@article{qiao_liu_gao_huang_2019, title={Graphene oxide model with desirable structural and chemical properties}, volume={143}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2018.11.063}, abstractNote={Due to unique chemical, electrical and optical properties, graphene oxide has been widely used as a promising candidate for many applications. Theoretical GO models developed so far present a good description of its chemical structure. However, when it comes to the structural properties, such as the size and distribution of vacancy defects, the curvature (or roughness), there exist significant gaps between computational models and experimentally synthesized GO materials. In this work, we carry out reactive molecular dynamics simulations and use experimental characteristics to fine tune theoretical GO models. Attentions have been paid to the vacancy defects, the distribution and hybridization of carbon atoms, and the overall C/O ratio of GO. The GO models proposed in this work have been significantly improved to represent quantitative structural details of GO materials synthesized via the modified Hummers method. The temperature-programmed protocol and the computational post analyses of Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, vacancy size and curvature distribution, are of general interest to a broad audience working on GO structures from other synthesis methods and other two-dimensional materials and their composites.}, journal={CARBON}, author={Qiao, Qi and Liu, Chang and Gao, Wei and Huang, Liangliang}, year={2019}, month={Mar}, pages={566–577} }
 @article{hu_huang_zhao_liu_gubbins_2016, title={Effect of confinement in nano-porous materials on the solubility of a supercritical gas}, volume={114}, ISSN={0026-8976 1362-3028}, url={http://dx.doi.org/10.1080/00268976.2016.1229871}, DOI={10.1080/00268976.2016.1229871}, abstractNote={ABSTRACT By combining Gibbs Ensemble Monte Carlo simulations and density functional theory, we investigate the influence of confinement in a slit-shaped carbon pore on the solubility of a supercritical solute gas in a liquid solvent. In the cases studied here, competing adsorption of the solvent and solute determines whether the solubility is enhanced or suppressed for larger pores. We find that the solubility in the confined system is strongly dependent on pore width, and that molecular packing effects are important for small pore widths. In addition, the solubility decreases on increase in the temperature, as for the bulk mixture, but the rate of decrease is greater in the pore due to a decrease in the partial molar enthalpy of the solute in the pore; this effect becomes greater as pore width is decreased. The solubility is increased on increasing the bulk pressure of the gas in equilibrium with the pore, and obeys Henry's law at lower pressures. However, the Henry constant differs significantly from that for the bulk mixture, and the range of pressure over which Henry's law applies is reduced relative to that for the bulk mixture. The latter observation indicates that solute–solute interactions become more important in the pore than for the bulk at a given bulk pressure. Finally, we note that different authors use different definitions of the solubility in pores, leading to some confusion over the reported phenomenon of ‘oversolubility’. We recommend that solubility be defined as the overall mole fraction of solute in the pores, since it takes into account the increase in density of the solvent in the pores, and avoids ambiguity in the definition of the pore volume.}, number={22}, journal={Molecular Physics}, publisher={Informa UK Limited}, author={Hu, Yaofeng and Huang, Liangliang and Zhao, Shuangliang and Liu, Honglai and Gubbins, Keith E.}, year={2016}, month={Sep}, pages={3294–3306} }
 @article{huang_seredych_bandosz_van duin_lu_gubbins_2013, title={Controllable atomistic graphene oxide model and its application in hydrogen sulfide removal}, volume={139}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.4832039}, DOI={10.1063/1.4832039}, abstractNote={The determination of an atomistic graphene oxide (GO) model has been challenging due to the structural dependence on different synthesis methods. In this work we combine temperature-programmed molecular dynamics simulation techniques and the ReaxFF reactive force field to generate realistic atomistic GO structures. By grafting a mixture of epoxy and hydroxyl groups to the basal graphene surface and fine-tuning their initial concentrations, we produce in a controllable manner the GO structures with different functional groups and defects. The models agree with structural experimental data and with other ab initio quantum calculations. Using the generated atomistic models, we perform reactive adsorption calculations for H2S and H2O/H2S mixtures on GO materials and compare the results with experiment. We find that H2S molecules dissociate on the carbonyl functional groups, and H2O, CO2, and CO molecules are released as reaction products from the GO surface. The calculation reveals that for the H2O/H2S mixtures, H2O molecules are preferentially adsorbed to the carbonyl sites and block the potential active sites for H2S decomposition. The calculation agrees well with the experiments. The methodology and the procedure applied in this work open a new door to the theoretical studies of GO and can be extended to the research on other amorphous materials.}, number={19}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Huang, Liangliang and Seredych, Mykola and Bandosz, Teresa J. and van Duin, Adri C. T. and Lu, Xiaohua and Gubbins, Keith E.}, year={2013}, month={Nov}, pages={194707} }
 @article{huang_bandosz_joshi_duin_gubbins_2013, title={Reactive adsorption of ammonia and ammonia/water on CuBTC metal-organic framework: A ReaxFF molecular dynamics simulation}, volume={138}, ISSN={["1089-7690"]}, DOI={10.1063/1.4774332}, abstractNote={We report ReaxFF molecular dynamics simulations for reactive adsorption of NH3 on dehydrated CuBTC metal-organic framework. If the temperature is moderate (up to 125 °C), the dehydrated CuBTC demonstrates a good hydrostatic stability for water concentrations up to 4.0 molecules per copper site. However, if the temperature increases to 550 K, the dehydrated CuBTC will collapse even at a small water concentration, 1.0 H2O molecule per copper site. When NH3 molecules are adsorbed in the channel and micropores of CuBTC, they prefer to chemisorb to the copper sites rather than forming a dimer with another NH3 molecule. The formation of equimolar Cu2(NH2)4 and (NH4)3BTC structures is observed at 348 K, which is in good agreement with previous experimental findings. The dehydrated CuBTC framework is partially collapsed upon NH3 adsorption, while the Cu–Cu dimer structure remains stable under the investigated conditions. Further calculations reveal that the stability of CuBTC is related to the ammonia concentration. The critical NH3 concentration after which the dehydrated CuBTC starts to collapse is determined to be 1.0 NH3 molecule per copper site. Depending on whether NH3 concentration is below or above the critical value, the dehydrated CuBTC can be stable to a higher temperature, 378 K, or can collapse at a lower temperature, 250 K. H2O/NH3 mixtures have also been studied, and we find that although water molecules do not demonstrate a strong interaction with the copper sites of CuBTC, the existence of water molecules can substantially prevent ammonia from interacting with CuBTC, and thus reduce the amount of chemisorbed NH3 molecules on CuBTC and stabilize the CuBTC framework to some extent.}, number={3}, journal={JOURNAL OF CHEMICAL PHYSICS}, author={Huang, Liangliang and Bandosz, Teresa and Joshi, Kaushik L. and Duin, Adri C. T. and Gubbins, Keith E.}, year={2013}, month={Jan} }
 @article{huang_joshi_duin_bandosz_gubbins_2012, title={ReaxFF molecular dynamics simulation of thermal stability of a Cu3(BTC)2 metal–organic framework}, volume={14}, ISSN={1463-9076 1463-9084}, url={http://dx.doi.org/10.1039/C2CP41511A}, DOI={10.1039/c2cp41511a}, abstractNote={The thermal stability of a dehydrated Cu(3)(BTC)(2) (copper(II) benzene 1,3,5-tricarboxylate) metal-organic framework was studied by molecular dynamics simulation with a ReaxFF reactive force field. The results show that Cu(3)(BTC)(2) is thermally stable up to 565 K. When the temperature increases between 600 K and 700 K, the framework starts to partially collapse. The RDF analysis shows that the long range correlations between Cu dimers disappear, indicating the loss of the main channels of Cu(3)(BTC)(2). When the temperature is above 800 K, we find the decomposition of the Cu(3)(BTC)(2) framework. CO is the major product, and we also observe the release of CO(2), O(2), 1,3,5-benzenetricarboxylate (C(6)H(3)(CO(2))(3), BTC) and glassy carbon. The Cu dimer is stable up to 1100 K, but we find the formation of new copper oxide clusters at 1100 K. These results are consistent with experimental findings, and provide valuable information for future theoretical investigations of Cu(3)(BTC)(2) and its application in adsorption, separation and catalytic processes.}, number={32}, journal={Physical Chemistry Chemical Physics}, publisher={Royal Society of Chemistry (RSC)}, author={Huang, Liangliang and Joshi, Kaushik L. and Duin, Adri C. T. van and Bandosz, Teresa J. and Gubbins, Keith E.}, year={2012}, pages={11327} }
 @article{jazdzewska_sliwinska-bartkowiak_beskrovnyy_vasilovskiy_ting_chan_huang_gubbins_2011, title={Novel ice structures in carbon nanopores: pressure enhancement effect of confinement}, volume={13}, ISSN={["1463-9084"]}, DOI={10.1039/c0cp02797a}, abstractNote={We report experimental results on the structure and melting behavior of ice confined in multi-walled carbon nanotubes and ordered mesoporous carbon CMK-3, which is the carbon replica of a SBA-15 silica template. The silica template has cylindrical mesopores with micropores connecting the walls of neighboring mesopores. The structure of the carbon replica material CMK-3 consists of carbon rods connected by smaller side-branches, with quasi-cylindrical mesopores of average pore size 4.9 nm and micropores of 0.6 nm. Neutron diffraction and differential scanning calorimetry have been used to determine the structure of the confined ice and the solid-liquid transition temperature. The results are compared with the behavior of water in multi-walled carbon nanotubes of inner diameters of 2.4 nm and 4 nm studied by the same methods. For D(2)O in CMK-3 we find evidence of the existence of nanocrystals of cubic ice and ice IX; the diffraction results also suggest the presence of ice VIII, although this is less conclusive. We find evidence of cubic ice in the case of the carbon nanotubes. For bulk water these crystal forms only occur at temperatures below 170 K in the case of cubic ice, and at pressures of hundreds or thousands of MPa in the case of ice VIII and IX. These phases appear to be stabilized by the confinement.}, number={19}, journal={PHYSICAL CHEMISTRY CHEMICAL PHYSICS}, author={Jazdzewska, Monika and Sliwinska-Bartkowiak, Malgorzata M. and Beskrovnyy, Anatoly I. and Vasilovskiy, Sergey G. and Ting, Siu-Wa and Chan, Kwong-Yu and Huang, Liangliang and Gubbins, Keith E.}, year={2011}, pages={9008–9013} }
 @article{petit_huang_jagiello_kenvin_gubbins_bandosz_2011, title={Toward Understanding Reactive Adsorption of Ammonia on Cu-MOF/Graphite Oxide Nanocomposites}, volume={27}, ISSN={["0743-7463"]}, DOI={10.1021/la202924y}, abstractNote={The adsorption of ammonia on HKUST-1 (a metal-organic framework, MOF) and HKUST-1/graphite oxide (GO) composites was investigated in two different experimental conditions. From the isotherms, the isosteric heats of adsorption were calculated from the Clausius-Clapeyron equation following the virial approach. The results on HKUST-1 were compared with those obtained using molecular simulation studies. All materials exhibit higher ammonia adsorption capacities than those reported in the literature. The ammonia adsorption on the composites is higher than that measured separately on the MOF component and on GO. The strong adsorption of ammonia caused by chemical interactions on different adsorption sites is evidenced by the trends in the isosteric heats of adsorption. The molecular simulations conducted on HKUST-1 support the trends observed experimentally. In particular, the strong chemisorption of ammonia on the metallic centers of HKUST-1 is confirmed. Nevertheless, higher adsorption capacities are predicted compared with the experimental results. This discrepancy is mainly assigned to the partial collapse of the MOF structure upon exposure to ammonia, which is not accounted for in the simulation study.}, number={21}, journal={LANGMUIR}, author={Petit, Camille and Huang, Liangliang and Jagiello, Jacek and Kenvin, Jeffrey and Gubbins, Keith E. and Bandosz, Teresa J.}, year={2011}, month={Nov}, pages={13043–13051} }
 @article{sliwinska-bartkowiak_jazdzewska_gubbins_huang_2010, title={Melting Behavior of Bromobenzene within Carbon Nanotubes}, volume={55}, ISSN={["0021-9568"]}, DOI={10.1021/je1002576}, abstractNote={We report experimental results on the melting behavior of a dipolar substance, bromobenzene, adsorbed in multiwalled carbon nanotubes (MWNTs) of (2.4, 4.0, and 10) nm inner diameter. Dielectric relaxation spectroscopy (DRS) and differential scanning calorimetry (DSC) methods have been used to show a solid−liquid transition of confined C6H5Br. The C6H5Br melting point in pores has been found to increase with decreasing pore diameter. This result is in qualitative agreement with that obtained in molecular simulation for CCl4 in similar MWNTs, where the adsorbate−wall interactions are strong compared to the adsorbate−adsorbate interactions (see Jazdzewska et al., Phys. Chem. Chem. Phys. 2005, 7, 3884−3887).}, number={10}, journal={JOURNAL OF CHEMICAL AND ENGINEERING DATA}, author={Sliwinska-Bartkowiak, Malgorzata and Jazdzewska, Monika and Gubbins, Keith E. and Huang, Liangliang}, year={2010}, month={Oct}, pages={4183–4189} }