Гальвано-, потенциостатическое восстановление многослойного оксида графена в щелочном электролите

The results of the study of the electrochemical reduction of multilayer graphene oxide in the potentiostatic mode are presented and the possibility of using alkaline electrolyte (KOH) with the concentration below 0.1 M is shown. The identification of the electrochemically reduced graphene oxide was carried out using the XRD, FTIR and Raman-spectroscopy methods. Applying the method of Raman spectroscopy the increase in the intensity of the G and 2D bands, indicating the formation of few-layer forms of reduced graphene oxide was found. The surface morphology of the electrochemically reduced graphene oxide was studied by means of the SEM method.

Three-dimensional (3D) graphene networks are performance boosters for functional nanostructures in energy-related fields. Although tremendous intriguing nanostructures-decorated 3D graphene network...

Economic procedure for facile and eco-friendly reduction of graphene oxide by plant extracts; a comparison and property investigation

In recent years, there has been remarkable progress in the reduction and functionalization of graphene oxide (GO) using nanoparticles and high-energy optical photons. Most of these reactions are carried out in solutions, whereas the local modification of GO on solid substrates still remains a challenge. In this work, we demonstrate the local reduction of GO and its further destruction, leading to the synthesis of polyaromatic hydrocarbons (PAHs) stimulated by localized surface plasmons (LSPs). The reduction of GO and the synthesis of PAHs have been carried out on a substrate designed for surface-enhanced Raman spectroscopy (SERS). We found that LSPs initiate the destruction of water molecules entrapped in the nanogaps between silver nanoparticles after the deposition of GO from the aqueous suspension. It was demonstrated that OH radicals, as a result of water decomposition, initiate the reduction of GO, leading to the synthesis of PAHs. The reactions have been observed in real time by using SERS. The measurement of current-voltage (I-V) characteristics through conductive atomic force microscopy (AFM), recorded in an LSP-stimulated area, have shown the increased electrical conductivity (more than ten times) compared with the conductivity of GO. The synthesis of new compounds in the LSP-stimulated area has been confirmed by the appearance of new peaks in the Raman spectra and nonlinear I-V characteristics typical for PAHs. We show that the used method allows the local modification of electrical properties of GO and controlled nanopattering of organic compounds on the surface.

Enhanced hydrogen gas barrier performance of diaminoalkane functionalized stitched graphene oxide/polyurethane composites

This study presents the electrochemical reduction of graphene oxide (GO) to reduced graphene oxide (rGO) directly onto flexible interdigitated gold electrodes and its application as a strain sensor. GO reduction is achieved using cyclic voltammetry (CV). Remarkably, only a single CV cycle transformed GO into rGO to obtain low‐resistance (≈100 Ω) devices. The reduction of GO is confirmed using Raman spectroscopy and electrical measurements. rGO on flexible interdigitated gold electrodes exhibits graphene‐like characteristics when used as electrolyte‐gated field‐effect transistors. The fabricated devices display a gauge factor (GF) of ≈3.7 in the 0–794 με range. This value represents a substantial improvement, ≈60% higher than traditional metallic strain sensors, which have a GF of ≈2.1. Most importantly, the rGO strain sensor exhibits fast response (1.1 s) and recovery (0.92 s) times. The rGO sensor is mounted on a clamp with an adjustable diameter, which reveals exceptional flexibility and bendability without damage or degradation. These results highlight the potential of rGO for advancing strain‐sensing applications, offering promising opportunities for the future of this technology.

Tuning the electrochemical reduction of graphene oxide: structural correlations towards the electrooxidation of nicotinamide adenine dinucleotide hydride

The well-controlled graphene was prepared by pre-oxidisation, full-oxidisation and hydrothermal reduction of flake graphite. The graphene oxide (GO) reveals the overlapped few-layer structure and the reduced graphene oxide (RGO) shows well-dispersed few-layer structure. Raman spectra analysis indicates that the RGO shows higher B band/G band ratio value than GO, indicating well-restored SP2 carbon atom arrangement and crystal structure. Both fewer-layer GO and RGO were coated on nickel form for supercapacitor electrode application. The GO with sufficient hydroxyl, epoxy and carboxyl groups reveals low conductivity and low current response, which causes low specific capacitance of 0.36, 0.38 and 0.55 F g−1 at 0.5 A g−1 in Na2SO4, KOH and LiOH electrolyte solution, respectively. The RGO with high conductivity reveals the enhanced specific capacitance of 37.12, 51.80 and 61.31 F g−1 at 0.5 A g−1. The LiOH electrolyte with superior ionic diffusion coefficient leads to higher capacitance performance of fewer-layer GO and RGO than other electrolytes. The RGO shows much higher current response than GO at the same scan rate in cyclic voltammetry measurement, which is ascribed to its higher electroactivity. The similar capacitance enhancement of RGO was achieved through cyclic voltammetry-based capacitance and galvanostatic charge/discharge-based capacitance measurements. Accordingly, fewer-layer RGO reveals the superior electrochemical capacitance performance in LiOH electrolyte for the effective energy-storage application.

Periodic nanopatterning and reduction of graphene oxide by femtosecond laser to construct high-performance micro-supercapacitors

Herein, we present an electrochemically assisted method for the reduction of graphene oxide (GO) and the assembly of polyoxometalate clusters on the reduced GO (rGO) nanosheets for the preparation of nanocomposites. In this method, the Keggin-type H4 SiW12O40 (SiW12) is used as an electrocatalyst. During the reduction process, SiW12 transfers the electrons from the electrode to GO, leading to a deep reduction of GO in which the content of oxygen-containing groups is decreased to around 5%. Meanwhile, the strong adsorption effect between the SiW12 clusters and rGO nanosheets induces the spontaneous assembly of SiW12 on rGO in a uniformly dispersed state, forming a porous, powder-type nanocomposite. More importantly, the nanocomposite shows an enhanced capacity of 275 mAh g(-1) as a cathode active material for lithium storage, which is 1.7 times that of the pure SiW12. This enhancement is attributed to the synergistic effect of the conductive rGO support and the well-dispersed state of the SiW12 clusters, which facilitate the electron transfer and lithium-ion diffusion, respectively. Considering the facile, mild, and environmentally benign features of this method, it is reasonable as a general route for the incorporation of more types of functional polyoxometalates onto graphene matrices; this may allow the creation of nanocomposites for versatile applications, for example, in the fields of catalysis, electronics, and energy storage.

The paper focused on the description of the reduced graphene oxide (rGO) structure. This material is obtained from a multistage production process. Each of these stages has a large impact on its structure (the number and type of functional groups, number of defect or the size of the flakes), and this in turn affects its properties. We would like to visualize the reduced graphene oxide, both using a diagram showing the atomic structure, as well as by imaging using scanning electron microscopy (SEM) and atomic force microscopy (AFM). In the paper, the elementary composition of selected elements and data obtained from X-ray photoelectron spectroscopy technique (XPS) will be also presented. Full Text: PDF ReferencesX. Peng, Y. Wu, N. Chen, Z. Zhu, J. Liu, and H. Wang, "Facile and highly efficient preparation of semi-transparent, patterned and large-sized reduced graphene oxide films by electrochemical reduction on indium tin oxide glass surface", Thin Solid Films 692, 137626 (2019). CrossRef L. Guo, Y.-W. Hao, P.-L. Li, J.-F. Song, R.-Z. Yang, X.-Y. Fu, S.-Y. Xie, J. Zhao and Y.-L. Zhang, "Improved NO2 Gas Sensing Properties of Graphene Oxide Reduced by Two-beam-laser Interference", Sci. Rep. 8, 1 (2018). CrossRef Y. S. Milovanov, V.A. Skryshevsky, , O.M. Slobodian, , D.O. Pustovyi, X.Tang, J.-P. Raskin, and A.N. Nazarov, "Influence of Gas Adsorption on the Impedance of Graphene Oxide", 2019 IEEE 39th Int. Conf. Electron. Nanotechnology, ELNANO 2019 - Proc. 8783946, CrossRef M. Reddeppa, B.-G. Park, , M.-D. Kim, K.R. Peta, N.D. Chinh, D. Kim, S.-G. Kim, and G. Murali, "H2, H2S gas sensing properties of rGO/GaN nanorods at room temperature: Effect of UV illumination", Sensors Actuators B. Chem. 264, (2018). CrossRef W. L. Xu, C. Ding, , M.-S. Niu, X.-Y. Yang, F. Zheng, J. Xiao, M. Zheng and X.-T. Hao, "Reduced graphene oxide assisted charge separation and serving as transport pathways in planar perovskite photodetector", Org. Electron. 81, 105663 (2020). CrossRef K. Sarkar, M. Hossain, P. Devi, K. D. M. Rao, and P. Kumar, "Self‐Powered and Broadband Photodetectors with GaN: Layered rGO Hybrid Heterojunction", Adv. Mater. Interfaces, 6, 20 (2019). CrossRef S. Pei and H. M. Cheng, "The reduction of graphene oxide", Carbon, 50, 9 (2012). CrossRef R. Muzyka, S. Drewniak, T. Pustelny, M. Chrubasik, and G. Gryglewicz, "Characterization of Graphite Oxide and Reduced Graphene Oxide Obtained from Different Graphite Precursors and Oxidized by Different Methods Using Raman Spectroscopy", Materials 11, 7 (2018). CrossRef M.-H. Tran and H. K. Jeong, "Influence of the Grain Size of Precursor Graphite on the Synthesis of Graphite Oxide", New Phys. Sae Mulli, 63, 2 (2013). CrossRef M.-H. Tran, C.-S. Yang, S. Yang, I.-J. Kim, and H. K. Jeong, "Influence of graphite size on the synthesis and reduction of graphite oxides", Curr. Appl. Phys., 14, SUPPL. 1 (2014). CrossRef N. Sharma, Y. Jain, , M. Kumari, R. Gupta, S.K. Sharma, K. Sachdev, "Synthesis and Characterization of Graphene Oxide (GO) and Reduced Graphene Oxide (rGO) for Gas Sensing Application", Macromol. Symp. 376, 1 (2017). CrossRef M. Wei, L. Qiao, , H. Zhang, S. Karakalos, K. Ma, Z. Fu, M.T. Swihart, G. Wu, "Engineering reduced graphene oxides with enhanced electrochemical properties through multiple-step reductions", Electrochim. Acta, 258 (2017). CrossRef S. Drewniak, M. Procek, R. Muzyka, T. Pustelny, "Comparison of Gas Sensing Properties of Reduced Graphene Oxide Obtained by Two Different Methods", Sensors, 20, 11 (2020). CrossRef L. Li, R.-D. Lv, S. -C. Liu, Z. D. Chen, J. Wang, Y.-G. Wang, W. Ren, "Using Reduced Graphene Oxide to Generate Q-Switched Pulses in Er-Doped Fiber Laser", Chinese Physics Letters, 35, 11 (2018) CrossRef

The electrochemical reduction of graphene oxide (GO) is an environmentally friendly and energy-saving method for improving the characteristics of GO. However, GO films must be coated on the cathode electrode in advance when usingthis technique. Thus, the formed electrochemically reduced GO (ERGO) films can be used only as sensing or conductive materials in devices because mass production of the flakes is not possible. Therefore, this study proposes a facile electrochemical reduction technique. In this technique, GO flakes can be directly used as reduced materials, and no GO films are required in advance. A 0.1 M phosphate buffered saline solution was used as the electrolyte, which is a highly safe chemical agent. Experimental results revealed that the as-prepared GO flakes were electrochemically reduced to form ERGO flakes by using a −10 V bias for 8 h. The ratio of the D-band and G-band feature peaks was increased from 0.86 to 1.12, as revealed by Raman spectroscopy, the π-π stacking interaction operating between the ERGO and GO has been revealed by UV-Vis absorption spectroscopy, and the C–O ratio was increased from 2.02 to 2.56, as indicated by X-ray photoelectron spectroscopy. The electrical conductivity of the ERGO film (3.83 × 10−1 S·cm−1) was considerably better than that of the GO film (7.92 × 10−4 S·cm−1). These results demonstrate that the proposed electrochemical reduction technique can provide high-quality ERGO flakes and that it has potential for large-scale production.

This paper describes anodic electrophoretic deposition of graphene oxide (GO) on 316L SS with pH-dependent microstructures. GO flakes were synthesized by modified Hummers’ method. Detailed studies on structural characteristics, thermal stability, and elemental composition of the GO flakes were carried out using advanced characterization techniques. Results showed successful oxidation and exfoliation forming GO flakes that are hydrophilic in nature. Acidic (pH 3.4) and basic (pH 11) aqueous GO suspensions were prepared, and the zeta potential as well as the average particle size distribution of the suspensions was ascertained. The GO suspensions were exhibiting zeta potential values of −32.9 and −36.8 mV and average particle size of 1–2 µm and 800–900 nm at acidic pH of 3.4 and alkaline pH of 11, respectively. Using anodic electrophoretic deposition (EPD) methods, GO was coated on 316L SS substrate from acidic and alkaline suspension and coatings were characterized. The increased value of ID/IG by Raman spectra analysis, partial restoration of C = C skeleton in the de-convoluted C 1s XPS spectra analysis, and the presence of C–C and C–H stretching bands in ATR-FTIR spectra were correlated with partial reduction of GO during the deposition on 316L SS surface. Though there was no difference in the chemical composition of the coatings formed from the acidic and alkaline pH suspension, atomic force microscopy and field emission scanning electron microscopy characterization showed difference in topography and morphology of the coatings. 316L SS substrates coated with GO in acidic pH showed higher RMS and average roughness and dense agglomerated wrinkled microstructure compared to substrates coated with alkaline pH suspension. Again GO coating from acidic pH suspension showed hydrophobicity. The present study showed that the microstructures of the GO coatings on 316L SS can be tuned by varying the pH of the GO suspension during EPD process.

A green approach for the reduction of graphene oxide by the ultraviolet/sulfite process

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