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Two-dimensional transition-metal dichalcogenides have gained increasing concerns because of their distinct structural features and also display great potential in mercury removal. Herein, a defect-rich MoS2 nanosheet is synthesized by using hydrothermal method and applied for adsorptive capture of elemental mercury (Hg0) in simulated flue gas at low temperature. It exhibits excellent Hg0 removal performance due to its ultra-thin lamellar and defective structures with ample exposed adsorption sites. The Hg0 removal efficiency of the defective MoS2 nanosheet is all above 93% when the reaction temperature is within 25–150 °C. Besides, presence of NO has no influence on Hg0 removal, while SO2 subtly reduces the Hg0 removal efficiency due to competitive adsorption. Mo4+, S2−, and S22− ions take part in the Hg0 removal process, which transfers Hg0 into Mo–Hg amalgam and HgS. The process of Hg0 adsorption on the defective MoS2 nanosheet obeys the pseudo-first-order and pseudo-second-order kinetic model.

Hexagonal boron nitride (h-BN), as a novel carbon-free layered material, has received extensive attention owing to its high mechanical strength and excellent chemical and thermal stability. Herein,...

Mercury emission from industrial activities has become a major environmental health concern, because mercury is one of the most toxic metals encountered in the environment. Elemental mercury is the dominant Hg species in gas streams. Adsorption is regarded as a practical technique for Hg0 removal, for which developing efficient and economic adsorbents are needed. Chalcogenides have recently gained increasing research interest owing to their high binding affinity for Hg0. Chalcogen-based adsorbents include S-modified adsorbents, H2S- and SO2-activated adsorbents, polysulfide chalcogels, mineral sulfides and metal selenides. This article reviews chalcogen-based adsorbents for Hg0 capture from gas streams, with focus on removal performances, mechanisms, advantages and disadvantages. Results show that S modification, and H2S and SO2 activation generate a great variety of active sulfur species on the adsorbent surface, resulting in enhanced Hg0 removal activity. Sulfur species include elemental sulfur, sulfide, thiophene and sulfate. Nonetheless, removal efficiency decreases to some extent due to the presence of acidic flue gas components and steam. On the other hand, mineral sulfides and metal selenides exhibit outstanding Hg0 removal performances with fast adsorption rate, high mercury capacity and excellent resistance to SO2 and H2O. Yet most mineral sulfides and metal selenides perform well below 100 °C, which might limit industrial applications.

CO2 emission is partly responsible for climate change induced by greenhouse effects. Carbon capture, utilization and storage is a major pathway to reduce CO2 emission. This article reviews conversion of CO2 into value-added products by photocatalytic, electrocatalytic and photoelectrocatalytic processes, which involve a catalyst, a reducing agent, an electrolyte and a reactor. An ideal catalyst should be cheap, abundant, non-toxic, less corrosive and chemically stable. Doping various catalysts can increase product yields up to 207 times. Furthermore, monolith reactors generated 23 times and 14 times higher yields than slurry and cell reactors, respectively. Photoelectrocatalytic conversion standout because it combines the advantages of photocatalytic and electrocatalytic processes such as high product yield and selectivity, no electrical energy required, cost-effectiveness, more catalysts option and no sacrificial donor.

In this study, biochars prepared under 500–900 °C interacted with cellulose volatiles at 500 °C, and the effects of volatile–char interactions on the changes of biochar functional groups and its re...

A novel two-step sorption enhanced staged gasification of biomass for H2 production was proposed and studied using Aspen Plus software. An equilibrium model based on Gibbs free energy minimization was developed and validated. The results showed that the two-step process was more advantageous for H2 production compared with the conventional steam gasification and the one-step process. The independent control of each stage could realize a high temperature steam gasification in the first stage and a subsequent lower temperature steam reforming in the second stage, which thus promoted the gasification of biomass and benefited the water gas shift (WGS) reaction to produce more H2. Meanwhile, the in situ CO2 absorption of CaO in the second stage could enrich the H2 concentration in the product gas, and also further shifted the WGS reaction equilibrium to convert more CO to H2. With further introduction of catalyst for steam methane reforming (SMR), high-purity H2 with the concentration of 99.7 vol% and yield of 142.8 g/kg daf biomass could be achieved.

There is currently an outbreak of respiratory disease caused by a novel coronavirus. The virus has been named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the disease it causes has been named coronavirus disease 2019 (COVID-19). More than 16% of patients developed acute respiratory distress syndrome, and the fatality ratio was 1%–2%. No specific treatment has been reported. Herein, we examined the effects of favipiravir (FPV) versus lopinavir (LPV)/ritonavir (RTV) for the treatment of COVID-19. Patients with laboratory-confirmed COVID-19 who received oral FPV (Day 1: 1600 mg twice daily; Days 2–14: 600 mg twice daily) plus interferon (IFN)-α by aerosol inhalation (5 million international unit (IU) twice daily) were included in the FPV arm of this study, whereas patients who were treated with LPV/RTV (Days 1–14: 400 mg/100 mg twice daily) plus IFN-α by aerosol inhalation (5 million IU twice daily) were included in the control arm. Changes in chest computed tomography (CT), viral clearance, and drug safety were compared between the two groups. For the 35 patients enrolled in the FPV arm and the 45 patients in the control arm, all baseline characteristics were comparable between the two arms. A shorter viral clearance median time was found for the FPV arm versus the control arm (4 d (interquartile range (IQR): 2.5–9) versus 11 d (IQR: 8–13), P < 0.001). The FPV arm also showed significant improvement in chest CT compared with the control arm, with an improvement rate of 91.43% versus 62.22% (P = 0.004). After adjustment for potential confounders, the FPV arm also showed a significantly higher improvement rate in chest CT. Multivariable Cox regression showed that FPV was independently associated with faster viral clearance. In addition, fewer adverse events were found in the FPV arm than in the control arm. In this open-label before-after controlled study, FPV showed better therapeutic responses on COVID-19 in terms of disease progression and viral clearance. These preliminary clinical results provide useful information of treatments for SARS-CoV-2 infection.

Pyrolysis is an important thermochemical route to decompose lignocellulose biomass into biogas, bio-oil, and biochar, which can be then converted into value-added biofuels, chemicals, and biomateri...

Graphite-phase carbon nitrides (g-C3N4), composed of only C, N, and some impurity H, have been synthesized by direct thermal polymerization of urea in air and employed to capture elemental mercury ...

Air pollution caused by mercury emissions from combustion and pyrolysis of fossil fuels, biomass, and solid wastes is a major health issue. Elemental mercury (Hg0), the dominant species in flue gas, is poorly captured by actual control equipments because Hg0 has a high volatility and is insoluble in water. Alternatively, photocatalytic processes can oxidize Hg0 into Hg compounds that are easier to remove. Here we review the recent research on oxidative removal of Hg0 by photocatalysts, with focus on titanium dioxide, bismuthides, silver compounds and hybrid photocatalysts. We discuss the Hg0 removal performances and mechanisms of catalytic oxidation. The TiO2 photocatalyst often suffers from low absorption of solar energy and easy recombination of photoinduced electron–hole couples. BiOIO3 appears as a promising photocatalyst due to its high Hg0 oxidation activity under visible light irradiation. Silver carbonates and silver halides are newly developed visible-light-responsive photocatalysts for Hg0 removal. Fast separation and transformation of photogenerated electrons and holes control the performance of Hg0 removal by photocatalysts.

Stretchable electronics can be summarized as an emerging electronic technology that manufactures electronic devices on flexible substrates, and has broad application prospects due to its unique ductility. In order to improve product reliability, it has become critical to understand all the failure modes that caused it to fail. Interface delamination is an important factor leading to its failure, especially at the interface between the flexible substrate and the metal conductive layer. In this study, in order to explore the stress distribution of the interface layer between the substrate (PDMS) and the metal conductive layer (Cu) under load, a uniaxial tensile simulation and a three-point bending simulation were first performed, and it was found that stress occurred at the corners Concentration phenomenon. Therefore, a peeling model without prefabricated cracks was used. The finite element model with cohesive elements is used for numerical simulation, and the stripping process is described in detail. Finally, the influence of cohesion parameters on peeling force is analyzed. It is found that with the increase of C1, the maximum peel force also increases, but it has no effect on the stable expansion stage. This research content is of great significance for quantitative analysis of the delamination of stretchable electrons and improving the reliability of stretchable electrons.

Integrated gasification combined cycle (IGCC) and solid oxide fuel cell (SOFC) systems are considered as the most promising clean coal technologies. Syngas derived from coal gasification is the major fuel sources for IGCC and SOFC power systems; however, large amounts of sulfur compounds, mainly in the form of hydrogen sulfide, are produced during gasification. Hydrogen sulfide has to be removed prior to syngas utilization to protect downstream equipment from high-temperature corrosion. Therefore, hydrogen sulfide removal from raw syngas plays a key role in successful application of IGCC and SOFC systems. Hot coal gas desulfurization using solid sorbents is a more efficient technique for hydrogen sulfide removal, compared with conventional cold coal gas desulfurization with amine solution. This article reviews solid sorbents for high-temperature desulfurization, e.g., transition metal oxides, rare-earth oxides, spinel oxides, perovskite oxides, nanoelemental metals and mesoporous desulfurizers. Composite oxides that combine the properties of diverse metal oxides are promising candidates for hot coal gas desulfurization. The extensive background knowledge and the state of the art on high-temperature sorbents for hydrogen sulfide removal in this review provides inspiration and guidance to develop new cost-effective sorbents.

Graphitic carbon nitride (g-C3N4) as a 2D layered carbon material with exceptional electronic, thermal, and catalytic property has attracted increasing research attention. A porous g-C3N4 nanosheet (PCNN) has been synthesized via a facile two-step thermal etching oxidation approach and applied in low-temperature elemental mercury (Hg0) removal. PCNN exhibits good reactivity toward Hg0 adsorption at temperatures of 40–200 °C. CuO impregnation can prominently enhance the Hg0 capture performance of PCNN on account of the intimate interaction of CuO and PCNN. Temperature has a positive effect on Hg0 capture ability of PCNN and CuO/PCNN. Hg0 is mainly oxidized by the chemisorbed oxygen species that are generated from the O–C–N of g-C3N4 and the lattice oxygen of CuO. CuO modification can efficiently activate g-C3N4 with significantly improved Hg0 capture ability presumably owing to the Mott–Schottky effect at the interface of CuO and g-C3N4.

Graphene oxide (GO) nanosheets of planar flake-like structures are fabricated by using a modified Hummers method. Fractal theory is introduced to characterize the topological surfaces and porous structures of the GO nanosheets, the fractal dimensions estimated by using box-counting method are close to 2, indicating that the GO nanosheets possess perfectly smooth surfaces, which agrees well with high resolution transmission electron microscopy (HRTEM) images, and the higher porous fractal dimension of 2.74 determined by using Frenkel-Halsey-Hill (FHH) model suggests a wealth of microporous structures of the GO nanosheets.

Anaerobic digestion is a promising technology for the treatment of high strength organic wastes, since it produces renewable energy (biogas) and valuable digestate as fertilizer. The emphasis of this paper lies in demonstrating the net energy characteristics of a small-scale biogas self-supply anaerobic digestion system under three operation modes, considering the digestion temperatures varying from the psychrophilic to thermophilic and dry matter concentrations from 4 to 10%. The system mainly includes the reactor and biogas boiler at Mode 1, which is added slurry waste heat recovery at Mode 2 and further incorporated a thermal pretreatment process at Mode 3. In addition, a numerical energy balance model and an evaluation framework are developed for net energy feature exploration and contrastive analysis between different modes. The results show that the required digestion conditions (the highest digestion temperature, the lowest dry matter concentration) to guarantee the benchmark at Mode 1, are (25 °C, 4%), (35 °C, 6%), (40 °C, 8%), and (55 °C, 10%), and become more lenient at Mode 2. The maximum net energy production occurs at approximately 25 °C or 50 °C, depending on the concentration and operation mode. Moreover, thermal pretreatment for sterilization would not reduce much net energy. Therefore, it should consider net energy production, operation mode, digestion temperature, concentration as well as other related factors for optimal operation parameter determination of anaerobic digestion system.

Sorption enhanced gasification of biomass is a novel technology for high purity H2 production and simultaneous carbon negative emission. The effect of CaO on the H2 production process was normally qualitatively explained. To quantitatively study the enhancing mechanism of CaO, the sorption enhanced gasification of cellulose for H2 rich syngas production was carried out in a fixed-bed pyrolysis-gasification system, the amount of CO2 absorbed, the carbon conversion rate of volatiles as well as the changes in the role of CaO under different gasification conditions were quantitatively studied. The results showed that CaO acted as a CO2 absorbent and/or a catalyst depending on the gasification temperature. It functioned as both a CO2 absorbent and a catalyst at lower temperatures of 550–700 °C, and a maximum amount of CO2 absorbed by CaO was achieved at 550 °C as 189.88 ml/g cellulose, CaO catalyzed the volatiles gasification to produce more H2 and achieve more sufficiently conversion with increasing temperature. While when the gasification temperature ≥750 °C, CaO acted only as a catalyst. The optimized condition for sorption enhanced pyrolysis-gasification of cellulose was of gasification temperature of 650 °C and of mass ratio of CaO/cellulose of ≥4, under which the actual carbon conversion rate of volatiles achieved ∼90 wt.%.

The mercury emission pollution of coal-fired power plants has posed big threatens to the human heath and the environment. Here, a graphene-analogous carbon nitride (GCN) is used to capture Hg0 from simulated flue gas in a fixed-bed reactor at low temperatures. The GCN displays good Hg0 adsorption capability with Hg0 removal efficiency of 32.4–69.4% within 25–200 °C. CuS incorporation can greatly reinforce the Hg0 capture ability of the GCN. The optimal loading value of CuS is 10 wt%. Complete mercury capture is reached over 10CuS/GCN in the temperature range of 25–100 °C. Existence of NO marginally suppresses the Hg0 removal process, while presence of SO2 has hardly influence on Hg0 capture. The copper and polysulfide active sites as well as the graphene-analogous nanosheet structure of the GCN contribute to the prominent Hg0 capture performance of CuS-anchored GCN.

CuO-based and MnOx-based sorbents modified with Ce and La using sol-gel method, were employed for elemental mercury removal at 120–240 °C. The Hg0 removal activity of Mn2O3/ZSM-5 can be significantly enhanced by doping 50 at.% Ce or 10 at.% La, the Hg0 removal efficiency increased by 94% and 71%, respectively. The Hg0 removal ability of CuO/ZSM-5 subtly improved by addition of 50 at.% Ce or 10 at.% La, the Hg0 removal efficiency ascended only by 6% and 18%, respectively. The XPS results revealed that Hg0 transformed to HgO, and CuO (or Mn2O3) was reduced to Cu2O (or Mn3O4), which is in agreement with Mars-Maessen mechanism.

Graphitic carbon nitride (g-C3N4) as a nanocarbon material has attracted accelerated concern because of its layered structure, facile synthesis route and lower capital cost. Here, three kinds of g-C3N4 are fabricated via simply thermal polycondensation of dicyandiamide, melamine, and urea at high temperature, and they are applied for elemental mercury (Hg0) capture in a fixed-bed reactor. We found that the g-C3N4 attained by urea pyrolysis exhibited prominent Hg0 capture ability with Hg0 removal efficiency of ∼84% which is much higher than that of the g-C3N4 derived from dicyandiamide and melamine pyrolysis, probably attributed to its bigger BET surface area and pore volume.

The Co3O4/g-C3N4 hybrids are constructed via the incipient wetness impregnation method by depositing Co3O4 onto the exterior of g-C3N4, and then employed for Hg0 capture within 60&ndash, 240 &deg, C. The results show that the Co3O4/g-C3N4 hybrid with a Co3O4 content of 12 wt% performs optimally with the highest Hg0 removal efficiency of ~100% at or above 120 &deg, C. The high performances of the Co3O4/g-C3N4 hybrids are probably attributed to the tight interfacial contact between Co3O4 and g-C3N4, with its improved electron transfer, inferring that cobalt oxide and g-C3N4 display a cooperative effect towards Hg0 removal. NO and SO2 shows a significant suppressive influence on the mercury capture performance, plausibly owing to the competing adsorption and side reactions.

Effective charge-carrier separation and molecular oxygen activation are crucial factors for photocatalytic environmental purification. Herein, an efficient Fe-doped Bi7O9I3 microflowers photocatalyst was synthesized. It was discovered that Fe doping could not only tune the concentration of oxygen vacancies of Bi7O9I3 to optimize the dissociation of excitons, but also promote the separation of charge-carriers and the activation of oxygen molecules. Meanwhile, the inducing of surface oxygen vacancies and Fe3+/Fe2+ by Fe optimal doping can act as the activation center for catalytic reactions, which also significantly enhances the photocatalytic activity. Benefiting from the optimized properties, the photocatalytic activity of Fe-doped Bi7O9I3 photocatalyst has been significantly improved by more than 4 times. Finally, we proposed that a highly efficient catalytic oxidation reaction mechanism can be achieved via modulating Fe doping to induce oxygen vacancies to promote charge separation and molecular oxygen activation. This work provides a novel approach for designing efficient photocatalysts.

Thermal performances of light-emitting diode (LED) lamp with three types of thermal interface materials (TIMs) under different convection coefficients and input powers are investigated by using finite-element method. Three types of TIMs are conductive silver, Sn63Pb37 of tin alloy solder, and graphene in this paper. The results demonstrate that the temperature of the LED lamp decreases sharply using the interface material of graphene. With the increasing convection coefficient in a certain range, the junction temperature will be effectively decreased. When under high input powers, graphene has a much better performance than other two TIMs. It implies that graphene may be a possible potential for thermal design, which can effectively prolong the life of LED, especially for high power devices. The simulation offers a test of LED heat dissipation using different TIMs, and the results can provide a reference for the application of graphene in LED thermal design as TIMs and build a motivation for future material research directions. It builds a basis for progressive study of physical property for LED lamp. The obtained results may give insight to the reliability of the LED lamp.

This study investigates the degradation of light-emitting diode (LED) lamp modules by various stress–load test approaches, namely, step-up stress accelerated degradation testing, step-down stress accelerated degradation testing (SDSADT), and constant stress accelerated degradation testing. Two types of commercial LED lamps with different capabilities of heat dissipation (CHDs) are utilized in the experiment. LM-80 testing on two types of LED packages is further implemented to reproduce the degradation reaction of Lamp B. Result shows that SDSADT can effectively alleviate the initial increase in optical parameters. Lamp B with a strong CHD exhibits a similar lumen decay rate at each stress of step stress testing; this similarity implies that the decay rate of Lamp B is only related to the current loaded stress. The lumen decay rate of the initial decay paths for Lamp B as the thermal stress increases exhibits a parabolic law. This parabolic pattern is also detected in the LM-80 testing for the LED packages and is explained by the strong CHD of Lamp B. The thermally induced mechanisms, which influence the optical emission of LEDs, should be responsible for the parabolic decay law. Moreover, the color shift of the LED modules with increasing loaded stresses is more sensitive than lumen degradation.

The high-temperature H2S removal was conducted over xLayCu/ZSM-5 sorbents prepared via citric acid method. The sorbents showed good desulphurization performance, the maximal sulfur capacity of 2240.5 μmol S/g over 5La5Cu/ZSM-5 was achieved at 700 °C. The presence of H2 obviously shortened the breakthrough time and reduced the sulfur capacity. However, the presence of CO had little influence on the desulphurization behavior. The sulfidation activity of La2O3 can be significantly enhanced by introduction of Cu due to the intimate mixing of La2O3 and CuO, the formation of La2CuO4 compound.

The routine method using statistical analysis theory with enough historical data to predict risk factor probability (index failure probability) has defects, as historical data, especially the ones that far away from today, often can not precisely reflect the current situation of the gas network. Therefore, the risk factor probability should be predicted or evaluated by rational using the historical data and combining with the current situation. This paper presented a risk factor probability comprehensive evaluation model which considers historical data as well as the experts' analysis of the object system in recent years, namely, the risk factor probability evaluation model based on information revision, and employed for risk evaluation of the city gas transmission and distribution system with a case study.

Performance of CeO2-La2O3/ZSM-5 sorbents for sulfur removal was examined at temperature ranging from 500 oC to 700 oC. The sulfur capacity of 5Ce5La/ZSM-5 was much bigger than that of CeO2/ZSM-5. H2 had a negative impact on the sulfidation; however, CO had little influence on sulfur removal. The characterization results showed that CeO2 and La2O3 were well dispersed on ZSM-5 because of the intimate admixing of La2O3 and CeO2, the major sulfidation products were Ce2O2S and La2O2S, the XRD and SEM results revealed that ZSM-5 structure could remain intact during preparation and sulfidation process, the H2-TPR showed that the reducibility of CeO2 can be remarkably enhanced by addition of La.

Perovskite LaMnO3/ZSM-5 was used for reactive adsorption of hydrogen sulfide at 500–700 °C. The sorbents showed good desulphurization performance, the highest sulfur capacity of 1020 µmol S/g over 5La5Mn/ZSM-5 was obtained at 600 °C. The reducing gases (H2 and CO) can obviously shorten the breakthrough time and reduce the sulfur capacity. Incorporating Mn ions into La2O3 lattice improved the sulfidation activity due to the formation of perovskite LaMnO3 with good reducibility and structure stability.

xCeyMn/ZSM-5 sorbents were prepared using sol–gel method and employed for H2S removal in the temperature range of 600–800 °C. The sorbents exhibited high performance in sulfur removal due to the cooperative effect of CeO2 and MnOx. The presence of H2 was unfavorable for sulfidation and obviously shortened the breakthrough time and reduced the sulfur capacity. However, the existence of CO had little impact on the sulfur-removal performance. The characterization results revealed that the ZSM-5 structure remained intact during preparation and sulfidation process. And active species, such as CeO2 and Mn2O3, were well dispersed on ZSM-5, which would suppress the mechanical disintegration and improve the thermal stability of xCeyMn/ZSM-5.

A CuS microsphere is facilely synthesized by using one-pot template-free hydrothermal method and applied for the capture of elemental mercury (Hg0) from flue gas at low temperature. It exhibits outstanding Hg0 removal performance due to the presence of multiform sulfur active sites and the spherical-like morphology with abundant exposed active sites. The Hg0 removal efficiencies are all nearly 100% within 25−100 °C. Besides, NO and SO2 exert negligible impacts on Hg0 adsorption over the CuS microsphere. Cu2+ and S2− ions both participate in mercury removal process, which converts Hg0 into HgS. Therefore, the CuS microsphere seems to be a promising non-carbon adsorbent for Hg0 capture from flue gas.

Graphitic carbon nitride (g-C3N4) has attracted increasing interest owing to its unique electronic property, facile synthesis, chemical and thermal stability. In this work, a graphene-like g-C3N4 is synthesized by direct thermal polymerization of environmentally benign guanidine thiocyanate. The graphene-like g-C3N4 is further modified with NH4Br via incipient-wetness impregnation approach and applied to remove Hg0 from coal-fired flue gas. The results indicate that the optimal polymerization temperature is 700 °C. The Hg0 removal performance of g-C3N4 is enhanced by NH4Br modification. The optimal NH4Br content and reaction temperature range are 3 wt% and 120–180 °C, respectively. NO exerts a promotional effect on mercury removal, while SO2 displays a dual impact on Hg0 adsorption. Low concentration of SO2 is beneficial for mercury removal, whereas high concentration of SO2 restrains Hg0 removal to some extent. The edge carbons of g-C3N4 may function as the principal reactive sites for Hg0 removal. The Hg0 might be captured on the armchair edge carbons of the g-C3N4 by forming covalent carbon-mercury bonds via Lewis acid-base conjugation. Loading NH4Br onto g-C3N4 may produce carbenium bromine ion pairs at the zigzag edge carbons that represent as oxidation sites, which convert Hg0 into HgBr2. Besides, the adsorbed Hg0 may also be oxidized into HgO by the chemisorbed oxygen.

Mercury emission, derived from natural gas exploitation, metal sintering, coal gasification and combustion, gold mining, etc., has posed great threaten to the environment and human beings due to its volatility, mobility, toxicity, and bioaccumulation in ecosystem and food chains. Adsorption using carbon materials is regarded as one of the most promising techniques for mercury emission control due to its simple equipment, convenient operation, high removing efficacy, less secondary pollution, etc. This review comments the new research progress of elemental mercury capture by novel carbon-based sorbents in recent five years, particularly emerging carbon materials, such as bio-chars, graphene and graphene oxide, carbon nanotubes and nanofibers, carbon spheres, carbon aerogels, metal-organic frameworks, and graphitic carbon nitrides. The mercury removal performances and reaction mechanisms of diverse carbon-based sorbents along with their merits and drawbacks are fully discussed, which aims to strengthen the understanding of this emerging research topic and outline future research directions for the development of sustainable, recyclable, and cost-effective carbon-based mercury sorbents.

Mesoporous carbon aerogels (MCA) synthesized via aqueous polymerization of resorcinol and formaldehyde were modified by copper chloride and applied for adsorption removal of elemental mercury (Hg0) at a low temperature. The sorbents were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), nitrogen adsorption/desorption isotherms, and X-ray photoelectron spectroscopy (XPS) techniques. The results show that CuCl2-modified MCA exhibited good ability for Hg0 adsorption in the 40&ndash, 160 &deg, C temperature range, with Hg0 removal efficiency all above 95.0%. The Hg0 removal efficiency first increased and then decreased with the elevation of reaction temperature. It performed optimally at 80 &deg, C with the highest Hg0 removal efficiency of 98.7%. XPS results indicate that covalent chlorines (C-Cl groups) play an important role in elemental mercury adsorption process. Hg0 is firstly captured in the form of oxidized mercury (Hg2+) and then reacts with C-Cl groups to form HgCl2.

Graphitic carbon nitride (g-C3N4) with unique and versatile properties has gained increasing research concerns. Here, CuO/g-C3N4 nanocomposite is fabricated and employed for gas-phase mercury (Hg0) removal at low temperature. Pure g-C3N4 performs well toward Hg0 adsorption at 40–200 °C with the optimal Hg0 removal efficiency of ~ 54.5% at 120 °C. CuO-modification can significantly promote the Hg0 capture ability of g-C3N4, probably due to the intimate interface contact of CuO and g-C3N4. The Hg0 removal efficiency of g-C3N4 first increases and then decreases with rising temperature, while temperature shows a promotional effect on Hg0 removal efficiency of CuO/g-C3N4. Hg0 is oxidized into HgO by the chemisorbed oxygen originated from the O–C–N structure of g-C3N4 and the lattice oxygen of CuO. g-C3N4 can be efficiently activated by modifying with CuO toward enhanced Hg0 oxidation ability, presumably attributed to the electron transfer at the interface of CuO and g-C3N4.

By using the density functional theory, the first-principles calculations were used to research the gas sensitive properties of small gas molecules (H 2 S, SO 2 , NH 3 , H 2 O, O 2 ) on the blue phosphorene monolayer. Parameters of adsorption energy, adsorption distance as well as charge transfer helped us find the optimum adsorption point from three adsorption sites: Center; P; Bridge. By the results of electronic density of states and electron localization function, we can make a conclusion that these five gas molecules are physically adsorbed on blue phosphorene. Besides, it is also clear that small gas molecules adsorption can tune the band gap and work function of blue phosphorene in different degrees. Our studies can provide a theoretical guidance for practical applications.

In recent years, all kinds of heat dissipation method are carried out for high-power high-density packaging devices such as an air forced convection heat sink, single phase liquid-cooled cold plate, two-phase cold plate and so on. With the nanotechnology development, high conductivity, low thermal resistance material and sintering connect technology was developed for Micro/Nanoelectromechanical Systems (MEMS/NEMS). In this background, nano silver/graphene composite paste material was prepared to study thermal transport performance for the demand of electronic product under high temperature condition. Firstly, the different ratio of nano silver/graphne composite material was prepared by a third step method. The morphology feature of the sample was observed and the thermogravimetry (TG) curve and differential scanning calorimetry (DSC) were studied to analyze the thermal properties and crystallization behaviors, respectively. Secondly, the two kinds of finite element models of chip/substrate and LED device and heat sink are established by using ANSYS software. Thirdly, the temperature distribution and equivalent stress of three thermal interface materials such as thermal grease, solder and composite material for two models were investigated. The obtained results are important for the application of TIM in high power device.

Urban gas transmission and distribution system mainly consists of three subsystems: storage station, gas network, and users. The subsystem fault trees are established on the basis of the in...

Fe2O3, Co3O4 and NiO nanoparticles were prepared via a citrate method and further functionalized with Pd by impregnation. The pure oxides as well as Pd/Fe2O3, Pd/Co3O4, and Pd/NiO (1, 5 and 10 wt % Pd) were employed for catalytic methane combustion under methane lean (1 vol %)/oxygen rich (18 vol %, balanced with nitrogen) conditions. Already, the pure metal oxides showed a high catalytic activity leading to complete conversion temperature of T100 ≤ 500 °C. H2-TPR (Temperature-programmed reduction) experiments revealed that Pd-functionalized metal oxides exhibited enhanced redox activity compared to the pure oxides leading to improved catalytic combustion activity at lower temperatures. At a loading of 1 wt % Pd, 1Pd/Co3O4 (T100 = 360 °C) outperforms 1Pd/Fe2O3 (T100 = 410 °C) as well as 1Pd/NiO (T100 = 380 °C). At a loading of 10 wt % Pd, T100 could only be slightly reduced in all cases. 1Pd/Co3O4 and 1Pd/NiO show reasonable stability over 70 h on stream at T100. XPS (X-ray photoelectron spectroscopy) and STEM (Scanning transmission electron microscopy) investigations revealed strong interactions between Pd and NiO as well as Co3O4, respectively, leading to dynamic transformations and reoxidation of Pd due to solid state reactions, which leads to the high long-term stability.

Fe2O3/ZSM-5 modified with Ce via citrate route (sol-gel approach) is applied for H2S removal in 500–700 °C temperature range. The sulfidation activity of Fe2O3/ZSM-5 is appreciably promoted by introduction of Ce plausibly attributed to the synergy of Fe2O3 and CeO2. 5Fe5Ce/ZSM-5 performs the optimal desulfurization behavior at 600 °C with sulfur capacity of 1020 μmol S/g, and the sulfidation process conforms to non-catalytic gas-solid redox reaction mechanism, which yields FeS2, Ce2S3, and S. Fractal analysis is introduced to evaluate the surface porous structure and the adsorption capacity of the sorbent. Its surface fractal dimension is estimated by using Frenkel-Halsey-Hill (FHH) model. It considerably increases after sulfidation plausibly attributed to the formation of a few heterogeneous sulfides or elemental sulfur, which block or cover the surface pore structures of sorbents.

Coal is found in huge amounts throughout the world and has lower cost as compared to other fossil fuels, it represents at present about 70% of the world’s proven fossil fuel resources; therefore, coal is probably to remain one of the most important sources of primary energy for a long time, playing a strategic role in the medium–long-term energy production systems. However, coal utilization has a few negative impacts on the environment and atmosphere; the critical issue in promoting coal utilization is environmental pollution control without reducing the energy efficiency. Coal is a complex chemical mixture composed of carbon, hydrogen, and dozens of trace elements. When coal is severed as a fuel source, some of these elements would convert to gaseous emissions, such as sulfur dioxide (SO2) or hydrogen sulfide (H2S), nitrogen oxides (NO x ), mercury, and other chemical by-products via the coal combustion or thermal decomposition. These emissions have been established to possess detrimental effects on the environment and human health, which contributes to acid rain, lung cancer, and cardiovascular disease.

The new three-dimensional structure that the graphene connected with SWCNTs (G-CNTs, Graphene Single-Walled Carbon Nanotubes) can solve graphene and CNTs′ problems. A comprehensive study of the mechanical and electrical performance of the junctions was performed by first-principles theory. There were eight types of junctions that were constituted by armchair and zigzag graphene and (3,3), (4,0), (4,4), and (6,0) CNTs. First, the junction strength was investigated. Generally, the binding energy of armchair G-CNTs was stronger than that of zigzag G-CNTs, and it was the biggest in the armchair G-CNTs (6,0). Likewise, the electrical performance of armchair G-CNTs was better than that of zigzag G-CNTs. Charge density distribution of G-CNTs (6,0) was the most homogeneous. Next, the impact factors of the electronic properties of armchair G-CNTs were investigated. We suggest that the band gap is increased with the length of CNTs, and its value should be dependent on the combined effect of both the graphene’s width and the CNTs’ length. Last, the relationship between voltage and current (U/I) were studied. The U/I curve of armchair G-CNTs (6,0) possessed a good linearity and symmetry. These discoveries will contribute to the design and production of G-CNT-based devices.

In this work, the work function (WF) of graphenes, which are used as electronic devices, has been designed and evaluated by using the first-principle approach. Different states of graphene were considered, such as surface modification, doping, and defects. Firstly, WF strongly depends on the width of pristine graphene. A bigger width leads to a smaller WF. In addition, the effects of hydroxyls, defects, and positions of hydroxyls and defects are of concern. The WF of the graphene which is modified with hydroxyls is bigger than that of the pristine graphene. Moreover, the WF value increases with the number of hydroxyls. Positions of the hydroxyls and defects that deviated from the center have limited influence on the WF, whereas the effect of the position in the center is substantial. Lastly, B, N, Al, Si, and P are chosen as the doping elements. The n-type graphene doped with N and P atoms results in a huge decline in the WF, whereas the p-type graphene doped with B and Al atoms causes a great increase in the WF. However, the doping of Al in graphene is difficult, whereas the doping of B and N is easier. These discoveries will provide heavy support for the production of graphene-based devices.

Zeolite (ZSM-5), as a kind of carbon-free sorbent or catalyst, has been widely applied in many fields due to its big surface area, good chemical and thermal stability, and excellent adsorption performance. In this study, Mn-Fe modified ZSM-5 are synthesized via sol-gel approach and employed for elemental mercury (Hg0) removal from simulated flue gas at low temperature. The results show that pure ZSM-5 shows poor mercury capture ability with Hg0 removal efficiency of ~8.5–18.8% at 100–300 °C. Mn or Fe modification can both efficiently enhance the Hg0 removal efficiency of the ZSM-5. The sorbent with Mn/Fe molar ratio of 1:2 exhibits the optimal mercury capture ability with the highest Hg0 removal efficiency near 100% at temperatures of 200 and 250 °C due to the significant synergy effect between Mn2O3 and Fe2O3. The presence of NO has a negligible effect on the Hg0 removal performance of Mn/ZSM-5 and Mn1Fe2/ZSM-5, while the existence of SO2 considerably degrades the Hg0 capture performance of Mn/ZSM-5 owing to competing adsorption and side reactions. Fe addition can protect Mn active sites from SO2 poisoning and thereby enhancing the SO2 resistance of Mn/ZSM-5 to some extent.

The kinetic behavior of gas phase mercury sorption on ZSM-5 supported cerium- and lanthanum-based composite oxides in the temperature range of 120–240∘C is investigated. The Hg0 sorption abilities all first increase and then decrease with the elevation of the temperatures, the cerium-based composite oxides show better Hg0 sorption abilities than that of the lanthanum-based composite oxides. CeO2–Mn2O3/ZSM-5 performs the best Hg0 sorption ability with Hg0 removal efficiency of nearly 100% at 180∘C. Doping Cu or Mn into La2O3 lattice causes the decrease in the Hg0 removal efficiency of the lanthanum-based composite oxides due to the formation of perovskite or perovskite-like compounds. The sorption of elemental mercury over metal oxides is governed both by diffusion processes as well as chemical reactions, and the sorption of elemental mercury on the cerium- and lanthanum-based composite oxides are chemisorption processes.

From the perspective of the irreversible energy loss of the second law of thermodynamics, that is entropy generation, theoretical analysis on the influence of delamination appeared at the die attach (DA) layer on the chip junction temperature of high power LED-COB package is carried out. First, thermal simulation of chip-on-board LED package with different position of interface delamination is investigated. The results show that delamination occurs at the edge position is more harmful for blocking heat transfer in the overall LED package than that of the center position. Second, entropy generation of edge position and center position in die attach layer with non-delamination is calculated. In the same conditions, the entropy generation value of the edge position is larger than that of the center position, that is, compared to center position, the larger irreversible heat flux loss in the edge position of die attach in the heat conduction process is higher.

At present, owing to the remarkable properties of mechanical properties and electrical conductivity, the carbon nanotubes (CNTs) have been used in many areas such as sensors, field-effect transistor (FET), photoelectronic devices and composite materials, etc. It should be noted that the performance of electronic device is depended on the properties of CNTs. Therefore, we investigated the mechanical properties of pristine and modified CNTs and their corresponding electrical conductivity (the band structure) under the tensile behavior through the first principle theory based on density functional theory (DFT). First of all, the pristine (10, 0) CNTs were chose and their mechanical properties were calculated. The results showed that the pristine (10, 0) CNTs had an excellent ductility that the deformation can be up to 18%. Then, the band gaps corresponding to the deformation were analyzed. We found that the band gap was increased with the degree of deformation. At last, the mechanical properties of the modified (10, 0) CNTs was studied. Compared with the pristine CNTs, the CNTs modified with hydroxyl had larger ductility and yield strength. These discoveries will provide a heavy support for the CNTs based nano-sized devices.

In this paper a novel package structure of chip on board (COB) LED is proposed. Compared with the normal COB with a large number of layer structures, the substrate is removed in the novel. So the LED chip can directly bonded to the radiator, the cooling path is also effectively reduced. The heat generated by the chip can directly dissipate to the outside through the radiator. Then two kinds of finite element modules of LED package are established and simulated by ANSYS software, respectively. From the thermal analysis results, the junction temperature of the proposed module is 15°C lower than the normal one in the case of 4×4 modules, and the temperature distribution is also more uniform; from the thermal stress analysis results, the maximum stress of the novel is 55.0MPa lower than the normal in the case of 4×4 modules. So the results demonstrate the novel module structure of LEDCOB has a better heat dissipation and a lower thermal stress. And the results also provide a better suggestion for designing LED module structure in the future.

With the development of science and technology, the electronic devices trend to miniaturization and high-density integration. And the nano-scale device becomes the inevitable trend. The thermal dissipation question was concerned as following. The thermal conductivity of graphene and silicon heterostructure is investigated by molecular dynamic simulation in this paper. The relationship between thermal conductivity and temperature is analyzed when the contact defect area is from 0 to 35%. The thermal conductivity of the model is calculated from 300K to 800K. It was found that when the temperature was between 300K∼800K, the thermal conductivity of the perfect heterostructure showed a decreasing tendency. However, when the temperature was between 300K∼500K, the thermal conductivity showed slowly rising tendency. When the defect contact area of heterostructure's reached to 35%, it was thought that the main reason for the decrease of thermal conductivity affected by the temperature was the coupling of the graphene phonon ZA mode and silicon wave. Our results show that graphene can enhance the thermal transfer properties of silicon nanofilm. The investigation implies that graphene can open up opportunities for MEMS/NEMS devices.

In this paper, a novel new package solution for CMOS image sensor (CIS) based on molding compound interconnect substrate (MIS) is proposed. First, a 13 million pixel CIS packaged by quad flat no lead (QFN) is chosen as a reference. Considering the design parameters, a new package structure based on MIS is designed. Second, Two kinds of three-dimensional finite element models of CIS package are respectively established by ANSYS Workbench. One is packaged by QFN, and the other one is packaged by MIS. Then the thermal-mechanical property of the two package structures during the cooling process just after molding is analyzed. In the initial simulation, warpage of new package structure based on MIS is 22.915µm, which is less than it in QFN model. However, the peak equivalent stress in CIS chip of QFN is 74.307Mpa much less than 335.53Mpa in MIS model. Third, as the geometry parameters and epoxy molding compound (EMC) characteristics influencing the reliability of the package, a series of comprehensive parametric studies are conducted in this paper. From the simulation, the opening size and the CTE of EMC are found to be the most critical factors, which affect the warpage of package and equivalent stress in CIS chip.