rGO Composites Research Articles

Regulating high specific capacitance NCS/α-MnO2 cathode and a wide potential window α-Fe2O3/rGO anode for the construction of 2.7 V for high performance aqueous asymmetric supercapacitors

The long-term durability, safety, and high specific power, supercapacitors (SCs) hold unlimited promise for replacing non-renewable energy sources. Aqueous asymmetric supercapacitors (AASCs) offer numerous economic and environmental benefits. The small voltage of AASCs, however, limits their progress for large-scale industrial applications. AASCs with voltage windows (>2.0 V) have made significant progress in the last few years. Herein, a novel hierarchical α-Fe2O3 ultra-thin nanowires grown on rGO aerogel (denoted as α-Fe2O3/rGO) composite was designed as the anode. Taking advantage of the rGO aerogel protective layer, the α-Fe2O3/rGO anode reveals a prolonged voltage window up to -1.5–0 V, which considerably boosts capacitance up to (270 F g−1@1 A g−1), and (106.7 F g−1@ 10 A g−1) along with superb stability owing to the good integration of rGO network and α-Fe2O3. Moreover, NiCo2S4 nanosheets coated on α-MnO2 nanorods (denoted as NCS/α-MnO2) as a protection layer to complement the wide potential cathode, as a result, the NCS/α-MnO2 composite displays an optimized voltage window of 0–1.2 V, a high capacitance (594 F g−1@1 A g−1), and outstanding cycling stability. More importantly, the assembled NCS/α-MnO2//α-Fe2O3/rGO AASC device functions in an optimized voltage (2.7 V) by means of ultra-high specific energy of 142.1 Wh kg−1, at the specific power of 1350 W kg−1 with the downfall of the specific energy of 18.75 Wh kg−1 at the specific power of 67,500 W kg−1 with exceptional stability (79% of its initial capacitance retention). Additionally, we demonstrated a single AASC device with enough energy to light a 20 mW green LED and emitted light over 40 s, which opens up possible realistic applications. Finally, this study provides an avenue for fabricating and designing a wide voltage using a compositing technique, which seems to be one of the promising route to increase specific energy of AASCs.

Monodisperse Cu3P nanoplates in situ grown on reduced graphene oxide via hydrophobic interaction for water splitting

The monodisperse Cu3P nanoplate/reduced graphene oxide (rGO) composite was obtained by in situ growing Cu3P on the surface of rGO via the hydrophobic interaction in the colloidal solution. The monodisperse Cu3P nanoplates is about 55 nm due to the modification of hexadecylamine. The composite structure not only offered more catalytic active sites by Cu3P nanoplates, but also facilitated rapid electron transfer due to rGO for water splitting. The Cu3P/rGO showed a high hydrogen evolution reaction efficiency, which yielded low overpotentials of 144 mV at current density of 10 mA cm−2.

Cellulose nanocrystals‑silver nanoparticles-reduced graphene oxide based hybrid PVA nanocomposites and its antimicrobial properties

Towards fabricating a hybrid biodegradable multifunctional nanocomposite, cellulose nanocrystal (CNC), reduced graphene oxide (rGO) and silver (Ag) nanoparticles were reinforced into polyvinyl alcohol (PVA) polymer matrix. One-step reduction process was followed, composed of reducing graphene oxide (GO) and silver nitrate (AgNO3) into rGO and Ag nanoparticles through hydrazine hydrate (chemical reduction method), respectively. Uniformly dispersed CNC, rGO and Ag nanoparticles in PVA matrix led to an increment in modulus by 184% of PVA demonstrating the reinforcement outcome of CNC, rGO and Ag. PVA/CNC/rGO/Ag nanocomposite showed the Ag+ ions sustained release from PVA studied using Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The incorporation and elemental composition of CNC, rGO and Ag nanoparticles into nanocomposite were interpreted through FTIR (Fourier Transform Infrared Spectroscopy) and XPS (X-ray photoelectron spectroscopy) technique, respectively. All prepared nanocomposites with different wt% of Ag (PVA, PVA/CNC, PVA/CNC/rGO/Ag) were non-toxic to HEK-293 cell line and exhibited improved antibacterial property against E. coli and S. aureus due to a combination of Ag+ ions (release from Ag nanoparticles) and rGO (having antibacterial effect). Thus, the combined effect of CNC, rGO and Ag in PVA matrix distinctively resulted into a multifunctional hybrid nanocomposite for potential use in tissue engineering and packaging applications.

Influence of aggregation and dispersion of minium nanoparticles decorated reduced graphene oxide platelets and their super-capacitive performances

This paper presents the synthesis, characterization, and fabrication of a prototype supercapacitor employing lead oxide nanoparticles (Pb3O4 Nps) dispersed reduced graphene oxide (rGO) nanocomposite as electrode material. Novel minium Pb3O4 Nps and the rGO platelets are synthesized using the precipitation method and modified microwave treatment. The various weight percentages of Pb3O4 Nps (1 wt%, 3 wt%, & 5 wt%) are blended with rGO using ultrasonication process followed by stirring process. The prepared nanomaterials are characterized to predict diffraction patterns, molecular vibrations, surface morphology, and elemental composition of Pb3O4 Nps, rGO, and Pb3O4-rGO nanocomposites. The Pb3O4-rGO nanocomposites are coated on the brass substrate and the charge storing characteristics of the electrode systems are evaluated using an electrochemical workstation which displays a remarkable specific capacitance value of 377F/g for Pb3O4-rGO nanocomposite prepared using 3 wt% Pb3O4 Nps coated electrode system at the scan rate of 5 mV/s and displays high retention stability of 95% after 2500 cycles. A prototype is fabricated in a pilot-scale study, where its charge-discharge behavior is demonstrated using a 9 V battery. After charging, a green light-emitting diode is activated for around 11 min while connecting 7 devices in series.

Electrocatalytic Activity of Reduced Graphene Oxide Supported Cobalt Cinnamate for Oxygen Evolution Reaction

The stability of porous coordination polymers during an electrochemical reaction could be improved by introducing supporter materials. An I3O0-type inorganic hybrid electrocatalyst, cobalt cinnamate, supported on reduced graphene oxide (rGO) was successfully prepared for an oxygen evolution reaction. The electrocatalytic activity and stability of cobalt cinnamate(catalyst)/rGO composite were significantly improved due to the strong interaction between catalyst and supporter, which led to enhanced anchoring stability and electrical conductivity. The catalyst/rGO composite shows ~30 mV reduction in overpotential and improvement in durability from ≥35% to ≥70% after a reaction time of 12 h, compared to the catalyst alone.

Nanosheet array-like Cu@Cu2O-CuNiAl(O)/rGO composites for highly efficient reduction of nitrophenol: Electronic and structure promotion effect of nickel

Series of hierarchical nanosheet array-like composites xCu@Cu2O-CuNiAl(O)/rGO (x = 1.0, 1.5, 2.0) were constructed via proper calcination of pre-prepared hybrids CuxNi3-xAl-layered double hydroxide/rGO in N2 flow, upon the LDH layer atomic-level lattice confined in situ self-reduction for Cu2+ ions by rGO substrate along with the dispersion effect of Ni-OH groups. Systematic characterizations reveal that core@shell-type Cu@Cu2O nanoparticles (NPs) are definitely trapped in the border space among the vertically adjacent CuNiAl(O) nanosheets and rGO substrates. All the xCu@Cu2O-CuNiAl(O)/rGO composites exhibit excellent catalytic activities for the reduction of 4-nitrophenol (4-NP), particularly 1.5Cu@Cu2O-CuNiAl(O)/rGO possesses the highest activity (kapp: 7.6 × 10-2 s−1, TOF: 265.0 h−1), and superb reusability with insignificant loss in activity for continuous 25 cycles, much better than those of recently reported Cu-based catalysts and even comparable to some noble metal catalysts. The best performance of 1.5Cu@Cu2O-CuNiAl(O)/rGO can be mainly attributed to the most uniformly dispersed electrophilic core@shell Cu@Cu2O NPs modified by NiO species structurally and electronically, the strongest Cu–Cu2O–CuNiAl(O)–rGO synergistic effect upon the unique nanosheet array-like morphology providing more ion-accessible active sites, and much improved adsorption for 4-NP via rGO layer due to π-π stacking. The universality and fixed bed tests further demonstrate potential practical applications of the present hierarchical non-noble composites for water remediation. The present facile synthesis strategy of the nanosheet array-like Cu@Cu2O-CuNiAl(O)/rGO composites with multi-phases synergy may be greatly beneficial to the design and construction of many other highly efficient multi-transition metal-based catalysts with excellent structural robustness for a broad range of applications in related catalysis processes.

Influence of free electron charge and free extra framework anions in calcium aluminate@ rGO (CA@ rGO) cement composites with enhanced dielectric and electrochemical properties

Nowadays, the metal oxide-based composites loaded with reduced graphene oxide (rGO) nano sheets are believed to enhance both the electrochemical and dielectric properties. In this study, therefore, the effect of rGO loading contents on the calcium aluminate (CA), namely CA@ rGO, cement composites with high dielectric and electrochemical properties is presented. CA@ rGO composites were successfully synthesized via a simple direct mixing of CA cement with various contents of graphene oxide (GO) precursors followed by a conventional thermal reduction method. Based on XRD and Raman spectroscopy results, all prepared CA@ rGO composites clearly confirmed both the structure of the pristine CA cement as well as the complete conversion of GO precursors to rGO after thermal reduction, and the existence of rGO nano sheets on the surface of CA@ rGO composites. The impedance value results revealed that the enhancement of a high dielectric constant was achieved in the CA@ rGO composites due to both typical interface polarization and the micro-capacitor of CA cement and rGO nano sheets. Meanwhile, the prepared CA@ rGO-4 composite electrode exhibited the highest of electrochemical double-layer capacitive behavior with the specific capacitance (Csc) value of 79.33 F g−1 at 0.2 A g−1. The enhanced super-capacitive performance of CA@ rGO composite can be improved by the synergistic effect of free electron transfer and electron diffusion between the CA cement interface and rGO nano sheets.

Synthesis of Nickel Fumarate and Its Electrochemical Properties for Li-Ion Batteries

Metal–organic frameworks (MOFs) have found a potential application in various domains such as gas storage/separation, drug delivery, catalysis, etc. Recently, they have found considerable attention for energy storage applications such as Li- and Na-ion batteries. However, the development of MOFs is plagued by their limited energy density that arises from high molecular weight and low volumetric density. The choice of ligand plays a crucial role in determining the performance of the MOFs. Here, we report a nickel-based one-dimensional metal-organic framework, NiC4H2O4, built from bidentate fumarate ligands for anode application in Li-ion batteries. The material was obtained by a simple chimie douce precipitation method using nickel acetate and fumaric acid. Moreover, a composite material of the MOF with reduced graphene oxide (rGO) was prepared to enhance the lithium storage performance as the rGO can enhance the electronic conductivity. Electrochemical lithium storage in the framework and the effect of rGO on the performance have been investigated by cyclic voltammetry, galvanostatic charge–discharge measurements, and EIS studies. The pristine nickel formate encounters serious capacity fading while the rGO composite offers good cycling stability with high reversible capacities of over 800 mAh g−1.

Overlapped T-Nb2O5/Graphene Hybrid for a Quasi-Solid-State Asymmetric Supercapacitor with a High Rate Capacity

To utilize the special intercalation pesudocapacitive behavior of T-Nb2O5 and good conductivity of reduced graphene (rGO), a T-Nb2O5/rGO composite with an overlapping structure is developed to meet the demands of energy storage devices with a remarkable electrochemical performance. T-Nb2O5 nanowires (NWs) prepared by a hydrothermal method are assembled layer by layer onto the GO surface by electrostatic interaction to obtain T-Nb2O5/rGO hybrids. The overlapped T-Nb2O5/rGO composites exhibit an outstanding capacitance of 1492 F g–1 at 1 A g–1, which is superior to that of pure T-Nb2O5 NWs, and also present a better cycling stability of 88.6% of the initial capacitance after 3000 charge–discharge cycles in KOH aqueous solution. The supercapacitive performances of an asymmetric supercapacitor (ASC) of T-Nb2O5/rGO//activated carbon (AC) are evaluated in KOH aqueous solution and a quasi-solid KOH/poly(vinyl alcohol) gel. The quasi-solid ASC device of T-Nb2O5/rGO//AC delivers an energy density of 72 Wh kg–1 at 479 W kg–1. Furthermore, the ASC device could power a digital timer and a red light-emitting diode upon fast charging, exhibiting potential applications in future portable electronics.

NiFe‐NiFe2O4/rGO composites: Controlled preparation and superior lithium storage properties

AbstractBinary transition‐metal oxides with spinel structure have great potential as advanced anode materials for lithium‐ion batteries (LIBs). Herein, NiFe‐NiFe2O4/ reduced graphene oxide (rGO) composites are obtained via a facile cyanometallic framework precursor strategy to improve the lithium storage performance of NiFe2O4. In the composites, NiFe‐NiFe2O4 nanoparticles with adjustable mass ratios of NiFe2O4 to NiFe alloy are homogeneously deposited on rGO sheets. As anode material for LIBs, the optimized NiFe‐NiFe2O4/rGO composite displays remarkably enhanced lithium storage performance with an initial specific capacity as high as 1362 mAh g−1 at 0.1 A g−1 and a decent capacity retention of ca. 80% after 130 cycles. Besides, the composite delivers a reversible capacity of 550 mAh g−1 at 1 A g−1 after 300 cycles. During the charge–discharge cycles, the aggregation of the NiFe‐NiFe2O4 nanoparticles and the structural collapse of the electrode can be well alleviated by rGO sheets. Moreover, the conductivity of the electrode can be significantly improved by the well‐conductive NiFe alloy and rGO sheets. All these contribute to the improved lithium storage performance of NiFe‐NiFe2O4/rGO composites.

Nano-sized FeSe2 decorated rGO as a potential anode material with enhanced lithium-ion storage

FeSe2@reduced graphene oxide (rGO) composite was prepared by a facile one-step hydrothermal technique with FeSe2 nanoparticles uniformly achored on rGO nanosheets. The nano-sized FeSe2 particles effectively reduce the transfer length of Li ion and increase the sufficient contact area between the electrolyte and active material. Moreover, rGO can not only improve the electrical conductivity, but also prevent the agglomeration of nano-sized FeSe2, as well as accommodate the volume expansion and strain generated from the charge/discharge process. As an anode material applied in Li-ion storage, FeSe2/rGO composite delivers superior specific capacity of 1167.6 mAh/g, good cycling stability (908.2 mAh g−1 after 120 cycles at the current density of 500 mA g−1) and high-power characteristics (728.0 mAh g−1 at 1000 mA g−1), due to coexistent Li-ion storage mechanisms of surface capacitive behavior and diffusion-controlled process.

WITHDRAWN: Improving Mechanical strength of bone-implant with primitive and gyroid lattice of PLA/cHAP and rGO composites

Abstract The development, fabrication, and production of scaffolds that help in the regurgitation of tissues are significant setbacks in the world of tissue engineering. Therefore, This research analyses the potential development of scaffold reinforced with primitive and gyroid lattice of a poly(lactic acid) (PLA), calcium hydroxyapatite (cHAP) and Reduce Graphene Oxide (rGO) into new composite materials with superior mechanical properties for a bone implant. The biomaterial composites and lattice structure mimics bone structure and materials through gradual dissemination of interconnected PLA, cHAP and rGO materials into the 3D printer. Assessment and nano-structural analysis of the biodegradable composite was carried out, using surface roughness evaluation, mechanical and bioactivity analysis tests for the structure. The results show evidence that the scaffolds exhibited a quite high porosity level, with uniformity in the distribution of cHAP and rGO particles. The results obtained from in-vitro tests showed that the PLA/cHAP/rGO scaffolds were non-toxic with good biocompatibility and biodegradability. These results indicate that PLA/cHAP/rGO could provide improved osseointegration while maintaining the structural integrity of bone necessary for orthopaedic applications. Hence, the present study demonstrated that the PLA/cHAP/rGO scaffolds have a potential application in bone Implant.

NiO/ZnO composite decorated on rGO for detection of NO2

A novel NO 2 sensor based on rGO (0.5 wt%)-NiO/32ZnO composite was successfully prepared by hydrothermal method and hydrazine hydrate reduction method. Compared with the ZnO, the rGO (0.5 wt%)-NiO/32ZnO composite has a significant improvement in the sensing performance of NO 2 , indicating the new rGO (0.5 wt%)-NiO/32ZnO composite with p-n heterojunction is a promising sensing material for the detection of NO 2 gases. • One-step hydrothermal method synthesized a novel gas sensing of NiO/ZnO composite. • The triadic composite exhibits high sensitivity, higher response and shorter response time to NO2. • The improvement is due to the formation of junction and the modification of rGO. The rGO-NiO/ZnO composites were successfully synthesized by hydrothermal and hydrazine hydrate reduction methods and were used to detect NO 2 . The structure and morphology of the composites were characterized using spectrum techniques. The sensing tests showed that the triadic composite of rGO (0.5 wt%)-NiO/32ZnO exhibits a liner response toward NO 2 in the concentration range of 0.5–3 ppm and the highest response reaches 75.3 to 2 ppm NO 2 at 140 °C, which is 4.55 times and 1.38 times higher than that of pure ZnO and binary composite of NiO/32ZnO, respectively. The composite also exhibits a fast response of 39 s and a low detection limit of 46 ppb. The improvement mechanism is ascribed to the formation of p-n heterojunction that benefits from the formation of an additional depletion layer at the junction interface and the decoration of rGO increases surface active sites and accelerates electron transfer.

Fabrication of flower-like surface Ni@Co3O4 nanowires anchored on RGO nanosheets for high-performance microwave absorption

Novel composite microwave absorption (MA) materials with multiple loss mechanism have attracted considerable attention. In this work, flower-like surface Ni@Co3O4 nanowires were designed and fabricated through chemical reduction method induced by magnetic field, followed by in-situ polymerization, low temperature oil bath and thermal annealing. Then, the Ni@Co3O4/RGO composites were prepared through a hydrothermal reaction of the Ni@Co3O4 nanowires and graphene oxide suspension. The electromagnetic properties of different loading content samples (15 wt%, 25 wt% and 35 wt%) were measured to investigate the influence of loading content on the MA performance. For the 35 wt% loading sample, the minimum reflection loss (RLmin) value of −60.0 dB was determined at the thickness of 2.3 mm, and the maximum effective absorption bandwidth (EAB, RL < −10 dB) of 4.62 GHz can be achieved when the thickness is 1.6 mm. This research provides a reference for exploiting high-efficient flower-like surface magnetic-dielectric composites in the field of MA.

A Green and Scalable Synthesis of Na3 Fe2 (PO4 )P2 O7 /rGO Cathode for High-Rate and Long-Life Sodium-Ion Batteries.

Sodium-ion battery has been considered as one of the most promising power sources for large-scale energy storage systems due to its similar electrochemistry to the lithium-ion battery and the crust abundance of Na resources. Essentially, developing low-cost electrode materials along with a facile and economical synthesis procedure is critically important to promote the commercialization of sodium-ion batteries. However, applicable cathode materials capable of being massively produced are still scarcely reported to date. Herein, a green and scalable synthesis approach is developed to obtain Na3 Fe2 (PO4 )P2 O7 (NFPP)/rGO composite by using FePO4 and Na3 PO4 as the resources, during which all the atoms present in the starting materials end up in the product. The prepared Na3 Fe2 (PO4 )P2 O7 /rGO cathode exhibits an ultralong cycle life (capacity retention of 72.4% after 8000 cycles at 20 C) and outstanding rate capability (42.4 mAh g-1 at 100 C). In particular, the NFPP/rGO-HC full battery assembled by the Na3 Fe2 (PO4 )P2 O7 /rGO cathode and hard carbon anode demonstrates an energy density of 192Wh kg-1 and superior cycling performance (capacity retention of 85.2% after 500 cycles). These results will contribute to the development of sodium-ion batteries from applicable Na3 Fe2 (PO4 )P2 O7 /rGO cathode material.

Role of surfactants on the synthesis of copper (II) oxide nanosheets-rGO composites

CuO-reduced graphene oxide (rGO) composite is the potential candidate in the fields of optoelectronics and sensor applications. In the present work, we synthesized CuO nanosheets-rGO composites (CG) by a simple room-temperature preparation method. The prepared composites were named as CG1 (without any surfactant), CG2 (with polyethyleneglycol-400), and CG3 (polyvinylpyrrolidone). The equal intensity of (002,111)/(200,111) patterns in XRD (monoclinic CuO), double absorption peaks in UV–Vis spectra at 263 nm and 294 nm, and the FE-SEM images are evidenced for the sheet-like morphology of CuO. The FT-IR bands appeared at 547 and 596 cm−1 for the Cu–O vibrations. Micro-Raman studies also evidenced the formation of CuO-rGO structures. CG3 has larger sheets compared to others due to the interaction of long-chain PVP with rGO as well as CuO. The peak at 933.5 eV in XPS spectrum of CG1 confirms the presence of CuO in the sample.

Three-dimensional flower-like FeCoNi/reduced graphene oxide nanosheets with enhanced impedance matching for high-performance electromagnetic wave absorption

Nanostructured magnetic metal/reduced graphene oxide (rGO) composites, benefiting from well-performed losses including high dielectric/magnetic losses, have garnered considerable interest as advanced microwave absorbers (MAs) in recent years. Optional approaches of unique trimetallic/rGO nanostructures, however, are still limited to attain high electromagnetic (EM) absorption and broad bandwidth as well as improved impedance matching. Herein, porous flower-like FeCoNi/rGO nanosheets, synthesized via magnetic-field-assisted (MFA) reduction, presents facilitated microwave absorption performance. The zigzag-like attachments of neighbored nanosheets constitute the porous flower-like architecture; average thickness of the nanosheets is 5–20 nm. The reduction process, determined by appropriate GO dosage, plays a key role to tune geometry and distribution of the flower-like nanosheet structures. The optimal sample, owning a relatively high surface area (157.3 m2 g−1), achieves an impressive reflection loss (RL) intensity of − 75.95 dB and its maximum effective absorption bandwidth (RL ≤ −10 dB) is up to 4.69 GHz, along with improved impedance matching. This work provides a facile and alternative route for exploring other novel nanoalloy-based MAs.

Flash sintering of alumina/reduced graphene oxide composites

The flash sintering behavior of Al2O3/reduced graphene oxide (rGO) composites was investigated. rGO was used as a composite component and a conductive additive. Under the electric fields of 250–400 V cm−1, the flash event occurred at extremely low temperatures of 236–249 °C. The current density limit played a significant role in the degree of densification. A larger current density resulted in a higher density of the sample. However, current densities larger than 33.33 A cm−2 resulted in broken samples because of the localization of high current density coupled with the formation of hot spots. Flash sintering at a furnace temperature of 800 °C, electric field of 300 V cm−1 and current density limit of 33.33 A cm−2 produced nearly completely dense Al2O3/rGO composites. In addition to the current limit, the furnace temperature is also a key parameter that controls the degree of densification to achieve “safe” flash sintering.

Magnetic porous carbon nanopolyhedron modified rGO composites as recyclable sorbent for effective removal of bisphenol A from water

The effective removal of endocrine disruptors from water is important for human health. Herein, magnetic sorbents, composed of ZiF-67-derived carbon polyhedrons containing Co nanocrystals (Co-C) modified reduced graphene oxide (rGO) nanosheets (Co-C/rGO), were synthesized. The optimized Co-C/rGO-2 exhibited a high adsorption capacity of 175.1 mg g−1 for removal of bisphenol A (BPA) from water because of the optimized porous structure including micropores, mesopores and macropores as well as high surface area of 284.4 m2 g−1. In addition, the adsorption equilibrium of BPA was almost reached within 3 h and showed almost stable at pH 2–7. Existence of humic acid, Ca2+, K+, Na+ had little effect, while the Al3+ showed negative on the adsorption of BPA. Furthermore, the magnetic Co-C/rGO-2 can be easily recovered and showed high reuse performance remaining 83.7% of the initial adsorption capacity after the 4th recycling. The fixed-bed experiment indicated that the removal efficiency of BPA (10 μg L–1) from water can reach almost 100% at bed volume lower than 4000. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results revealed that the adsorption of BPA was mainly dominated by the π-π interaction.

One-step, low temperature synthesis of reduced graphene oxide decorated with ZnO nanocrystals using galvanized iron steel scrap

Production of a ZnO–rGO composite, using a novel one-pot method consisting in continuously flowing argon into a GO aqueous suspension heated at 80 °C, in the presence of galvanized iron steel scrap is presented. FTIR shows the complete disappearance of GO functional groups and only the C=C band remained, indicating extensive GO reduction. Raman spectra indicated sp2 character increase after reaction and the presence of the E2h mode of ZnO. SEM showed submicron crystals identified by XRD as ZnO in the hexagonal phase, while TEM images indicate ZnO nanoparticles decorate mainly the rGO borders. Optical band gap of 3.5 eV corresponding to ZnO, and optical transitions at 4.1 and 5.5 eV related with n → π and π → π* were observed. Electrochemical characterization by cyclic voltammetry shows an specific capacitance of 4.7 F g−1 at a scan rate of 5 mVs−1, which drops to ca. 0.8 F g−1 at 200 mVs−1. By electrochemical impedance spectroscopy, the relaxation time was ca. 5 ms. The proposed mechanism for the materials‘ synthesis includes Zn dissolution from scrap, galvanic displacement of oxygen moieties at the GO sheet, Zn deposition onto the carbon surface, and further oxidation and growth of ZnO nanocrystals.