Electrochemically Reduced Graphene Oxide Research Articles

Graphene Synthesis by Electrochemical Reduction of Graphene Oxide and Its Characterizations

Graphene is one of the nanoscale materials that has attracted many researchers to continue in-depth study on its unique properties where both the graphene oxide (GO) and electrochemical reduced graphene oxide (ERGO) are the derivatives of graphene. GO and ERGO can be further modified chemically for many types of application such as sensor and water filter membrane. However, to restore the electrical property of graphene, GO should be reduced to ERGO. There are several types of reduction methods which are fast to produce good quality and high yield of graphene material. However, those methods use toxic chemicals to reduce GO which can bring negative impact to both human and environment. Therefore, an electrochemical approach can be carried out to solve this issue. This study presents the electrochemical synthesis of GO and electrochemical reduction of ERGO. All characterizations were conducted by using Fourier transform infrared (FTIR) spectroscopy, X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM).

Simultaneous Electrochemical Detection of Catechol and Hydroquinone Based on a Carbon Nanotube Paste Electrode Modified with Electro-Reduced Graphene Oxide.

Effectively detecting catechol (CC) and hydroquinone (HQ) simultaneously is crucial for environmental protection and human health monitoring. In the study presented herein, a novel electrochemical sensor for the sensitive simultaneous detection of CC and HQ was constructed based on an electrochemically reduced graphene oxide (ERGO)-modified multi-walled carbon nanotube paste electrode (MWCNTPE). Scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and electrochemical techniques were utilized to characterize the sensing interface and investigate the sensing mechanism. Under the optimal detection conditions, the oxidation peak currents of CC and HQ show a good linear relationship with their concentrations in the range of 0.4-400 μM with a detection limit of 0.083 μM for CC and 0.028 μM for HQ (S/N = 3). Moreover, the sensor exhibits good performance and can be applied successfully in the simultaneous detection of CC and HQ in tap water samples and urine samples with satisfactory results, indicating its promising application prospects.

Facile Fabrication of Bio-Nanohybrid Electrode with Guanine/Cytosine-Modified Electrochemically Reduced Graphene Oxide Electrode and Its Application in Doxorubicin Analysis

Graphene, known for its outstanding physical and chemical properties, is widely used in various fields, including electronics and biomedicine. Reduced graphene oxide (rGO) is preferred for electrochemical applications due to its enhanced water solubility and dispersion. Electrochemically reduced graphene oxide (ErGO) is particularly advantageous as it can be prepared under mild conditions and simplifies sensor fabrication; however, ErGO-based electrochemical sensors often lack specificity. Bioreceptors like proteins, enzymes, and DNA/RNA aptamers are incorporated to provide high specificity. This study introduces a guanine (G)/cytosine (C)-modified ErGO electrode (G/C@ErGO-GCE) for the sensitive electrochemical detection of doxorubicin (DOX) with good selectivity. The G/C mixture acts as a bioreceptor and is anchored on the ErGO-GCE surface via π-π interactions. The G/C@ErGO-GCE was characterized using scanning electron microscopy, contact angle measurement, Raman spectroscopy, and electrochemical methods. The sensor demonstrated excellent dynamic range (DPV: 10 nM to 1 µM, CA: 30 nM to 1.3 µM), sensitivity (DPV: 2.17 µA/µM, CA: 6.79 µA/µM), limit of detection (DPV: 84 nM, CA: 34 nM), and selectivity for DOX detection, highlighting its potential for biomedical applications and pharmacokinetic studies.

Disposable electrochemical sensors based on reduced graphene oxide/polyaniline/poly(alizarin red S)-modified integrated carbon electrodes for the detection of ciprofloxacin in milk.

Anelectrochemical sensor based on an electroactive nanocomposite was designedfor the first timeconsisting of electrochemically reduced graphene oxide (ERGO), polyaniline (PANI), and poly(alizarin red S) (PARS) for ciprofloxacin (CIPF) detection. The ERGO/PANI/PARS-modified screen-printed carbon electrode (SPCE) was constructed through a three-step electrochemical protocol and characterized using FTIR, UV-visible spectroscopy, FESEM, CV, LSV, and EIS. The new electrochemical CIPF sensor demonstrated a low detection limit of 0.0021μM, a broad linear range of 0.01 to 69.8μM, a high sensitivity of 5.09 μA/μM/cm2, and reasonable selectivity and reproducibility. Moreover, the ERGO/PANI/PARS/SPCE was successfully utilized to determine CIPF in milk with good recoveries and relative standard deviation (< 5%), which were close to those with HPLC analysis.

A self-powered photoelectrochemical and non-enzymatic glucose sensor based on ERGO/ZnONWs/CdS photoanode

We have developed an efficient, self-powered, non-enzymatic photoelectrochemical (PEC) glucose sensor operating in the visible spectrum. The sensor is based on electrochemically reduced graphene oxide (ERGO) and zinc oxide (ZnO) nanowalls (NWs) decorated with cadmium sulfide (CdS) quantum dots (QDs). We used a one-pot electrochemical process to grow vertically aligned ZnONWs on ERGO, followed by using the sequential ionic layer adsorption and reaction (SILAR) technique to decorate the ZnONWs with CdS QDs. The resulting ERGO/ZnONWs/CdS photoelectrode exhibits a three-dimensional hierarchical morphology, providing a large surface area for enhanced surface-substrate interactions and increased optical path length, leading to high absorptivity at visible light. Under one solar light illumination without a bias voltage, the electrode generated a significantly higher photocurrent density (1150 µAcm-2) in the presence of glucose (15.00 mM) than in the absence of glucose (150 µAcm-2). As a PEC glucose sensor, the ERGO/ZnONWs/CdS photoelectrode demonstrated two linear correlations in the glucose concentration range of 0.01–1.00 mM and 1.00–15.00 mM. The sensor has 430.06 and 25.75 µA cm-2mM-1 sensitivities and a low detection limit (1.1 µM). This novel visible light-mediated self-powered electrochemical sensing platform is cost-effective, reproducible, and stable for non-enzymatic glucose detection.

Manganese cobalt sulfide nanoparticles wrapped by reduced graphene oxide: a fascinating nanocomposite as an efficient electrochemical sensing platform for vanillin determination

In this work, a fascinating nanocomposite based on manganese-cobalt sulfide (MnS/Co3S4) wrapped by electrochemically reduced graphene oxide (ERGO) has been successfully synthesized on the surface of a glassy carbon electrode (GCE) by a facile hydrothermal assisted electrochemical reduction method. The modified electrode was fully characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The morphological results illustrate that MnS/Co3S4 are embedded in the ERGO layers, resulting in a rough surface and three-dimensional (3D) microstructure. The as-synthesized MnS/Co3S4-ERGO/GCE displays distinctly enhanced electrocatalytic activity for vanillin oxidation in comparison with that of the ERGO/GCE and MnS/Co3S4/GCE. Therefore, the MnS/Co3S4-ERGO/GCE can be used as an effective electrochemical sensing platform for the sensitive determination of vanillin, and the fabricated sensor displays a wide linear range of 0.02−1.00 μmol/L and 1.0−40.0 μmol/L, low detection limit of 4.0 nmol/L and satisfactory recoveries between 98.0% and 102.8%.

Development of a Cu@ERGO-p(L-Lys) Modified GCE Electrochemical Sensor for the Simultaneous Detection of Ascorbic Acid, Dopamine, and Uric Acid

In this work, a sensitive sensing platform was developed using a glassy carbon electrode (GCE) to simultaneously determine AA, DA, and UA. Cu nanostructures, the poly-L-Lysine (p(L-Lys)), and the electrochemically reduced graphene oxide (ERGO) modified GCE (GCE/Cu@ERGO-p(L-Lys)) was developed via the electrodeposition of Cu and electropolymerization of the ERGO-p(L-Lys). Simultaneous detection makes analysis more efficient and cost-effective by reducing the need for multiple sensors. The GCE/Cu@ERGO-p(L-Lys) was characterized by electrochemical impedance spectroscopy, cyclic voltammetry, and scanning electron microscopy. The limit of detection values for AA, DA, and UA analytes were 0.16, 0.033, and 0.021 μM, respectively, while the linear ranges were 0.53–50.0, 0.11–100.0, and 0.070–0.75 μM. The proposed sensor was found to be applicable for the determination of target analytes in fetal bovine serum samples. The proposed GCE/Cu@ERGO-p(L-Lys) hybrid composite modified electrode is a promising material for simultaneous determination in biological fluids with excellent analytical performance and anti-interference effect.

A highly sensitivity electrochemistry biosensor for E. coli DNA detection based on hollow and porous dCuO@rGO composite

A highly sensitive DNA (deoxyribonucleic acid) sensor was prepared by using dCuO particles (derived from HKUST-1), electrochemical-reduced graphene oxide (rGO) and chitosan (CS) composite modified glassy carbon electrode (CS/dCuO@rGO/GCE). The morphology and nanostructure features of dCuO have been characterized with the HRTEM and SEM techniques. Electrochemical impedance spectroscopy characterisation (EIS) test showed that dCuO@rGO composite with a straight line which displaying the faster electron transfer rate compared to the Rct value obtained on dCuO (267 Ω) and rGO (47 Ω), this high conductivity was according with cyclic voltammetry (CV) results. It was ascribed to the octahedral hollow, porosity dCuO accelerated the electrolyte permeation capacity, and rGO with large surface area enhancing the electro-active site. Besides, the electro-reduction formed hybrid material of dCuO@rGO with well-synergetic effect significantly promoted the conductivity property. Of noteworthy, FT-IR spectroscopy indicating the retained carboxyl groups of dCuO, which could serve as functional arm-linker for capturing 5′-NH2 modified probe DNA (S1) to build the bio-sensing electrode (S1-CS/dCuO@rGO/GCE). Differential pulse voltammetry (DPV) characterization showed this manufactured biosensor with super-highly sensitivity for colitoxin DNA detection. The specific ssDNA sequences were detected in the concentration range from 0.001 to 37.5 pM with lower detection limit value of 3.89 × 10−1 fM (S/N = 3). This biosensor also showed well discrimination ability to the non-complementary and mismatched DNA sequences.

Hydrothermal vs. Electrochemical reduction of graphene oxide: A physico-chemical and quartz crystal microbalance study

Reduced Graphene Oxide possesses numerous interesting properties, making it one of the most studied materials today. By this way, applications in various fields, including fundamental research, can be found. Nevertheless, the complexity of reduced Graphene Oxide lies in its fabrication process which defines their properties. In this paper, two fabrication methods -electrochemical and hydrothermal reduction of graphene oxide - were compared using physico-chemical and electrogravimetric analysis. Our findings reveal significant morphological differences between the two methods, accompanied by different electrochemical behaviors, when tested in aqueous electrolyte (i.e. 0.5 M Na2SO4). Specifically, electrochemically reduced graphene oxide exclusively involves sodium (whether hydrated or not) in its charge compensation mechanism, whereas hydrothermally reduced graphene oxide also involves proton in sodium sulfate solution.

Exfoliation of Graphite into Graphene Oxide and Reduction by Plant Extract to Synthesize Graphene

Graphene oxide (GO) is a demand material in industrial field for many applications such as electronic devices, capacitor and sensor. This is due to its unique structures and excellent properties. The GO sheets were exfoliated from graphite rod in electrochemical exfoliation. To reduce GO, an electrochemical reduction of GO using green tea was carried out in this research. The conventional chemical reduction method consumed highly toxic and strongly hazardous chemicals such as hydrazine to reduce GO to reduced GO (RGO). Therefore, a green synthesis method was proposed by using green tea leaves extract as the reducing agent to synthesize RGO. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) results show that low amount of oxygen-containing functional groups was remained after green tea reduction due to weak reduction capability by green tea. In addition, EDX indicates that oxygen content of GO was decreased from 23.23 to 16.89 Mass% after green tea reduction.

Cytosine-Rich Oligonucleotide and Electrochemically Reduced Graphene Oxide Nanocomposite for Ultrasensitive Electrochemical Ag+ Sensing.

Silver ions (Ag+) are crucial in various fields, but pose environmental and health risks at high concentrations. This study presents a straightforward approach for the ultra-trace detection of Ag+, utilizing a composite of a cytosine-rich oligonucleotide (CRO) and an electrochemically reduced graphene oxide (ERGO). Initially, ERGO was synthesized on a glassy carbon electrode (GCE) through the reduction of graphene oxide (GO) via cyclic voltammetry. A methylene blue-tagged CRO (MB-CRO) was then anchored to the ERGO surface through π-π interactions, resulting in the formation of an MB-CRO-modified ERGO electrode (MB-CRO/ERGO-GCE). The interaction with Ag+ ions induced the formation of silver-mediated C-Ag+-C coordination, prompting the MB-CRO to adopt a hairpin structure. This conformational change led to the desorption of the MB-CRO from the ERGO-GCE, causing a variation in the redox current of the methylene blue associated with the MB-CRO. Electrochemical assays revealed that the sensor exhibits extraordinary sensitivity to Ag+ ions, with a linear detection range from 1 femtomolar (fM) to 100 nanomolars (nM) and a detection limit of 0.83 fM. Moreover, the sensor demonstrated high selectivity for Ag+ ions and several other benefits, including stability, reproducibility, and straightforward fabrication and operational procedures. Additionally, real sample analyses were performed using the modified electrode to detect Ag+ in tap and pond water samples, yielding satisfactory recovery rates.

Direct electrochemical reduction of graphene oxide thin film for aptamer-based selective and highly sensitive detection of matrix metalloproteinase 2

Simple and low-cost biosensing solutions are suitable for point-of-care applications aiming to overcome the gap between scientific concepts and technological production. To compete with sensitivity and selectivity of golden standards, such as liquid chromatography, the functionalization of biosensors is continuously optimized to enhance the signal and improve their performance, often leading to complex chemical assay development. In this research, the efforts are made on optimizing the methodology for electrochemical reduction of graphene oxide to produce thin film-modified gold electrodes. Under the employed specific conditions, 20 cycles of cyclic voltammetry (CV) are shown to be optimal for superior electrical activation of graphene oxide into electrochemically reduced graphene oxide (ERGO). This platform is further used to develop a matrix metalloproteinase 2 (MMP-2) biosensor, where specific anti-MMP2 aptamers are utilized as a biorecognition element. MMP-2 is a protein which is typically overexpressed in tumor tissues, with important roles in tumor invasion, metastasis as well as in tumor angiogenesis. Based on impedimetric measurements, we were able to detect as low as 3.32 pg mL−1 of MMP-2 in PBS with a dynamic range of 10 pg mL−1 – 10 ng mL−1. Further experiments with real blood samples revealed a promising potential of the developed sensor for direct measurement of MMP-2 in complex media. High specificity of detection is demonstrated – even to the closely related enzyme MMP-9. Finally, the potential of reuse was demonstrated by signal restoration after experimental detection of MMP-2.

Iron/Iron(III) Oxide Decorated on Electrochemically Reduced Graphene Oxide: a Novel One-Step Electrosynthesis and a Fabrication of an Electrochemical Ascorbic Acid Sensor

Considering on required detection time and sensitivity, electrochemical method is an excellent candidate for ascorbic acid (AA) sensing. We propose using the synergistic effects of iron(0)/iron(III) oxide decorated on the electrochemically reduced graphene oxide (ERGO/Fe-Fe2O3) modified Pt microelectrode as an electrochemical AA sensor using cyclic voltammetry (CV) technique. Herein, ERGO/Fe-Fe2O3 was directly fabricated on the Pt microelectrode using a novel one-step electrosynthesis. Fe-Fe2O3 acts as an oxidized-nanozyme with works as redox centers on the electrode for oxidation of AA. Fe-Fe2O3 nanozymes are immobilized on electrochemically reduced graphene oxide (ERGO), which supports a large electroactive and excellent electrically conductive surface for electron-transfer during electrochemical oxidation of AA. The developed electrochemical sensor allowed for sensing AA in medical samples with high sensitivity in concentration range from 0.05 to 10.00 mM and a limit of detection (LOD) of 5.93 μM.

Activity and stability of electrochemically reduced graphene oxide films for applications requiring mixed conductivity

A protonic and electronic conductor composed of partially reduced graphene oxide (GO) has been prepared by electrochemical methods. Conductivity measurements and detailed surface analysis by XPS, FTIR, and Raman methods show that the electrochemically reduced GO (ERGO), prepared under different reduction potentials, exhibits a unique dual (protonic and electronic) conductivity which is tunable by adjusting the surface conditions. Selected removal of the oxygenated groups, evolution of C(sp2)/C(sp3) hybrid carbon structure, and surface structure of ERGO can impact the protonic and electronic transport mechanisms. The ERGO samples reported here are ideal support materials with proper ratios of protonic and electronic transport. The as-prepared ionomer-free and flexible ERGO-supported Pt (Pt/ERGO) electrodes were characterized for oxygen reduction reaction (ORR) reactivity in acidic solution. The results showed not only higher electrochemical surface area (ECSA), but also improved mass activity towards ORR compared to conventional carbon supported Pt catalysts.

A novel electrochemical strategy to detect hydrogen peroxide by utilizing peroxidase-mimicking activity of cerium oxide/graphene oxide nanocomposites

We herein describe a novel electrochemical strategy to detect hydrogen peroxide (H2O2) by utilizing the peroxidase-mimicking activity of cerium oxide nanoparticles (CeO2 NP) and reduced graphene oxide (rGO). Particularly, CeO2 NP/rGO nanocomposites were deposited on the commercial electrode by a very convenient and direct electrochemical reduction of graphene oxide. Due to the peroxidase-mimicking activity of CeO2 NP and the outstanding electrochemical properties of reduced graphene oxide, the reduction current of H2O2 was greatly enhanced. Based on this strategy, we reliably determined H2O2 down to 1.67 μM with excellent specificity and further validated its practical capabilities by robustly detecting H2O2 present in heterogeneous human serum samples. We believe that this work could serve as a new facile platform for H2O2 detection.

Triple multivalent aptamers within DNA tetrahedron on reduced graphene oxide electrode: Unlocking enhanced sensitivity and accelerated reactions in electrochemical sensing

DNA nanostructures are emerging as promising biosensing platforms due to their programmability, predictable assembly, and compatibility with aptamers for enhanced selectivity. This study focuses on a triple-multivalent aptamer (tApt) complex immobilized on a tetrahedral DNA nanostructure (TDN) and integrated with an electrochemically reduced graphene oxide (ERGO) electrode for highly sensitive mercury ion (Hg2+) detection. Compared to a linear multivalent aptamer-modified electrode (S2/ERGO-GCE), the 3D tApt/ERGO-GCE aptasensor exhibits superior sensitivity, signal amplification, and reaction kinetics. The tApt/ERGO-GCE sensor achieves an exceptional limit of detection (LOD) of 4.1 zM, surpassing the LOD of 0.71 fM for S2/ERGO-GCE. Additionally, the tApt/ERGO-GCE sensor demonstrates faster response times, with a half-saturation time (T1/2) of 6 minutes compared to 17 minutes for S2/ERGO/GCE. The 3D tApt aptamer's superior performance is attributed to its tetrahedral DNA structure integrated on ERGO, providing multiple aptamer binding sites, facilitating oriented immobilization on the electrode surface, and enhancing analyte capture and concentration. In contrast, the linear S2 aptamers lack rigidity, resulting in a disordered orientation on the electrode surface, hindering efficient Hg2+ binding and reducing target molecule binding efficiency. This study underscores the potential of triple-multivalent aptamer-based nanostructures for ultrasensitive and rapid biosensing applications. The tApt/ERGO-GCE aptasensor's exceptional sensitivity, signal amplification, and reaction kinetics make it a promising tool for Hg2+ detection and other biosensing applications.

The impact of interdigitated metal electrode on properties and performance of electrochemically reduced graphene oxide (ErGO) UV photodetector

The impact of interdigitated metal electrode on properties and performance of electrochemically reduced graphene oxide (ErGO) UV photodetector

Enhancement of Electrochemically Reduced Graphene Oxide (ErGO) UV Photo Detector Performance via Direct One-Step Electrode Deposition Technique

Recently, photodetectors have garnered significant attention owing to their broad spectrum of applications across fields such as the biomedical, industrial, agricultural, and telecommunications sectors. This research focuses on the development of a UV photodetector based on electrochemically reduced graphene oxide (ErGO) and incorporates reduced graphene oxide (rGO) thin films on interdigitated Au electrodes. The rGO thin films were synthesized using the direct one-step deposition method, maintaining a constant water bath temperature of 40 °C, and a consistent GO concentration of 0.15 g, while varying the pH levels within the range of pH 8 to pH 10. The investigation primarily concentrated on assessing the surface morphological, structural, and electrical properties of the rGO thin films by altering the pH level when exposed to 365 nm ultraviolet (UV) irradiation. The significant parameters for evaluating photodetector performance, including photosensitivity, stability, repeatability, response time, and recovery time. To achieve this, advanced techniques such as field-emission scanning electron microscopy (FESEM), Raman spectroscopy, and current-time measurement are employed. As a finding, the fabricated UV PD of rGO-Au at pH 9 achieved the photosensitivity 96.5% with the stability that was 30 times greater than rGO-Au (pH 10) and superior repeatability as well as rapid switching rate as compared to pH 8 and pH 10 with 0.6 V bias. This implies that rGO-Au prepared at pH 9 is a suitable material for application in UV detection.

Synergistic coupling of reduced graphene oxide with Ni0.85Se for highly active bifunctional electrocatalyst for water splitting

Electrochemical water splitting can provide eco-friendly fuel. Nevertheless, this method requires efficient bifunctional electrocatalysts. In this study, a bifunctional electrocatalyst was synthesized by coating Ni0.85Se and hydrothermally-reduced graphene oxide on nickel foam (NF) using two-step electrodeposition. Moreover, graphene oxide was reduced through hydrothermal means prior to the pulse reverse electrodeposition. As confirmed by FT-IR, hydrothermally and electrochemically reduced graphene oxide on NF (HERGO) reveals a higher reduction degree in comparison to electrochemically-reduced graphene oxide on NF (ERGO). Ni0.85Se covered HERGO through the on-off cathodic pulse electrodeposition. Therefore, excellent electrocatalytic activity was obtained using the synergetic effect of RGO and Ni0.85Se. The ECSA values of 431 and 3500 cm2 were attained through coating HERGO and Ni0.85Se/HERGO on bare NF, respectively. The Ni0.85Se/HERGO revealed Ƞ10 of 67 and 230 mV for HER and OER, respectively. For overall water splitting, the Ni0.85Se/HERGO ǁ Ni0.85Se/HERGO device requaired 1.533 V at 10 mA/cm2.

Electrochemically Reduced Graphene Oxide Supported Palladium-Cobalt Alloy Nanoparticles as Highly Efficient Electrocatalyst for Oxygen Reduction Reaction

Pd-Co alloy nanoparticles were synthesized on electrochemically reduced graphene oxide (ErGO) for electrocatalytic oxygen reduction reaction (ORR) in alkaline media. The morphological structure, chemical composition, and crystallinity of the afforded ErGO/Pd-Co catalyst were examined by various techniques, including transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction analysis. The Pd-Co alloy nanoparticles were evenly distributed on the ErGO sheet and had a narrow size distribution, with an average particle size of 4.25 nm. The ORR activity of the as-prepared ErGO/Pd-Co alloy catalyst was evaluated by cyclic voltammetry, linear sweep voltammetry, rotating disk electrode, and rotating ring disk electrode techniques in an alkaline electrolyte. The ErGO/Pd-Co catalyst exhibits a very high electrocatalytic activity in ORR with the mass activity more than 2.0 times of the commercial 20% Pt/C due to the synergistic catalytic effect of both ErGO and Pd-Co nanoparticles. Electrocatalytic kinetics investigation shows that, the ORR on the ErGO/Pd-Co catalyst proceeds through four electrons transferred mechanism with negligible amount of peroxide species. Moreover, the ErGO/Pd-Co shows an excellent methanol tolerance than the commercial 20% Pt/C.