Design and modeling of the superconducting magnet system of an ECRIS for applications in graphene doping

Surface doping of graphene into BiOCl for efficient photocatalytic amine coupling under visible light

We measured the effect of optical excitations on the back-gating of epitaxial quasi-free-standing single-layer graphene grown on a semi-insulating vanadium-doped 6H SiC. With the help of measurements of the electric field profiles in SiC, we show that graphene gating is directly related to the field effect at the graphene-SiC interface caused by changes in the distribution of the electric field in the SiC substrate under illumination. This provides a novel pathway for a comprehensive understanding of the photogenerated charge and the critical role of the substrate in optoelectronic devices. The change in graphene conductivity after the gating voltage is switched off is slow because of a very slow charge de-trapping from deep levels in silicon carbide. However, additional band-to-band optical excitation can significantly accelerate switching dynamics in graphene, especially when the light absorption is strongly localized below the graphene. Such an optically assisted field effect was enhanced by additional infrared light because of optical manipulation of the SiC deep level occupancy. • Optical assistance enables effective back-gating in epitaxial graphene on SiC. • Band-to-band illumination of the SiC substrate enhances gate-channel coupling. • Below-bandgap light eliminates slow gate response caused by deep-level traps. • Optical gating manipulates charge density without additional fabrication steps. • A physical model is supported by E-field measurements and drift simulations.

Research on the structural regulation mechanism of non-metallic doped graphene dual functional OER/ORR electrocatalyst based on DFT

Graphene incorporation into polymer fibers offers a strategy to tune nanoscale morphology while preserving mechanical conformity for flexible composite applications. Graphene-based dopants can enable modulation of polymer fiber structure; however, the relationship between graphene incorporation, fiber morphology, and mechanical flexibility must be evaluated. This study investigates the integration of graphene oxide (GO) and reduced graphene oxide (RGO) into fibrous materials to tailor the structural and surface characteristics by fabricating GO- and RGO-enhanced poly(vinylidene fluoride) (PVDF) fibers via a wet-spinning process and examining the tunability of their morphology and its influence on mechanical properties. The effect of graphene doping and reduction state on fiber architecture is explored using scanning electron microscopy (SEM), atomic force microscopy (AFM), and Brunauer-Emmett-Teller (BET) surface area analysis. Fourier transform infrared (FTIR) and Raman spectroscopy analyses confirmed the incorporation and reduction of graphene derivatives within the PVDF matrix while revealing corresponding changes in chemical functionality and the piezoelectric phase of PVDF. Mechanical flexibility is assessed through tensile testing, revealing increased stiffness with graphene addition, although maintaining sufficient structural integrity for wearable applications. These results collectively demonstrate that graphene doping provides a facile route to engineer composite fibers, enabling a balance between morphological complexity and mechanical compliancy, while establishing graphene-enhanced fibers as promising materials for flexible sensing systems and wearable smart textiles.

Designing sensitive materials capable of efficiently adsorbing AsH3 is of great significance for industrial safety protection and toxic gas monitoring. In this work, we systematically investigate the adsorption behavior of AsH3 on pristine graphene and transition metal-doped divacancy graphene (TM-DVG, TM = Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) using first principles calculations. The results show that AsH3 interacts with pristine graphene primarily via weak physisorption. In contrast, TM-DVG exhibits significantly enhanced adsorption performance. The adsorption strength is governed by the degree of energy level matching and the competition between bonding and antibonding states in the electronic structure. Among numerous sensitive materials, Fe-DVG exhibits significant charge transfer (-0.211e), moderate adsorption energy (-0.930 eV), and rapid recovery characteristics (420 s at 300 K), indicating its excellent sensing potential. Further analysis reveals that the strong interaction between the HOMO of AsH3 and the dz2 orbital of the Fe atom originates from appropriate energy level matching, symmetry matching, and maximal orbital overlap. Meanwhile, Fe-DVG exhibits good selectivity toward AsH3, making it an ideal candidate for AsH3 detection. This study provides a theoretical foundation for the design of graphene-based AsH3 sensors with high sensitivity and selectivity.

A First-Principles Study on the Catalytic Reduction of CO2 to CH4 on Boron Doped Graphene: Role of B-Concentration

Influence of mild fluorination on strain and charge doping in graphene

Elucidating the electron-driven mechanism of H2O dissociation on Pt nanoclusters via modulating the doped graphene substrate and applied electrode potential.

Effect of graphene doping on the electrical and optical properties of ZnO:PDMS composite films

We study broadband terahertz (THz) conductivity and ultrafast photoconductivity spectra in lithographically fabricated multilayer epitaxial graphene nanoribbons grown on C-face of 6H-SiC substrate. THz near-field spectroscopy reveals local conductivity variations across nanoscale structural inhomogeneities such as wrinkles and grain boundaries within the multilayer graphene. Ultrabroadband THz far-field spectroscopy ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:mn>0.15</a:mn> <a:mtext>–</a:mtext> <a:mn>16</a:mn> <a:mspace width="0.28em"/> <a:mi>THz</a:mi> </a:mrow> </a:math> ) distinguishes doped graphene layers near the substrate from quasineutral layers (QNLs) further from the substrate. Temperature-dependent THz conductivity spectra are dominated by intraband transitions both in the doped and QNLs. Photoexcitation then alters mainly the response of the QNLs: these exhibit very high carrier mobility and large positive THz photoconductivity with picosecond lifetime. The response of QNLs strongly depends on the carrier temperature <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:msub> <c:mi>T</c:mi> <c:mi mathvariant="normal">c</c:mi> </c:msub> </c:math> : the scattering time drops by an order of magnitude down to ∼10 fs upon an increase of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"> <e:msub> <e:mi>T</e:mi> <e:mi mathvariant="normal">c</e:mi> </e:msub> </e:math> from 50 K to <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"> <g:mrow> <g:msub> <g:mi>T</g:mi> <g:mi mathvariant="normal">c</g:mi> </g:msub> <g:mo>&gt;</g:mo> <g:mn>1000</g:mn> <g:mspace width="4pt"/> <g:mi mathvariant="normal">K</g:mi> </g:mrow> </g:math> , which is attributed to an enhanced electron-electron and electron-phonon scattering and to an interaction of electrons with mid-gap states.

This work investigates how effective fractional dimensionality and substitutional doping jointly affect particle-density symmetry in AA-stacked bilayer graphene (BLG). The system consists of one pristine graphene layer and one doped layer, where 50% of the atomic sites are substituted. Doping is described within a tight-binding framework through a dimensionless parameter α (with 0 &lt; α &lt; 1), which uniformly reduces the intralayer hopping energy in the doped layer, while an effective fractional dimension D &gt; 2 phenomenologically accounts for structural inhomogeneities such as ripples or corrugations. Analytical expressions for the energy spectrum and number of states are obtained, and the electronic asymmetry between layers is characterized by a symmetry parameter P. We find that substitutional doping breaks the particle-density symmetry of pristine BLG and strongly enhances the number of states near the Fermi level as α decreases, due to the accumulation of low-energy states in the doped layer. Departures from the ideal dimensionality D = 2 further amplify this enhancement. The combined effects of reduced α and increased D lead to a pronounced layer asymmetry, reflected in a nonzero P, while stronger interlayer coupling partially counteracts this imbalance. Results show that doping, effective fractional dimensionality, and interlayer coupling offer tunable control over the low-energy electronic properties of BLG.

This study investigates the interaction mechanisms between human serum albumin (HSA) and two structurally distinct ligands S-allyl-cysteine (SAC) and S, N-co-doped graphene quantum dots functionalized by S-allyl-cysteine (DGQD/SAC) using multispectroscopic and computational approaches. Steady-state and time-resolved fluorescence measurements revealed distinct quenching mechanisms: SAC exhibited static quenching through ground-state complex formation (KSV = 2 × 10-4 ppm1 at 298 K) with preserved HSA conformation (Δα-helix < 10%), while DGQD/SAC showed dynamic-dominated quenching (KSV = 0.2648 ppm-1 at 298 K and Kq = 26.48 × 106 ppm-1s-1) accompanied by partial protein unfolding (15% α-helix reduction). Förster resonance energy transfer (FRET) analysis confirmed donor-acceptor distances of 2.85 nm for HSA-DGQD/SAC, within optimal range for energy transfer (0.5R0< r < 1.5R0). Circular dichroism (CD) spectra demonstrated SAC's localized binding at Sudlow's site I, whereas N, S-GQD/SAC induced tertiary structure perturbations. Thermodynamic profiling revealed entropy-driven binding for both ligands (ΔS > 0), with SAC showing temperature-enhanced affinity (Ka increased from 1.2474 to 1.9902 ppm-1, 298-318 K). These findings provide critical insights for designing HSA-based delivery systems, highlighting SAC's structural preservation advantages and DGQD/SAC's tunable interfacial interactions.

ABSTRACT Semiconducting graphene is expected to replace silicon in the electronics industry, and various methods have been proposed for this purpose. In this study, we demonstrate that the long-term exposure of multilayer graphene to 80 bar of molecular hydrogen induces electron doping in graphene. Ambipolarity behavior disappeared, and the current in the transfer curves decreased and increased in the negative gate voltage (V g ) and positive V g regions, respectively. The charge neutrality point shifted from 4.18 to over −80 V. Two resonant scatterings due to hydrogen adatoms were observed in the temperature-dependent transfer curves. For multilayer graphene with a boundary (edge), different behavior was observed in the transfer characteristics. Upon exposure to 80 bar of H2 pressure, the drain current of the time-dependent transfer curve rapidly decreased; however, it increased in the positive V g region after 60 h of exposure to H2. Structural changes, particularly an increase in C‒H bonding, were observed using various characterization methods. These results were interpreted by the dissociative H2 adsorption of graphene. Molecular dynamics simulations also revealed the presence of electron doping due to dissociative adsorption. Furthermore, the simulations confirmed that dissociative adsorption occurred on the surface layer and at vacancies and defects.

Metal/non-metal doped graphene quantum dots as dual fluorescent probes for detection of pesticide residues and heavy metal ions.

Abstract This study focuses on developing a morphologically stable nitrate-based composite phase change material (PCM) tailored for medium-low temperature thermal energy storage (TES) applications, addressing the limitations of pure molten salts such as low thermal conductivity and insufficient thermal stability. The eutectic ternary nitrate system with a weight ratio of 53:12:35 was selected as the phase change matrix, and graphene nanoparticles were incorporated as a functional additive to modulate thermophysical properties. Through systematic characterization using thermogravimetry (TG), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR), the effects of graphene loading on the composite’s thermal behavior, microstructure, and chemical compatibility were investigated. Results indicate that graphene doping significantly modulates the ternary nitrate’s properties: the composite with 1.0 wt.% graphene exhibits the highest initial decomposition temperature, maximum phase change enthalpy, and a reduced melting point compared to the pure salt. Microstructural analysis reveals that graphene induces the formation of chain-like/fractal structures, with 0.5 wt.% graphene yielding the most homogeneous grain distribution, while 1.0 wt.% graphene forms a continuous thermal conduction network. FTIR and EDX confirm no chemical reactions between graphene and the salt matrix, ensuring excellent chemical compatibility. These findings provide a theoretical basis for the application of ternary nitrate/graphene composites in concentrated solar power (CSP) systems, highlighting their potential for efficient thermal energy management in renewable energy technologies.

ABSTRACT To design high performance of organic/inorganic thermoelectric composite materials by molecular simulation, composite materials (PPy/NG) are constructed by incorporating graphene (GE) modified with N atoms (NG) into the Polypyrrole (PPy) matrix. For different GE doping concentrations and different concentration N atoms modified in GE (mod‐Ns), the thermoelectric properties of PPy/ n ‐NG composite materials ( n represents different N atoms modified concentration) is systematically investigated using the non‐equilibrium molecular dynamics (NEMD) and density functional theory (DFT). It is found that N‐modification on GE has a significant influence on the reduction on the thermal conductivity of composites with 7.06 wt.% graphene concentration. Moreover, when the mod‐Ns concentration reached 3.66%, the thermal conductivity of the PPy/NG composite material is decreased by 49.19%. Additionally, the electron properties of PPy/ n ‐NG are studied. It is found that the energy differences between the HOMO of n ‐NG and the LUMO of PPy decrease with the increase of mod‐Ns concentration in NG. Overall, this study reveals that n ‐NG reduces the thermal conductivity of PPy/ n ‐NG composites and promotes the transfer of electrons between n ‐NG and PPy. It establishes a theoretical foundation for designing high‐performance organic/ inorganic thermoelectric materials.

Graphene functionalized with catalytic transition metals offers high-performance chemiresistive gas sensing by coupling graphene's exceptional electronic transport with the metal's catalytic activity; yet the atomistic relationships connecting synthesis parameters, morphological outcomes, and sensor gas-surface reaction kinetics remain elusive. We developed an equivariant machine-learning interatomic potential with DFT accuracy to enable high-fidelity molecular dynamics (MD) simulations, from metal nanostructure growth on graphene to device-level sensing kinetics. Demonstrating our approach, we specifically investigate Pt-functionalized graphene for H2 detection. MD simulations validated by TEM show that Pt deposition begins with dispersed nuclei coalescing into polycrystalline nanoclusters, while both MD and Raman spectroscopy reveal predominantly noncovalent metal-graphene interactions that induce moderate local strain and doping, while preserving graphene's structural integrity. MD simulations confirm H2 dissociative chemisorption and recombinative desorption primarily on Pt nanoclusters, with negligible spillover or chemical interaction with pristine graphene. However, H adsorption on Pt attenuates the Pt-graphene interfacial binding, providing an indirect electronic pathway for gas sensing. Adsorption/desorption kinetics reveal that an intermediate loading of metal nanostructures minimizes the detection limit; lower loadings facilitate faster response and recovery kinetics and enhance signal transduction, whereas higher loadings increase interfacial binding and graphene doping. The developed machine-learned MD framework accurately models metallic nanostructure growth on graphene, elucidates the gas-sensing mechanism, and correlates figures of merit─detection limit, sensitivity, and response/recovery times─extracted from gas-surface kinetics with metal nanostructure morphology, establishing a multiscale predictive pipeline from synthesis conditions to gas-sensor kinetics.

Poly (3,4-ethylenedioxythiophene polystyrene sulfonate) (PEDOT:PSS) is a solution-processable hole transport layer known for its high work function and excellent hole mobility. The incorporation of graphene serves as an effective strategy to augment the hole-transport properties of PEDOT:PSS. In this study, the electronic structure of graphene-doped PEDOT:PSS (G-PEDOT:PSS) was investigated using X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). It was found that the work function of PEDOT:PSS increases with graphene doping concentration, rising from 4.86 eV for undoped PEDOT:PSS to 5.03 eV for PEDOT:PSS incorporating 10 wt% graphene. The impact of this modification on the energy-level alignment with zinc phthalocyanine (ZnPc), which is a prototypical p-type organic semiconductor, was examined through in situ XPS and UPS analyses. Despite the increased work function, the hole injection barriers for both PEDOT:PSS and G-PEDOT:PSS to ZnPc were determined to be identical at 0.26 eV. This lack of change in the barrier is explicitly attributed to Fermi-level pinning, where the integer charge transfer level of ZnPc is pinned to the Fermi level of the substrate, preventing a further reduction in the energy offset. That said, for other p-type organic semiconductors with higher ionization energies, the use of G-PEDOT:PSS could potentially enable more efficient hole injection.

Optical phase modulators are critical components in integrated photonics, but conventional designs suffer from a trade-off between modulation efficiency and optical loss. Two-dimensional materials like graphene offer strong electro-optic effects, yet their high optical absorption at telecom wavelengths leads to significant insertion losses. Although monolayer transition metal dichalcogenides (TMDs) provide exceptional telecom-band transparency for low-loss electro-refractive response, their practical implementation in phase modulators requires top electrodes to enable vertical electric field tuning, which typically introduces parasitic absorption. Here, we address this challenge by developing hybrid tungsten oxyselenide/graphene (TOS/Gr) electrodes that minimize optical loss while enabling efficient phase modulation in TMD-based devices. The UV-ozone-converted TOS (from WSe2) acts as a heavy p-type dopant for graphene, making the graphene transparent in the NIR region while enhancing its conductivity. Our complete device integrates a hybrid TOS/graphene transparent electrode with a hexagonal boron nitride dielectric spacer and monolayer WS2 electro-optic material on a SiN microring platform. This achieves a high modulation efficiency of 0.202 V·cm while maintaining an exceptionally low extinction ratio change of just 0.08 dB, demonstrating superior performance compared to modulators employing conventional electrodes. Our breakthrough in near-lossless phase modulation opens new possibilities for energy-efficient optical communications, photonic computing, and fault-tolerant quantum networks.