Pure Graphene Research Articles

Enhancing osteogenesis of adipose-derived mesenchymal stem cells using gold nanostructure/peptide-nanopatterned graphene oxide

Graphene derivatives are highly promising materials for use in stem-cell-based regenerative therapies, particularly for bone regeneration. Herein, we report a graphene oxide (GO)-based hybrid platform (GOHP) that is highly effective for guiding the osteogenesis of human adipose-derived mesenchymal stem cells (hAMSCs). A GO-coated indium tin oxide (ITO) substrate was electrochemically modified with Au nanostructures (GNSs), following which a cysteine-modified quadruple-branched arginine-glycine-aspartic acid was self-assembled on the ITO-GO-GNS hybrid via Au-S bonds. The synthesized GOHP, with the highest density of GNSs (deposition time of 120 s), exhibited the highest osteogenic differentiation efficiency based on the osteogenic marker expression level, osteocalcin expression, and osteoblastic mineralisation. Remarkably, although GO is known to be less efficient than the high-quality pure graphene synthesised via chemical vapour deposition (CVD), the fabricated GOHP exhibited an efficiency similar to that of CVD-grown graphene in guiding the osteogenesis of hAMSCs. The total RNA sequencing results revealed that CVD graphene and GOHP induced the osteogenesis of hAMSCs by upregulating the transcription factors related to direct osteogenesis, Wnt activation, and extracellular matrix deposition. Considering that GO is easy to produce, cost-effective, and biocompatible, the developed GOHP is highly promising for treating various diseases/disorders, including osteoporosis, rickets, and osteogenesis imperfecta.

Understanding the enhanced electrorheological effect of reduced graphene oxide‐supported polyaniline dielectric nanoplates by a comparative study with graphene oxide as the support core

Graphene has attracted scientific interest as a substrate or additive for developing high-performance stimuli-responsive materials. Research on graphene-based polymer dielectric composites has shown an enhanced electroresponsive electrorheological (ER) effect. However, the mechanism behind the enhanced electroresponse is still incompletely understood. Here, an investigation was performed into dielectric polarization and the ER effect of reduced graphene oxide-supported polyaniline nanoplates by comparing them with pure granular polyaniline and graphene oxide-supported polyaniline nanoplates based on dielectric spectroscopy and rheologic analysis. We discovered that both anisotropic morphology and electrical properties have dominant roles in the enhanced ER effect of reduced graphene oxide-supported polyaniline nanoplates, whereas only anisotropic morphology has a dominant role in the enhanced ER effect of graphene oxide-supported polyaniline nanoplates. The analysis also showed that reduced graphene oxide-supported polyaniline nanoplates have a good ER response to both DC and AC electric field actions in the wide shear rate region. This is highly desirable for practical engineering applications. Therefore, the analysis reveals the reason for the enhanced ER effect of reduced graphene oxide-supported polyaniline nanoplates and also may provide a guide for designing high-performance ER materials for practical engineering applications by combining the advantages of conducting a reduced graphene oxide core and ER active shell.

Penetration resistance and mechanical properties of graphene oxide/epoxy resin—A molecular dynamics investigation

AbstractThe penetration of salt solution into graphene oxide/epoxy resin (GO/EP) will cause structural damage, decrease in mechanical properties, and reduce service life. In this study, molecular dynamics method was used to simulate the penetration of the 3.5% NaCl solution through the GO/EP. In order to understand the effect of GO surface functional groups on the barrier properties of the GO/EP, a pure graphene model and three kinds of GO models modified with oxygen‐containing functional groups (ether, hydroxyl, and carboxyl) were established, respectively. The penetration resistance of GO/EP was analyzed. The type of oxygen‐containing functional group affects the penetration rate of the salt solution and the GO/EP interface performance. The spatial distribution and kinetic behavior of the salt solution were studied. The results show that the salt solution molecules trapped in GO/EP were mainly concentrated at the interface between GO and EP, which is the main reason for the degradation of the GO/EP interface performance. Affected by GO, the penetration process of ions can be divided into multiple stages, and its motion state was different depending on the type of functional group.

Highly conductive graphene film with high-temperature stability for electromagnetic interference shielding

Lightweight, flexible and highly conductive electromagnetic interference (EMI) shielding materials are urgently needed to protect the electronic and telecommunication devices from interference failure. Carbon-based films have attracted much interest to provide EMI shielding with minimal thickness in recent years, particularly exemplified by macroscopic graphene film. However, the inferior electrical conductivity to metal or the un-stability of doped graphene film cannot meet the ever-growing demands for harsh environment applications. Here, we prepare highly conductive copper chloride intercalated graphene film (GF-CuCl2) with high-temperature stability up to 400 °C. The intercalation of CuCl2 significantly improves the hole density, and the achieved electrical conductivity (1.09 × 107 S m−1) is nearly 10 times that of pure graphene film. The ultra-low temperature coefficient of resistance (4.31 × 10−4 K−1) makes GF-CuCl2 electrically stable over a broad temperature range. A 35-μm-thick GF-CuCl2 exhibits an average EMI shielding effectiveness of ∼110 dB from 2 to 18 GHz and ∼126 dB from 8.2 to 12.4 GHz, which is the highest among materials of comparable thickness. Moreover, the EMI shielding capability of GF-CuCl2 shows long-term durability under extreme conditions. All these characteristics demonstrate the GF-CuCl2 is suitable for the practical EMI shielding applications.

Amino-assisted AHMT anchored on graphene oxide as high performance adsorbent for efficient removal of Cr(VI) and Hg(II) from aqueous solutions under wide pH range

The adsorbents with high adsorption capacity for simultaneously removing Cr(VI) and Hg(II) from aqueous solutions under broad working pH range are highly desirable but still extremely scarce. Here, a novel adsorbent with multidentate ligands was facilely fabricated by covalently bonding 4-amino-3-hydrazino-5-mercapto- 1,2,4-triazole on graphene oxide via the Schiff’s base reaction. The maximum adsorption capacities of Cr(VI) and Hg(II) on the current adsorbent were 734.2 and 1091.1 mg/g, which were 14.36 and 5.61 times higher than that of the pure graphene oxide, respectively, exceeding those of most adsorbents previously reported. More interestingly, Cr(VI) and Hg(II) concentrations were decreased from 2 mg/L to 0.0001 mg/L for Hg(II) and 0.004 mg/L for Cr(VI), far below the WHO recommended threshold for drinking water. Moreover, the adsorbent shows an excellent performance for simultaneous removal of Cr(VI) and Hg(II) with more than 99.9% and 98.6% removal efficiencies in aqueous solutions. Finally, the adsorbent was successfully applied in dealing with the real industrial effluent, implying huge potential in industrial application. This work offers a new possibility for the removal of the metallic contaminants by rational designing target groups and ligands.

N-methylene phosphonic acid chitosan/graphene sheets decorated with silver nanoparticles as green antimicrobial agents

A green and scalable approach for the preparation of few-layered graphene utilizing the biowaste of potato peels has been developed. The potato peels have been dried and carbonized to obtain a new graphite structure that has been exfoliated in N-methylene phosphonic acid chitosan (MPC). The exfoliation process assisted the formation of graphene sheets with a high size diameter and quality of 50% based on the weight of graphite structure. The graphene sheets were green decorated with silver nanoparticles using microwave power to obtain new nanocomposites. The mass ratio between the graphite and silver nitrate was optimized and observed to change the morphology and size diameter of silver nanoparticles. The as-prepared MPC structure, graphene, and silver decorated graphene nanocomposites were characterized using 1HNMR, FTIR, XRD, UV/Vis spectrophotometer, SEM, and TEM besides tested as antimicrobial agents. The bacterial performance was also controlled by changing the number of AgNPs distributed on graphene sheets based on the mass ratios of graphite/AgNO3. The inhibition diameter of silver decorated graphene was considerably increased to 24.8, and 20.1 mm as in the case of MPC-GRP-Ag30 composite compared to the pure graphene (11.2, 13.5 mm) for E. coli and S. aureus, consecutively proposing that the blade edge of graphene sheets can destroy the bacteria membrane and release silver cations promptly that are directed for the interaction with the cytoplasmic parts of the bacteria cell. Such findings offer green and biocompatible antibacterial agents based on the graphene derived from the biowaste products.

Nanofiltration Using Graphene-Epoxy Filter Media Actuated by Surface Acoustic Waves

We exploit the enhancement of liquid transport through a graphene-epoxy film actuated by surface acoustic waves to demonstrate effective and efficient nanoparticle filtration. Unlike previously reported findings using graphene films, the addition of silver epoxy to create a composite film allows higher excitation powers to be sustained over extended operation durations without disintegration of the film such that an increase in the liquid flow rate through the film by up to fourfold can be achieved. Counter to intuition that suggests that the epoxy would fill the interstitial voids between the layers that make up the graphene film so as to reduce the efficiency of liquid transport through the film, we show instead that the higher density and elastic stiffness of the composite film enhances the transmission of acoustic energy into the film that, in turn, leads to more efficient liquid transport through it. Filtration efficiencies above $99$% are obtained for 26-nm particles, decreasing to 99% for 10-nm and 5-nm particulates, which is a significant improvement compared to that obtained with a pure graphene film. While a decrease in filtration rate over time is observed (up to 50% over 3 h of continuous operation) typical to that of graphene and other filter media, the introduction of a simple backwash process allowed for up to 87% recovery of the initial filtration rate. The significant performance enhancement, namely the fourfold increase in throughput, filtration efficiencies of up to 99% for nanoparticles down to 5 nm, and the ability to sustain extended operation at higher powers without disintegration through such a facile and cost-effective modification to the film highlights its potential applicability in practical nanofiltration systems.

Heat‐transfer and hydrodynamic performance investigation of graphene‐titanium dioxide composite nanofluid in micro‐heat exchangers

AbstractNanofluids have made a breakthrough contribution toward maximizing the efficiency of heat exchangers. Consequently, graphene nanofluids have attracted significant attention, as they yield the best heat‐transfer enhancement among all nanofluids; however, graphene is highly expensive, and further studies on hybrid graphene nanofluids are required to optimize costs. Research has been performed on the performance of pure graphene nanofluids, though little has been conducted on hybrid graphene nanofluids. Therefore, we investigated the hydrodynamic and convective heat‐transfer performance of graphene‐titanium dioxide composite (GTNC) nanofluid in a micro‐heat exchanger, and compared the results with the performance of pure graphene and pure titanium dioxide nanofluids under similar conditions. Herein, we report the synthesis of GTNC using our novel green micro‐synthesis technique and the preparation of graphene, titanium dioxide, and GTNC nanofluids using a two‐step method at three concentrations (0.02~0.08 wt%) using a surfactant. Furthermore, the stability and thermo‐physical properties of nanofluids were investigated, and nanofluids were studied for their effect on the performance of a counter‐current laminar flow micro‐heat exchanger at different flow rates (Re = 750‐1460). Findings show that thermal conductivity enhancement of GTNC nanofluid and pure graphene nanofluid at the highest mass fraction (0.08%) was 25.8% and 31.6%, respectively, while the maximum enhancement of convective heat‐transfer coefficient was 64.6% and 87%, respectively. These results indicate that hybrid GTNC nanofluid showed proximate thermal performance and stability level to graphene nanofluid with 50% less graphene content, which improves the economics of the process.

The Parameters of the Field Emission Model and the Fabrication of Zinc Oxide Nanorod Arrays/Graphene Film

A large-scale growth of zinc oxide (ZnO) nanorod arrays on graphene sheets was fabricated by a hydrothermal technique, and the Fowler–Nordheim theory was used to build a model to describe the properties of the arrays’ field emission. The results indicated that the morphological characteristics of the ZnO nanorods grown on the graphene sheets can be easily tuned by varying the reaction time and concentrations of the reaction solution. The regular ordered ZnO nanorods arrays on the graphene sheets were obtained under the appropriate experimental conditions. Further, this composite cathode was demonstrated to possess excellent field emission properties due to the outstanding mechanical and electrical properties of graphene. The field emission current density of the composite cathode reached 1,448 μA cm–2 at the electric field of 16.5 V μm–1. The key parameter, field enhancement factor, reached 6,366, while the pure graphene cathode field is about 1,660. These specific nanorod arrays with enhancement of the field emission properties would be useful to sensor or modulator units for accessing networks.

A new methodology for evaluating the performances of electrocatalysts for rechargeable Li-O2 batteries: (Ru-Sn)O2@graphene nanowalls/Ti electrodes as an example

The bi-functional activities of electrocatalysts for the oxygen reduction reaction (ORR) and discharge products decomposition in the typical organic electrolyte of rechargeable Li-O2 batteries are proposed to be effectively evaluated by cyclic voltammetry (CV) with varying the lower potential limit. The free-standing Ru-Sn oxides-decorated graphene nanowalls are employed as examples to demonstrate this interesting methodology. Both Ru-enriched and Sn-enriched Ru-Sn oxides (RTO73 and RTO37) show higher bi-functional activities than two mono-oxides and pure graphene from CV and confirmed by the charge–discharge results. The full cell performances such as rate capability, cycle life and charge–discharge voltage gaps can be correlated to the findings from CV.

Electrochemical approach toward reduced graphene oxide-based electrodes for environmental applications: A review.

Graphene has shown great potential in various application fields due to its excellent carrier transportation, ultra-high specific surface area, good mechanical properties, and light transmittance. However, pure graphene still exhibits some insurmountable defects, such as difficulty in simple and large-scale preparation, and limitations in application. The electrochemical method is a simple, clean, and environmentally friendly method. The rapid and simple preparation of graphene and its derivatives by electrochemical methods has important environmental significance. Moreover, rGO-based nanohybrids can be prepared by convenient and quick electrodeposition or cyclic voltammetry (CV), or to change the morphology and structure of graphene and its derivatives to achieve the purpose of improving material properties. This work mainly summarizes electrochemically related graphene from four aspects: (i) the method of electrochemical exfoliation of graphene; (ii) types of electrodeposition rGO-based nanohybrids; (iii) electrochemical regulation of the structure of rGO-based mixtures; (iv) environmental applications of rGO-based nanohybrids prepared by electrodeposition. This article critically discusses the advantages and disadvantages of electrochemical-related graphene, outlines future challenges, and provides insightful views and references for other researchers.

Studying the adsorption energy of CO gas molecule in different nano-systems using density function theory

In this report density function theory calculations were used to computed ground state properties for pure and Aluminum doped nano-system (graphene/boron-nitride). Ground state calculation provide relaxation structure, molecular orbital energy, adsorption process and charge transfer. Hybrid function used in this study was (B3LYP) and basis set 6-31G*. bond length calculation for pure and doped nano-system was agreements with experimental measurements. Adsorption energy calculations show low energy raising during interaction between gas molecule and surface of nano-systems. Also, result show that type of adsorption was physical. Molecular orbital energy doesn’t effect during interaction process. Charge transfer calculation show that CO gas molecule act as donor in system pure graphene, boron-nitride and Al-graphene and act as acceptor in Al-boron-nitride.

Na2CO3 and graphene nanocomposites toward efficient lubrication

Lubrication by graphene from nanoscale to macroscale has attracted increasing interest in recent years. However, the graphene can only withstand load of 2 N (corresponds to Hertzian contact stress of 0.41 GPa) during sliding. In this work, a composite of graphene and sodium carbonate coating shows an improved load-carrying capability during lubricated contacts. Compared to the pure graphene deposited coating, the composite can reduce the friction from 0.6 to 0.16 and wear by one order of magnitude at 1.29 GPa, and can provide an effective lubrication even at the high load of 40 N (corresponds to maximum Hertzian contact stress of 2.06 GPa). The improved lubricating property by the composite of sodium carbonate and graphene results from the stronger adhesion of the composite on the steel surface and the sliding induced soft tribofilm formed at the rubbing interface. Interface observation indicates a high sp2 fraction of carbon at the top of the tribofilm which contributes to the easy slippery. This study provides a new approach to widen the applications of graphene to lubricated contacts under heavier loads.

Synthesis and Characterization of Tio2-Rgo Nanocomposite by Pulsed Laser Ablation in Liquid (PLAL-Method)

The graphene oxide was prepared by the modified Hammer method, and then the rGO-TiO2 nano composite was successfully created using Q-switch Nd:YAG pulsed laser(λ=1064 nm, Energy per pulse 1000 mJ, No. of pulses 500, and the pulse duration 10 n sec) (PLAL). Prepared nanomaterials were characterized by a variety of techniques, including UV-Vis. spectroscopy, X-ray diffraction (XRD), FTIR, Field emission scanning electron microscopy (FE-SEM) and EDX. The absorption peak of GO is equal to 230 nm with energy gap 5.391 eV while The edge of absorption for the TiO2-rGO nanocomposite displays a red shift with respect of pure TiO2. Crystallite size of prepared TiO2/rGO nanocomposite was measured by XRD and is equal to 53.97 nm. The intensity of peaks C=C and peaks O-H is lower compared to peaks of pure graphene oxide, indicating the transformation of graphene oxide into reduced graphene oxide. The TiO2/rGO nanocomposite show enhanced adsorption properties. The removal efficiency of GO is 37 %, and The removal effectiveness for rGO-TiO2 nanocompound is 40 %. The TiO2-rGO nanocomposite has high dye adsorption efficiency, and Can be used for the elimination of the Rh B from aqueous solution.

Comparisons of nonlinear vibrations among pure polymer plate and graphene platelet reinforced composite plates under combined transverse and parametric excitations

The comparative researches of the nonlinear vibrations are obtained among the pure polymer plate and three types of graphene platelet reinforced polymer composite plates under combined the transverse and parametric excitations. All edges of the pure polymer and graphene platelet reinforced polymer composite plates are simply supported. Both the uniform and functionally graded distribution forms of the graphene platelets are considered. The differential governing equations of motion for the pure polymer and graphene platelet reinforced polymer composite plates are derived based on the first-order shear deformation plate theory, von Kármán strain displacement relationship and Hamilton principle. The fourth-order Galerkin truncation is employed to discretize the partial differential governing equations of motion to four-degree-of-freedom nonlinear dynamical system. The natural frequencies of the first four vibration modes are examined for the pure polymer and graphene platelet reinforced polymer composite plates with different geometric characteristics. In order to compare the nonlinear vibrations of the prestressed pure polymer and prestressed graphene platelet reinforced polymer composite plates subjected to the transverse point excitation and in-plane uniaxial/biaxial excitations, the time histories, phase portraits and Poincare maps are presented. Some validated results are conducted to present the accuracy of the present approach. The effects of the distribution forms and weight fractions of the graphene platelets on the nonlinear vibrations for the graphene platelet reinforced polymer composite plates are investigated in detail. The research results demonstrate that the nonlinear vibration behaviors of the prestressed pure polymer plate under the complex excitations can be remarkably stabilized by the reinforcement of the graphene platelets.

Functionalized carbon nanotube doped gel electrolytes with enhanced mechanical and electrical properties for battery applications

We report the functionalized carbon nanotubes (fCNTs) and graphene oxide (GO) doped polyvinyl alcohol (PVA) based gel electrolytes (GEs). The multiwalled carbon nanotubes (CNTs) were treated via microwave irradiation to alter the degree of carboxylation. The fCNT doped gel electrolyte (fCNTGE) showed significantly improved ionic conductivity, mechanical strength as well as electrochemical stability when compared to the pure GE and graphene oxide doped gel electrolyte (GOGE). The homogeneous distribution of ionic channels provided by fCNTs served as redox shuttle and facilitated the ion migration in the gel. The fCNTGE exhibited the best performance when the oxygen content was 12.8% by weight. The ionic conductivity was significantly improved by introducing fCNTs into the PVA gel and reached 6.9 × 10−2 S cm−1, revealing that the diffusion and transport of ions into electrolyte were much better than the GE and GOGE. A significant enhancement in the gel mechanical properties was observed as the Young's module (E = 2.3) and tensile strength (22.3 kPa) of fCNTGE was higher than that of GE and GOGE. Furthermore, the composite Zn–Ag2O batteries were made and tested using the fCNTGE, GE, and GOGE in the 3D-printed battery casings. The fCNTGE based batteries demonstrated good electrochemical stability with specific capacity reaching 204.3 mAh g−1 (C/20).

Hybridized Graphene for Supercapacitors: Beyond the Limitation of Pure Graphene

Graphene-based supercapacitors have been attracting growing attention due to the predicted intrinsic high surface area, high electron mobility, and many other excellent properties of pristine graphene. However, experimentally, the state-of-the-art graphene electrodes face limitations such as low surface area, low electrical conductivity, and low capacitance, which greatly limit their electrochemical performances for supercapacitor applications. To tackle these issues, hybridizing graphene with other species (e.g., atom, cluster, nanostructure, etc.) to enlarge the surface area, enhance the electrical conductivity, and improve capacitance behaviors are strongly desired. In this review, different hybridization principles (spacers hybridization, conductors hybridization, heteroatoms doping, and pseudocapacitance hybridization) are discussed to provide fundamental guidance for hybridization approaches to solve these challenges. Recent progress in hybridized graphene for supercapacitors guided by the above principles are thereafter summarized, pushing the performance of hybridized graphene electrodes beyond the limitation of pure graphene materials. In addition, the current challenges of energy storage using hybridized graphene and their future directions are discussed.

Investigations on the electronic structure and optical properties of (Ga,N,Ga-N) doped graphene by first-principle calculations

The optical and electronic properties of pure graphene, nitrogen doped graphene, gallium doped graphene and nitrogen and gallium co-doped graphene were researched based on the first-principle method of density functional theory (DFT). Pure graphene has a zero-band structure, and when doped in graphene, its bands are opened. In this study, the bandgap of N-doped graphene was 0.20 eV, Ga-doped graphene was 0.35 eV and N–Ga co-doped graphene was 0.49 eV. They also have different electron density. In the N–Ga co-doped graphene, the N atom gained more electrons (−0.6 1e) than the N-doped graphene (−0.27 e), and the Ga atom lost more electrons (1.80 e) than the Ga-doped graphene (1.75 e). Moreover, the optical properties of pure graphene and doped graphene were analyzed and compared. These properties include complex refractive index, dielectric function and light absorption. From these analysis results, it can be seen that the doping study in graphene has effectively improved the optical and electrical properties of graphene. This study provides an effective theoretical foundation for the future development of graphene-based photoelectric devices.

Multifunctional Cement Mortars Enhanced with Graphene Nanoplatelets and Carbon Nanotubes.

Recent findings have brought forward the potential of carbon nano-species, especially nanotubes and graphene, to impart exceptional multifunctional potential to cement, offering simultaneous enhancement of mechanical, fracture mechanical and electrical properties. While available knowledge on the topic is still limited, there is a complete absence of direct comparisons of the potential of the nano-species to improve strength and toughness and provide multifunctionality to the mortars. The study offers a comprehensive overview of these potentials, for mortars modified with pure graphene nanoplatelets and carbon nanotubes at consistent, directly comparable, concentrations up to 1.2 wt.%. Testing included flexure under pure bending moments, axial compression, electrical resistivity measurements and fracture tests under three point bending configuration; the latter were also independently assessed by acoustic emission. Differences in documented properties and optimal concentrations associated with improved mechanical performance were directly compared and rationalized in terms of nanospecies morphology. Dramatic, statistically consistent improvements in fracture behavior, up to 10-fold of control values, were documented for specific nanofiller concentrations, indicating an excellent potential of the material system for contemporary smart construction applications. An exceptionally favorable comparison of acoustic emission and fracture energy data confirmed that the non-destructive technique can independently assess the fracture performance of mortars with exceptional precision.

Solving Gravimetric-Volumetric Capacitive Paradox of 2D Materials through Dual-Functional Chemical Bonding-Induced Self-Constructing Graphene-MXene Monoliths.

High electrical conductivity and all-open microstructure characteristics intrinsically endow both graphene and MXenes with superior electrochemical energy storage capability. However, the above two-dimensional (2D) thicker electrodes (>20 μm) severely dilute their unique rapid electronic-ionic transferring characteristic, posing a paradox of high gravimetric and high volumetric capacitive properties due to massively excessive macropores or an unduly restacked issue. Herein, we elaborately construct novel monolithic NH2-graphene and Ti3C2Tx MXene (NG@MX) composites through dual-functional induced self-assembly with the help of both covalent and hydrogen bonding interactions. Notably, much thicker monolithic NG@MX electrodes (>90 μm) fabricated by a conventional roll-coating method without any further compaction treatment can simultaneously deliver two times gravimetric (gra.) and volumetric (vol.) performance than those of pure graphene (in vol.) or MXene (in gra.) materials. Moreover, monolithic NG@MX-based supercapacitors can remarkably present two times energy density as that of graphene and four times as MXene, respectively. Such greatly enhanced electrochemical properties are closely related to the appropriate equilibrium of the volumetric density and the open structure, which can effectively guarantee the rapid transfer of both electrons and ions in the thick monolithic NG@MX electrodes. Undoubtedly, dual-functional chemical bonding-induced self-constructing NG@MX monoliths efficiently solve the long-existing gra. and vol. capacitive paradox of the thicker 2D materials used in supercapacitors, which will guide the design of high-performance capacitive materials and promote their practical application in electrochemical energy storage.