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In this study, the effect of cellulose nanofibers (CNF) prepared from carrot slag on the properties of agar biocomposite films is investigated. The composite film was characterized by ultraviolet–visible spectroscopy (UV-Vis), tensile test, fourier transforms infrared (FT-IR) spectroscopy and Transmission electron microscopy (TEM). The transmittance, mechanical properties and chemical structure of the composite film containing different CNF content (0.1, 0.3 and 0.5 phr based on agar) were studied. The UV-Vis showed that the transmittance of the film was decreased with increasing content of CNF. The FT-IR spectrum showed that the generation of hydrogen bonds leads to good interface bonding between Agar and CNF. Moreover, the performance of the bionanocomposite was improved by the addition of CNF. The composite containing 0.3 phr CNF results in a maximum tensile strength of 25.97 MPa. However, the tensile strength of the 0.5 phr CNF containing one is reduced to 24.42 MPa due to the agglomeration of CNF. The TEM shows that the diameter of CNF is 2.5 nm and the length is 18.20 nm. The usage of CNF obtained from carrot slag can not only recycle the waste from food industry, but also can be used as a reinforcing agent for preparing biodegradable composite film. It has potential uses in the development of biodegradable food packaging materials and biomedical applications.

Nowadays, thermal energy production from solid fuels as biomass materials focused on the densified biofuels to overcome the disadvantages of raw biomass as irregular shape, low bulk density, and high moisture content. The quality of biomass pellets is sensitive to the pelletization conditions. Consequently, in this work the impact of the operating parameters as applied pressure, die temperature, and moisture content on the physical properties of solid and hollow pellets as pellet length (Lp), normal volume expansion (Vexp, n), initial and relaxed pellet densities (ρp, i and ρp, rel), moisture content of pellet (Mp), water absorption rate (k), and absorption volume expansion (Vexp, ab) of rice straw (RS) pellets was studied. Furthermore, the synergic effect of these parameters on the pellet properties was evaluated at the optimum conditions. The operating parameters were optimized using a multi-objective optimization approach of response surface method (RSM) based on the predicted significant models that describe the physical properties of the pellets. The optimization results showed that high-quality pellets could be produced at a pressure of 72.76 MPa, temperature of 110°C, and moisture of 7.23% for solid pellets and 81.5 MPa, 109°C, and 7.72% for hollow pellets. Significant individual and interaction effects of all independent parameters on the pellets properties were investigated using statistical analysis results, main plot curves, and 2D interaction contour plots. New four significant empirical dimensionless relationships that correlate the properties of pellets were proposed for calculating ρp, rel, Mp, k, and Vexp, ab directly based on other physical and mechanical properties and indirectly based on the operating parameters through the predicted models for different properties. These relationships can be generalized to any type of pellets that are produced under various operating conditions. Hollow pellets are recommended being used in the industrial sector due to their enhanced heat transfer which resulted from the high surface to volume ratio besides their ease of production at normal operating condition similar to that required for solid pellets.

Biomass pelletization technology overcame the poor utilization and handling properties of loose materials. The quality of pellets is sensitive to the pelletization conditions. In this work the impact of the operating parameters as pressure, temperature, and moisture content on the mechanical characteristics as the compression strength ( $${\sigma }_{max}$$ ) and durability ( $$Du$$ ) and energy consumption for both production ( $${E}_{c,p}$$ ) and ejection ( $${E}_{c,ej}$$ ) of rice straw (RS) pellets was studied. Furthermore, the synergic effect of these parameters on the pellet characteristics was evaluated at the optimum conditions. The operating parameters were optimized using a multi-objective optimization approach of Response Surface Method (RSM) based on the predicted significant models that describe the physical characteristics of the pellets. The optimization results showed that high quality pellets could be produced at a pressure of 68.4 MPa, temperature of 110.0 °C, and moisture of 8.2% for solid pellets and 63.6 MPa, 110.0 °C, and 8.7% for hollow pellets. Significant individual and interaction effects of all independent parameters on the pellets characteristics were investigated using statistical analysis results, main plot curves and 2D interaction contour plots. New significant empirical dimensionless relationships that correlate the characteristics of pellets were proposed. These relationships can be generalized for any type of pellets that produced under various operating conditions. Hollow pellets are recommended to be used in the industrial sector due to their enhanced heat transfer which resulted from the high surface to volume ratio besides their ease production at normal operating condition similar to that required for solid pellets.

Effective grounding is the most important aspect in every electrical installation because it can ensure efficient equipment operation in the event of electrical faults. Measurement data of soil resistivity is used to assess the suitability of the soil for grounding purpose and also to evaluate the structures of the soil. However, the limitation of soil resistivity measurement is various investigations on two‐layer soil structures cannot be performed due to the variation of natural soil structures is limited. Therefore, in this work, modelling of soil resistivity of two‐layer soil structures was proposed using finite element analysis method to estimate the depth of upper layer of non‐homogeneous soil based on the measurement results from Wenner and Schlumberger methods. Also, using the proposed method, the effect of soil resistivity of each layer on the overall two‐layer soil resistivity was investigated. To validate the results obtained from the proposed method, comparison between the FEA results and measured field data was made. It was found that the average error between both results is

Raman spectroscopy, as a rapid, high-precision, and nondestructive tool, can be used for analyzing the samples from gas to solid, from ex situ to in situ, from organic macromolecule to minerals. It...

The evolutions of different types of coke deposition, including amorphous carbon, carbon networks (CNWs) and carbon nanotubes (CNTs), were clarified on Ni-based catalyst during catalytic cracking and reforming of biomass tar. Different from the changing of total coke, the amount of amorphous carbon gradually increased at the decreasing rate, while the amount of graphite carbon (CNWs and CNTs) firstly increased and then decreased after 60min reactions. The formation of amorphous carbon was prior to that of graphite carbon, and it was proved that a part of amorphous carbon converted to graphite carbon. After the 60min reaction, the proportion of graphite carbon and graphitization degree of coke decreased. The graphite carbon underwent the aging process in which the graphite structure would be destroyed to amorphous carbon. In cracking reaction, CNWs was the main type of graphite carbon which encapsulated the Ni particles with graphitic layers. After the addition of steam, the toluene conversion and coke amount remarkably increased in reforming reaction. Plenty of CNTs grew on the surface of catalysts and the amount of CNTs reached the maximum of about 200mg/g-cata at 60min. These research results are important for understanding the formation mechanism of coke and optimization the produced CNTs.

A robust monolith catalyst has been fabricated involving the combination of nanodiamonds (NDs) and mesoporous carbon modified by nitrogen and phosphorus (ND@NMC-xP, x = amount of ammonium biphosphate) on a β-SiC foam. The ND@NMC-0.02 P/SiC monolith catalyst with 0.2 at.% of P elements exhibits an excellent catalytic performance for oxidative dehydrogenation of ethylbenzene (EB), delivering 90.2% selectivity to styrene (ST) up to 32.6% conversion. The specific conversion rate of monolith catalyst based on the unit weight of NDs and mesoporous carbons (25.3 mmol gact. phase−1 h−1) is 3-fold higher than that of unsupported NDs. The role of nitrogen is believed to enhance the density of active sites and thus offering a high EB conversion, whereas the addition of phosphorus inhibits deep oxidation of EB to carbon oxides and therefore for a high selectivity to ST. The monolith catalyst not only contributes a high utilization efficiency of NDs but also mitigates the high pressure drop across the catalytic bed, which is potentially suitable for a real industrial process.

Si nanostructures (Si-NSs) epitaxially grown or adsorbed on Si (111) surface, with various shapes including pit-like, bars, islands, hill-like, diamond-like and double cage, were studied theoretically using density-functional theory (DFT) calculations. The electronic and optical properties of these Si-NSs were calculated, showing that the designed Si-NSs modifications can enhance the optical absorption for Si surface.

Electronic properties of monolayer tellurium (Te) with three proposed atomic configurations under external electric field were investigated through first-principles calculations. The calculated results demonstrate that α-Te and γ-Te have indirect band gaps, whereas β-Te, when no electric field is applied, can be considered as a direct semiconductor. An interesting structural change occurs in α- and γ-phase Te under a specific electric field strength, as does a change in structural chirality. In the presence of a perpendicular electric field, the band gaps can be modified and drawn close to 0 eV at a certain critical electric field strength. Before that, the band gaps of α-Te and γ-Te are nearly constant, while that of β-Te shows a quadratic relationship to electric field strength. These findings not only enrich our understanding of the electronic properties of monolayer tellurium but also show that monolayer tellurium has tremendous potential in nanoscale electronic devices owing to its tunable band gaps.

The formation of highly graphitic phenolic resin chars (GPFCs) during catalytic carbonization at relatively low reaction temperature (1200-1600 °C) using novel Ni-Zn-B alloy catalyst with small amount of addition (5-15%) was systematically studied. Only two kinds of graphites (turbostratic graphite and ordered graphite) can be found in GPFCs after catalytic carbonization with Ni-Zn-B and their proportions were changed with reaction conditions. When Ni-Zn-B was involved at 1200-1600 °C, the phenolic resin char was fully transformed to be graphite, and ordered graphite content increased to 28.42% at 1400 °C, which was also almost twice of ordered graphite content in the char catalyzed by pure Ni. But the order graphite content would decrease due to sintering at higher reaction temperature. The addition of Zn and B can promote nickel-based alloy catalytic action by reducing melt point and accelerating graphitization respectively. It was also found that ordered graphite content could be used as a key evaluation parameter to directly reflect the quality of GPFCs based on detailed characteristics analysis. The model between three reaction conditions (reaction temperature, retention time, catalyst content) and ordered graphite content was built with artificial neural network (ANN), and the prediction accuracy of ANN was high up to 91.48%.

Facile green oxidation methods are always desired to functionalize carbon nanotubes (CNTs) in the production of advanced CNT/epoxy composites. In the present work, an optimized H2O2/H2O/O3 oxidation method was developed, and performances of the H2O2/H2O/O3 oxidized CNT in epoxy matrix were tested and compared with that of the H2O/O3 oxidized CNT and the most commonly used concentrated HNO3 oxidized CNT. The physical and chemical characteristics of the obtained oxidized CNTs were systematically characterized via transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Raman. Mechanical performances of the obtained composites were explored by tensile tests, impact tests, dynamic mechanical analysis (DMA) and fracture toughness tests. It was found that the H2O2/H2O/O3 oxidized CNT exhibited all-around overwhelming advantages over the concentrated HNO3 oxidized CNT on reinforcing the epoxy matrix, while the H2O/O3 oxidized CNT only improved the material strength. Reinforcing mechanisms for the different methods oxidized CNTs were studied and compared. The optimized H2O2/H2O/O3 oxidation method makes scaled production possible, avoids environment pollutions, and holds great potentials to replace the most commonly used concentrated HNO3 oxidation method to oxidize CNT during the preparation of the advanced CNT/epoxy composite.

The electronic structures and optical properties of novel 2D biphenylene and hydrogen-terminated nanoribbons of different widths which are cut from a layer of biphenylene were explored by first-principles calculation. The findings of phonon computations demonstrate such biphenylene is dynamically stable and shows metallic properties. The crystal orbital Hamilton population analysis indicates that the tetra-ring local structure results in an anisotropic mechanical property. For 1D nanoribbons, their band gaps shrink, and a direct-indirect transition occurs in the band gap as the width increases, transforming the nanoribbon to a metallic characteristic at a certain width. This is attributed to the weak coupling between tetra-ring atoms, shrinking the direct band gap at Y point in the Brillouin zone. Finally, the contribution of interband transitions to the dielectric function in 6-, 9-, and 12-armchair biphenylene nanoribbon (ABNR) was identified. The lowest peaks in the imaginary part of the dielectric function e2 spectrum was mainly contributed by a Γ-Γtransition. As the width of ABNR increases, the transitions in the x direction become stronger while the transition strength in the y direction was not significantly altered. This investigation extends understanding of the electronic and optical properties of 2D biphenylene and 1D nanoribbons, which will benefit the practical applications of these materials in optoelectronics and electronics.

Metallic nanostructures exhibit superior catalytic performance for diverse chemical reactions and the in-depth understanding of reaction mechanisms requires versatile characterization methods. Plasmon-enhanced Raman spectroscopy (PERS), including surface-enhanced Raman spectroscopy (SERS), shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), and tip-enhanced Raman spectroscopy (TERS), appears as a powerful technique to characterize the Raman fingerprint information of surface species with high chemical sensitivity and spatial resolution. To expand the range of catalytic reactions studied by PERS, catalytically active metals are integrated with plasmonic metals to produce bifunctional metallic nanostructures. In this minireview, we discuss the recent advances in PERS techniques to probe the chemical reactions catalysed by bifunctional metallic nanostructures. First, we introduce different architectures of these dual-functionality nanostructures. We then highlight the recent works using PERS to investigate important catalytic reactions as well as the electronic and catalytic properties of these nanostructures. Finally, we provide some perspectives for future PERS studies in this field.

Density functional theory (DFT) calculations have been employed to systematically investigate the strain-modulated electronic properties of monolayer tellurium. The results demonstrate that at zero strain γ-phase monolayer tellurium is found to be more energetically favorable than either the α-phase or β-phase which were fabricated through molecular-beam epitaxy. All studied phases are found to exhibit semiconductor characteristics, of which α- and γ-phases possess indirect band gaps whereas β phase is a direct band gap semiconductor. It is also found that the resulting band gap values approach zero at a large strain regime for all systems and the effective mass of electron and hole can be effectively modified by biaxial strain as well. These findings extend the knowledge on two-dimensional tellurium and provide potential applications in electronic devices.

Activity and immobilization of catalysts in liquid-phase reactions seem not to coexist. We report here the excellent activity of an MoOx nanoparticle (NP) catalyst for d-glucose epimerization to d-mannose and the electrical immobilization of NPs in a flow reaction. Prior to that, a green and one-pot method to synthesize the MoOx NPs (3.05 nm) via oxidizing metal Mo by hydrogen peroxide was presented. The NPs overwhelmed the reported catalysts including epimerase for d-glucose epimerization, originating from a strong interaction between the NPs and the reactant that was demonstrated by ex situ and in situ characterizations and theoretical calculations. The electrically charged feature of NPs inspired us to find a convenient way to "immobilize" them inside an activated carbon bed, and thereby, a flow reactor was assembled. The continuous epimerization was run under 24 V for 16 days with an almost unchanged activity, and only 3.2% of total Mo was lost.

We present experimental and theoretical studies of a metamaterial-based plasmonic structure to build a plasmonic-molecular coupling detection system. High molecular sensitivity is realized only when molecules are located in the vicinity of the enhanced field (hot spot region); thus, introducing target molecules in the hot spot region to maximize plasmonic-molecular coupling is crucial to developing the sensing technology. We design a metamaterial consisting of a vertically oriented metal insulator metal (MIM) structure with a 25 nm channel sandwiched between two metal films, which enables the delivery of molecules into the large ravinelike hot spot region, offering an ultrasensitive platform for molecular sensing. This metamaterial is applied to carbon dioxide and butane detection. We design the structure to exhibit resonances at 4033 and 2945 cm

A series of AgIO3 modified BiOI/CoFe2O4 heterojunction photocatalysts synthesized by a solvothermal and subsequent deposition–precipitation method were utilized to remove gaseous Hg0 from simulated flue gas under fluorescent light irradiation. The effects of AgIO3 content, photocatalyst dosage, solution temperature, fluorescent lamp irradiation, pH value, inorganic anions, and SO2 and NO on Hg0 removal performances were investigated in detail. Moreover, the ternary AgIO3–BiOI/CoFe2O4 composites were characterized by XRD, magnetic hysteresis, N2 adsorption–desorption, SEM, TEM, XPS, DRS, ESR, and photocurrent analyses. The results indicated that the AgIO3–BiOI/CoFe2O4 materials possessed enhanced visible-light-driven photocatalytic activities for Hg0 removal, which were much higher than those for AgIO3 and BiOI, and the Hg0 removal efficiency by optimum AgIO3(7%)/BC can reach as high as 99%. The AgIO3 content, solution temperature, FSL irradiation, and SO2 all exhibited significant effects on Hg0 removal. ...

A series of novel ternary Ag2WO4/BiOI/CoFe2O4 hybrids synthesized by a facile modified deposition-precipitation method were utilized to explore their activities for toxic elemental mercury (Hg0) removal under fluorescent light (FSL) irradiation. The as-prepared materials were characterized by various methods and the experimental parameters such as Ag2WO4 content, fluorescent light irradiation, and inorganic anions were investigated in detail. The characterizations revealed that Ag2WO4 and CoFe2O4 were successfully dispersed on the surface of BiOI and heterogeneous hybrid was generated. The separation of electrons and holes (h+) could be efficiently promoted due to the combination of Ag2WO4, BiOI and CoFe2O4 with suitable match of band gaps under FSL irradiation. The experimental results manifested that Ag2WO4 content, fluorescent light irradiation, inorganic carbonate ions and SO2 gas all possessed conspicuous effects on Hg0 removal. Among the heterogeneous photocatalysts, Ag2WO4(0.1)BiOI/CoFe2O4 demonstrated the optimal activity for Hg0 removal and superior stable performance, which also could be easily recovered from the reaction solution by an extra magnet. Superoxide radicals ( O2−) and holes (h+) were confirmed to be the main reactive substances for higher Hg0 removal.

Supported gold nanoparticles with sizes below 5 nm display attractive catalytic activities for heterogeneous reactions, particularly those promoted by secondary metal (e.g., Cu) because of the well-defined synergy between metal compositions. However, the specific atomic structure at interfaces is less interpreted systematically. In this work, various bimetallic Au-CuOx catalysts with specific surface structures were synthesized and explored by aberration-corrected scanning transmission electron microscopy (AC-STEM), temperature-programmed experiments and in situ DRIFT experiments. Results suggest that the atomic structure and interfaces between gold and CuOx are determined by the nucleation behaviors of the nanoparticles and result in subsequently the distinctive ability for CO activation. Bimetallic CuO*/Au sample formatted by gold particles surrounded with CuOx nanoclusters have rough surface with prominently exposed low-coordinated Au step defects. Whereas the bimetallic Au@CuO sample formatted by copp...

The spent SCR catalyst as the hazardous waste would seriously affect the ecological environment and human life. In this study, a new method of spent SCR catalyst harmless treatment was proposed by blending the spent SCR catalyst with coal for combustion. The combustion characteristics of coal blending with spent SCR catalyst, melting solidification characteristics of V/As in spent catalyst, and leaching characteristics of V/As in bottom ash were explored by TG, ICP-MS, XRD, SEM analysis. The results show that the proper amount of spent catalyst blending with coal could promote coal combustion by reducing the ignition and burnout temperature of coal particles due to the catalytic effects of TiO2. The co-combustion of spent SCR catalyst with coal could well solidify the V/As in the bottom ash. In this process, the solidification rate of V decreased but the solidification rate of As increased with the increasing of temperature. Both of V and As solidification rate decreased with the increasing of spent catalyst blending ratios. The leaching concentration and leaching rate of V and As in the bottom ash were lower than the emission standards. The leaching concentration of As and V of the bottom ash significantly decreased due to melting of bottom ash when the temperature reached to 1300 °C. When the blending ration of catalyst blending amount increased, the leaching concentration and leaching rate of V and As increased slightly due to the decreasing of the relative amount of CaO in bottom ash, which played an important roles in the solidification of V and As.

Thermal characteristics and kinetic parameters of rice straw (RS) and sawdust (SD) raw materials were investigated under an oxidizing atmosphere using a non-isothermal thermogravimetric analysis (TGA). The effect of H2O and CO2 on the oxy-steam combustion was studied by performing the TGA experiments using a mixture of (O2/CO2/H2O/N2) at different compositions. Kinetic parameters were determined using a volumetric model (VM), random pore model (RPM), double parallel random pore model (DRPM), mixed volumetric random pore model (MVRPM) and a new proposed double parallel volumetric model (DVM). The good fit between the experimental and modeled data was obtained from the parallel and mixed models results when the fractional conversion was used in these models. While the models’ solutions didn’t fit with the experimental results when they were solved based on the conversion rate. The new proposed DVM model gave the best fit with experimental conversion (α). The ignition delayed at high concentration of H2O due to the highest specific heat of H2O that lowered the temperature of the fuel particles. The activation energy and the frequency factor of RS were lower than that of SD. The char conversion rate of SD exceeded that of RS.

In recent years, some arguments about the existence of medium-range order (MRO) in the Zr-Rh system have been put forward. However, research on the structural features of the Zr-Rh binary alloy at the atomic level is still lacking. This study uses ab initio molecular dynamics simulations to systematically study the local structures of Zr77Rh23 from the liquid to the glassy states. Pair correlation function (PCF), coordination number (CN), Honeycutt–Anderson(HA) index, bond-angle distribution functions, and the Voronoi tessellation method are used to reveal a clear icosahedral-like configuration in the amorphous Zr77Rh23 alloy. It is noteworthy that the splitting in the second peak of the partial PDF implies the existence of a medium range order (MRO) in the Zr77Rh23 system. We obtain the local order in three-dimensional atomic density distributions by using a new atomistic cluster alignment (ACA) method. Interestingly, a Bergman-type MRO is observed in the glassy Zr77Rh23. Furthermore, the spatial distribution and connections of icosahedral-like clusters are shown to further demonstrate the MRO network. Our findings shed light on the nature of atomic local structures of amorphous Zr77Rh23 alloy and have important implications to understanding the formation of various MROs in metallic glasses.

In this work, first principle DFT calculations are carried out to identify the active center and reveal the reaction pathway on nitrogen and boron doped carbon catalysts in acetylene hydrochlorination. Various different dopant configurations including pyridine, graphitic, and pyrrolic are explored and compared. The different geometries of dopants give the distinct electronic structure, which indicate that pyridine configuration with three dopants around a vacancy, have more states around Fermi level. The adsorption of acetylene (C2H2) is predicted to be the first step of the reaction as it has much bigger binding energy than another reactant, HCl. Boron and nitrogen doping exhibit opposite effect on the charge transfer between adsorbed C2H2 and the catalyst. The curvature of tube also influences acetylene adsorption and the binding energy decreases with increasing tube diameter. Moreover, the detailed reaction pathway is revealed from the calculations. A balanced activity for C2H2 adsorption and HCl activation is required to improve catalytic performance and too strong binding of C2H2 hinders the followed steps on the pathway and cause large barrier. This work clarify the confusions facing by the metal-free doped carbon catalyst and lay out solid base for the future improvements in acetylene hydrochlorination.

We report a nanocarbon material with nanodiamond (ND) core and graphene shell (ND@G) as a support for Pd nanocatalysts. The designed catalyst performed good selectivity of styrene (85.2%) at full conversion of phenylacetylene and superior stability under mild conditions. Supported Pd catalysts are characterized by means of high resolution transmission electron microscopy (HRTEM), Raman, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and H2 temperature-programmed reduction (H2-TPR). The results clearly show that formation of the strong metal-support interaction (SMSI) between Pd nanoclusters and the defective graphene shell helpfully modifies the selectivity and stability of the Pd-based catalysts.

The post-Claus selective catalytic oxidation of H2S reaction in a continuous mode is demonstrated on N-doped 3D mesoporous carbon/carbon nanotube (N-C/CNT) monoliths at a reaction temperature highe...

In the field of surface plasmon-mediated photocatalysis, the coupling reactions of p-aminothiophenol (PATP) and p-nitrothiophenol (PNTP) to produce p, p'-dimercaptoazobenzene (DMAB) are the most widely investigated systems. However, a clear understanding of the structure-function relationship is still required. Here, we used tip-enhanced Raman spectroscopy (TERS) to study the coupling reactions of PATP and PNTP on well-defined Ag(111) and Au(111) surfaces using 632.8 and 532 nm lasers. On Au(111), the oxidative coupling of PATP can proceed under irradiation by a 632.8 nm laser, and the reductive coupling of PNTP can only occur under irradiation by a 532 nm laser. Neither wavelength of laser light can induce the coupling reactions of these two molecules on Ag(111). Density functional theory (DFT) was used to calculate the stable adsorption configurations of PATP and PNTP on Ag(111) and Au(111). Both the adsorption configurations of the two molecules on the surfaces and laser energies were, experimentally and theoretically, found to determine whether the coupling reactions can occur on different substrates. These results may help the rational design of photocatalysts with enhanced reactivity.

The presence of SO3 severely affects not only the safe and economic operation of coal-fired power plants but also the atmospheric environment. The purpose of this study was to investigate the generation of SO3 over V2O5-WO3/TiO2 catalysts. The SO3 generated during the reaction was collected by the controlled condensation method. N2 adsorption, X-ray fluorescence (XRF), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), SO2 temperature-programmed desorption (SO2-TPD), and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments were performed to evaluate the catalyst properties. The experimental results show that the generation of SO3 on the catalyst is complicated and can be promoted by NO and NH3. The generation rate of SO3 increased from 0.5 vol% to 3.29 vol% with an increase in the NO concentration from 0 to 1000 ppm. When 500 ppm NH3 was added to an atmosphere containing 500 ppm NO, the generation rate of SO3 increased from 2.23 vol% to 4.23 vol%. The addition of NH3 led to a significant reduction in the specific surface area of the catalyst due to the generation of ammonium bisulfate (ABS). In addition, the results show that the proportion of lattice oxygen (Oα) and the adsorption of SO2 on the catalyst would be promoted by NO and NH3, and DRIFTS experiments further proved that NO and NH3 promoted the generation and transformation of the intermediate products VOSO4 and HSO4−.

In this work first principles DFT calculation were carried out to identify the active center for 3d, 4d and 5d transition metal (TM) atoms adsorption on the surface of graphene (G) and single walled carbon nanotube (SWCNT) with mono (m)- and di-vacancy defects. The stability of TM atoms on the surface of pristine, defected G and SWCNT have been investigated by calculating binding energy of TM atoms at different sites. Inverse relationship was found among binding energy, bond distance and d-band center of TM atoms. When the binding energy increases, d-band center and bond distance experiences a decrease in their values; and more charge is transferred to the support from TM atoms and vice versa. Sc, Rh, and Ir have strongest binding energy among all kinds of TM elements while Au, Ag and Zn have smallest adsorption energy. Oxygen molecule (O2) adsorbed on the surface of V, Nb and W TM atoms have stronger binding energy compared to Zn, Ag and Pt. Furthermore, O2 adsorption and dissociation barrier is estimated to be small and is related with the binding energy of supported metal atoms. Our calculation sheds the light on the future applications of metal-carbon based catalysis.

Controllable synthesis of well-defined supported intermetallic catalysts is desirable because of their unique properties in physical chemistry. To accurately pinpoint the evolution of such materials at an atomic-scale, especially clarification of the initial state under a particular chemical environment, will facilitate rational design and optimal synthesis of such catalysts. The dynamic formation of a ZnO-supported PdZn catalyst is presented, whereby detailed analyses of in situ transmission electron microscopy, electron energy-loss spectroscopy, and in situ X-ray diffraction are combined to form a nanoscale understanding of PdZn phase transitions under realistic catalytic conditions. Remarkably, introduction of atoms (H and Zn in sequence) into the Pd matrix was initially observed. The resultant PdHx is an intermediate phase in the intermetallic formation process. The evolution of PdHx in the PdZn catalyst initializes at the PdHx /ZnO interfaces, and proceeds along the PdHx ⟨111⟩ direction.

A carbon supported carbon nitride is reported here as a catalyst for the direct conversion of acetylene and 1,2-dichloroethane (EDC) to vinyl chloride monomer (VCM). We demonstrate that increasing ...

This study investigates the seismic behavior of composite frames with initial heavy load conditions. Two frame specimens consisting of square concrete-filled steel tube (CFST) columns and steel-reinforced concrete (SRC) deep beams were fabricated and poured using ordinary concrete and high-strength concrete, respectively. Thereafter, the two specimens were tested under cyclic loadings, and the failure models, hysteretic behavior, bearing capacity, ductility, and accumulated energy dissipation of the specimens were investigated in detail. The experimental results revealed that both of the specimens failed owing to the local buckling at the column ends. This kind of composite frame has good seismic performance and can be regarded as a high-ductility structure. Moreover, a finite element (FE) model was developed and verified by the experimental results. The effects of the typical parameters, such as the material strength and axial compression ratio, were studied using the FE model. The parametric study demonstrates that increasing the yield strength of the steel tube can effectively improve the ultimate bearing capacity of the composite frame and that decreasing the axial compression ratio is a valid method for improving the ductility of the structure.

The knowledge about the formation of the heavy tars of bio-oil during pyrolysis is of great importance for the further utilization of bio-oil. This work focuses on the formation of the heavy tars during pyrolysis of bio-oil at various temperatures and heating rates in a fixed-bed reactor. In order to investigate the detailed composition of the heavy tar, the bio-oil and tars were characterized with a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS). Our results indicate that low temperature promotes the formation of heavy tars via the polymerization of bio-oil components, especially at slow heating rates, therein the condensed aromatics are formed via the polymerization of small aromatics with one or two rings. High temperature promotes the breakage of the oxygen-containing functional groups, meanwhile the highly condensed aromatics with more than 4 rings are formed at 800 °C via the strong secondary reactions (e.g. recombination), especially at fast heating rates.

The understanding of the generation mechanism of SO3 on V/W/Ti catalysts provides needed information for the achievement of ultra-low emission of pollutants and effective control of SO3 generation. This study predominantly investigates the catalytic oxidation mechanism of V/W/Ti catalysts for SO3 generation under H2O and CO2 conditions. Ion Chromatography (IC), X-ray Fluorescence (XRF), Brunauer–Emmett–Teller (BET) specific surface area, Scanning Electron Microscopy image (SEM), Energy Dispersive X-ray (EDX), SO2 Temperature-Programmed Desorption (SO2-TPD), X-ray Photoelectron Spectroscopy (XPS) experiments, and Fourier Transform Infrared spectroscopy (FT-IR) were used to characterize catalyst properties and the catalytic oxidation generation mechanism of SO3. Results show that Catalyst V content was more influential than physical property on the generation of SO3. In this study, when H2O or CO2 was added into the reaction atmosphere, the generation amount of SO3 would increase firstly, and then gradually decrease with the further increase of H2O or CO2 concentration. Through further mechanistic analysis, it was found that the influence mechanism of H2O and CO2 on the generation of SO3 was different. Various kinds of intermediate species such as [OH] and HOSO2 were introduced by the addition of H2O, resulting in the increase of lattice oxygen (Oα) proportion and SO3 generation path. However, the inhibition effects of high concentration of H2O on SO2 adsorption and sulfur oxides migration were the main reason for the decrease of SO3 generation under high H2O containing conditions. Conversely, although the adsorption SO2 was promoted by CO2, high CO2 addition leads to the apparently reduction of Oα proportion on catalyst resulting in the decrease of SO3 generation.

This work aimed at studying the roles of moisture and cyclic loading in microstructures and their effects on mechanical properties for typical Chinese bituminous coals. Different relative moisture contents (100%, 75%, 50%, 25%, and 0%) for Shenmu coal (SM), Hongshaquan coal (HSQ), and Wucaiwan coal (WCW) were chosen to study the effects of moisture. The raw SM was then further selected to investigate the effects of cyclic loading. Images of coals surfaces and mechanical properties during simulated crushing process were recorded and combined to be analyzed. The results showed that the moisture possessed significant effects on coal mechanical properties, which strongly depended on their porosities. As for low porosity coal (SM), the adsorption of moisture can soften and lubricate the microstructures, weakening mechanical properties. While the drying process would destroy the microstructures and decease mechanical properties for high porosity coals (HSQ and WCW). Under the cyclic loading process, the cumulative effects of strain showed a step-up state and the first cyclic loading can typically cause the biggest change of microstructures and produce the largest strain under different stress levels. Finally, a normalized quantitative relationship ( σ r = - 0.67 D r 2 + 1.62 D r + 0.07 ) between the relative fractal dimension and relative stress was built.

Though photoluminescence (PL) of Si quantum dots (QDs) has been known for decades and both theoretical and experimental studies have been extensive, their luminescence mechanism has not been elaborated. Several models have been proposed to explain the mechanism. A deep insight into the origin of light emissions in Si QDs is necessary. This work calculated the ground- and excited state properties of hydrogenated Si QDs with various diameters, including full hydrogen passivation, single Si[double bond, length as m-dash]O ligands, single epoxide and coexisting Si[double bond, length as m-dash]O and epoxide structures in order to investigate the dominant contribution states for luminescence. The results revealed that even a single oxygen atom in hydrogenated Si QDs can dramatically change their electronic and optical properties. Intriguingly, we found that a size-independent emission, the strongest among all possible emissions, was induced by the single Si[double bond, length as m-dash]O passivated Si-QDs. In non-oxidized Si-QDs exhibiting a core-related size-tunable emission, the luminescence properties can be modulated by the ligands of Si QDs, and a very small number of oxygen ligands can strongly influence the luminescence of nanocrystalline silicon. Our findings deepen the understanding of the PL mechanism of Si QDs and can further promote the development of silicon-based optoelectronic devices.

Nanostructured (BiO)2CO3 samples were prepared, and their thermal decomposition behaviors were investigated by thermogravimetric analysis under atmospheric conditions. The method of preparation and Ca2+ doping could affect the morphologies of products and quantity of defects, resulting in different thermal decomposition mechanisms. The (BiO)2CO3 nanoplates decomposed at 300&ndash, 500 &deg, C with an activation energy of 160&ndash, 170 kJ/mol. Two temperature zones existed in the thermal decomposition of (BiO)2CO3 and Ca-(BiO)2CO3 nanowires. The first one was caused by the decomposition of (BiO)4(OH)2CO3 impurities and (BiO)2CO3 with surface defects, with an activation energy of 118&ndash, 223 kJ/mol, whereas the second one was attributed to the decomposition of (BiO)2CO3 in the core of nanowires, with an activation energy of 230&ndash, 270 kJ/mol for the core of (BiO)2CO3 nanowires and 210&ndash, 223 kJ/mol for the core of Ca-(BiO)2CO3 nanowires. Introducing Ca2+ ions into (BiO)2CO3 nanowires improved their thermal stability and accelerated the decomposition of (BiO)2CO3 in the decomposition zone.

Fluorescence interference in Raman spectrum is a big barrier for rapid and precise analysis of coal structures by Raman spectroscopy. Dealing with fluorescence interference suitably is one of the key tasks before efficient application of Raman spectroscopy in coal assessment. In this study, Raman spectra and coal combustion characteristics of 32 kinds of Chinese coals were respectively obtained in a micro-Raman spectrometer and Thermal Gravimetric Analyzer. The degree of fluorescence interference in Raman spectrum was firstly defined and quantified as the drift coefficient α using a simple method without curve-fitting the spectrum. The correlations between the degree of fluorescence interference and coal property, coal combustion characteristics were set up and multivariable analysis was done. The results indicate that the degree of fluorescence interference is well related to the coal structures, and it is synthetically determined by volatile, moisture and ash content in coal. With the increase of volatile, moisture content in coal, the fluorescence interference increases continuously, and it can be reduced but not eliminated by drying the moisture in coals. Significant mathematical relations between the drift coefficient α and volatile, moisture content, coal combustion characteristic temperatures have been found. Coal with more evident fluorescence interference in Raman spectrum usually has lower degree of coalification, more polar functional groups, and burns at a lower temperature. The drift coefficient α can act as an efficient probe for coal property and coal combustion characteristics. This study provided a new and simple approach for evaluating coal property and coal combustion characteristics by fluorescence interference in Raman spectrum.

β-FeOOH nanorods were prepared by a poly ethylene glycol (PEG) assisted precipitation of FeCl3 ∙ 6H2O aqueous solution with urea. Na2CO3 aqueous solution was introduced to maintain their shapes under annealing. The one-dimensional porous iron oxide nanorods were synthesized successfully. The as-prepared catalysts were characterized by X-ray diffraction, transmission electron microscopy, N2 adsorption-desorption isotherms and X-ray photoelectron spectroscopy. The hydrogenation of nitrobenzene to aniline was taken as probe reaction to evaluate their catalytic performance. FeOOH (iron oxides hydroxide) nanorods, fabricated by annealing β-FeOOH nanorods at 250 °C in Ar atmosphere for 4 h, exhibited high catalytic activity for the transfer hydrogenation of nitrobenzene to aniline with hydrazine hydrate as hydrogen donors.

Developing economic, effective and stable bifunctional electrocatalysts to achieve sustainable hydrogen production is highly desired. Herein, C-coated CoP hollow microporous nanocages (C-CoP-1/12) are synthesized by calcination of a Prussian blue analog precursor and subsequent phosphorization treatment. Under alkaline condition, the C-CoP-1/12 exhibit splendid electrocatalytic performance with a low overpotential of 173 mV for hydrogen evolution reaction (HER) and 333 mV for oxygen evolution reaction (OER) at a current density of 10 mA cm-2. The C-CoP-1/12 show high electrocatalytic performance for overall water splitting at a low potential of only 1.650 V for the driving current density of 10 mA cm-2, and they exhibit remarkable stability for at least 24 h. The engineering of phosphating is the critical step for the synthesis of pure-phase CoP with hollow nanoarchitecture. Compared with Co2P, CoP possesses lower water dissociation barrier and favorable ΔGH* value according to theoretical calculations, resulting in superior electrocatalytic performance. Such impressive water splitting performance is mainly attributed to the collective effects of metal phosphide with unique electronic structure, the shortened electron transport paths, and the conductive C coating. This strategy is believed to provide a basis for the development of electrode materials with highly efficient electrocatalytic water-splitting capability.

The interface at the metal oxide-carbon hybrid heterojunction is the source to the well-known "synergistic effect" in catalysis. Understanding the structure-function properties is key for designing more advanced catalyst-support systems. Using a model MnIII-O x single-layer catalyst on carbon, we herein report a full elucidation to the catalytic synergism at the hybrid heterojunction in the oxygen reduction reaction (ORR). The successful fabrication of the single-layer catalyst from bottom-up is fully characterized by the X-ray absorption fine structure and high-resolution transmission electron microscopy. For oxygen electrocatalysis over this model hybrid heterostructure, our results, from both theory and experiment, show that the synergistic ORR truly undergoes a cooperated two-step electrocatalysis with catalytic promotion (Δ Eonset = 60 mV) near the heterojunction and over the single-layer catalyst through an interfacial electronic interplay, rather than an abstruse transition towards a one-step dissociative pathway. Finally, we report a superior peroxide-reducing activity of 432.5 mA cm-2 mg(M)-1 over the MnIII-O x single-layer.

Two-dimensional materials (such as graphene, MXenes) usually perform remarkably well as catalysts in comparison with their three-dimensional counterparts. In this work, Ti3AlC2-derived Ti3C2Tx MXene (T = O, OH, F) was prepared and employed in the direct dehydrogenation of ethylbenzene. A 92 μmol m–2 h–1 reactivity and a 40 h stability with almost no deactivation were observed, which is much better than those of the previously reported nanocarbon catalysts. The graphene-like layered structure and the C–Ti–O termination groups induced by the preparation process were thought to account for the good catalytic performance of Ti3C2Tx MXene from both experimental and computational perspectives. The discovery expands the application of two-dimensional MXenes and provides more choices in exploring high-activity catalysts for hydrocarbon dehydrogenation reactions.

Resolving atomic site-specific electronic properties and correlated substrate-molecule interactions is challenging in real space. Now, mapping of sub-10 nm sized Pt nanoislands on a Au(111) surface was achieved by tip-enhanced Raman spectroscopy, using the distinct Raman fingerprints of adsorbed 4-chlorophenyl isocyanide molecules. A spatial resolution better than 2.5 nm allows the electronic properties of the terrace, step edge, kink, and corner sites with varying coordination environments to be resolved in real space in one Pt nanoisland. Calculations suggest that low-coordinate atomic sites have a higher d-band electronic profile and thus stronger metal-molecule interactions, leading to the observed blue-shift of Raman frequency of the N≡C bond of adsorbed molecules. An experimental and theoretical study on Pt(111) and mono- and bi-atomic layer Pt nanoislands on a Au(111) surface reveals the bimetallic effect that weakens with the increasing number of deposited Pt adlayer.

For the worldwide rapid growing pressure from environmental pollution and energy shortages, the lightweight epoxy based materials, which owe great potential to be qualified structure materials to replace steel alloys on transportations, are attracting increasing attentions. A way of high rate of quality and price to reinforce the epoxy is always desired. In this work, activated carbon (AC) was found to be an effective reinforcing nanofiller. A comprehensive improvement (tensile properties, fracture toughness, impact strength and dynamic mechanical properties) occurred after AC was further modified by nitrogen groups. The modification was simple, economic, efficient and eco-friendly. The reinforcing method for the epoxy matric was of high rate of quality and price. The reinforcing mechanism was discussed. The present work aims to give out some ideas for the fabrication of low-price high-performance nanocomposites.

Coke can be formed once the bio-oil was heated, even at very low temperatures, causing almost always serious problems in the upgrading and direct utilization of bio-oil. To minimize the negative impacts from coke formation, the key point is to fully understand the formation and evolution of coke during the thermal treatment of bio-oil. Thus, in this study, the cokes formed from the pyrolysis of bio-oil at different temperatures (300–800 °C) and heating rates were characterized by using a range of advanced analytical instruments. The evolution of cokes (e.g. morphology, elemental composition, chemical structure and concentration of radicals) with increasing temperature and heating rate was traced. The results show that the cokes generated at slow heating rates are imporous with smooth surface but porous at high temperatures and fast heating rates. The radical concentration of the cokes reaches the highest level at 600 °C, then decreases rapidly with further increasing temperature to form more free radicals, which promote the condensation reaction of aromatic systems to form larger ring structures of the coke at high temperatures, with lower H/C and O/C ratios. The O-containing functional groups could be brought into the coke via the interactions between light and heavy components of bio-oil.

Supported metal nanoparticle catalysts are widely used in industry but suffer from deactivation resulting from metal sintering and coke deposition at high reaction temperatures. Here, we show an efficient and general strategy for the preparation of supported metal nanoparticle catalysts with very high resistance to sintering by fixing the metal nanoparticles (platinum, palladium, rhodium and silver) with diameters in the range of industrial catalysts (0.8–3.6 nm) within zeolite crystals (metal@zeolite) by means of a controllable seed-directed growth technique. The resulting materials are sinter resistant at 600–700 °C, and the uniform zeolite micropores allow for the diffusion of reactants enabling contact with the metal nanoparticles. The metal@zeolite catalysts exhibit long reaction lifetimes, outperforming conventional supported metal catalysts and commercial catalysts consisting of metal nanoparticles on the surfaces of solid supports during the catalytic conversion of C1 molecules, including the water-gas shift reaction, CO oxidation, oxidative reforming of methane and CO2 hydrogenation. Supported metal nanoparticles are indispensable catalysts in industry, yet they are often subjected to severe sintering. Now, a general method based on metal immobilization within zeolite is reported for the preparation of highly sinter-resistant catalysts for a broad range of industrially relevant processes.

By using an alpha-amino acid as an interfacial protector and pH adjustor, we demonstrate the synthesis of the long-range ordered mesoporous alumina (OMA) via a modified solvent evaporation induced self-assembly (EISA) method. Characterization results of XRD, TEM, and N2 adsorption-desorption indicate that the long-range highly ordered OMA was successfully obtained by using aluminum iso-propoxide as a precursor and Pluronic P123 as a template via the alpha-amino acid assisted EISA process. Moreover, by simply changing the alpha-amino acid, the textural property of the OMA was easily regulated, the extent of which depends on the molecular structure and coordination ability of the alpha-amino acid. The facile formation of the long-range highly ordered OMA was explained based on the function of the alpha-amino acids.

A series of MnxOy /Al2O3 sorbents with different tissue and chemical structures were prepared by repeated incipient wet impregnation method with different calcination conditions, including calcination temperature from 500 °C to 900 °C and calcination time from 3 h to 9 h. The H2S absorption performances of the prepared sorbents were investigated by a model synthesis gas containing 2000 mg/m3 H2S at 850 °C. The chemical and physical structures of the samples were characterized by Brunauer–Emmett–Teller, X-ray diffraction and scanning electron microscopy techniques to obtain fundamental information about the deactivation of MnxOy/Al2O3 sorbents during desulfurization–regeneration cycles. Results showed that the structural features of the sorbents at high reaction temperature played an important role in the stability of desulfurization performance. The analysis of the characteristics of the sorbents indicated that the sorbents obtained stabilized chemical and physical structures during desulfurization–regeneration cycles when the calcination temperature was 900 °C and the calcination time was above 6 h. The sorbent suffered serious deactivation during five successive desulfurization–regeneration cycles when the calcination temperature of sorbents was below 850 °C. The sulfur capacity decreasing of MnxOy/Al2O3 sorbents may probably be attributed to a part of MnxOy covered by Al2O3, which can un-sulfide during adsorption process. The coverage of active phase MnxOy may be caused by the shrinking and disappearing of some micropores, and phase transformation of Al2O3, as well as the transformation of MnAl2O4 lead to a part of MnxOy on the sorbents being covered by alumina.

The effects of catalyst supports (γ-Al2O3 and α-Al2O3) on hydrogen yield and carbon nanotubes formation were studied during steam reforming of toluene over Ni-based catalysts. Hydrogen yield and CNTs quality over Ni/γ-Al2O3 were better than those over Ni/α-Al2O3 at S/C ratio of 1 due to the high Ni dispersion of Ni/γ-Al2O3. With the increasing of steam addition, CNTs production remarkably increased over Ni/α-Al2O3, while it decreased over Ni/γ-Al2O3. The CNTs on Ni/γ-Al2O3 were corroded at S/C ratio of 3 by excess steam. Toluene conversion and hydrogen yield over Ni/α-Al2O3 were significantly larger than those over Ni/γ-Al2O3, which was attributed to the different effects of CNTs on catalytic activity. The strong interaction between Ni particle and γ-Al2O3 led to the base-growth mechanism of CNTs on Ni/γ-Al2O3 in which Ni particles located at the bottom of CNTs, thus the growth of CNTs covered Ni active sites and decreased catalytic activity of Ni/γ-Al2O3. By contrast, owing to weak interaction, CNTs grown on Ni/α-Al2O3 followed tip-growth mechanism that would increase Ni dispersion and promote reforming reaction.

A simple, economic, efficient and eco-friendly nanodiamond (ND) modifying method to reinforce the ND/epoxy composite for the industrialization of the high-performance ND/epoxy composite is always desired. In the present work, the ND was successfully modified only using aqueous ammonia through an easy-to-operate method by replacing the hydrogen atoms in the carboxyl group with ammonium ions. Ammonia, which is the only pollutant in the process, could be recycled. The modified ND/epoxy composite showed an overwhelming advantage over the neat epoxy or the ND/epoxy composite in storage modulus in their glassy state without any degradation of tensile strength, hardness and fracture toughness.