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Role of oxygen vacancy inducer for graphene in graphene-containing anodes

《化学科学与工程前沿(英文)》 2023年 第17卷 第3期   页码 326-333 doi: 10.1007/s11705-022-2213-8

摘要: Currently, graphene is only considered as a conductive additive and expansion inhibitor in oxides/graphene composite anodes. In this study, a new graphene role (oxygen vacancy inducer) in graphene/oxides composites anodes, which are treated at high-temperature, is proposed and verified using experiments and density functional theory calculations. During high-temperature processing, graphene forms carbon vacancies due to increased thermal vibration, and the carbon vacancies capture oxygen atoms, facilitating the formation of oxygen vacancies in oxides. Moreover, the induced oxygen vacancy concentrations can be regulated by sintering temperatures, and the behavior is unaffected by oxide crystal structures (crystalline and amorphous) and morphology (size and shape). According to density functional theory calculations and electrochemical measurements, the oxygen vacancies enhance the lithium-ion storage performance. The findings can result in a better understanding of graphene’s roles in graphene/oxide composite anodes, and provide a new method for designing high-performance oxide anodes.

关键词: oxide     oxygen vacancy     graphene     anode     density functional theory calculation    

Ammonia adsorption on graphene and graphene oxide: a first-principles study

Yue PENG, Junhua LI

《环境科学与工程前沿(英文)》 2013年 第7卷 第3期   页码 403-411 doi: 10.1007/s11783-013-0491-6

摘要: Motivated by the recent realization of graphene sensor to detect gas molecules that are harmful to the environment, the ammonia adsorption on graphene or graphene oxide (GO) was investigated using first-principles calculation. The optimal adsorption and orientation of the NH molecules on the graphene surfaces were determined, and the adsorption energies ( ) as well as the Mulliken charge transfers of NH were calculated. The for the graphene are small and seem to be independent of the sites and orientations. The surface epoxy or hydroxyl groups can promote the adsorption of NH on the GO; the enhancement of the for the hydroxyl groups is greater than that for the epoxy groups on the surface. The charge transfers from the molecule to the surfaces also exhibit the same trend. The Br?nsted acid sites and Lewis acid sites could stably exist on the GO with surface hydroxyl groups and on the basal, respectively.

关键词: graphene oxide     first-principles calculations     NH3 adsorption    

Mechanical properties and microstructure of multilayer graphene oxide cement mortar

《结构与土木工程前沿(英文)》 2021年 第15卷 第4期   页码 1058-1070 doi: 10.1007/s11709-021-0747-3

摘要: This study reports on the effects of multilayer graphene oxide (MGO) on compressive strength, flexural strength, and microstructure of cement mortar. The cement mortar was prepared with type P. II. 52.5 Portland cement, standard sand, and MGO. Four mixes were prepared with inclusion of MGO (0%, 0.02%, 0.04%, and 0.06% by weight of cement). The testing result shows that the compressive of GO-cement mortar increased by 4.84%–13.42%, and the flexural strength increased by 4.37%–8.28% at 3 d. GO-cement mortar’s compressive strength and flexural strength at 7 d increased by 3.84%–12.08% and 2.54%–13.43%, respectively. MGO made little contribution to the increases of compressive strength and flexural strength of cement mortar at 28 d. The results of X-ray diffraction (XRD), scanning electron microscope (SEM), and nitrogen (N2) adsorption/desorption tests show that the types of hydration products and crystal grain size did not change after adding MGO. Still, it can help to improve the microstructure of the cement mortar via regulating hydration products and can provide more condensed cores to accelerate hydration. Furthermore, the regulating action of MGO for the microstructure of cement mortar at an early age was better than that at 28 d.

关键词: graphene oxide     cement     mortar     mechanical properties     microstructure    

Mechanism of ethanol/water reverse separation through a functional graphene membrane: a molecular simulation

《化学科学与工程前沿(英文)》 2023年 第17卷 第3期   页码 347-357 doi: 10.1007/s11705-022-2246-z

摘要: Reverse-selective membranes have attracted considerable interest for bioethanol production. However, to date, the reverse-separation performance of ethanol/water is poor and the separation mechanism is unclear. Graphene-based membranes with tunable apertures and functional groups have shown substantial potential for use in molecular separation. Using molecular dynamics simulations, for the first time, we reveal two-way selectivity in ethanol/water separation through functional graphene membranes. Pristine graphene (PG) exhibits reverse-selective behavior with higher ethanol fluxes than water, resulting from the preferential adsorption for ethanol. Color flow mappings show that this ethanol-permselective process is initiated by the presence of ethanol-enriched and water-barren pores; this has not been reported in previous studies. In contrast, water molecules are preferred for hydroxylated graphene membranes because of the synergistic effects of molecular sieving and functional-group attraction. A simulation of the operando condition shows that the PG membrane with an aperture size of 3.8 Å achieves good separation performance, with an ethanol/water separation factor of 34 and a flux value of 69.3 kg∙m‒2∙h‒1∙bar‒1. This study provides new insights into the reverse-selective mechanism of porous graphene membranes and a new avenue for efficient biofuel production.

关键词: reverse separation     graphene membrane     ethanol/water separation     molecular simulation    

Effect of graphene and its derivatives on thermo-mechanical properties of phase change materials and

《能源前沿(英文)》 2022年 第16卷 第2期   页码 150-186 doi: 10.1007/s11708-021-0795-3

摘要: Phase change materials (PCMs) play a leading role in overcoming the growing need of advanced thermal management for the storage and release of thermal energy which is to be used for different solar applications. However, the effectiveness of PCMs is greatly affected by their poor thermal conductivity. Therefore, in the present review the progress made in deploying the graphene (Gr) in PCMs in the last decade for providing the solution to the aforementioned inadequacy is presented and discussed in detail. Gr and its derivatives ((Gr oxide (GO), Gr aerogel (GA) and Gr nanoplatelets (GNPs)) based PCMs can improve the thermal conductivity and shape stability, which may be attributed to the extra ordinary thermo-physical properties of Gr. Moreover, it is expected from this review that the advantages and disadvantages of using Gr nanoparticles provide a deep insight and help the researchers in finding out the exact basic properties and finally the applications of Gr can be enhanced.

关键词: phase change materials (PCMs)     graphene     thermal conductivity     characterization    

Nitrogen-doped graphene approach to enhance the performance of a membraneless enzymatic biofuel cell

Alireza AHMADIAN YAZDI, Jie XU

《能源前沿(英文)》 2018年 第12卷 第2期   页码 233-238 doi: 10.1007/s11708-018-0529-3

摘要: Heteroatom-doping of pristine graphene is an effective route for tailoring new characteristics in terms of catalytic performance which opens up potentials for new applications in energy conversion and storage devices. Nitrogen-doped graphene (N-graphene), for instance, has shown excellent performance in many electrochemical systems involving oxygen reduction reaction (ORR), and more recently glucose oxidation. Owing to the excellent sensitivity of N-graphene, the development of highly sensitive and fast-response enzymatic biosensors is made possible. However, a question that needs to be addressed is whether or not improving the anodic response to glucose detection leads to a higher overall performance of enzymatic biofuel cell (eBFC). Thus, here we first synthesized N-graphene via a catalyst-free single-step thermal process, and made use of it as the biocatalyst support in a membraneless eBFC to identify its role in altering the performance characteristics. Our findings demonstrate that the electron accepting nitrogen sites in the graphene structure enhances the electron transfer efficiency between the mediator (redox polymer), redox active site of the enzymes, and electrode surface. Moreover, the best performance in terms of power output and current density of eBFCs was observed when the bioanode was modified with highly doped N-graphene.

关键词: enzymatic fuel cell     nitrogen-doped graphene     reduced graphene oxide     catalyst-free synthesis    

Enhanced permeability and biofouling mitigation of forward osmosis membranes via grafting graphene quantum

《化学科学与工程前沿(英文)》 2023年 第17卷 第10期   页码 1470-1483 doi: 10.1007/s11705-023-2329-5

摘要: In this paper, graphene oxide quantum dots with amino groups (NH2-GOQDs) were tailored to the surface of a thin-film composite (TFC) membrane surface for optimizing forward osmosis (FO) membrane performance using the amide coupling reaction. The results jointly demonstrated hydrophilicity and surface roughness of the membrane enhanced after grafting NH2-GOQDs, leading to the optimized affinity and the contact area between the membrane and water molecules. Therefore, grafting of the membrane with a concentration of 100 ppm (TFC-100) exhibited excellent permeability performance (58.32 L·m–2·h–1) compared with TFC membrane (16.94 L·m–2·h–1). In the evaluation of static antibacterial properties of membranes, TFC-100 membrane destroyed the cell morphology of Escherichia coli (E. coli) and reduced the degree of bacterial adsorption. In the dynamic biofouling experiment, TFC-100 membrane showed a lower flux decline than TFC membrane. After the physical cleaning, the flux of TFC-100 membrane could recover to 96% of the initial flux, which was notably better than that of TFC membrane (63%). Additionally, the extended Derjaguin–Landau–Verwey–Overbeek analysis of the affinity between pollutants and membrane surface verified that NH2-GOQDs alleviates E. coli contamination of membrane. This work highlights the potential applications of NH2-GOQDs for optimizing permeability and biofouling mitigation of FO membranes.

关键词: forward osmosis membrane     graphene oxide quantum dots     graft modification     anti-fouling membrane     XDLVO theory    

Electrocatalytic debromination of BDE-47 at palladized graphene electrode

Hongtao YU, Bin MA, Shuo CHEN, Qian ZHAO, Xie QUAN, Shahzad AFZAL

《环境科学与工程前沿(英文)》 2014年 第8卷 第2期   页码 180-187 doi: 10.1007/s11783-013-0552-x

摘要: Graphene electrodes (Ti/Gr) were prepared by depositing Gr sheets on Ti substrate, followed by an annealing process for enhancing the adhesion strength. Electrochemical impedance spectroscopies and X-ray diffraction patterns displayed that the electrochemical behavior of Ti/Gr electrodes can be improved due to the generation of TiO layer at Ti-Gr interface during the annealing process. The palladized Gr electrodes (Ti/Gr/Pd) were prepared by electrochemical depositing Pd nanoparticles on Gr sheets. The debromination ability of Ti/Gr/Pd electrodes was investigated using BDE-47 as a target pollutant with various bias potentials. The results indicated that the BDE-47 degradation rates on Ti/Gr/Pd electrodes increased with the negative bias potentials from 0 V to -0.5 V (vs. SCE). Almost all of the BDE-47 was removed in the debromination reaction on the Ti/Gr/Pd electrode at -0.5 V for 3 h, and the main product was diphenyl ethers, meaning it is promising to debrominate completely using the Ti/Gr/Pd electrode. Although the debromination rate was slightly slower at -0.3 V than that under -0.5 V, the current efficiency at -0.3 V was higher, because the electrical current acted mostly on BDE-47 rather than on water.

关键词: graphene     palladium     debromination     BDE-47    

Preparation, with graphene, of novel biomimetic self-healing microcapsules with high thermal stability

《结构与土木工程前沿(英文)》 2023年 第17卷 第8期   页码 1188-1198 doi: 10.1007/s11709-023-0027-5

摘要: This paper reports a comparative study of microcapsules with enhanced thermal stability and electrical conductivity inspired by the bionic thermal insulation of birds’ feathers for self-healing aged asphalt. The work is based on an in situ polymerization with composite shell components of graphene and hexamethoxymethylmelamine resin. By using graphene, microcapsules with rough surfaces are achieved, improving the interface between microcapsules and asphalt. In addition, the microcapsules’ initial thermal decomposition temperature is appropriately high, so that the stability of the microcapsule in the asphalt highway system is protected. The proportion of graphene in the microcapsule shell can regulate the microcapsule’s heat resistance because graphene modifies the shell’s structural makeup. Additionally, the microcapsules’ electrical conductivity is relatively high. The self-healing capability of bitumen sharply increases, providing benefit to the effect of microcapsules on the properties of aged asphalt.

关键词: graphene     microcapsule     bitumen     heat insulation     conductivity    

Hydrophilic/underwater superoleophobic graphene oxide membrane intercalated by TiO

Zhichao Wu, Chang Zhang, Kaiming Peng, Qiaoying Wang, Zhiwei Wang

《环境科学与工程前沿(英文)》 2018年 第12卷 第3期 doi: 10.1007/s11783-018-1042-y

摘要: Membrane technology for oil/water separation has received increasing attention in recent years. In this study, the hydrophilic/underwater superoleophobic membrane with enhanced water permeability and antifouling ability were fabricated by synergistically assembling graphene oxide(GO) nanosheets and titanium dioxide (TiO ) nanotubes for oil/water separation. GO/TiO membrane exhibits hydrophilic and underwater superoleophobic properties with water contact angle of 62° and under water oil contact angle of 162.8°. GO/TiO membrane shows greater water permeability with the water flux up to 531 L/(m ·h·bar), which was more than 5 times that of the pristine GO membrane. Moreover, GO/TiO membrane had excellent oil/water separation efficiency and anti-oil-fouling capability, as oil residual in filtrate after separation was below 5 mg/L and flux recovery ratios were over 80%.The results indicate that the intercalation of TiO nanotubes into adjacent GO nanosheets enlarged the channel structure and modified surface topography of the obtained GO/TiO membranes, which improved the hydrophilicity, permeability and anti-oil-fouling ability of the membranes, enlightening the great prospects of GO/TiO membrane in oil-water treatment.

关键词: Hydrophilic     Superoleophobic     Graphene oxide     Membrane     Titanium dioxide nanotubes     Oil-water separation    

Synthesis of hydrophobic carbon nanotubes/reduced graphene oxide composite films by flash light irradiation

Kai Wang, Jinbo Pang, Liwei Li, Shengzhe Zhou, Yuhao Li, Tiezhu Zhang

《化学科学与工程前沿(英文)》 2018年 第12卷 第3期   页码 376-382 doi: 10.1007/s11705-018-1705-z

摘要:

Carbon nanotubes/graphene composites have superior mechanical, electrical and electrochemistry properties with carbon nanotubes as a hydrophobicity boosting agent. Their extraordinary hydrophobic performance is highly suitable for electrode applications in lithium ion batteries and supercapacitors which often employ organic electrolytes. Also the hydrophobic features enable the oil enrichment for the crude oil separation from seawater. The ever reported synthesis routes towards such a composite either involve complicated multi-step reactions, e.g., chemical vapor depositions, or lead to insufficient extrusion of carbon nanotubes in the chemical reductions of graphene oxide, e.g., fully embedding between the compact graphene oxide sheets. As a consequence, the formation of standalone carbon nanotubes over graphene sheets remains of high interests. Herein we use the facile flash light irradiation method to induce the reduction of graphene oxides in the presence of carbon nanotubes. Photographs, micrographs, X-ray diffraction, infrared spectroscopy and thermogravimetric analysis all indicate that graphene oxides has been reduced. And the contact angle tests confirm the excellent hydrophobic performances of the synthesized carbon nanotube/reduced graphene oxide composite films. This one-step treatment represents a straightforward and high efficiency way for the reduction of carbon nanotubes/graphene oxides composites.

关键词: carbon nanotubes     graphene composite     flash irradiation method     reduced graphene oxide     contact angles    

Platinum on nitrogen doped graphene and tungsten carbide supports for ammonia electro-oxidation reaction

《化学科学与工程前沿(英文)》 2022年 第16卷 第6期   页码 930-938 doi: 10.1007/s11705-021-2130-2

摘要: Ammonia electrooxidation reaction involving multistep electron-proton transfer is a significant reaction for fuel cells, hydrogen production and understanding nitrogen cycle. Platinum has been established as the best electrocatalyst for ammonia oxidation in aqueous alkaline media. In this study, Pt/nitrogen-doped graphene (NDG) and Pt/tungsten monocarbide (WC)/NDG are synthesized by a wet chemistry method and their ammonia oxidation activities are compared to commercial Pt/C. Pt/NDG exhibits a specific activity of 0.472 mA∙cm–2, which is 44% higher than commercial Pt/C, thus establishing NDG as a more effective support than carbon black. Moreover, it is demonstrated that WC as a support also impacts the activity with further 30% increase in comparison to NDG. Surface modification with Ir resulted in the best electrocatalytic activity with Pt-Ir/WC/NDG having almost thrice the current density of commercial Pt/C. This work adds insights regarding the role of NDG and WC as efficient supports along with significant impact of Ir surface modification.

关键词: Ammonia electro-oxidation reaction     electrocatalyst supports     platinum     nitrogen doped graphene     tungsten carbide    

Plasma-enabled healing of graphene nano-platelets layer

Xiuqi Fang, Carles Corbella, Denis B. Zolotukhin, Michael Keidar

《化学科学与工程前沿(英文)》 2019年 第13卷 第2期   页码 350-359 doi: 10.1007/s11705-018-1787-7

摘要: Graphene platelet networks (GPNs) were deposited onto silicon substrates by means of anodic arc discharge ignited between two graphite electrodes. Substrate temperature and pressure of helium atmosphere were optimized for the production of the carbon nanomaterials. The samples were modified or destroyed with different methods to mimic typical environments responsible of severe surface degradation. The emulated conditions were performed by four surface treatments, namely thermal oxidation, substrate overheating, exposition to glow discharge, and metal coating due to arc plasma. In the next step, the samples were regenerated on the same substrates with identical deposition technique. Damaging and re-growth of GPN samples were systematically characterized by scanning electron microscopy and Raman spectroscopy. The full regeneration of the structural and morphological properties of the samples has proven that this healing method by arc plasma is adequate for restoring the functionality of 2D nanostructures exposed to harsh environments.

关键词: graphene platelet networks     anodic arc discharge     plasma healing     scanning electron microscopy     Raman spectroscopy    

Biomimetic mineralization and cytocompatibility of nanorod hydroxyapatite/graphene oxide composites

Peizhen Duan, Juan Shen, Guohong Zou, Xu Xia, Bo Jin

《化学科学与工程前沿(英文)》 2018年 第12卷 第4期   页码 798-805 doi: 10.1007/s11705-018-1708-9

摘要: Nanorod hydroxyapatite (NRHA)/graphene oxide (GO) composites with weight ratios of 0.4, 1.5, and 5 have been fabricated by a facile ultrasonic-assisted method at room temperature and atmospheric pressure. The chemical structure properties and morphology of the composites were characterized by field emission source scanning electron microscope, X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. The results indicate that the NNRHA/GO composites have an irregular surface with different degree wrinkles and are stable, and NRHA are well combined with GO. In addition, the biomimetic mineralization mechanism of hydroxyapatite on the NNRHA/GO composites in simulated body fluid (SBF) is presented. The presence of a bone-like apatite layer on the composite surface indicate that the NNRHA/GO composites facilitate the nucleation and growth of hydroxyapatite crystals in SBF for biomimetic mineralization. Moreover, the NNRHA-1.5/GO composite and pure GO were cultured with MC3T3-E1 cells to investigate the proliferation and adhesion of cells. In vitro cytocompatibility evaluation demonstrated that the NNRHA/GO composite can act as a good template for the growth and adhesion of cells. Therefore, the NNRHA/GO composite could be applied as a GO-based, free-template, non-toxic, and bioactive composite to substitute for a damaged or defect bone.

关键词: hydroxyapatite     graphene oxide     biomimetic mineralization     cytocompatibility    

Application of extreme gradient boosting in predicting the viscoelastic characteristics of graphene oxide

《结构与土木工程前沿(英文)》 2024年 第18卷 第6期   页码 899-917 doi: 10.1007/s11709-024-1025-y

摘要: Complex modulus (G*) is one of the important criteria for asphalt classification according to AASHTO M320-10, and is often used to predict the linear viscoelastic behavior of asphalt binders. In addition, phase angle (φ) characterizes the deformation resilience of asphalt and is used to assess the ratio between the viscous and elastic components. It is thus important to quickly and accurately estimate these two indicators. The purpose of this investigation is to construct an extreme gradient boosting (XGB) model to predict G* and φ of graphene oxide (GO) modified asphalt at medium and high temperatures. Two data sets are gathered from previously published experiments, consisting of 357 samples for G* and 339 samples for φ, and these are used to develop the XGB model using nine inputs representing the asphalt binder components. The findings show that XGB is an excellent predictor of G* and φ of GO-modified asphalt, evaluated by the coefficient of determination R2 (R2 = 0.990 and 0.9903 for G* and φ, respectively) and root mean square error (RMSE = 31.499 and 1.08 for G* and φ, respectively). In addition, the model’s performance is compared with experimental results and five other machine learning (ML) models to highlight its accuracy. In the final step, the Shapley additive explanations (SHAP) value analysis is conducted to assess the impact of each input and the correlation between pairs of important features on asphalt’s two physical properties.

关键词: complex modulus     phase angle     graphene oxide     asphalt     extreme gradient boosting     machine learning    

标题 作者 时间 类型 操作

Role of oxygen vacancy inducer for graphene in graphene-containing anodes

期刊论文

Ammonia adsorption on graphene and graphene oxide: a first-principles study

Yue PENG, Junhua LI

期刊论文

Mechanical properties and microstructure of multilayer graphene oxide cement mortar

期刊论文

Mechanism of ethanol/water reverse separation through a functional graphene membrane: a molecular simulation

期刊论文

Effect of graphene and its derivatives on thermo-mechanical properties of phase change materials and

期刊论文

Nitrogen-doped graphene approach to enhance the performance of a membraneless enzymatic biofuel cell

Alireza AHMADIAN YAZDI, Jie XU

期刊论文

Enhanced permeability and biofouling mitigation of forward osmosis membranes via grafting graphene quantum

期刊论文

Electrocatalytic debromination of BDE-47 at palladized graphene electrode

Hongtao YU, Bin MA, Shuo CHEN, Qian ZHAO, Xie QUAN, Shahzad AFZAL

期刊论文

Preparation, with graphene, of novel biomimetic self-healing microcapsules with high thermal stability

期刊论文

Hydrophilic/underwater superoleophobic graphene oxide membrane intercalated by TiO

Zhichao Wu, Chang Zhang, Kaiming Peng, Qiaoying Wang, Zhiwei Wang

期刊论文

Synthesis of hydrophobic carbon nanotubes/reduced graphene oxide composite films by flash light irradiation

Kai Wang, Jinbo Pang, Liwei Li, Shengzhe Zhou, Yuhao Li, Tiezhu Zhang

期刊论文

Platinum on nitrogen doped graphene and tungsten carbide supports for ammonia electro-oxidation reaction

期刊论文

Plasma-enabled healing of graphene nano-platelets layer

Xiuqi Fang, Carles Corbella, Denis B. Zolotukhin, Michael Keidar

期刊论文

Biomimetic mineralization and cytocompatibility of nanorod hydroxyapatite/graphene oxide composites

Peizhen Duan, Juan Shen, Guohong Zou, Xu Xia, Bo Jin

期刊论文

Application of extreme gradient boosting in predicting the viscoelastic characteristics of graphene oxide

期刊论文