Three-dimensional Porous Reduced Graphene Oxide Research Articles

Ultrasensitive Electrochemical Sensor Based on SnO2 Anchored 3D Porous Reduced Graphene Oxide Nanostructure Produced via Sustainable Green Protocol for Subnanomolar Determination of Anti-Diabetic Drug, Repaglinide

Herein, we have reported on a simple, environmentally friendly, and ultra-sensitive electrode material, SnO2@p-rGO, used in a clean sustainable manner for rapid electrochemical determination of an anti-diabetic agent, repaglinide (RPG). Three-dimensional porous reduced graphene oxide nanostructure (p-rGO) was prepared via a low-temperature solution combustion method employing glycine. The aqueous extract of agricultural waste “cotton boll peel” served as stabilizing and reducing agents for the synthesis of SnO2 nanoparticles. The structural and morphological characterization was carried out by XRD, Raman, SEM, EDX, FTIR, absorption, and TGA. The oxidation process of RPG was realized under adsorption controlled with the involvement of two protons and electrons. The sensor displayed a wider linearity between the concentration of RPG and oxidation peak current in the ranges of 1.99 × 10−8–1.45 × 10−5 M and 4.99 × 10−8–1.83 × 10−5 M for square-wave voltammetric and differential pulse voltammetric methods, respectively. The lower limit of detection value of 0.85 × 10−9 M was realized with the SWV method. The proposed sensor was applied for the quantification of RPG in fortified urine samples and pharmaceutical formulations. Furthermore, the sensor demonstrated reproducibility, long-term stability, and selectivity in the presence of metformin and other interferents, which made the proposed sensor promising and superior for monitoring RPG.

Three-dimensional porous reduced graphene oxide modified electrode for highly sensitive detection of trace rifampicin in milk.

Antibiotic overuse poses a serious food safety problem. Therefore, it is of great importance to develop efficient assays that respond to antibiotics to establish early-warning mechanisms. Here, we prepared a three-dimensional (3D) porous reduced graphene oxide (pRGO) modified electrode, which was characterized by scanning electron microscopy and transmission electron microscopy. As a result of the introduction of the 3D pRGO film, the electrocatalytic activity was considerably improved, which could efficiently trigger the redox reaction of rifampicin (RIF). By employing differential pulse voltammetry, the reduction peak current of RIF showed a good linear relationship with the logarithm of the RIF concentration in the range 1.0 × 10-9 to 1.0 × 10-7 mol L-1. The linear equation was ip (-10-6 A) = 3.11 + 0.28 log cRIF (R2 = 0.9908) with a detection limit of 2.7 × 10-10 mol L-1 (S/N = 3). Additionally, the final electrode displayed long stability, good reproducibility and high selectivity, and could detect trace RIF in milk with satisfactory results. This study reveals the great potential in utilizing 3D pRGO to develop efficient electrochemical sensors for safeguarding food safety.

Three-dimensional porous reduced graphene oxide decorated with carbon quantum dots and platinum nanoparticles for highly selective determination of azo dye compound tartrazine

In this work, an electrochemical sensor for the azo dye compound tartrazine (TRT) determination was proposed. A screen-printed carbon electrode (SPCE) was modified by depositing three-dimensional porous reduced graphene oxide decorated with carbon quantum dots and platinum nanoparticles (Pt/CQDs@rGO/SPCE). The resulting amount of TRT was observed by differential pulse voltammetry. Under optimal conditions, the sensor exhibited two wide linearities ranging from 0.01 to 1.57 μM and 1.57–9.3 μM with the reliability coefficient of determination of 0.991 and 0.992, respectively. The detection limit (LOD) was also estimated to be 7.93 nM. Moreover, the Pt/CQDs@rGO/SPCE suggested high selectivity in the presence of several interfering agents and azo dye compounds that have a similar structure. Additionally, the Pt/CQDs@rGO/SPCE revealed superior recovery values of about 96.5–101.6% for candy, 99.7–103.5% for soft drinks, 96.0–101.2% for jelly powder, and 98.0–103.0% for water samples. Furthermore, the fabricated sensor exhibits excellent selectivity, stability, reproducibility, and repeatability, indicating a great perspective in the monitoring of TRT. Therefore, it can be speculated that the proposed electrode could be effectively applied to determine TRT in food samples.

Facile synthesis of an air-stable 3D reduced graphene oxide-phosphorene composite by sonication

Phosphorene, a two-dimensional semiconductor, has promising applications in energy storage, photodetectors, field-effect transistors fields etc., owing to its all kinds of the fascinating properties. However, sluggish electron kinetics and poor stability under ambient conditions restrict the development of phosphorene. Currently, the main method to solve the above challenges is to coat phosphorene with graphene. Nevertheless, the reported method cannot solve the two problems simultaneously and effectively. Therefore, in this paper, a facile and valid method was developed to prepare three-dimensional porous reduced graphene oxide -phosphorene composite by short-time ultrasonic assisting, for the first time. The composite was characterized by XRD, Raman, TGA, SEM, AFM, FT-IR, XPS, UV–Vis and Optical microscope techniques. The relevant results indicated that a strong P-O-C bond between phosphorene and reduced graphene oxide was formed, which makes the phosphorene exhibit excellent stability even when its dispersion in water was exposed to air for 96 h. Furthermore, the three-dimensional porous cross-linked reduced graphene oxide conductive network was also formed, and the pore size of the composite ranges from a few hundred nanometers to several micrometers.

Three-dimensional porous reduced graphene oxide decorated with MoS2 quantum dots for electrochemical determination of hydrogen peroxide

Three-dimensional (3D) graphene-based nanomaterials have shown wide applications in electrochemical fields such as biosensors. In this study, we displayed a simple fabrication of 3D structural reduced graphene oxide (3D structural RGO) decorated with molybdenum disulfide quantum dots (MoS2QDs) through a three-step reaction process. With its abundant raw materials, this strategy is economic and non-toxic. Various characterization techniques were utilized to characterize the morphologies of the synthesized MoS2QDs, graphene oxide (GO), and 3D structural RGO-MoS2QDs composites. Simultaneously, X-ray photoelectron spectroscopy was applied to characterize the structure and properties of composites. In order to understand the effects of the reaction period on the structure of 3D structural RGO-MoS2QDs, a series of samples with various reaction periods were prepared for morphological characterization. Finally, the fabricated 3D structural RGO-MoS2QDs composites were used to modify a glassy carbon electrode as an electrochemical non-enzymatic hydrogen peroxide (H2O2) sensor. The obtained results indicate that the fabricated electrochemical H2O2 sensor exhibits a wide detection range (0.01–5.57 mM), low detection limit (1.90 μM), good anti-interference performance, and long-time stability (18 days).

Synthesis of three-dimensional porous reduced graphene oxide hydrogel/carbon dots for high-performance supercapacitor

A composite composed of reduced graphene oxide hydrogel/carbon dots (rGH/CDs) is prepared hydrothermally. The composite has a three-dimensional (3D) interconnected network structure and exhibits good electrical conductivity and mechanical robustness, making it ideal electrode materials in supercapacitors. The carbon dots (CDs) in the reduced graphene oxide hydrogel promotes electron transport and reduces the internal resistance and charge transfer resistance in addition to providing a large surface area. The flexible solid-state supercapacitor comprising the 130μm thick rGH/CDs electrode delivers excellent performance including high gravimetric specific capacitance of 264Fg−1 (up to 301Fg−1 for a 40μm thick electrode), areal specific capacitance of 394mFcm−2 (up to 432Fcm−2 for a 200μm thick electrode), excellent cycling stability (9.1% deterioration after 5000cycles), larger energy density (35.3Whkg−1), as well as high power density (516Wkg−1). This study demonstrates the tremendous potential of rGH/CDs in high-performance flexible energy storage devices.

Direct growth of Cu2ZnSnS4 on three-dimensional porous reduced graphene oxide thin films as counter electrode with high conductivity and excellent catalytic activity for dye-sensitized solar cells

Well-crystallized Cu2ZnSnS4 (CZTS) nanoparticles contain ultrasmall nanocrystals (~ 10 nm) have been grown directly on three-dimensional (3D) transparent porous reduced graphene oxide (rGO) thin films by a facile and scalable solution-based strategy. Few-layer rGO prepared by modified Hummers’ method was used to fabricate hierarchical ultraporous 3D rGO thin films (3DGTFs) with high transmittance (> 75% for 200-nm thick). Single-phase kesterite CZTS nanocrystalline particles were grown uniformly on the surface active sites within the 3D rGO network by hydrothermal method. The as-prepared CZTS/rGO composite thin films exhibited excellent electrocatalytic ability by taking advantages of the high conductivity and high surface area of 3DGTFs and the high catalytic activity of CZTS nanoparticles. As expected, the composite thin films demonstrate more than one order of magnitude lower in electrical resistivity and in charge transfer resistance than the individual CZTS thin films. The conversion efficiency of dye-sensitized solar cells using CZTS/rGO thin films as the counter electrode (CE) approached 6.12%, comparable to that using Pt CE (6.45%) and superior to those using individual CZTS CE (1.07%) and rGO CE (0.18%).

Colloidally synthesized MoSe2 nano-flowers anchored on three-dimensional porous reduced graphene oxide thin films as advanced counter electrode for dye-sensitized solar cells

In this letter, MoSe2 nanosheets with flower-like nanostructure was in-situ grown on pre-coated three-dimensional (3D) porous reduced graphene oxide (rGO) thin films on fluorine-doped tin oxide glass by a facile hydrothermal method. The synergistic effect between the highly catalytic MoSe2 nanostructure and the highly conductive and large surface-area 3D rGO network endows the resultant MoSe2/rGO composite excellent electrocatalytic ability. As expected, dye-sensitized solar cells (DSSCs) prepared with MoSe2/rGO thin films as counter electrode (CE) exhibited a conversion efficiency of 6.56%, which was higher than that of DSSCs with sputtered Pt CE (6.08%).

Electrochemical synthesis of three-dimensional porous reduced graphene oxide film: Preparation and in vitro osteogenic activity evaluation

In this study, three-dimensional reduced graphene oxide (3D-rGO) porous films were fabricated using a two-step electrochemical method, including an electrochemical deposition process for the self-assembly of GO and an electrochemical bubbling-based transfer. The morphology, physical properties, and phase composition of the 3D-rGO films were characterized, and the cellular bioactivities were evaluated using pre-osteoblasts (MC3T3-E1 cells). The attachment, proliferation and differentiation of the MC3T3-E1 cells on the 3D-rGO films was analyzed by scanning electron microscopy (SEM), Cell Counting Kit-8 (CCK-8) assays and live/dead cell staining, and alkaline phosphatase (ALP) activity assays, respectively. The expression of osteogenic-related genes in MC3T3-E1 cells was evaluated by reverse transcription-polymerase chain reaction (RT-PCR). The results showed that the 3D-rGO films supported cell viability and proliferation, as well as significantly enhanced ALP activity and osteogenic-related genes (ALP, OPN, Runx2) expressions. Our findings indicate the promising potential of the 3D-rGO porous films for bone tissue engineering.

Interfacial Deposition of Three-Dimensional Nickel Hydroxide Nanosheet-Graphene Aerogel on Ni Wire for Flexible Fiber Asymmetric Supercapacitors

Burgeoning interest in flexible and wearable electronics sparks the rapid development of flexible fiber-shape supercapacitors (SCs). Herein, three-dimensional porous reduced graphene oxide (RGO) aerogel is deposited on flexible Ni wire via a simple aqueous reduction method. RGO aerogel exhibits good capacitive performance, thanks to its unique porous structure and good electrical conductivity. In order to fabricate an asymmetric SC, nickel hydroxide nanosheets are controllably deposited on the RGO sheets as the positive electrode while the RGO aerogel coated Ni wire is used as negative one. The obtained flexible fiber SCs exhibit good performance with high power/energy densities (10.3 kW kg–1/3430 mW cm–3, 24.5 Wh kg–1/0.83 mWh cm–3) and good cycling stability (83% retention, even after 6000 cycles). The solid-state nature combined with good flexibility makes the fiber SCs attractive for energy storage applications in portable and wearable electronics. The interfacial deposition of reduced graphene oxide ...

Highly exposed copper oxide supported on three-dimensional porous reduced graphene oxide for non-enzymatic detection of glucose

Copper oxide nanoparticles were anchored on porous reduced graphene oxide (PrGO) by a simple and mild hydrothermal method. The as-prepared product was characterized by X-ray diffraction, N2 adsorption–desorption isotherms, scanning electron microscopy, and used to build a novel glucose sensor. The CuO/PrGO nanocomposite showed an enhanced electrocatalytic activity to direct glucose oxidation compared with the non-porous reduced graphene oxide-CuO (CuO/rGO). The CuO/PrGO modified glass carbon electrode (CuO/PrGO-GCE) responded linearly to glucose in the range of 0.001 to 6mM and the detection limit of the transducer was found to be 0.50μM. High reproducibility, wide linear range, good anti-interference, stability and enough precision in real sample analysis made it promising for the development of enzyme-free sensors.

Facile fabrication of self-supported three-dimensional porous reduced graphene oxide film for electrochemical capacitors

In this work, an intriguing replicating and an embossing strategy was developed to fabricate self-supported three-dimensional (3D) porous reduced graphene oxide (rGO) film towards high-performance electrochemical capacitors. The unique 3D porous rGO film delivered a large specific capacitance (SC) of 206Fg−1 at 1Ag−1, and even 141Fg−1 at a current density of 10Ag−1, and desirable electrochemical stability in 1M H2SO4 electrolyte, owing to its appealing micro-structural feature.