of a typical protein, bovine serum albumin (BSA), with graphene materials of varying degrees of functionalisation. We find significant differences in molecular orientation and confirmation, mass adsorption and biochemical functionality of BSA on different graphene surfaces, determined by both the population of functional groups of GO and the protein concentration. The dominant forces during the adsorption of biomolecules onto GO and rGO are shown to be hydrophilic and hydrophobic interactions, respectively. The GO surface yielded higher BSA adsorption than both rGO and control standard gold electrodes due to the high density of functional groups. The biochemical functionality of adsorbed BSA was investigated through the interaction with its anti-BSA antibody counterpart. BSA on GO can retain its binding sites while, in contrast, a denatured ad-layer of BSA forms on the rGO followed by further binding of active BSA molecules, depending on the concentration of the protein. Intermediate conformations are observed for partially-reduced GO. These results also suggest that QCM-D is a viable readout technique for graphene-based biosensors. This QCM-D approach could be further extended to study the interaction of a host of biomolecules and their assemblies, including whole cells, with 2-dimensional materials.

Fast Identification and Quantification of Graphene Oxide in Aqueous Environment by Raman Spectroscopy.

Today, graphene nanomaterials are produced on a large-scale and applied in various areas. The toxicity and hazards of graphene materials have aroused great concerns, in which the detection and quantification of graphene are essential for environmental risk evaluations. In this study, we developed a fast identification and quantification method for graphene oxide (GO) in aqueous environments using Raman spectroscopy. GO was chemically reduced by hydrazine hydrate to form partially reduced GO (PRGO), where the fluorescence from GO was largely reduced, and the Raman signals (G band and D band) were dominating. According to the Raman characteristics, GO was easily be distinguished from other carbon nanomaterials in aqueous environments, such as carbon nanotubes, fullerene and carbon nanoparticles. The GO concentration was quantified in the range of 0.001–0.6 mg/mL with good linearity. Using our technique, we did not find any GO in local water samples. The transport of GO dispersion in quartz sands was successfully quantified. Our results indicated that GO was conveniently quantified by Raman spectroscopy after partial reduction. The potential applications of our technique in the environmental risk evaluations of graphene materials are discussed further.

One-pot sonochemical synthesis of CuS nanoplates decorated partially reduced graphene oxide for biosensing of dopamine neurotransmitter.

The sonochemical methods have been used as a straight forward method for the synthesis of various composite materials, including the transition metal dichalcogenide composites. In the present work, we report a simple sonochemical synthesis of CuS nanoplates decorated partially reduced graphene oxide (PrGO) nanocomposite for the first time. The PrGO-CuS nanocomposite was synthesized using bath-sonication (frequency: 37kHz; power: 150W) of graphene oxide (GO), and CuS precursors at 80°C for 60min. The physicochemical characterization (FESEM, XRD, FTIR, and Raman spectroscopy) results confirmed the successful formation of CuS nanoplates on PrGO nanosheets. The as-synthesized PrGO-CuS nanocomposite was further utilized for electroanalysis of dopamine neurotransmitter. The obtained electroanalytical results revealed that PrGO-CuS nanocomposite has superior electrochemical activity towards dopamine than those obtained for GO, CuS, and GO-CuS composite. The fabricated biosensor shows a lower limit of detection (0.022µM) with a more comprehensive linear response range (0.1-155.1µM) for the detection of dopamine. Moreover, the PrGO-CuS nanocomposite electrode was successfully used for the detection of dopamine in bovine serum albumin.

Enhanced water oxidation catalytic performance of graphene oxide by gamma ray irradiation post-treatment

Herein, we report the influence of γ-ray irradiation process on the physicochemical properties of partially reduced graphene oxide (PRGO) thin films. It is found that γ-ray irradiation at 25 kGy alters the surface, chemical environment, and wettability properties of PRGO via inducing edge sites and oxygen moieties, resulting in enhanced water oxidation performance.

Fully integrated wearable humidity sensor based on hydrothermally synthesized partially reduced graphene oxide

In this paper, partially reduced graphene oxide (PRGO) nanosheets were prepared by an environmentally friendly hydrothermal route and their morphology, structure and humidity sensing performance were investigated. The sensor structure with gold interdigitated electrodes was fabricated on flexible polyimide substrate via standard lithography technology. The integration of a commercial Bluetooth module enabled real-time wireless transmission of sensing data to the smart phone application. Characterization data showed a decrease in the amount of oxygen functional groups attached to the PRGO nanosheets when the hydrothermal reduction time was increased. It was found that the flexible PRGO-4h sensor exhibits impressive response and quick response/recovery times over a wide range of RH levels. According to the experimental results, the enhanced response of PRGO-4h is attributed to the considerable oxygen functional groups and the improved response/recovery times are attributed to the restoration of sp2 carbon network. The performance of sensor remained nearly unchanged under bending condition. Taking the advantage of fast response/recovery time and flexibility, the sensor can monitor human respiration in real time. This work demonstrates that the potential application of PRGO-4h as a sensitive material for indication of environmental humidity as well as future generation of wearable humidity sensors.

Hydrothermally synthesized Pd-loaded SnO2/partially reduced graphene oxide nanocomposite for effective detection of carbon monoxide at room temperature

In this paper, palladium (Pd)-loaded tin dioxide (SnO2)/partially reduced graphene oxide (PRGO) nanocomposites with different proportions of Pd loading and PRGO nanosheets were synthesized by the facile hydrothermal method for carbon monoxide (CO) sensing applications. The crystal structure, morphology and composition of sensitive materials were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectrometer (EDX), respectively. Characterization data show that PRGO nanosheets act as a template for growth of small-sized SnO2 nanoparticles. The gas sensing properties of all sensors were investigated by exposing them to various concentrations of CO gas ranging from 50 to 1600ppm at 26°C. The synthesized 5%Pd-loaded SnO2/PRGO-1.5% sensor exhibited a very reproducible performance with fast response and recovery time (∼2min) at 26°C. The ability of detecting CO gas at room temperature could be attributed to the high specific surface area of PRGO nanosheets, good conductivity of PRGO and special interactions between PRGO nanosheets and Pd-loaded SnO2 nanoparticles.

Partially Reduced Graphene Oxide Modified Tetrahedral Amorphous Carbon Thin-Film Electrodes as a Platform for Nanomolar Detection of Dopamine

In this study we present for the first time tetrahedral amorphous carbon (ta-C)—a partially reduced graphene oxide (PRGO) hybrid electrode nanomaterial platform for electrochemical sensing of dopamine (DA). Graphene oxide was synthesized with the modified Hummer’s method. Before modification of ta-C by drop casting, partial reduction of the GO was carried out to improve electrochemical properties and adhesion to the ta-C thin film. A facile nitric acid treatment that slightly reoxidized the surface and modified the surface chemistry was subsequently performed to further improve the electrochemical properties of the electrodes. The largest relative increase was seen in carboxyl groups. The HNO3 treatment increased the sensitivity toward DA and AA and resulted in a cathodic shift in the oxidation of AA. The fabricated hybrid electrodes were characterized with scanning electron microscopy (SEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray...

Methane gas sensing properties of Pd-doped SnO2/reduced graphene oxide synthesized by a facile hydrothermal route

In this paper, palladium (Pd)-doped tin oxide (SnO2)/partially reduced graphene oxide (PRGO) and Pd-doped SnO2/reduced graphene oxide (rGO) nanocomposites are synthesized via a simple hydrothermal route. Field emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD) are used to characterize the structure, morphology and composition of the crystalline phases of the prepared gas sensitive materials. The FESEM images confirm the existence of homogeneous dispersion of Pd-doped SnO2 nanoparticles anchored onto the rGO/PRGO nanosheets. Then the application of these nanocomposites is investigated as methane (CH4) gas sensor and compared with each other. The performance of sensors is studied toward CH4 gas concentrations ranging from 800 to 16000 part per million (ppm) at room temperature. The fabricated sensors show an enhancement in the electrical conductivity with increasing CH4 concentration. The synthesized Pd-doped SnO2/rGO nanocomposite in comparison with Pd-doped SnO2/PRGO, exhibits better sensitivity, excellent selectivity and relatively short response time to CH4 at room temperature. The excellent sensing performance of sensor could be ascribed to the presence of Pd nanoparticles and rGO nanosheets in the sensing nanocomposite.