Metal-doped Graphene Research Articles

Theoretical calculations of pyridine adsorption on the surfaces of Ti, Zr, N doped graphene

In this paper, the adsorption behavior of pyridine, a typical basic nitrogen compound in diesel oil, on Ti-doped, Zr-doped, N-doped and intrinsic graphene has been investigated by density functional methods. The corresponding adsorption energy, adsorption configurations, Mulliken charge transfer, differential charge density and density of states were discussed. The results show that doping graphene with metal atoms such as Ti or Zr can significantly obviously enhance the adsorption energy between pyridine and graphene surfaces, while non-metal N doping has a relatively minor effect. The magnitude of the adsorption energy of pyridine on the surfaces of graphene modified with different atoms follows the order: Ti-doped>Zr-doped>N-doped>intrinsic graphene. Pyridine interacts with Ti- or Zr-doped graphene through N−Ti, N−Zr and π−π interactions, while with N-doped and intrinsic graphene, it interacts via N−N, C−N and π−π interactions. There are significantelectron transfer and chemical bond formation between pyridine and metal-doped (Ti, Zr) graphene surfaces, indicating chemical adsorption. However, there is no chemical bond formation with non-metal N-doped graphene and intrinsic graphene, suggesting physical adsorption in these cases. Overall, pyridine exhibits more stable adsorption on the surfaces of Ti, Zr-doped graphene.

Adsorption of aminomethylphosphonic acid on pristine graphene and graphene doped with transition metals: A theoretical study

Aminomethylphosphonic acid (AMPA), a glyphosate breakdown product, exhibits environmental persistence, raising concerns. This study investigates AMPA adsorption on pristine and transition metal-doped graphene using quantum theory of atoms in molecules calculations. Results revealed favorable adsorption energies for pristine graphene, significantly enhanced by doping, with Co-doped graphene exhibiting the highest adsorption energy. Interactions were predominantly physisorption, and doping did not significantly alter graphene’s electronic structure. Tight-binding dynamics simulations demonstrated efficient AMPA adsorption on doped graphene, with Co exhibiting the strongest binding affinity. These findings highlight the potential of transition metal-doped graphene as an effective adsorbent for removing AMPA from water sources.

Biosensor for the early diagnosis of lung cancer: A DFT study on the applicability of metal-doped graphene structures

The usability of metal-doped graphene structures as biosensor was investigated to develop a preliminary diagnosis of lung cancer in this study. The adsorption and sensing properties of graphene structures formed by doping metal atoms (Pt, Pd, Ni, Ir and Cu) toward aniline, toluene, styrene and benzene gases were examined. Using the DFT/WB97XD method with 6–31 G (d, p)/LANL2DZ basis sets, significant charge transfer from the target gases to the metal-doped graphene structures were observed. After adsorption, the HOMO-LUMO gap values of graphene structures doped with Pt, Cu, and Ni atoms have decreased. All adsorption processes are spontaneous according to the adsorption Gibbs free energy. The findings indicate that copper-doped and platinum-doped graphene have strong potential as electronic and work function sensors for detecting aniline, toluene, styrene, and benzene, which are biomarkers for lung cancer.

Machine Learning-Assisted Study of RENxC6-x-Doped Graphene as Potential Electrocatalysts for Oxygen Electrode Reactions.

In the application of renewable energy, the oxidation-reduction reaction (ORR) and oxygen evolution reaction (OER) are two crucial reactions. Single-atom catalysts (SACs) based on metal-doped graphene have been widely employed due to their high activity and high atom utilization efficiency. However, the catalytic activity is significantly influenced by different metals and local coordination, making it challenging to efficiently screen through either experimental or density functional theory (DFT) calculations. To address this issue, this study employed a combination of DFT calculations and machine learning (DFT-ML) to investigate rare earth-modified carbon-based (RENxC6-x) electrocatalysts. Based on computational data from 75 catalysts, we trained two ML models to capture the underlying patterns of physical properties and overpotential. Subsequently, the candidate catalysts were screened, leading to the discovery of four ORR catalysts, nine OER catalysts, and five bifunctional electrocatalysts, all of which were thoroughly validated for their stability. Lastly, by integrating the ML models with the SHAP analysis framework, we revealed the influence of atomic radius, Pauling electronegativity, and other features on the catalytic activity. Additionally, we analyzed the physicochemical properties of potential catalysts through DFT calculations. The revolutionary DFT-ML approach provides a crucial driving force for the design and synthesis of potential catalysts in subsequent studies.

Mechanistic insight into the C1 product selectivity for the catalytic hydrogenation of CO2 over metal-doped graphene

The conversion of CO2 into fuels and valuable chemicals presents a viable path toward carbon neutrality. The aim of this study is to investigate the potential of metal-doped graphene catalysts in the reduction of CO2 to C1 products. 20 typical M-graphene (M = metal) catalysts were established based on DFT calculations. Six candidate catalysts, i.e., V-, Cr-, Mn-, Ni-, Mo-, and Ta-graphene catalysts, were selected by combining the hydrogen dissociation ability and the energy band gap of the catalysts. Subsequently, the adsorption characteristics and hydrogenation reactions of CO2 over the six candidates were explored. CO2 tends to adsorb at the M site through vertical adsorption and carbon–oxygen co-adsorption. V- and Cr-graphene catalysts promote the production of intermediate COOH, whereas Mn-, Ni-, Mo-, and Ta-doped surfaces are more favorable for HCOO formation. Concerning the hydrogenation to CO and HCOOH, V-, Cr-, Ni- and Mo-graphene catalysts preferentially yield CO from COOH, whereas Ta-doped graphene favors the formation of HCOOH. In total, the competitive hydrogenation of CO2 reveals the selectivity of the C1 products. Cr- and Ni-graphene favor the production of HCOOH and CH3OH, whereas V-, Mn-, Mo-, and Ta-graphene primarily yield CH3OH.Graphical

Chemical reactivity of graphene doped with 3d transition metals: nothing compares to a single vacancy.

Finding catalysts that do not rely on the use of expensive metals is one of the requirements to achieve sustainable production. The reactivity of graphene doped with 3d transition metals was studied. All dopants enhanced the reactivity of graphene and performed better than Stone-Wales defects and divacancies, but were inferior to monovacancies. For hydrogenation of doped-monovacancies, Sc, Ti, Cr, Co, and Ni induced more prominent reactivity on the carbon atoms. However, the metals were the most reactive center for V, Mn, and Fe-doped graphene. Cu and Zn turned the four neighboring carbon atoms into the preferred sites for hydrogenation. The addition of oxygen to doped graphene with Ti, V, Cr, Mn, Fe, Co, and Ni on a monovacancy revealed a more uniform pattern since the metal, preferred to react with oxygen. However, Sc induced a larger reactivity on the carbon atoms. The affinity of the 3d metal-doped graphene systems towards oxygen was inferior to that observed for single-vacancies. Therefore, vacancy engineering is the most favorable and least expensive method to enhance the reactivity of graphene. We applied Truhlar's M06-L method accompanied by the 6-31G* basis sets to perform periodic boundary conditions calculations as implemented in Gaussian 09. The ultrafine grid was employed and the unit cells were sampled employing 100k-points. Results were visualized employing Gaussview 5.0.1.

Gold-Deposited Graphene Nanosheets for Self-Cleaning Graphene Surface-Enhanced Raman Spectroscopy with Superior Charge-Transfer Contribution.

The interaction of graphene with metals initiates charge-transfer interaction-induced chemical enhancements, which critically depend on the doping effect from deposited metallic configurations. In this paper, we have explored the gold nanoparticle-decorated monolayer graphene nanosheets for the large graphene-induced Raman enhancement of adsorbed analytes, indicating the surface-enhanced Raman spectroscopy (SERS) capabilities of metal-doped graphene (G-SERS). Here, the systematically sputtered Au thickness optimization procedure revealed noticeable modifications in the graphene Raman spectra and photoluminescence (PL) background quenching, which indicated favorable charge transfer through n-type doping of chemical vapor deposition-grown graphene nanosheets. The highly consistent, individually distributed morphology of the gold nanoislands over graphene nanosheets depicted a reproducibly uniform G-SERS signal with excellent relative standard deviation values (<5%), resulting in the strongest Raman intensity enhancement factors of ∼108 (MB) (methylene blue) and 107 (DPA) (2,6-pyridinedicarboxylic acid) composed of the weakest PL background. The combined charge-transfer-induced chemical enhancement and electromagnetic enhancement from individual Au nanoislands result in a lowering of detectability down to 10-16 M (MB) and 10-11 M (DPA) concentrations with efficient time-dependent signal stability. Additionally, the GAu demonstrated its effective (∼94.4%) photocatalytic degradation capabilities by decomposing MB dye molecules from a concentration of 1 μM to 2.52 fM within 60 min. Therefore, the prominent charge-transfer contribution through controlled Au decoration over graphene nanosheets provides a potential strategy for fabricating superior SERS sensors and photocatalysts exhibiting adequate signal consistency, stability, and photodegradation efficiency through overcoming the limitations of the traditional sensing platforms.

An ab-initio investigation of transition metal-doped graphene quantum dots for the adsorption of hazardous CO2, H2S, HCN, and CNCl molecules

The quantum confinement and size effects make graphene quantum dots (GQDs) remarkable candidates for sensing applications. Gas molecules can easily be adsorbed on GQDs because of their large specific areas and exposed edges. This computational work concerns the adsorption performance of pristine and transition metal [chromium (Cr) or nickel (Ni)]-doped coronene GQD to hazardous gases carbon dioxide (CO2), hydrogen sulfide (H2S), hydrogen cyanide (HCN), and cyanogen chloride (CNCl), along with structural properties such as bond length and angle, electronic properties including molecular orbital analysis, natural bond orbital and Mulliken charge analysis, spectroscopic properties of infrared and ultraviolet spectra, quantum theory of atoms in molecules with non-covalent interaction analysis, and sensing properties of recovery time, work function, and sensing response. As pristine GQDs show poor gas adsorption, doping with Cr and Ni enhance performance. The results of Cr-doped coronene GQD indicate that the gas molecules have strong interaction with GQDs as the computed adsorption energies are highly negative (−3.56, −3.81, −4.02, and −4.81 eV). Since the computed recovery times are extremely long, the Cr-doped GQDs can be used as removers of CO2, H2S, HCN, and CNCl gas molecules from specific environments. In the case of Ni-doped GQDs, only the interaction with CNCl yields chemisorption, with adsorption energy of −0.83 eV. However, the short recovery time (9.36 ms–93.6 s) indicates its potential candidature as a CNCl sensor.

Effect of surface curvature on the hydrogen storage capacity of the Sc-, Ti-, and V-doped graphene surfaces: Theoretical study

Hydrogen (H2) is an excellent energy carrier and can be produced in an environmentally friendly way. The H2 binding performance of different Sc-, Ti-, and V-doped carbon surfaces (i.e., graphenes, circumcoronenes, and circumtrindenes) is investigated using density functional theory. The calculated H2 binding energies are ranging from −12 kJ mol−1 to −22 kJ mol−1 for one H2 molecule per transition metal (TM) atom. Such binding energies are suitable for reversible H2 adsorption and desorption cycle. Obtained results suggest that the curvature of the TM-doped carbon surfaces enhances their H2 binding ability. TM atom in the curved carbon surfaces, representing an active site, is sterically more easily accessible for H2 binding than in the case of the planar metal-doped graphene surfaces. For comparison, the N2 binding ability of the same set of TM-doped carbon surfaces is studied as well.

DFT investigation of transition metal-doped graphene for the adsorption of HCl gas

Graphene-based toxic HCl gas sensors and adsorption materials are seldom reported. Utilizing density functional theory (DFT), the adsorption energy, charge density, and density of states, the sensitivity and recovery time of HCl gas adsorbed on graphene and six different transition metal-doped graphenes (TMDGs: TM = Ti, V, Cr, Mn, Fe, Co) were investigated. It indicates that TMDG has larger adsorption energy and chemical adsorption capacity than graphene. The Fe-doped graphene (FeDG) demonstrated better adsorption capacity and higher stability even at high temperature. The Mn- and Co-doped graphenes (MnDG & CoDG), exhibited magnetic changes after the adsorption of HCl molecules. Moreover, MnDG has both fast responsiveness and fast recovery time at a certain temperature. Thus, comparative speaking, among the six TMDGs, MnDG is the most suitable material for the detection of HCl gas, its magnetic property implied a novel application in HCl gas sensor.

Combined effects of direct plasma exposure and pre-plasma functionalized metal-doped graphene oxide nanoparticles on wastewater dye degradation

The current study investigates the combinatorial effect of the photocatalytic performance of plasma pre-treated Ti-Cu-Zn doped graphene oxide (TCZ-GO) nanoparticles (NPs) and advanced oxidation processes of a non-thermal atmospheric pressure plasma on the degradation of reactive orange-122 (RO-122) dye compounds. Firstly, in order to enhance the photocatalytic performance of the synthesized composite NPs, they were subjected to glow discharge plasma treatments operating in different gases (Ar, air, O2 and N2). Their surface morphology, chemical composition and band gap were examined by means of scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and UV–Vis spectrophotometry respectively. XPS results revealed that plasma-treated NPs exhibited a higher content of oxygen vacancies and a variation in their oxidation states (Ti4+ → Ti3+, Cu+ → Cu2+). These plasma-induced surface chemical changes hindered the recombination of photo-generated electron-hole pairs which led to a drop in the bandgap of the NPs with N2 plasma-treated NPs acquiring the lowest bandgap. Lastly, the article examined the actual decomposition of RO-122 dye in wastewater by an Ar plasma treatment alone or combined with the plasma-treated TCZ-GO NPs via spectrophotometric analyses, electrical conductivity, pH and total organic carbon (TOC) removal measurements. Moreover, the reactive species produced during the combined plasma/photocatalysis induced degradation were detected in situ by optical emission spectroscopy. Results revealed that the processes carried out by combining N2 plasma-treated TCZ-GO NPs and Ar plasma exhibited the highest degradation efficiency (85 %) due to the generation of more OH and H2O2. Overall, it can be concluded that plasma-aided treatment processes used synergistically as indirect surface functionalization of TCZ-GO NPs and direct plasma treatment of wastewater are extremely efficient in the degradation of toxic compounds and can be extrapolated to various environmental applications.

Modification of plasmonic properties in several transition metal-doped graphene studied by the first principles method.

Graphene doped with different transition metal (TM) atoms, namely, Co, Ni, Cu, Zn, and Au, have been investigated through first-principles calculations. The TM atom forms a substitutional defect, replacing one carbon atom in the graphene basal plane, which considerably can be obtained through wet or dry chemical processes as reported elsewhere. The calculation results showed that TM atom substitution leads to the opening of a band gap and the emergence of mid-gap states with the Fermi energy in the middle of it. The effects on optical properties were seen from the calculated optical absorption and Electron Energy Loss Spectroscopy (EELS) spectra. Two EELS bands are seen in the far UV region corresponding to the π and (π + σ) plasmons but the influence of the substituted TM effects on the plasmon frequency is small. On the other hand, as the Fermi energy level appears in the middle of the mid-gap state band while the real part of its dielectric permittivity at low photon energy is negative, these TM-doped graphene have a metal-like characteristic. Hence, plasmon wave excitation can be expected at the THz region which is dependent on the dopant TM atom. The plasmon excitation in these TM-doped graphene is thus principally similar to the plasmonic excitation in pure graphene by electric or magnetic fields, where the Fermi energy level is shifted from the graphene Dirac point leading to the possibility of an intraband transition.

Heteroatoms (B, N, and P) doped on nickel-doped graphene for phosgene (COCl2) adsorption: insight from theoretical calculations

Nanomaterials have been used for different applications including sensing environmental gases. Exposure to hazardous gas in the environment leads to major health issues such as swelling throats, delayed nervous system responses, and many more. Similarly, the development of sensors for fast environmental COCl2 monitoring is currently necessary. In this work, a molecular study on the adsorption of COCl2 onto metal-doped graphene nanoflakes and the heteroatom-decorated graphene nanoflakes (Ni, B, N, and P) has been computed using the density functional theory method at the ωB97XD/6-311 + G (d, p) level of computation. Total density of state analysis shows that the Ni-doped and decorated (B, N, P) surfaces decrease the HOMO-LUMO energy gap and therefore have a significant influence on the electric properties of the surfaces. The deviation in bond length on complexation with gas molecules infers that surfaces can adsorb COCl2 gas. In our work, two configurations are used: sites Cl and O. From our result for adsorption energies, it is observed that COCl2 is better adsorbed on the metal-doped graphene than the heteroatom-decorated graphene with an adsorption energy of −6.466 eV at orientation O-atom site. The calculated adsorption energies indicate that at site Cl of the COCl2 gas is physisorbed and chemisorbed at site O. The adsorption energy is in the order of GP_Ni > GP_NiP > GP_NiB > GP_NNI. The order of decreasing stabilization energy is as follows: GP_NiB > GP > GP_Ni > GP_NiN > GP_NiP; this contributes to the stability of adsorbent materials. The quantum theory of atom in molecules and non-covalent interaction analysis validate that the interaction between COCl2 and model surfaces is more non-covalent. Therefore, studied graphene nanoflake models can adsorb COCl2 gas molecules and can be considered an effective gas-sensing material.

A DFT studies on absorbing and sensing possibilities of glucose on graphene surface doped with Ag, Au, Cu, Ni & Pt atoms

The adsorption of glucose is theoretically examined using the Density Functional Theory method (DFT) over pure graphene and graphene surface doped with transition metal atoms (silver, gold, copper, nickel, and platinum). The graphene sheets are altered by substitutional doping of silver, gold, copper, nickel, and platinum atoms remarks in altering the electronic properties and actively reassuring glucose absorption. The outcomes revealed that metal atoms doped with graphene sheets improve the reactivity. Our study found that the interaction of glucose with pure graphene is weak when compared to metal-doped graphene flakes. Our studies concluded that due to strong adsorption energies, high bandgap variation, and excellent work function values of metal-doped graphene sheets make them beneficial for glucose sensing devices. The sensitivity and conductivity variations are high for the metal doped graphene sheets except nickel, however the recovery time value is high, suggesting that these sheets can be used as a disposable sensor.

Decomposition of formic acid via carboxyl mechanism on the graphene nanosheet decorated by Cr, Mn, Fe, Co, Ni, Pd, Ag, and Cd metals: A DFT study

The carboxyl mechanism of formic acid decomposition was investigated on the graphene nanosheet decorated with 8 single metal atoms from the thermodynamics and kinetics point of view using DFT computations. The thermodynamic results showed that for all metal-doped graphene surfaces, the adsorption of studied entities in the gas phase was more favorable compared to the solution phase. The Mn-doped graphene surface was more suitable for the adsorption of studied entities than the other surfaces. Adsorption of CO as a poisoning entity was also more favored on Mn-doped graphene with the highest adsorption energy of −47.56 kJ/mol while the Pd and Co samples were less poisoned with CO intermediate. Our kinetic studies demonstrated that the C–H bond activation was the rate-determining step of formic acid decomposition for all of the examined systems in the gas and solution phases. Additionally, formic acid decomposition was kinetically more suitable on the Mn-doped graphene nanosheet with the lowest activation energy of 73.19 kJ/mol.

Correlation between the activity of Fe@ (N, S, and P) doped graphene catalysts and the coordination environment: A density functional theory study

Transition metal-doped graphene single-atom catalysts exhibit great application prospects for catalyzing hydrogen evolution applications. However, the precise timing and control of the activity of central atoms is a key problem to ensure the further development of catalysts. Revealing the correlation between the catalytic activity of the central atom and the coordination environment (atomic species, coordination number, and geometric configuration) is regarded as quite crucial for solving this key problem. Along these lines, in this work, Fe as the central atom and N, S, and P doped porous graphene (DPG) as the matrix material were used to systematically study the correlation between the coordination environment and the stability, catalytic activity of the catalyst. From the acquired results, it was demonstrated that: (1) The binding strength between the Fe atom and the N-atom DPG is the highest, and the anchoring strength of the Fe atom on two-element doping doped graphene is relatively low. Under the tetrad coordination condition, the catalyst doped with S and P atoms showed excellent performance in hydrogen evolution and water activation. A moderate correlation between the hydrogen evolution performance (ΔGH∗, EA, and ΔGOH∗) and d-band electronic properties (d-CU and d-SE) under single element doping (four and three coordination) was also detected. In addition, a certain correlation between the Fe atom outer-shell electron (3d 4s) and the hydrogen evolution performance was found. A weak correlation between the electronic properties of the double element doped graphene and the hydrogen evolution performance was also confirmed from our simulations. The results are of great significance for the regulation of the single-atom catalyst activity.

Dual-Mode Fluorescence/Ultrasound Imaging with Biocompatible Metal-Doped Graphene Quantum Dots.

Sonography offers many advantages over standard methods of diagnostic imaging due to its non-invasiveness, substantial tissue penetration depth, and low cost. The benefits of ultrasound imaging call for the development of ultrasound-trackable drug delivery vehicles that can address a variety of therapeutic targets. One disadvantage of the technique is the lack of high-precision imaging, which can be circumvented by complementing ultrasound contrast agents with visible and, especially, near-infrared (NIR) fluorophores. In this work, we, for the first time, develop a variety of lightly metal-doped (iron oxide, silver, thulium, neodymium, cerium oxide, cerium chloride, and molybdenum disulfide) nitrogen-containing graphene quantum dots (NGQDs) that demonstrate high-contrast properties in the ultrasound brightness mode and exhibit visible and/or near-infrared fluorescence imaging capabilities. NGQDs synthesized from glucosamine precursors with only a few percent metal doping do not introduce additional toxicity in vitro, yielding over 80% cell viability up to 2 mg/mL doses. Their small (&lt;50 nm) sizes warrant effective cell internalization, while oxygen-containing surface functional groups decorating their surfaces render NGQDs water soluble and allow for the attachment of therapeutics and targeting agents. Utilizing visible and/or NIR fluorescence, we demonstrate that metal-doped NGQDs experience maximum accumulation within the HEK-293 cells 6-12 h after treatment. The successful 10-fold ultrasound signal enhancement is observed at 0.5-1.6 mg/mL for most metal-doped NGQDs in the vascular phantom, agarose gel, and animal tissue. A combination of non-invasive ultrasound imaging with capabilities of high-precision fluorescence tracking makes these metal-doped NGQDs a viable agent for a variety of theragnostic applications.

Adsorption performance of CNCl, NH3 and GB on modified graphene and the selectivity in O2 and N2 environment

Two-dimensional materials have shown desirable application prospects in the field of gas sensing. Through the modification of graphene gas-sensitive materials, more efficient and sensitive gas sensors can be further developed. The use of metal atoms or oxygen-containing groups to modify graphene can improve its detection performance for gases. Modified-graphene could be selected as an excellent gas sensor for poisonous gas detection. In this work, adsorption systems of CNCl, NH3 and GB on metal doped graphene (Au, Ag, Cu and Fe) and graphene oxide were established by the using of density functional theory (DFT). The adsorption energy, charge transfer, DOS, PDOS and energy band of these adsorption systems were investigated. The gas adsorption strength and gas selectivity factor were introduced to evaluate the selectivity of each substrate to these harmful gases in O2 and N2 environments. The calculation shown strong adsorption between the metal-doped graphene and the adsorbed gas, with Fe-doped graphene having better adsorption performance. By contrast, between graphene oxide and the adsorbed gas, the effect was slight. Moreover, the energy band change of metal- doped graphene was more obvious than that of graphene oxide. In addition, under O2 and N2 environment, Au-doped graphene may have good selectivity for CNCl and NH3 while Ag-doped graphene may have good selectivity for GB. This result will provide reference for the development of graphene based gas sensors for CNCl, NH3 and GB.

Transition metal-doped SnO2 and graphene oxide (GO) supported nanocomposites as efficient photocatalysts and antibacterial agents.

In the present work, pristine and transition metal (TM) (W, Ag, Zn)-doped SnO2 nanocrystals using a facile sol-gel approach were synthesized. The grown products were anchored on graphene oxide (GO) sheets via a simple ultrasonication technique to fabricate binary nanocomposites. The structural, optical, and morphological properties of as-synthesized samples were studied by XRD, FTIR, Raman, EDX, UV-Visible, PL, and FE-SEM. The charge transferability of graphene oxide-based samples was investigated by EIS. The XRD exhibited the TM doping in SnO2 and the development of GO-based nanocomposite. FTIR data evidenced the existence of the metal-oxygen bonds. Raman spectra presented the optical phonon modes of SnO2 and the existence of oxygen vacancy defects. FE-SEM images demonstrated the anchoring of particles on the GO sheet, and EDX further approved the existence of desired dopants. The integration of SnO2 with TM doping remarkably reduced optical bandgap (3.65-3.10eV), which was further decreased (3.10-2.99eV) by making composite with GO. The photodegradation results exhibited that GO-based nanocomposites have the higher potential to degrade synthetic dyes (methyl red (MR), and methyl orange (MO) and SnZnO2/GO have shown superb photocatalytic performance after 80-min sunlight illumination (99.9% MR and 95.0% MO dyes) with the higher rate constant and superior stability up to 6th cycle against MR dye. The grown samples were tested for bacterial disinfection, and SnZnO2/GO sample showed a higher zone of inhibition towards S. aureus and K. pneumoniae bacteria strains. The greater charge transfer rate and lower recombination of charge carriers in GO-based composites were also observed by EIS and PL analysis. Moreover, the present article ascribed that the photocatalytic and antibacterial properties of bare SnO2 could be improved by TM doping and fabricating their composite with GO.

Predicting Selective Sensing Capability of Armchair Graphene Nanoribbon toward Hydrogen Halide Gases: A Density-of-State Analysis

Nonequilibrium Green’s function formalism is used to set the chemiresistor device for analyzing the sensing ability of pristine and metal-doped (Al, Fe and Mn) armchair graphene nanoribbons (AGNRs) for the detection of hydrogen halide gases — HF, HCl and HBr. Metal doping is found to enhance the adsorptive strength and sensing ability of the ribbon. On Al-AGNR, all three halide gases follow dissociative chemisorption while on Fe-AGNR and Mn-AGNR, these gases adsorb nondissociatively. The computed current–voltage characteristics indicate selective response of Mn-AGNR toward HF and of Fe-AGNR toward HBr. The origin of this selectivity has been discussed in terms of difference in the density-of-state profiles of the studied AGNR systems.