Electrodeposition Of Graphene Oxide Research Articles

Electrochemical Determination of Thiophene by Dicyandiamide/Graphene Oxide/Modified Graphite Electrode in Gasoline by Square Wave Voltammetry (SWV)

An efficient stable electrochemical method for the determination of thiophene as a sulfur model compound in gasoline has been investigated based on the electrodeposition of graphene oxide and dicyandiamide on graphite electrode by cyclic voltammetry. The electroactive layer performance was considered by linear sweep voltammetry and square wave voltammetry by examining scan rates and their relevant equations to evaluate the electrochemical parameters. This modified electrode has high electrocatalytic characteristics to irreversible electrooxidation of thiophene. The electron transfer coefficient (α) was equal to 0.78, the electron transfer rate constant (log KS) was 3.2 s−1, and the saturated adsorptive capacity of the electroactive substance at the electrode surface (Γmax) was 1.14 × 10−8 mol cm−2 at pH 8 at low working potential of 0.5 V versus Ag/AgCl reference electrode. Scanning electron microscopy of the surface revealed the nanostructure of electrodeposited films and the morphology. This sensor is capable of electrochemical response to thiophene over the concentration range from 25 to 250 nmol L−1 with a detection limit of 8.31 nmol L−1, and a quantification limit of 25.18 nmol L−1. The method’s reliability was checked regarding the simulated gasoline samples and the desired response and sensitivity were provided. The wide dynamic range, low detection limit, favorable precision and accuracy, and fast response with no interferences confirm the ability of this sensor for thiophene determination. This nano-sensor can be used for electrochemical in-situ direct monitoring of liquid fuel desulfurization processes.

Effect of Graphite Exfoliation Way on the Efficiency of Exfoliated Graphene for the Determination of Hydroxychloroquine in Urine and Waste Water

Graphene oxide (GO) electrodeposited on graphite electrode has been used as a sensor for the detection of hydroxychloroquine (HCQ). It was synthesized via a simple and low-cost electrochemical approach by exfoliation of graphite pencil core in aqueous solution of Na2SO4 using a direct current (DC) and alternating current (AC), then electrodeposited at the graphite electrode surface by cyclic voltammetry. The electrochemical performance of the DC−GO and AC−GO toward HCQ oxidation was tested. Graphene oxide (GO) and reduced graphene oxide (rGO) were characterized by UV–vis absorption spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to study the HCQ oxidation mechanism as well as electron transfer and HCQ quantification at the modified electrode AC−rGO@CPE, respectively. Parameters, such as potential range, scan rate, and the number of segments (half cycle) in cyclic voltammetry were optimized for the electrodeposition of GO. The AC−rGO@CPE shows good sensitivity toward HCQ in the range from 4.0 × 10−7 to 4.0 × 10−6 mol l−1. The detection limit was calculated to be 3.2 × 10−8 mol l−1 with an RSD of 3.47%. Furthermore, the modified electrode was successfully used to detect HCQ in human urine and wastewater.

An enhanced quasicrystalline Ti1.4V0.6Ni alloy electrode modified by uniformly covered RGO for nickel metal hydride battery

Herein, we provided a facile route to coat a flat and uniformly covered reduced graphene oxide (RGO) film on Ti1.4V0.6Ni quasicrystal alloy electrode surface by electrodeposition of graphene oxide and subsequent reduction with HI vapor. Raman spectrum showed HI has a better reduced effect than electrochemical reduction. The RGO coated alloy electrode exhibited a higher discharge capacity of 290.3 mA h g−1 and 23.8% higher capacity retention than the bare one after 50 cycles for the RGO layer effectively forbidding the direct contact of electrode and electrolyte. Moreover, Ti1.4V0.6Ni quasicrystal alloy with RGO coating exhibited faster hydrogen uptake kinetics by initial activation curve of gaseous hydrogen storage measurement and higher maximum hydrogen storage performance of 1.66 wt% than the bare Ti1.4V0.6Ni alloy. Thus, the enhanced properties of RGO as a multifunctional layer for Ti1.4V0.6Ni quasicrystal alloy were proved which could be achieved by a facile route.

Osteoblast differentiation and gene expression analysis on anodized titanium samples coated with graphene oxide

Surface modifications of titanium (Ti) to improve the potential of implantable materials for orthopedic applications are widely studied. Coating the surface of a biomaterial with graphene oxide (GO) increases the durability of orthopedic implants due to the biocompatibility and antibacterial properties of GO. In the present study, anodized titanium (ATi) was coated with GO via anodization of Ti and anodic-electrophoretic deposition of GO at 200 µg/ml (ATiGO200). Cell culture results suggested that the surface topographic features of ATi and GO coating act synergistically to improve synthesis of the bone matrix and mineralization. Total protein content, calcium deposition, and alkaline phosphatase activity assays confirmed that osteogenic differentiation was improved on ATiGO200. Expression of the bone matrix protein genes (Bglap and Alpl) was upregulated on ATiGO200 during late-stage osteoblast differentiation. Combined anodization of Ti and electrodeposition of GO provides a bioactive surface for osteogenic differentiation to enhance osseointegration of orthopedic implants.

Fabrication of electrochemically interconnected MoO3/GO/MWCNTs/graphite sheets for high performance all-solid-state symmetric supercapacitor

Binder-free MoO3/GO/MWCNTs/graphite sheets were successfully fabricated via electrodeposition of graphene oxide and functionalized multi walled carbon nanotube onto graphite sheets followed by electrodeposition of molybdenum oxide. The capacitive behavior of the MoO3/GO/MWCNTs/G sheet was found to be superior with respect to those of MoO3/MWCNTs/graphite and MoO3/GO/G sheets. The high wettability, interconnected structure and synergetic effects between MoO3, GO and MWCNTs made the MoO3/GO/MWCNTs/G sheet exhibited a high areal capacitance of 103 mF cm−2 at current density of 0.7 mA cm−2 in 1.0 M KCl. An all-solid-state symmetric supercapacitor device prepared by using the MoO3/GO/MWCNTs/G sheet as both positive and negative electrodes showed high cell voltage of 2.5 V and remarkable cycle life of 86.8% retention after 2000 cycles, suggesting the possibility for practical applications in energy storage device.

Improvement of the antifouling performance and stability of an anion exchange membrane by surface modification with graphene oxide (GO) and polydopamine (PDA)

A novel surface modified anion exchange membrane (AEM) was prepared by electrodeposition of graphene oxide (GO) and polydopamine (PDA) coating, aiming at improving antifouling performance and stability. The AEM was firstly modified by electrodeposition of GO and then immersed into the dopamine solution to form a thin PDA layer. The effects of GO and PDA composite modification were investigated by various analytical techniques and electrodialysis application. The GO@PDA-modified AEM (GO@PDA-M) exhibited highly hydrophilic and negatively charged. In addition, the introduction of PDA coating helped to construct a smoother and denser composite modifying layer composed of GO and PDA, and reduced the roughness of membrane surface. Depending on these properties, the GO@PDA-modified AEM showed significant antifouling ability without compromising the desalination performance. After being fouled by 150 mg/L sodium dodecyl benzene sulfonate (SDBS) for 4 h, the desalination rate of GO@PDA-M increased by 39.3% compared to pristine membrane, while for PDA-modified membrane (PDA-M) and GO-modified membrane (GO-M) were 5.7% and 18.2% respectively. Moreover, it still maintained antifouling ability after 20 h of continuous operation. The stability of GO@PDA-M was immensely improved compared with the GO-M due to the introduction of PDA layer.

A Sensitive Photoelectrochemical Aptasensor for miRNA‐21 Based on the Sensitization Effect of CdSe Quantum Dots

AbstractA novel photoelectrochemical aptasensor for the sensitive detection of miRNA‐21 was designed based on the sensitization effect of CdSe quantum dots as a signal amplification strategy. The TiO2NTs/RGO/AuNPs electrode was prepared by the electrodeposition of graphene oxide and Au nanoparticles on TiO2 nanotubes with electrochemical reduction. The electrode was prepared as the matrix of the electrochemical aptasensor. The hairpin DNA strands decorated with CdSe quantum dots were immobilized on the surface of the electrode by Au−S bonds. Because of the card‐type structure of the hairpin DNA (HP‐DNA), the CdSe quantum dots were close to the base electrode, which would lead to the sensitization effect and cause the increase of the photocurrent intensity. When a certain concentration of the miRNA‐21 was added, miRNA‐21 hybridized with the complementary part of the HP‐DNA. At the same time, the hairpin structure of HP‐DNA was broken into a straight chain structure, so the CdSe quantum dots on the end of the DNA would move away from the electrode surface, the sensitization effect would be weakened, and the photocurrent intensity would be decreased. The designed photoelectrochemical aptasensor exhibited a low detection limit of 5.6 fM and a wide linear range from 20 fM to 0.2 nM, and it also showed good specificity, reproducibility and stability. The signal amplification strategy was also expected to provide a significant photoelectrochemical biosensor platform for the sensitive detection of biomolecules.

Modification and properties characterization of heterogeneous anion-exchange membranes by electrodeposition of graphene oxide (GO)

The heterogeneous anion exchange membranes (AEMs) were modified by electrodeposition of graphene oxide (GO) under different conditions. The physicochemical properties of GO-modified membranes were characterized systemically to obtain the optimized conditions for the electrodeposition of GO on the surface of AEMs. The results indicated that the contact angle and zeta potential of the modified AEMs decreased when increasing the concentration of GO from 0.05 g/L to 0.1 g/L. The higher concentration of NaCl, as the supporting electrolyte, could hinder the electrodeposition of GO on the AEMs for the competitive migration between the GO and Cl− ions. The increase of current density had a positive effect on properties of GO-modified membranes in the range of 1–5 mA/cm2. Compared with the pristine AEM, all the GO-modified AEMs exhibited smoother surface, higher hydrophilicity and negative zeta potential. It was also found that the GO modifying layer did not increase electrical resistance and had only a negligible effect on the desalination performance of AEMs. In the fouling experiments with sodium dodecyl benzene sulfonate (SDBS) as the model foulant, the GO-modified AEMs exhibited improved fouling resistance to SDBS.

A molecularly imprinted electrochemiluminescence sensor based on upconversion nanoparticles enhanced by electrodeposited rGO for selective and ultrasensitive detection of clenbuterol

A simple, efficient and sensitive molecularly imprinted electrochemiluminescence sensor (MIECLS) based on reduced graphene oxide (rGO) and upconversion nanoparticles (UCNPs) was developed for determination of clenbuterol (CLB). In this study, rGO generated by electrodeposition of graphene oxide not only acted as carrier for immobilizing UCNPs, but also had a significant impact in boosting electrochemiluminescence (ECL) response of UCNPs thanks to its high conductivity, superior electron transport rate and large specific surface area. UCNPs as an advanced ECL emitter possessed wonderful ECL performance. Furthermore, the introduction of molecularly imprinted polymers (MIP) endowed the ECL sensor a new character of specifically identifying analyte CLB. Under the optimal experimental conditions, the ECL signal was proportional to the logarithm of CLB concentration in the range of 10nM to 100µM with a low detection limit of 6.3nM. The proposed MIECLS combining the advantages of UCNPs-ECL and MIP exhibited good sensitivity, desirable selectivity and favorable stability, indicating enormous potential in the future of food safety detection.

Electrochemical sensor based on in situ polymerized ion-imprinted membranes at graphene modified electrode for palladium determination

In this work, an amperometric sensor was developed for the selective recognition and sensitive determination of palladium in complex matrices using a glassy carbon electrode (GCE) modified with a novel ion-imprinted membrane (IIM) and graphene. Graphene enhanced the sensor's electron transfer and sensitivity. The electrode surface was first directly modified with graphene through the electrodeposition of graphene oxide. An ion-imprinted polymer membrane was subsequently synthesized on this modified surface via in situ polymerization in acetonitrile using allylurea (NAU) as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linking agent, and azobisisobutyronitrile as an initiator at a molar ratio of template (PdCl2) to NAU to EGDMA of 1:4:40. Amperometric i-t curves were measured for the determination of palladium. The designed modified electrode was shown a linear response to Pd(II) ions in the range of 2.0×10−8–2.0×10−4molL−1 of Pd(II) ion with a detection limit of 6.4×10−9molL−1. Metal ions present at concentrations 15 times higher than that of Pd(II) did not interfere with the determination of Pd(II). The sensor was successfully applied to determine palladium in catalyst and plant samples with a relative standard deviation (RSD) of less than 3.3% (n=5) and recoveries in the range of 99.2–106.5%.

Facile electrodeposition of reduced graphene oxide hydrogels for high-performance supercapacitors.

We report both a facile, scalable method to prepare reduced graphene oxide hydrogels through the electrodeposition of graphene oxide and its use as an electrode for high-performance supercapacitors. Such systems exhibited specific capacitances of 147 and 223 F g(-1) at a current density of 10 A g(-1) when using H2SO4 and H2SO4 + hydroquinone redox electrolytes, respectively.