Graphene Sponge Research Articles

Perylene diimide-derived supramolecules-modified graphene sponge as a high-efficiency solar steam generator

Generating steam using solar energy appears to be an effective approach to obtaining clean water, especially from salty water and wastewater, since the sun is a natural and constant source. Compared to many methods, studies in solar steam generation have accelerated due to being highly efficient, sustainable, and low-cost. Graphene sponges (GrSs), possessing structural flexibility and effective photothermal activity, are widely used for this purpose. However, the hydrophobic character of these materials limits their effectiveness in solar steam generators. At this point, we prepared perylene diimide-derived supramolecules (PDI) modified three-dimensional (3D) gradient hydrophobic GrS (PDI/GGrS) as the highly efficient solar thermal converter for the generation of clean water. PDI allowed us to achieve perfect absorption of broad-band sunlight and GGrS facilitated water transport through channels of sponge structure. As a result, PDI/GGrS has achieved a high water evaporation rate of 3.5 kg h−1 m−2 with a superior solar thermal conversion efficiency of up to 90 %. This study can provide new possibilities for harvesting solar energy by producing clean water from seawater, wastewater, and even acidic/alkali solutions.

Microbial Fuel Cell: Optimizing Graphene-Sponge Anode Thickness and Chamber pH Using Taguchi Experimental Method

The rapid consumption of fossil fuels has led to calls to switch from non-renewable to renewable energy sources. Microbial fuel cells are a promising technology that simultaneously treats wastewater and produces power. This study used the Taguchi Experimental method to optimize anode thickness and pH to obtain the maximum power density of an air-cathode microbial fuel cell (ACMFC). The graphene-sponge (G-S) anode thickness and chamber pH were selected as operating parameters, with their corresponding levels. The L9 orthogonal array was chosen for the experimental design. According to the Taguchi Method, the optimum G-S anode thickness and chamber pH were determined to be 1.0 cm and 8.0, respectively. A confirmatory run was performed under these optimum conditions, and the maximum power density observed was 707.75 mW·m−3. Analysis of variance (ANOVA) was conducted to identify the percentage contributions of the operating parameters to the process, which were found to be 30.66% for pH and 69.34% for anode thickness.

Electrochemical removal of antibiotics and multi-drug resistant bacteria using S-functionalized graphene sponge electrodes

In this study, we synthesized S-functionalized graphene sponge electrode and applied it for electrochemical oxidation of five commonly used antibiotics, namely sulfamethoxazole, trimethoprim, ofloxacin, roxithromycin and erythromycin, and the inactivation of a multi-drug resistant Escherichia coli (E. coli). The experiments were performed using real drinking water in a flow-through, one-pass mode. Highly polar antibiotics such as sulfamethoxazole did not adsorb onto the graphene sponge but were completely removed (i.e., ≥95% removal) at low applied current densities (14.5 A m−2). Antibiotics with high affinity for π-π interactions such as ofloxacin were completely removed already in the open circuit, and current application led to their further degradation. S-doped graphene sponge anode resulted in 4.5 log removal of a multi-drug resistant E. coli at 29 A m−2. There was no regrowth of bacteria observed during storage of the electrochemically treated samples, suggesting that the treatment severely impacted the cell viability. Further E. coli removal of 0.7 log was observed after the storage of electrochemically treated samples. The energy consumption of a continuously operated electrochemical system that achieved 4.5 log inactivation of a multi-drug resistant E. coli and 87–99% removal of antibiotics was 1.1 kWh m−3.

Spatial confinement of free-standing graphene sponge enables excellent stability of conversion-type Fe2O3 anode for sodium storage

Spatial confinement of free-standing graphene sponge enables excellent stability of conversion-type Fe2O3 anode for sodium storage

Surface-Constrained Metropolis Monte Carlo: Simulation of Reactions on Triply Periodic Minimal Surfaces.

Triply periodic minimal surfaces (TPMS) inspired by nature serve as a foundation for developing novel nanomaterials, such as templated silicas, graphene sponges, and schwarzites, with customizable optical, poroelastic, adsorptive, catalytic, and other properties. Computer simulations of reactions on TPMS using reactive intermolecular potentials hold great promise for constructing and screening potential TPMS with the desired properties. Here, we developed an off-lattice, surface-constrained Metropolis Monte Carlo (SC-MMC) algorithm that utilized a temperature quench process. The presented SC-MMC algorithm was used to investigate the process of graphitization reactions on the Schwarz primitive, Schwarz diamond, and Schoen gyroid TPMS, all with a cubic lattice parameter of 8 nm. We show that the optimized carbon TPMS exhibits a low energy, approximately -7.1 eV/atom, comparable to that of graphite and diamond crystals, along with a variety of topological defects. Furthermore, these structures showcase extensive and smooth surfaces characterized by a negative discrete Gaussian curvature, a distinctive feature indicative of an interconnected morphology. They possess specific surface areas of ∼2700 m2/g, comparable to graphene, and exhibit a significant porosity of around 90%. The theoretical X-ray correlation functions and nitrogen adsorption isotherms confirm that the constructed TPMS exhibit remarkably similar surface properties, although the pore space topology varies significantly.

An effective material for solar steam generation applications: Gradient graphene sponge

The efficient use of solar energy for clean water is a renewable and environmentally-friendly route to solve global water scarcity. For this, we report the preparation of light, mechanically durable, and effective photothermal material. A simple acid impregnation method was applied to graphene sponge material (GSM) possessing hydrophobic character to gain partial hydrophilicity to obtain a gradient structure. The morphological and structural properties of the gradient graphene sponge material (GGSM) were carried out using scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray powder diffraction patterns, Fourier-transformed infrared spectroscopy, and water drop contact angle measurements. GGSM showed fast and effective water vapor conversion performance due to the gradient structure, as well as the high rate of sunlight absorption and photothermal conversion thanks to graphene. With the advantageous feature of gradient structure, GGSM achieved a high water vapor conversion capacity (1.79 kg/m2h) and solar thermal efficiency of 57% compared to GSM (1.58 kg/m2h; 45%). This new material provides a novel approach to solar energy applications.

Full‐Range On‐Body Strain Sensor of Laser‐Induced Graphene Embedded in Thermoplastic Elastomer via Hot Pressing Transfer for Monitoring of the Physiological Signals

AbstractAcquiring physical and mechanical strain information of the human body with wearable strain sensors can provide essential data from personal healthcare to human‐machine interfaces and others. Recent research reveals that CO2 laser scribing can convert polyimide films into porous graphene sponges under ambient atmospheres. However, the electrically conductive laser‐induced graphene (LIG) film mismatches with the tough and rigid plastic substrates when it is employed as stretchable strain sensors. In this work, by leveraging the advantageous properties of atoms‐level configured defects within crystalline LIG and heat transfer printing techniques, a flexible LIG‐SEBS (styrene‐ethylene‐butylene‐styrene) strain sensor is made. It is able to achieve exceptional electromechanical properties including a remarkable sensitivity in terms of gauge factor (413–3118), minimal hysteresis, and a broad strain range (>100% strain). Meanwhile, the SEBS‐LIG strain sensor has a stable and fast dynamic response and good repeatability. Additionally, the sensor can be integrated with a wireless communication module for remote monitoring of physiological signals in a real‐time manner with a smartphone App.

Embedded printing of graphene sponge sensors for sleep monitoring

This study presents an approach for developing sleep monitoring sensors with excellent satisfactory softness, sensitivity and stability by embedding three-dimensional graphene conductive network patterns onto sponges.

A green cross-linking method for the preparation of renewable three-dimensional graphene sponges for efficient adsorption of Congo red dye

Graphene-based materials possess significant potential for the treatment of dye wastewater due to their exceptional adsorption properties toward stubborn pollutants. However, their utilization is hindered by high preparation costs, low yields, environmental pollution during synthesis, and challenges in regenerating the adsorbent. This study proposes a novel approach to address these limitations by developing nitrogen-doped three-dimensional (3D) polyvinyl alcohol cross-linked graphene sponges (N-PGA) using a cross-linking method with ammonium carbonate. This method offers a relatively mild and environmentally friendly approach. Ammonium carbonate serves as both a reducing and modifying agent, facilitating the formation of the intrinsic structure of N-PGA and acting as a nitrogen source. Meanwhile, polyvinyl alcohol (PVA) is utilized as the cross-linking agent. The results demonstrate that N-PGA exhibits a favorable internal 3D hierarchical porous structure and possesses robust mechanical properties. The measured specific surface area (BET) of N-PGA was as high as 406.538 m2·g–1, which was favorable for its efficient adsorption of Congo red dye molecules. At an initial concentration of 50 mg·L–1, N-PGA achieved an impressive removal rate of 89.6% and an adsorption capacity of 112 mg·g–1 for Congo red (CR) dye. Furthermore, it retained 79% of its initial adsorption capacity after 10 cycles, demonstrating excellent regeneration performance. In summary, the synthesized N-PGA displays remarkable efficacy in the adsorption of CR dye in wastewater, opening up new possibilities for utilizing 3D porous graphene nanomaterials as efficient adsorbents in wastewater treatment.

Electro-oxidation of persistent organic contaminants at graphene sponge electrodes using intermittent current

Borophene (Bph) and hexagonal boron nitride (hBN)-modified graphene sponge anode coupled to N-doped graphene sponge cathode were applied for electrochemical degradation of persistent organic contaminants using intermittent current. Three different ON-OFF pulse cycles were tested using low-conductivity supporting electrolyte in flow-through mode. Functionalization of the reduced graphene oxide (RGO) with Bph and hBN improved the ability of the double layer to store electrical charge, thus maintaining the generation of H2O2, O3, and ·OH even during the OFF cycles. Both anodes tested showed enhanced contaminant removal during shorter OFF periods (e.g. 52.5 s/52.s and 75 s/30 s ON/OFF), due to the improved retention of anode charge during the shorter OFF stages. Electrochemical removal of the target contaminants required 24 kWh m−3 in continuous current mode for both hBN-RGO and Bph-RGO anodes at 231 A/m−2, which was lowered to 11.7 and 13.5 kWh m−3 respectively, using ON-OFF pulse cycles. Electrochemical degradation pathways were elucidated in both systems using carbamazepine as a representative persistent contaminant. Flow-through reactors with both Bph- and hBN-RGO anodes removed ≥60 % of the target contaminants in a single pass using continuous current, whereas intermittent current led to somewhat decreased removal efficiencies (43–58 %) due to the scavenging effect of the wastewater matrix. Thus, halving the current ON time led to less than 20 % decrease in the removal efficiencies due to the capacitive properties of RGO. Given that switching to intermittent current decreased the energy consumption from 9.3 kWh m−3 to 4.4 kWh m−3 (Bph-RGO anode) and from 6.9 kWh m−3 to 3.6 kWh m−3 (hBN-RGO anode), higher removal of the target contaminants can be achieved by coupling sequential reactors in the intermittent current mode.

Sandwich-structured graphene composite sponge with multiple cyclic compression for waste liquid treatment under dynamic electrical stimulation response

3D porous graphene nanosponge has broad application prospects in intelligent sensing, wastewater treatment, environmental remediation and other fields. However, the previously reported graphene-based 3D structure sponge column usually has difficulty achieving compression resistance and excellent adsorption effect. In this study, a novel, simple and low-cost sandwich structure is assembled. The carbon fiber/reduced graphene oxide/polydimethylsiloxane (CF/rGO/P) with excellent compression electrical properties is used as the intermediate layer, and the flexible polyvinylidene fluoride/rGO/P (PV/rGO/P) is used as the upper and lower layers. A composite assembled graphene sponge column with outer pressure resistance and middle compression resistance is prepared. Results show that this composite sponge has a small resistance(30–100 Ω/cm). Under 60% compression deformation, the resistance sensitivity could reach 36.44. The physical adsorption of methylene blue (MB) dye has reached more than 93.7% after 24 h, and the electrochemical adsorption rate is 3.12 times faster than the physical adsorption rate. This sandwich assembly structure exhibits an excellent positive synergistic effect, maintaining high adsorption and desorption properties for MB dyes under high compression cycles. It can be applied to the recovery of cationic dyes in the dynamic flow waste liquid, thereby broadening the application of hydrogel graphene nanosponge in the field of environmental protection.

Exploring the use of 3D graphene sponge composited phase change material for improved thermal performance in battery thermal management systems

The phase change material (PCM) cooling system is evolving towards lightweight, high thermal conductivity, and high integration with comprehensive heating and cooling capabilities to enhance its broader range of applications. In this study, a high-integrity thermal management system (TMS) based on 3D graphene sponge composited phase change material (CPCM) was developed comprising a melamine sponge (MS), reduced graphene oxide (RGO), and paraffin wax (PW). The RGO is discontinuously distributed on the MS skeleton, with no chemical bonding between the components. With the increase of the concentration of graphene oxide solution from 2 mg/ml to 10 mg/ml, the properties of thermal conductivity, leakage-proof performance, and electrifying heating were dramatically improved by 27 %, 8 %, and 15.6 times, respectively. At −10 °C, the cells can be heated by adding an electric current to the CPCM, with the heating power positively correlated with the loading current. The heating performance and energy consumption of composite PCM were comprehensively analyzed at different sizes. For the single cell, the temperature rise rate can reach 2.2, 4.3, 9, and 12 °C/min at 0.2, 0.3, 0.4, and 0.5 A current loading, respectively. In the charging-discharging cycle test under −10 °C, the heating of CPCM could maintain the temperature of the battery module between 22 °C and 27 °C at 1 charging rate (C-rate) operation. At normal conditions, the cooling performance of CPCM was close to pure PW. However, the temperature uniformity of CPCM was poorer than that of PW, especially at high-temperature conditions due to the low thermal conductivity of MS and discontinuous distribution of RGO. This study provides a new design for PCM system with comprehensive performance of lightweight, temperature control for low and high temperatures, and leak-proof.

Manganese oxide-functionalized graphene sponge electrodes for electrochemical chlorine-free disinfection of tap water

Low-cost reduced graphene oxide sponges functionalized with manganese oxide were used as electrodes for the disinfection of Escherichia coli in water. Manganese oxide was doped with amino groups (MnxOyNH2) to strengthen the bond with the graphene coating and improve the electrochemical stability of the sponge. The Mn II and Mn III incorporated into the graphene coating favored the formation of oxygen vacancies and enhanced the electric and catalytic properties of the anode. Electrooxidation of real tap water at 29 A/m−2 resulted in 2.2 log removal of E. coli. After storing the treated samples for 18 h at 25 and 37 °C, the removal of E. coli increased to 3.3 and 4.6 log, respectively, demonstrating the irreparable damage to the bacterial cells via low-voltage electroporation, and the key role of storage temperature in their further inactivation. The energy consumption of the system treating real low conductivity tap water was 1.2–1.6 kWh m−3. Finally, experiments with intermittent current suggest the contribution of the pseudo-capacitance of the graphene sponge to electrochemical disinfection during the OFF periods. This study demonstrates the feasibility of manganese oxide-functionalized graphene sponges for the chlorine-free disinfection of water.

Impact of supporting electrolyte on electrochemical performance of borophene-functionalized graphene sponge anode and degradation of per- and polyfluoroalkyl substances (PFAS)

Graphene sponge anode functionalized with two-dimensional (2D) boron, i.e., borophene, was applied for electrochemical oxidation of C4-C8 per- and polyfluoroalkyl substances (PFASs). Borophene-doped graphene sponge outperformed boron-doped graphene sponge anode in terms of PFASs removal efficiencies and their electrochemical degradation; whereas at the boron-doped graphene sponge anode up to 35% of the removed PFASs was recovered after the current was switched off, the switch to a 2D boron enabled further degradation of the electrosorbed PFASs. Borophene-doped graphene sponge anode achieved 32–77% removal of C4-C8 PFASs in one-pass flow-through mode from a 10 mM phosphate buffer at 230 A m−2 of anodic current density. Higher molarity phosphate buffer (100 mM) resulted in lower PFASs removal efficiencies (11–60%) due to the higher resistance of the graphene sponge electrode in the presence of phosphate ions, as demonstrated by the electrochemical impedance spectroscopy (EIS) analyses. Electro-oxidation of PFASs was more efficient in landfill leachate despite its high organic loading, with up to 95% and 75% removal obtained for perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), versus 77% and 57% removal in the 10 mM phosphate buffer, respectively. Defluorination efficiencies as determined relative to the electrooxidized fraction of PFASs indicated up to 69% and 82% of defluorination of PFOS and PFOA in 10 mM phosphate buffer, which was decreased to 16 and 29% defluorination, respectively, for higher buffer molarity (100 mM) due to the worsened electrochemical performance of the sponge. In landfill leachate, relative defluorination efficiencies of PFOS and PFOA were 33% and 45%, respectively, indicating the inhibiting effect of complex organic and inorganic matrix of landfill leachate on the C-F bond breakage. This study demonstrates that electrochemical degradation of PFASs is possible to achieve in complex and brackish streams using a low-cost graphene sponge anode, without forming toxic chlorinated byproducts even in the presence of >7 g L−1 of chloride.

Three-dimensional FeNiP decorated graphene sponge: A novel flexible electrode for high-performance asymmetric supercapacitor

Here, a three-dimensional (3D) flexible material was prepared based on FeNiP decorated graphene sponge (GrS) by a two-step method. Free-standing 3D GrS was fabricated through a simple foaming-drying method, then FeNiP was electrodeposited onto flexible GrS material to achieve a flexible FeNiP/GrS sponge electrode for high-performance electrochemical supercapacitors. This composite material exhibited a high specific capacitance of 2292 F/g and 90% of the specific capacitance was retained after 10,000 charge/discharge cycles at a current density of 1 A/g. An asymmetric supercapacitor (FeNiP/GrS//GrS) was fabricated and this flexible circuit delivered a maximum power density of 6545 W/kg and a high energy density of 330 Wh/kg. This outstanding electrochemical performance could be attributed to the high charge conductivity of FeNiP and porous graphene sponge which provides good structure stability, large reaction surface area, and high electron transfer.

3D graphene sponge biomass-derived with high surface area applied as adsorbent for nitrophenols

The present work used wood sawdust as a carbon precursor to produce 3D graphene sponge material, a carbon material with an added value, successfully used as an adsorbent for removing o-nitrophenol and p-nitrophenol from aqueous effluents. The resulting material’s structural, morphological, textural, and chemical characteristics (WS-Graphene) were evaluated. Textural analysis revealed a high surface area (∼3000 m2g−1) and high total pore volume (1.38 cm3 g−1). Raman, infrared and X-ray diffraction techniques evidenced the presence of a few layers of graphene, with some fraction of defects. Transmission electron microscopy confirmed the presence of a 3D-packed structure for the graphene. These WS-Graphene characteristics favored its application as an adsorbent for removing o-nitrophenol and p-nitrophenol pollutants. The adsorption process of both nitrophenols was extremely rapid and reached the equilibrium time in less than 5 min when the concentration of both adsorbates was fixed at 700 mg L−1. Furthermore, the maximum adsorption capacity (Qmax) values were 1842 mg g−1 (o-nitrophenol) and 879.6 mg g−1 (p-nitrophenol) at 30 °C. These results confirm that the WS-Graphene adsorbent acts as a 3D sponge. Langmuir’s isothermal was the best-fitted model for both nitrophenols in aqueous solution. The o-nitrophenol adsorption onto WS-Graphene might follow pseudo-second-order as well as general-order, while the adsorption of p-nitrophenol might follow only the general-order model. Thermodynamic studies revealed a spontaneous and endothermic adsorption process. The WS-Graphene adsorbent presents a high percentage (∼97 %) of removing the mixture of pollutants in effluents, showing an excellent adsorption capacity and making it a potential material to remove industrial wastewater.

Rapid removal of tetracycline by g-C3N4/high elastic graphene sponge via synergy effect of adsorption and photocatalysis under visible light

Rapid pollutant removal technology has increasingly become one of the main components of environmental governance technology. Herein, porous g-C3N4/three-dimensional high elastic graphene sponge (CN/HEGS) composites were fabricated by introducing porous g-C3N4 into three-dimensional highly elastic graphene sponge. The structure, morphology, light absorption ability and charge separation of the composite were characterized by a series of detection methods. The optimal CN/HEGS-90 presented high adsorption capacity and photocatalytic activity for tetracycline. The synergism of adsorption and photocatalysis is the main reason for the rapid degradation of the composites. The polymerization of amino compounds with epoxy bonds is the essence of the formation of three-dimensional interconnected porous sponge with high adsorption performance. The introduction of CN with visible light adsorption property and the composite structure formed between CN and HEGS promote efficient photogenerated charge transfer and transmission. This work provides an idea for the design and synthesis of composite catalysts with high efficiency and rapid pollutant degradation.

Porous Carbon Sponge from White-Rot Fungus Phanerochaete chrysosporium for the Removal of Oils and Organic Solvents.

Oil leakage incidentally occurs and leads to environmental disasters. Because of their porous and hydrophobic characteristics, graphene sponges are often studied as an oil adsorbent to repair oil spills at sea. Graphene materials are very expensive, and their biological toxicity has been given serious concerns; however, the easier preparation and eco-friendly, biomass-derived porous carbon materials can be used as an alternative to graphene materials. In this study, we prepared a porous carbon sponge (PCS) for oil and organic solvent removal by carbonizing white-rot fungus Phanerochaete chrysosporium, a fast-growing microorganism for the production of lignin-degrading enzymes and the environmental remediation. P. chrysosporium fungus balls were converted into black PCS by carbonization at high temperatures, where PCS was light (density of 56 g/L), hydrophobic (contact angle of 115°) and porous. According to the results of BET and XPS analysis, the surface area of PCS was 14.43 m2/g, and the carbon in PCS is mainly sp2 carbon. PCS could adsorb pure oils and organic solvents within seconds. The adsorption capacities of PCS were 20.7 g/g for gasoline, 30.1 g/g for peanut oil, 27.7 g/g for toluene, 18.5 g/g for dodecane, 32.5 g/g for chloroform, 27.1 g/g for tetrahydrofuran, 23.7 g/g for acetone and 13.7 g/g for ethanol. According to the reusability study, there was no obvious capacity loss after recycling up to 10 cycles. Our results indicated that white-rot fungi could be adopted as a cheap carbon resource for oil and organic solvent removal.

Design and synthesis of a MnCo-MOF modified flexible 3D graphene sponge electrode for an asymmetric supercapacitor with high power and energy density

Recently, 3D materials such as graphene sponges with metal–organic frameworks (MOFs) have received a lot of attention as electrodes in energy storage devices.

Fabrication of the superhydrophobic and oleophilic graphene-based sponge for the treatment of oil- and organic solvent-contaminated wastewater

Graphene, a 2D nanomaterial, has been extensively studied and applied in many applications including, but not limited to, energy storage, environmental treatment, additives for paints, rubber, and composite, sensors, and electronic devices. In this work, graphene-based sponge was facilely fabricated by simply immersing melamine sponge into well-dispersed graphene nanoplaletes solution. The prepared graphene sponge revealed superhydrophobic and oleophillic properties in nature. The graphene-based sponge showed remarkable adsorption performance toward oils and organic solvents with the adsorption capacity ranging from 40 to 70 folds of sponge’s weight. The sponge also exhibited high recyclability, which is considered as a promising material for the practical application.