Reduced Graphene Oxide Flakes Research Articles

Hybrid Epoxy Composites Based on Basalt Fabric: A Case Study of Low‐Temperature Plasma Treatment and Reduced Graphene Oxide Flakes Addition

The purpose of this study is to present a novel method for producing mechanically strong epoxy composite laminates of different compositions, reinforced with basalt fabric and reduced graphene oxide flakes. The laminates are prepared with basalt fabric, which is subjected to low‐temperature plasma treatment. This approach is aimed to enhance the adhesion of fabric to resin filled with reduced graphene oxide flakes. Physical properties, adhesion, and mechanical properties of the obtained materials are determined. Based on the experiments, it is found that the tensile strength is improved by 6–21% after using reduced graphene oxide filler, 9–23% after plasma treatment, and up to 27% using the combination of plasma and reduced graphene. It is found that the highest improvement of tensile strength is obtained for epoxy composite with 0.5 wt% graphene‐based filler and 3 min basalt fiber plasma treatment with 25 W plasma power.

Evaluation of Upscaling the Selective Electrophoretic Deposition of Reduced Graphene Oxide on Miniaturized Au Interdigital Electrodes from Chip-to Wafer-Level

Today’s novel materials challenge the research industry to enhance the performance and to reduce the power consumption of microchips as well as to develop new sensor principles. All this applies pressure on the investigation of new economical mass production technologies for the integration into standard process sequences or on top of state-of-the-art CMOS devices. Since the discovery of graphene in 2004, many different variations have been investigated, thus the number of publications of graphene-based content grew from a few in 2004 exponential to 1.2 million only in 2019, according to Google Scholar analysis. The deposition of graphene-based materials at wafer-level is still difficult to do economically on standard SEMI wafers up to 8” diameter. In this publication, the selective electrophoretic deposition (EPD) of reduced graphene oxide flakes (rGO) will be shown. This technique is a very promising deposition method for large scale fabrication. The EPD of rGO particles is the only known way to create 3D surface topologies for an enhanced sensing area of electrochemical sensor applications e.g. biosensors. The electrical and chemical properties of this novel material provides a broad range of applications for possible sensor solutions [1, 2]. Firstly, the deposition will be shown on chip scale to gain optimum parameters in suspension preparation and EPD deposition time/voltage for a uniform particle deposition over the sensor area. Shortcuts from particles between the transmission lines or co-deposition on reference electrodes have to be avoided. This leads to a high selectivity in rGO particle deposition on Au-structures. Afterwards designs and experiments have been made on array level and a proof of concept wafer-level deposition with a low volume suspension is demonstrated. In previous work, the adhesion of rGO on Au structures in electrochemical sensors with a liquid flow, showed a migration of the deposited particles with the friction of the liquid [3]. Therefore, standard separation of particle agglomeration or splitting of primary particles with ultra sonic sonotrodes are not sufficient to gain highly concentrated suspensions with homogenous target particle distributions (< 0,5µm ≤ 1µm ≥ 5µm). For this reason, a novel particle crushing preparation by ball milling is introduced and enhanced selectivity with an improved adhesion is demonstrated. A full process of the preparation of the colloidal suspension with the definition of target particle sizes with an optimum zeta potential will be provided and the cathodic electrophoretic deposition shown [4, 5]. For the evaluation of the deposition experiments, stereo microscopy is used to reveal the selectivity on the interdigital electrode (IDE) structures (sensor area) and scanning electron microscopy (SEM) analysis is used to characterize particle sizes and 3D topography, in terms of primary and secondary particles (agglomerates). For this study, IDE structures with 15 different geometry variations (3µm to 15µm lines and spaces) are used that were manufactured [6] to evaluate the rGO deposition on chip level. A novel multisensory array design with eight sensing areas are presented, combined with wafer-level deposition as a proof of concept on a 200mm wafer.

SnO2-QDs/Rgo Nanocomposites for Lithium Ion Battery Anodes

SnO2 is one of the most efficient materials for lithium ion battery (LIBs) anodes as it can theoretically provide a reversible capacity of 790 mAh/g (graphite, 372 mAh/g) for alloying reaction with lithium ion [(i) SnO 2 + 4 Li+ + 4e - = 2Li 2 O + Sn, (ii) Sn + xLi+ + xe- = LixSn (0 ≤ x ≤ 4.4)] during charge-discharge process [1]. In addition, SnO2 shows lowest operating potentials (average charge and discharge potentials: 0.3 V and 0.5 V vs. Li/Li+, respectively) in comparison with other transition metal oxides, facilitating a higher energy density when a full cell is constructed [2]. However, two issues: (1) poor electric conductivity, and (2) high volume fluctuation during lithiation-delithiation process (about 200-300%), limit its direct use as the anode material. To bit these issues, various carbon materials are employed to load the SnO2 [3].Graphene, a carbon allotrope, which possesses high electrical conductivity (106 s/cm), excellent mechanical flexibility (Young’s modulus up to 1.0 TPa) and high surface area (2630 m2/g) and in addition, lithium storage capacity of a single layer graphene is theoretically found to be 744 mAh/g. Consequently, graphene can be most suitable host to incorporate the SnO2 [3]. We have tailored SnO2 quantum dots (TOQDs) encapsulated reduced graphene oxide (RGO) nanocomposite (TOQDs/RGO) by in-situ growth of the TOQDs in the RGO flakes. A nanofluidic synthesis approach has been developed using 1D-Sn(OH)4 nanofluid [4] and graphene oxide (GO) nanofluid [5] as prim precursors for the homogeneous encapsulation of the TOQDs in RGO flakes. The 1D-Sn(OH)4 nanofluid was dropwise added to the graphene oxide (GO) nanofluid with continuous stirring. Then the resultant mixture was sonicated to get a nanofluidic mixture which was freeze-dried followed by calcination at 600 °C for 6 hrs under nitrogen gas. During these processes, in-situ growth of the TOQDs was proceeded on the RGO plane, leading to give their homogeneous distribution with encapsulation on the RGO plane. The cyclic voltammetry (CV) and glavanostatic charge-discharge (GCD) were performed on an Iviumstat Multichannel Potentiostat using a three-electrode cell and two-electrode cell, respectively. It is found that the developed TOQDs/RGO nanocomposite provides high reversible specific capacity with excellent rate capability. The results of these electrochemical studies implied that the developed TOQDs/RGO nanocomposite could be utilized for high-performance LIBs. References Lu et al., Porous SnO2/Graphene composites as anode materials for lithium-ion batteries: morphology control and performance improvement. Energy Fuels 2020, 34 (10), 13126-13136.Deng et al.,The developments of SnO2/graphene nanocomposites as anode materials for high performance lithium ion batteries: a review. J. Power Sources 2016, 304, 81-101.Han et al., Caging tin oxide in three-dimensional graphene networks for superior volumetric lithium storage. Nat. commun. 2018, 9 (1), 1-9.I. U. Hoque et al., One-dimensional Sn (iv) hydroxide nanofluid toward nonlinear optical switching. Mater. Horiz. 2020, 7 (4), 1150-1159.A. Khan et al., Synthesis of graphene oxide nanofluid based micro-nano scale surfaces for high-performance nucleate boiling thermal management systems. Case Stud. Therm. Eng. 2021, 28, 101436.

Electrochemical study of reduced graphene oxide@Zn2Ti3O8 nanocomposites as a superior anode for Li-ion battery

In this paper, a high-performance Li-ion battery anode, 2D reduced graphene oxide@Zn2Ti3O8 nanocomposite was successfully synthesized. In the mixing process, the porous Zn2Ti3O8 nanoplate and the reduced graphene oxide flakes were closely bonded by the electrostatic force, and then the heterojunction formed between them after 600 °C heat treatment in the N2 atmosphere. Due to the introduction of graphene, the electrochemical impedance of the composite is much reduced, and this two-dimensional heterostructure induced a large number of pseudocapacitance behaviors, which greatly increased the rate performance, cycling stability, and reversible capacity. In the long cycle performance tests at high current densities, the reduced graphene oxide@Zn2Ti3O8 composite can maintain stable capacities of 600 mAh g−1 at 1000 mA g-1and 265 mAh g−1 at 5000 mA g−1, exceeding all previous reports of Zn2Ti3O8 electrode. The excellent performance of the nanocomposite under high current density makes it a potential anode material for lithium-ion batteries.

An Electrochemical Biosensor for Detection of Cichoric Acid as an Anti-Alzheimer’s Disease Agent in Chicory Samples Based on Setaria-Like Trimetallic Nanodendrites Decorated NH2-RGO Flakes

Chicoric acid (CA), a phenolic acid from chicory, is regarded as a powerful ingredient against oxidative stress and obesity. It’s believed to be a promising drug candidate as its healing features prevent memory loss. However, existent methods for CA detection limit its practical applications in purification and further pharmacological study due to lack of accuracy. Therefore, it is crucial to find a forceful approach to precisely analyze cichoric acid for anti-AD research. In this work, we reported a facile method to synthesize Setaria-like trimetallic nanodendrites (G-PP NDs) in a non-compacted core–shell shape with high electrocatalytic activity. In addition, a sensitive biosensor to detect cichoric acid rapidly and accurately has been developed based on G-PP NDs and aminated reduced graphene oxide flakes (NH2-RGO@G-PP NDs). Owing to the great conductivity of NH2-RGO and significant electrochemical performance of G-PP NDs, the obtained sensor exhibited admirable capacities with a low LOD of 0.038 μM. It displayed a high sensitivity, rapid response, and excellent long-term stability, which made it accomplish the measurements CA in chicory samples. The proposed sensor is an auspicious tool for quality control and analysis of metabolism to investigate the beneficial impacts of CA as a functional ingredient to combat AD.

A high-performance electrode based on reduced graphene oxide/lignosulfonate/carbon microspheres film for flexible supercapacitors

Reduced graphene oxide (RGO) flexible film pillared with lignosulfonate (LS) and carbon microspheres (CM) was fabricated via a facile vacuum-filtration process to serve as a high-performance electrode material for supercapacitors. Composite electrodes comprising graphene and biomass materials have the advantages of being flexible, lightweight, cheap, and environmentally friendly. The addition of LS and CM between the RGO layers mitigated the self-restacking of reduced graphene oxide flakes. Composite film electrode displayed a high specific capacitance of 641 mF cm-2 at 0.2 mA cm-2, which was much higher than that of the RGO film (117.9 mF cm-2). The present findings indicate a great potential of the graphene films composited with biomass materials in fabricating flexible supercapacitor electrodes.

Effect of annealing temperature on electrical properties of RGO thin films deposited by Atomized Spray Pyrolysis

The modified Hummers method is an ideal method for the bulk production of reduced graphene oxide (RGO) using Sri Lankan natural vein graphite. Deposition of RGO as a thin film (TF) on a substrate is essential for electronic applications in various industries. A novel, improved spray pyrolysis technique called Atomized Spray Pyrolysis deposition method was used to deposit RGO-TFs at a substrate temperature of 150 °C. Thermal annealing (TA) was carried out after deposition of RGO-TFs since post-deposition treatment is essential to enhance its intrinsic properties. Then TA was done for 30 min at different temperatures from 230 to 430 °C. Electrical, morphological and structural characterizations suggested that TA at 330 °C yields optimum intrinsic properties of RGO-TFs. Annealing temperature up to 330 °C is adequate to eliminate most defects such as fabrication residues, residual oxygen functional groups, and folds at edges of RGO flakes. TA at 330 °C retains maximum possible hexagonal lattice structure and carbon to oxygen atomic ratio. However, TA beyond 330 °C exhibits doping of oxygen atoms to vacant carbon atoms at the hexagonal structure of RGO, increasing bandgap since oxygen atoms localize some electrons. At higher annealing temperatures, the formation of buckling, ripples, and wrinkles on the RGO sheets due to induced compressive strain was observed. This results in hindering charge transportation since they behave as scattering sites.

DC magnetization of titania supported on reduced graphene oxide flakes

Abstract DC magnetization of a series of titania nanocomposites modified with reduced graphene oxide (rGO) has been investigated. Hysteresis loops observed at room temperature disappeared at low temperatures. At a temperature of about 100 K, a phase transition to the superferromagnetic order state was observed, probably due to the linear expansion and self-reorientation of the magnetic moments. Processes associated with magnetic moment reorientation can cause a hysteresis loop to disappear at low temperatures as well as superferromagnetic ordering. It was suggested that the isolated nanoparticle in the nanopore could be used to create a “compass” at a nanometer-sized level that would be many times more sensitive than the conventional one. Measurements of the zero-field cooling and field cooling modes do not exclude the possibility of the coexistence of a superparamagnetic state.

Enhanced thermoelectric performance of low carbon cement-based composites by reduced graphene oxide

Cement-based composites with thermoelectric effect have broad application prospects in the fields of urban heat island effect mitigation, winter road snow melting and ice melting and energy harvesting. Although cement-based composites have made great strides in terms of thermoelectric properties, the high carbon content makes their mechanical properties low, this is the main obstacle to further improvement of thermoelectric performance. In this paper, we added reduced graphene oxide (RGO) to cement through a liquid-phase mixing process to make cement particles adhere to RGO flakes, which effectively reduced the degree of mutual agglomeration between the RGO and improves the dispersion effect of RGO in cement-based materials. When the RGO content is 5.0 wt%, it has higher electrical conductivity (2.01 S/cm) compared with the RGO cement-based composite prepared by the ball milling process, achieve the ZTmax value of 0.23 × 10−4, and have good temperature stability with the highest output power of 8.27 × 10−3 mW/m2. This facilitates large-scale energy harvesting using thermoelectric cement-based composites.

Thermal and electrical properties enhancement of a nanocomposite of industrial silicone rubber filled with reduced graphene oxide

In this work, a nanocomposite was developed by in-situ polymerization using industrial-grade diatom-containing silicone rubber (SR) as the matrix and reduced graphene oxide (RGO) as filler. The Concentration of RGO, was very low, varying from 0 to 1 wt%. In these nanocomposites, diatoms as well as RGO flakes of sizes smaller than 20 µm were dispersed homogeneously within the SR. According to thermogravimetric analysis (TGA), the thermal stability of the composite is improved by increasing the decomposition temperature of SR from 497 °C to 546 °C at 0.8 wt% of RGO. A TGA signal between 620 °C and 670 °C is identified as due to C-C bonds thermal breaking, whose integrated intensity increases in proportion to the concentration of RGO and can be used to determine the concentration of RGO in similar composite systems. When 1.0 wt% of RGO is added thermal conductivity increases by 47.5% and the electrical resistivity decreases four orders of magnitude, respect to SR values. The SR/RGO nanocomposite is flexible and represents a good candidate for applications in the development of sensors and biomedical applications. The use of industrial-grade SR reduces production costs of composites in comparison to those prepared with more expensive analytical grade rubbers.

Investigation into morphological and electromechanical surface properties of reduced-graphene-oxide-loaded composite fibers for bone tissue engineering applications: A comprehensive nanoscale study using atomic force microscopy approach

We decided to implement an extensive atomic force microscopy study in order to get deeper understanding of surface-related nanoscale properties of 3D printed pristine polycaprolactone and its reduced-graphene-oxide-loaded composites. The study included surface visualization and roughness quantification, elastic modulus and adhesion force assessment with force spectroscopy, along with kelvin probe force microscopy evaluation of local changes of surface potential. Atomic force microscopy examination was followed by scanning electron microscopy visualization and wettability assessment. Moreover, systematic examination of reduced graphene oxide flakes fabricated exclusively for this study was performed, including: scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and combustion elemental analysis.The addition of reduced graphene oxide resulted in thickening of the composite fibers and surface roughness enhancement. In addition, elastic modulus of composite fibers was higher and at the same time adhesion forces between scanning probe and tested surface was lower than for pristine polymeric ones. Lastly, we recorded local (nanoscale) alterations of surface potential of fibers with addition of graphene-derivative. The results clearly suggest graphene derivative’s dose-dependent alteration of elastic modulus and adhesion force recorded with atomic force microscope. Moreover, changes of the material's surface properties were followed by changes of its electrical properties.

New Insight into the Characterization of Graphene Oxide and Reduced Graphene Oxide Monolayer Flakes on Si-Based Substrates by Optical Microscopy and Raman Spectroscopy

Graphene oxide (GO) and reduced GO (RGO) have attracted interest as economical alternatives for pristine graphene with controllable properties spanning their applications in many fields. Abundant lattice defects present in GO and RGO have made their physical and chemical properties largely diverse from that of pristine graphene. This makes their identification and characterization ambiguous as the rules applied for pristine graphene may not be practical for GO and RGO. Here, we report a new insight into the characterization of GO and thermally reduced GO monolayer flakes deposited on different commonly used Si-based substrates by Raman spectroscopy along with optical visualization to address this uncertainty. It was found that the dielectric substrates with a lower reflectance in the visible range give a better optical contrast under normal white light illumination and intense Raman signals owing to the multiple reflection and interference at the interfaces of the multilayer system. Accordingly, a Si substrate with a 90 nm SiO2 layer gives the highest IG′/IG ratio along with a better optical visibility for monolayer RGO flakes.

Scalable chemical vapor deposited graphene field-effect transistors for bio/chemical assay

The adsorption of chemical species on the surface of graphene alters the concentration of charge carries by either increasing or decreasing it depending on the nature of the adsorbed chemical species and inducing noticeable changes in the material's electronic properties. This remarkable feature enables graphene-based sensors to detect a wide range of biomolecules, chemicals, and gas/vapors. A lot of progress has been made in this field and technologies based on reduced graphene oxide flakes have been well reviewed. Graphene grown by chemical vapor deposition has proven to be the most prominent route to large-scale production of devices. However, until now, a comprehensive review on scalable, macro-sized, chemical vapor-deposited, graphene-based field-effect transistor sensors was missing. Here we review the present status, current challenges, and future prospects for the bio/chemical sensing applications of scalable, chemical vapor-deposited, graphene field-effect transistors. We explain and examine the fabrication techniques, sensing mechanisms, and various assay strategies. We also discuss the sensing performance of graphene based on quantum mechanics simulations and theoretical calculations.

1D Ti-based H2Ti12O25 nanorod @2D RGO sheet composite as high-power anode for long-life Li-ion battery

ABSTRACT The increasing incompatibility for LIBs between high-rate capability and high specific capacity, except for its energy density, stimulates the research of new electrode materials. In order to obtain the superior power properties of LIBs, seeking new anode materials with the above merits is vital. Herein, a new 1D Ti-based H2Ti12O25 nanorod @2D RGO (reduced graphene oxide) sheet (H2Ti12O25/RGO) composite structure is designed as high-power anode for long-life li-ion battery, which can achieve high-capacity, and high-rate property at the same time. H2Ti12O25 nanorods, bonded on RGO flakes, is synthesized by mean of in-situ structure transformation during solvothermal/hydrothermal reaction processes. To be specific, except for the safety performance, the H2Ti12O25/RGO electrode unfolds an exceptionally better rate-capacity performance, namely, high reversible capacity up to 260 mA h g−1 at 0.5 C and 123, 114 and 101 mA h g−1 at high rate of 20 C, 30 C and 50 C, respectively. Importantly, the 750th discharge capacity still could be maintained at 105.3 mA h g−1 at 30 C. The outstanding properties can be ascribed to the synergistic interaction between H2Ti12O25 nanorod and RGO sheets and its multi-dimensional composite structure which makes the faster electronic and ionic conductivity of 1D-H2Ti12O25@2D-RGO achieved.

Magnetic moment centers in titanium dioxide photocatalysts loaded on reduced graphene oxide flakes

Abstract A whole series of titania nanocomposites modified with reduced graphene oxide (rGO) was prepared using solvothermal method followed by calcination. Modification of titania with rGO has been found to lead to better photocatalytic properties. The highest photocatalytic performance was obtained at calcination temperature of 600°C. Electron paramagnetic resonance/ferromagnetic resonance measurements showed oxygen defects and ferromagnetic ordering systems. The linewidth of resonance line of oxygen defects decreased linearly with calcination temperature increasing up to 600°C and an accompanying growth of mean crystallite size of anatase phase. The integrated resonance line intensity of oxygen defects depended on the calcination temperature and caused a very large increase in the intensity of resonance lines originating from oxygen defects, because inert atmosphere of calcination was enhanced by graphene presence. The occurrence of magnetic ordering system significantly influenced the performance of photocatalytic processes by changing the amount of oxygen defects.

Computational modelling of ammonia addition on partially reduced graphene oxide flakes.

Density functional theory is employed to model the chemisorption of ammonia on epoxy-containing polycyclic aromatic hydrocarbons (PAHs) and understand the reaction mechanism of ammonia addition on partially reduced graphene oxide flakes. Coronene (C24H12) and ovalene (C32H14) based four-epoxy group containing molecules are used to mimic the RGO surface properties. The reaction mechanism changing effect of a second ammonia molecule as well as explicit water molecules is considered. The proposed reaction mechanism consists of two steps: the migration of one epoxy group out of the modelled four-epoxy group formation to a thermodynamically less stable one and the nucleophilic addition of the ammonia molecule. The second step involves forming an amine group and reducing an epoxy group to a hydroxyl one. Interestingly, the forming amine group bonds to the carbon atom with the smallest bond order among the available ones and not necessarily to the carbon atom of the opening epoxy ring. Incorporating a second ammonia molecule has a negligible effect on the overall reaction mechanism, while in the presence of one water molecule, the reaction goes through a different pathway involving a trimolecular state during the nucleophilic addition. Including more than one water molecule or applying an implicit solvent model does not cause further changes in the reaction.

Effect of the substrate on the Raman spectra of reduced graphene oxide flakes

Effect of the substrate on the Raman spectra of reduced graphene oxide flakes

Gold nanoparticles modified graphene platforms for highly sensitive electrochemical detection of vitamin C in infant food and formulae

An easy and reliable method based on a novel electroanalytical nanostructured sensor has been developed to perform quantification of vitamin C in commercial and fortified cow-milk-based formulae and foods for infants and young children. The work is motivated by the need of a reliable analytical tool to be applied in quality control laboratories for the quantitative assessment of vitamin C where its rapid and cost-effective monitoring is essential.The ad hoc designed sensor, based on disposable screen-printed carbon electrodes modified with Au nanoparticles decorated reduced graphene oxide flakes, exhibits a LOD of 0.088 mg L−1. The low cost, easy sample preparation, fast response and high reproducibility (RSD ≈ 8%) of the proposed method highlight its suitability for usage in quality control laboratories for determining vitamin C in real complex food matrices, envisaging the application of the sensing platform in the determination of other compounds relevant in food chemistry and food manufacturing.

Laser scribed graphene/polymer composites: A possible verification of carbon nano-coil inductors

There is great interest in so-called nano-electronic devices due to the furious rate of device miniaturization. Fabrica-tion of micro and nano scale resistors and capacitors have already been achieved steadily, but so far, there has been little development in the way of nano-scale coil inductors. This is because of the physical limitations in miniaturiza-tion of the design of a solenoid with wires coiled around a metallic core. So, while transistors get steadily smaller, basic inductors in electronics remained relatively bulky. Few methods exist for creating conductive polymer coils and graphene-based kinetic nano-inductors, but their large-scale fabrication process is complex and mostly beyond the current commercial technology available. So, a simpler, scalable, and robust fabrication technique is needed to overcome this bottleneck. In this work we demonstrate a new technique consisting of the laser lithography using a laser engraver of a (poly)vinyl alcohol (PVA)/graphene oxide film composite which results in a large inductive effect. We attribute this behavior to the formation of high curvature twisted screw dislocation type conductive pathways composed of polyacetylene chains linked by pi-pi interactions to reduced graphene oxide flakes resulting in inductive effect.

Understanding the Detection Mechanisms and Ability of Molecular Hydrogen on Three-Dimensional Bicontinuous Nanoporous Reduced Graphene Oxide.

Environmental safety has become increasingly important with respect to hydrogen use in society. Monitoring techniques for explosive gaseous hydrogen are essential to ensure safety in sustainable hydrogen utilization. Here, we reveal molecular hydrogen detection mechanisms with monolithic three-dimensional nanoporous reduced graphene oxide under gaseous hydrogen flow and at room temperature. Nanoporous reduced graphene oxide significantly increased molecular hydrogen physisorption without the need to employ catalytic metals or heating. This can be explained by the significantly increased surface area in comparison to two-dimensional graphene sheets and conventional reduced graphene oxide flakes. Using this large surface area, molecular hydrogen adsorption behaviors were accurately observed. In particular, we found that the electrical resistance firstly decreased and then gradually increased with higher gaseous hydrogen concentrations. The resistance decrease was due to charge transfer from the molecular hydrogen to the reduced graphene oxide at adsorbed molecular hydrogen concentrations lower than 2.8 ppm; conversely, the resistance increase was a result of Coulomb scattering effects at adsorbed molecular hydrogen concentrations exceeding 5.0 ppm, as supported by density functional theory. These findings not only provide the detailed adsorption mechanisms of molecular hydrogen, but also advance the development of catalyst-free non-heated physisorption-type molecular detection devices.