Nanoparticle-decorated Reduced Graphene Oxide Research Articles

Facile preparation of copper nanoparticles-decorated reduced graphene oxide for the catalytic reduction of water toxins

Facile preparation of copper nanoparticles-decorated reduced graphene oxide for the catalytic reduction of water toxins

Capacitive immunosensing at gold nanoparticle-decorated reduced graphene oxide electrodes fabricated by one-step laser nanostructuration

Nanostructured electrochemical biosensors have ushered in a new era of diagnostic precision, offering enhanced sensitivity and specificity for clinical biomarker detection. Among them, capacitive biosensing enables ultrasensitive label-free detection of multiple molecular targets. However, the complexity and cost associated with conventional fabrication methods of nanostructured platforms hinder the widespread adoption of these devices. This study introduces a capacitive biosensor that leverages laser-engraved reduced graphene oxide (rGO) electrodes decorated with gold nanoparticles (AuNPs). The fabrication involves laser-scribed GO-Au3+ films, yielding rGO-AuNP electrodes, seamlessly transferred onto a PET substrate via a press-stamping methodology. These electrodes have a remarkable affinity for biomolecular recognition after being functionalized with specific bioreceptors. For example, initial studies with human IgG antibodies confirm the detection capabilities of the biosensor using electrochemical capacitance spectroscopy. Furthermore, the biosensor can quantify CA-19-9 glycoprotein, a clinical cancer biomarker. The biosensor exhibits a dynamic range from 0 to 300 U mL−1, with a limit of detection of 8.9 U mL−1. Rigorous testing with known concentrations of a pretreated CA-19-9 antigen from human fluids confirmed their accuracy and reliability in detecting the glycoprotein. This study signifies notable progress in capacitive biosensing for clinical biomarkers, potentially leading to more accessible and cost-effective point-of-care solutions.

One-Pot Solvothermal Synthetic Route of a Zinc Oxide Nanoparticle-Decorated Reduced Graphene Oxide Nanocomposite: An Advanced Material with a Novel Anticancer Theranostic Approach.

This study focuses on a one-pot solvothermal synthetic route for the preparation of uniformly decorated zinc oxide nanoparticles on the surface of reduced graphene oxide (rGO/ZnO-NC) by using Andrographis paniculata leaf aqueous extract as an eco-friendly reducing agent. After characterizing the samples by different physical and chemical techniques, the anticancer activity of the synthesized rGO/ZnO-NC was examined on two human cancerous cell lines (HCT116 and A549) and one normal cell line (hMSCs). The MTT assays revealed that rGO/ZnO-NC exhibited dose-dependent cytotoxicity at a maximum concentration range of 10 ppm and the viability of the cells was drastically decreased to 95-96%. Measurement of reactive oxygen species (ROS) generation and Annexin V-FTIC staining assay revealed that rGO/ZnO-NC induced apoptosis in HCT116 and A549 cell lines. Thus, this study shows that the green-synthesized rGO/ZnO-NC has great potential in developing an efficacious novel therapeutic agent for cancers.

Platinum nanoparticle-decorated reduced graphene oxide nanosheets: A recyclable and highly efficient catalyst towards the reduction of para-nitrophenol and methylene blue

The present study focuses on the design and development of Pt nanoparticle (PtNPs) decorated reduced graphene oxide (RGO) nanohybrid as an efficient heterogeneous catalyst towards the reduction of p-nitrophenol (p-NP) and methylene blue (MB). The citrate reduction of chloroplatinic acid in the presence of amino-propyl trimethoxy silane (APTMS) modified graphene oxide (GO) produced RGO/PtNPs nanohybrid comprised of uniform and high-density distribution of smaller-sized PtNPs. The APTMS provide efficient nucleation points via their amino groups and thereby play a vital role in regulating the size as well as the distribution of the anchored PtNPs in the present approach. The morphological and structural characterization of RGO/PtNPs nanohybrid was done by using X-ray powder diffraction, scanning and transmission electron microscopy, Fourier transform infrared and Raman spectroscopic techniques. The homogeneous and high-density dispersion of smaller-sized PtNPs endows superior catalytic activity to RGO/PtNPs nanohybrid. The nanohybrid exhibited outstanding catalytic performance enabling rapid reduction of both p-NP and MB at ambient conditions. The estimated rate constants for p-NP and MB reduction were 15.9 × 10−3, and 187 × 10−3 s−1 respectively, which outperform the rate constants of several previously reported metal-based GO/RGO nanocatalysts. The recycling tests showed that the nanohybrid maintained good catalytic stability even after the fifth recycle run. The RGO/PtNPs nanohybrid can be exploited for sustainable and efficient catalytic reduction of other environmental pollutants also. Further, the strategy followed in the present study to achieve homogenous and high-density distribution of Pt nanoparticles could be adopted for the anchoring of other metal/metal oxide/semiconductor nanoparticles.

Biofabricated Palladium Nanoparticle-Decorated Reduced Graphene Oxide Nanocomposite Using the Punica granatum (Pomegranate) Peel Extract: Investigation of Potent In Vivo Hepatoprotective Activity against Acetaminophen-Induced Liver Injury in Wistar Albino Rats.

Acute acetaminophen (APAP) toxicity is a predominant clinical problem, which causes serious liver injury in both humans and experimental animals. This study presents the histological and biochemical factor and antioxidant enzyme level changes induced by an acute acetaminophen overdose in Wistar albino rat livers to elucidate the effective hepatoprotective potential of biofabricated palladium nanoparticle-decorated reduced graphene oxide nanocomposites (rGO/PdNPs-NC) compared to silymarin. After detailed characterization of the hepatoprotective potential of the synthesized rGO/PdNPs-NC, the rats were divided into eight groups (n = 6): control group (normal saline, 1 mL/kg b.w.), silymarin, Punica granatum (pomegranate) peel extract, PdNPs, reduced graphene oxide (rGO-PG), and reduced graphene oxide palladium nanocomposites (rGO/PdNPs-NC, low and high doses) for 7 successive days. The acetaminophen (APAP)-treated group was administered a single dose of acetaminophen (2 g/kg b.w.) on the 8th day. The histopathological results showed that the acetaminophen overdose group exhibited massive intrahepatic hemorrhagic necrosis around the centrilobular region with hepatocytes with vacuolization and swollen cytoplasm found in the liver architecture. This hepatopotential was further assessed by various biochemical parameters such as SGOT, SGPT, ALB, ALP, LDH, direct bilirubin, total bilirubin, and total protein. Also, the antioxidant parameters such as SOD, CAT, MDA, GSH, GRD, and GST were assayed. Rats of groups 7 and 8 showed a significant decrease in SGOT, SGPT, ALP, LDH, direct bilirubin, and total bilirubin (p < 0.001), while a significant increase in the final total protein and ALB as compared to group 2 rats (p < 0.001) was observed. The antioxidant parameters exhibited that rats of groups 7 and 8 showed a significant (p < 0.001) increase in the level of SOD, CAT, GSH, GRD, and GST without affecting the MDA as compared to group 2 rats. Also, the hepatoprotective potential of rGO/PdNPs-NC (low and high doses) was comparable to that of the standard reference drug silymarin. The present study reveals that the rGO/PdNPs-NC possesses significant hepatoprotective activity and acts as an effective and promising curative agent against acetaminophen-induced hepatotoxicity.

Synthesis of NiO-Doped ZnO Nanoparticle-Decorated Reduced Graphene Oxide Nanohybrid for Highly Sensitive and Selective Electrochemical Sensing of Bisphenol A in Aqueous Samples

Synthesis of NiO-Doped ZnO Nanoparticle-Decorated Reduced Graphene Oxide Nanohybrid for Highly Sensitive and Selective Electrochemical Sensing of Bisphenol A in Aqueous Samples

Ultrafine Sb2O3 Nanoparticle-Decorated Reduced Graphene Oxide as an Anode Material for Lithium-Ion Batteries

Antimony (Sb)-based materials have shown great potential as anode materials for lithium-ion batteries (LIBs) owing to their high energy density as well as long lifespan. However, the huge volume variation upon cycling will result in severe capacity fading, thus hindering the practical application of Sb-based anode materials. Herein, an ultrafine Sb2O3 nanoparticle-decorated reduced graphene oxide (rGO) composite (denoted as Sb2O3/rGO) was developed through a facile thermal decomposition of antimony 2-ethylhexanoate on rGO in the air at low temperatures, where the ultrafine Sb2O3 nanoparticles are homogeneously anchored on the rGO substrate. Benefiting from the rich mesoporous structure, large specific surface area, moderate mass loading, and uniform dispersion of ultrafine Sb2O3 nanoparticles, the optimized Sb2O3/rGO-100 electrode showed enhanced electrode–electrolyte contact area and ion/electron transferability. When applied as an anode material for LIBs, the Sb2O3/rGO-100 electrode exhibited excellent cycling stability and rate performance, delivering a high reversible capacity of 513 mAh g–1 at 0.5 A g–1 after 300 cycles. Ex situ transmission electron microscopy reveals that the nanoscale configuration of rGO and Sb2O3 nanoparticles of Sb2O3/rGO-100 was well maintained, while the bulk Sb2O3 crushed into pieces after cycling, further confirming the robust structure of the composite. More importantly, the synthetic method may also be commonly applied to other metal oxides, which is promising for the development of high-performance next-generation electrochemical energy storage devices.

Efficient One-Pot Solvothermal Synthesis and Characterization of Zirconia Nanoparticle-Decorated Reduced Graphene Oxide Nanocomposites: Evaluation of Their Enhanced Anticancer Activity toward Human Cancer Cell Lines.

This study mainly deals with an effective one-pot solvothermal synthetic pathway for the preparation of uniformly dispersed zirconium oxide nanoparticles on the flattened rough surface of reduced graphene oxide (ZrO2/rGO NCs) using the aqueous leaf extract of Andrographis paniculata. After obtaining detailed information on the preparation and characterization, the anticancer activity of the synthesized ZrO2/rGO nanocrystals (NCs) was evaluated on two human cancer cell lines (A549 and HCT116) along with one normal human cell line (hMSC). The 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide assays revealed that ZrO2/rGO NCs exhibited a dose-dependent cytotoxicity pattern. The cell viability (%) drastically decreases up to 96-98% after exposure to an optimal concentration of 10 ppm nanocomposites. Analysis of both the reactive oxygen species generation and the Annexin V-FTIC staining assays reveal that ZrO2/rGO NCs have the ability to induce apoptosis in A549 and HCT116 cell lines. Thus, the green synthesis of ZrO2/rGO NCs shows potential in developing efficient therapeutic agents for cancer therapy.

Green synthesis of strontium-reduced graphene oxide biocomposite using gamma radiation

This study presents an environmentally benign approach for synthesizing of strontium nanoparticles-decorated reduced graphene oxide (rGO-Sr) nanosheets using a simple method. Reduced graphene oxide sheets decorated with strontium nanoparticles (rGO-Sr) were used in previous studies in polymer matrices to prepare 3D scaffolds for bone tissue regeneration. Graphene oxide is reduced and strontium nanoparticles have been successfully deposited on it using gamma radiation at room temperature. High-resolution transmission electron microscopy (HR-TEM) analysis assured the formation of strontium nanoparticles (Sr NPs) of 50 nm in size on reduced graphene oxide (rGO) nanosheets. The formed Sr NPs were homogeneously and uniformly distributed on rGO nanosheets forming rGO-Sr nanocomposite. The prepared materials' blood biocompatibility and antibacterial activities against Staphylococcus aureus were studied. The results revealed that the decoration of rGO sheets with strontium nanoparticles offered a significant increase in its antibacterial activity and exhibited good blood biocompatibility. This study shows that graphene-based composite prepared using Sr NPs seems to be a promising antibacterial coating material for biomedical applications.

CoFe Nanoparticle-Decorated Reduced Graphene Oxide for the Highly Efficient Reduction of 4-Nitrophenol.

High-performance, nonprecious metal catalysts with special morphologies and easy-to-recycle properties are essential for the treatment of environmental pollutants. Herein, CoFe nanoparticle-decorated reduced graphene oxide (RGO) catalysts were designed and successfully fabricated, and the catalyst was then used to reduce 4-nitrophenol into 4-aminophenol. Outstanding catalytic properties with a reduction rate constant of 4.613 min-1 were achieved due to the synergistic properties of the CoFe metal alloy and the high-conductivity RGO components in the catalysts. In addition, the catalyst was conveniently recovered via magnets due to its inherent magnetic properties. The facile preparation, outstanding catalytic performance, structural stability, and low material costs make the CoFe/RGO nanocatalyst a promising candidate for potential applications in catalysis.

Correction to “High-Performance All-Solid-State Flexible Asymmetric Supercapacitor Device Based on a Ag–Ni Nanoparticle-Decorated Reduced Graphene Oxide Nanocomposite as an Advanced Cathode Material”

Correction to “High-Performance All-Solid-State Flexible Asymmetric Supercapacitor Device Based on a Ag–Ni Nanoparticle-Decorated Reduced Graphene Oxide Nanocomposite as an Advanced Cathode Material”

Electrochemical Determination of Methamphetamine in Human Plasma on a Nanoceria Nanoparticle Decorated Reduced Graphene Oxide (rGO) Glassy Carbon Electrode (GCE)

Methamphetamine is an addictive and illegal psychostimulant drug. Due to its simple synthesis, it is widely accessible and abused. Long-term consumption affects the user’s body. Hence, its determination is of great importance. Its oxidation on electrode surfaces is difficult and requires a suitable modifier. In this work, cerium oxide nanoparticles (nanoceria) decorated on reduced graphene oxide were utilized as the electrode modifier to improve the electrochemical response. Decoration of nanoceria in reduced graphene oxide enhances the stability of reduced graphene oxide on the electrode surface and avoiding π-π stacking and the formation of a graphite structure. In addition, the agglomeration of nanoceria decorated on the reduced graphene oxide is decreased. The optimum ratio of cerium oxide-reduced graphene oxide composite provided a synergistic catalytic effect upon the methamphetamine signal. An enhancement of the methamphetamine oxidation peak on the modified electrode at +0.9 V in Britton-Robinson buffer was observed by cyclic voltammetry at pH 10.0 in comparison with a bare electrode. Square wave voltammetry (SWV) was used for analysis. Under the optimized conditions, the linear dynamic range and limit of detection for the reported electrode were from 25.0 to 166.6 µM and 8.7 µM. The determination of methamphetamine in plasma indicated no significant matrix interferences.

High-Performance All-Solid-State Flexible Asymmetric Supercapacitor Device Based on a Ag–Ni Nanoparticle-Decorated Reduced Graphene Oxide Nanocomposite as an Advanced Cathode Material

The development of wearable electronic devices and energy storage devices that are thin, lightweight, and flexible has led to the fabrication of flexible all-solid-state supercapacitors with skyscraping mechanical endurance and foldability. Herein, for the first time, we have delineated the assembly of a high-performance mechanically flexible all-solid-state asymmetric supercapacitor device from the nanocomposite comprising (Ag0.50Ni0.50)90-rGO10 and pure rGO as the cathode and anode electrode, respectively. Polyvinyl alcohol (PVA) gel containing 3 M KOH is used as the electrolyte and separator. This device delivers a high power density of 1700 W kg–1 without compromising with an energy density value of 49 W h kg–1 which is much higher in comparison to many of the existing supercapacitors in the market and substantive findings in the literature. Also, when the fabricated device is subjected to 5000 galvanostatic charge–discharge (GCD) cycles, a retention of ∼97% of the initial specific capacitance value is observed, displaying its high cycling stability. The omnidirectional mechanical robustness of this supercapacitor makes it flexible to that extent that it tends to exhibit high electrochemical performance even under extreme conditions and the specific capacitance value is pragmatically left unmodified when the device was subjected to different bending conditions. This device showcased its practical application by illuminating seven light-emitting diodes (LEDs) and appeared as an attractive energy storage unit for handy devices.

Electrocatalytic Ethanol Oxidation on Cobalt–Bismuth Nanoparticle-Decorated Reduced Graphene Oxide (Co–Bi@rGO): Reaction Pathway Investigation toward Direct Ethanol Fuel Cells

Direct ethanol fuel cells (DEFCs) are one of the resourceful and sustainable technologies for energy applications. Ethanol oxidation has been used to construct cost-effective and proficient electrocatalysts to substitute noble-based electrocatalysts like Rh, Pd, Ir, and Ag. Here in, we have presented a surface modification approach of doping a crucial oxophilic character metal onto a transition metal with carbon support. Noble metal-free cobalt–bismuth bimetallic nanoparticle-decorated reduced graphene oxide (Co–Bi@rGO) electrocatalysts were fabricated for enhanced ethanol oxidation reaction from their synergetic effect of rGO, Co, and Bi. A highly active, cost-effective, and efficient approach has been developed for the preparation of Co–Bi@rGO (Co NPs; ∼2 nm), initially Bi@rGO (Bi NPs@rGO; ∼50 nm), by a simple reduction method followed by Co, by Galvanic exchange of Bi atoms with Co. The as-synthesized nanocomposites were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and BET surface area measurement studies. Cyclic voltammetric studies show an ultralow onset potential of 0.28 V with a high current density of 10.25 mA/cm2, having a higher enhancement factor for Co–Bi@rGO compared to other individuals, including Bi NPs, Bi@rGO, and rGO under similar electrolyte conditions, which could be due to their synergetic cooperative interactions at electrified interfaces. Combined results from chronoamperometry (i–t) and electrochemical impedance spectroscopy show that Co–Bi@rGO is highly durable and sensitive toward the ethanol oxidation reaction compared to individual counterparts. This work also provides the noble metal-free bimetallic electrocatalysts for ethanol oxidation and assists in hydrogen production from an agricultural base.

Electrochemical performance of magnetic nanoparticle-decorated reduced graphene oxide (MRGO) in various aqueous electrolyte solutions

The objective of this work is twofold: (1) to improve the electrochemical performance of reduced graphene oxide (RGO) by decorating RGO sheets with magnetic nanoparticles (MNPs) and (2) to evaluate the electrochemical performance of RGO and MNP-decorated RGO (MRGO) in various aqueous electrolyte solutions (phosphate buffer solution (PBS) containing ferricyanide, PBS containing ferricyanide and KCl, Na2SO4, and KOH). The morphological and structural characteristics of solvothermal synthesized RGO and MRGO revealed the decoration of phase pure Fe3O4 nanoparticles on RGO sheets. In FC-PBS-KCl electrolyte solution, MRGO showed higher redox peak current (83.89 μA) and lower peak potential separation (0.11 V) at 50 mV s−1 scan rate compared with that in FC-PBS electrolyte solution. MRGO showed 15.5% higher peak current than that for the RGO in FC-PBS-KCl electrolyte solution. Moreover, the peak current for MRGO in FC-PBS-KCl was increased by 30% when compared with that in FC-PBS electrolyte solution. These results suggest that MRGO in FC-PBS-KCl electrolyte solution can be a good electron pathway between electrode and electrolyte solution for sensing applications. On the other hand, in both Na2SO4 and KOH electrolyte solution, RGO and MRGO showed supercapacitive behavior. In KOH, MRGO exhibited higher specific capacitance (180 Fg−1 at 3 A g−1) and superior cyclic stability (87% after 2000 cycles) compared with that in Na2SO4. MRGO showed 219% increase in specific capacitance than that of the RGO in KOH electrolyte solution. The superior electrochemical performance of MRGO compared with that of RGO is attributed to the synergistic effect of conductivity of RGO and redox activity of MNPs.

One-step fabrication of a highly dispersed palladium nanoparticle-decorated reduced graphene oxide electrocatalyst for methanol electro-oxidation in acidic media

Reduced graphene oxide (RGO) was successfully decorated with homogeneous highly dispersed palladium nanoparticles (PdNPs) by a novel single-step hydrothermal-assisted formic acid reduction reaction without the use of any surfactants. The structure, surface morphology, and elemental composition of the as-prepared PdNP-RGO electrocatalyst were extensively characterized. The PdNP-RGO electrocatalyst demonstrated outstanding electrocatalytic activity (8.65 mA/cm2) toward the methanol oxidation reaction (MOR) in an acidic medium that is 1.4 times higher than PdNP-decorated Vulcan XC72 (6.2 mA/cm2) and also comparable with that of Pd-based electrocatalysts in alkaline media from the previous reports. Furthermore, the as-prepared PdNP-RGO electrocatalyst also shows remarkable stability performance for the MOR in an acidic medium and thus offer new insights into the processing method of an outstanding electrocatalyst at the anode electrode in the direct methanol fuel cell with reasonable cost, clean and facile synthesis approach.

Hydrothermal Fabricated Ag Nanoparticles-decorated Reduced Graphene Oxide Composite for H2O2 Electrochemical Detection

Hydrothermal Fabricated Ag Nanoparticles-decorated Reduced Graphene Oxide Composite for H2O2 Electrochemical Detection

Silver nanoparticles-decorated reduced graphene oxide: A novel peroxidase-like activity nanomaterial for development of a colorimetric glucose biosensor

In this study, we present a novel approach to prepare of a colorimetric chemical sensor for H2O2 and a glucose biosensor basing on the use of peroxidase-like activity of silver nanoparticles decorated on reduced graphene oxide sheets (AgNPs@rGO) nanocomposite. Herein, AgNPs@rGO nanocomposite was synthesized by a one-step hydrothermal reducing method and its physico-chemical properties were characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Ultraviolet–visible spectroscopy (UV–Vis), Fourier-Transform Infrared spectroscopy (FT-IR) and Energy Dispersive X-ray spectroscopy (EDX). Obtained evaluation results shown that the synthesized AgNPs/rGO nanocomposite has performed an efficient peroxidase-like activity for the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMBred) by H2O2, leading to the oxidized form (TMBox) which presents a typical blue color (maximum of absorbance at λmax = 655 nm). A colorimetric assay for H2O2 detection was designed and fabricated with a limit of detection of 20 μM. Moreover, we have used of AgNPs/rGO nanocomposite combining with glucose oxidase (GOx) to develop of a colorimetric glucose biosensor with a low limit of detection of 40 μM and a linear dynamic range from 125 μM to 1 mM. This glucose test was applied to the detection of glucose in human serum samples.

One-Step Eco-Friendly Synthesis of Ag-Reduced Graphene Oxide Nanocomposites for Antibiofilm Application

This study focuses on the synthesis and characterization of Ag nanoparticle-decorated reduced graphene oxide (RGO) nanocomposites (Ag-RGO), which were obtained via a facile, green and efficient one-pot hydrothermal method. TEM results showed that the silver nanoparticles (20-50 nm) were uniformly attached onto RGO sheets with C/O ratio of 6.4 and 80% of sp2 carbon, obtained from XPS analysis. Compared with GO and RGO, the prepared Ag-RGO composites possessed significant antibacterial property; the minimum inhibitory concentration of Ag-RGO was just 31.25 μg/mL against Gram-positive bacteria S. aureus and Gram-negative bacteria E. coli. Particularly, the Ag-RGO nanocomposites released more Ag+ in acidic condition, promoting the produce of reactive oxygen species, which are acknowledged as disruption to the membrane integrity of the bacteria. Moreover, the Ag-RGO nanocomposites effectively dispersed and eliminated the maturely formed biofilm, showing superior advantages in responding to public health threats posed by biofilm-related infections.

Hollow porous gold nanoparticle/reduced graphene oxide composite films for electrochemical supercapacitor applications

Here, we report the synthesis of hollow porous gold nanoparticles-decorated reduced graphene oxide (HPAuNPs/RGO) nanocomposites and their electrochemical performances as active electrode material for supercapacitors. Accordingly, the HPAuNPs were first prepared using a simple solution phase template method according to the modified literature procedure, and the size control of hollow porous gold particles was achieved by varying the concentration of hydroquinone used as the reducing agent. Then, the surface of the RGO nanosheets was decorated with HPAuNPs through the self-assembly approach. The structural and morphological features of synthesized nanoparticles and nanocomposites were evaluated by spectroscopic and morphologic methods. Also, the electrochemical supercapacitive performances of the HPAuNPs/RGO/GC nanocomposite electrodes as both cathode and anode materials were analyzed in Na2SO4 solution using electrochemical methods. As a control sample, the RGO/GC electrode was also examined under identical experimental conditions. The results indicate that the composite materials display higher specific capacitances (107–325 F/g) compared with bare RGO (55 and 37 F/g) at a potential scan rate of 20 mV/s. Furthermore, it is obtained that the specific capacitances of the composite electrodes based on hollow porous gold nanoparticles are larger than those of previously reported supercapacitors with spherical gold nanoparticles/graphene as electrode materials. The improved electrochemical properties of the HPAuNPs/RGO/GC nanocomposite electrodes can be ascribed to the hollow and porous structure of the gold particles on RGO sheets.