Coil-to-Stretch Transition of Binder Chains Enabled by “Nano-Combs” to Facilitate Highly Stable SiOx Anode

The commercialized binder carboxymethyl cellulose sodium(CMC-Na) is considered unsuitable for micro-sized SiO_x anode as it cannot endure the large volume change to retain the conductive network during repeated charge/discharge cycles. Herein, a small amount of silicon nanoparticles(SiNPs) is added during slurry preparation process as “nano-combs” to unfold the convoluted CMC-Na polymer chains so that they undergo a coilto-stretch transition by interaction between polar groups(e.g., –O...     

Molybdenum Oxynitride Atomic Nanoclusters Bonded in Nanosheets of N-Doped Carbon Storage

Transition metal nitrides have attracted considerable attention as great potential anode materials due to their excellent metallic conductivity and high theoretical specific capacity.However,their cycling performance is impeded by their instability caused by the reaction mechanism.Herein,we report the engineering and synthesis of a novel hybrid architecture composed of MoO_2.0N_0.5 atomic nanoclusters bonded in nanosheets of N-doped carbon hierarchical hollow microspheres(MoO...     

Evaluation on the natural gas hydrate formation process

Gas hydrates have endowed with great potential in gas storage, and rapid formation of gas hydrates is critical to use this novel technology. This work evaluated the natural gas hydrate formation process, which was compared from six parameters, including conversion of water to hydrate, storage capacity, the rate of hydrate formation, space velocity (SV) of hydrate reaction, energy consumption and hydrate removal. The literature was selected by analyzing and comparing these six parameters mentioned above, meanwhile placing emphasis on the three parameters of storage capacity, the rate of hydrate formation and space velocity of hydrate reaction. Through analysis and comparison, four conclusions could be obtained as follows. Firstly, the overall performance of the stirring process and the spraying process were better than other processes after analyzing the six parameters. Secondly, the additive types, the reactor structure and the reactor size had influence on the natural gas hydrate formation process. Thirdly, the energy consumption via reciprocating impact in the hydrate formation process was higher than that via stirring, spraying and static higee. Finally, it was one key for hydrate removal to realize the hydrate industrial production.     

Simultaneously Regulating Uniform Zn2+ Flux and Electron Conduction by MOF/rGO Interlayers for High‑Performance Zn Anodes

Owing to the merits of low cost,high safety and environmental benignity,rechargeable aqueous Zn-based batteries(ZBs)have gained tremendous attention in recent years.Nevertheless,the poor reversibility of Zn anodes that originates from dendrite growth,surface passivation and corrosion,severely hinders the further development of ZBs.To tackle these issues,here we report a Janus separator based on a Zn-ion conductive metal-organic framework(MOF)and reduced graphene oxide(rGO),which is able to regulate uniform Zn2+flux and electron conduction simultaneously during battery operation.Facilitated by the MOF/rGO bifunctional interlayers,the Zn anodes demonstrate stable plating/stripping behavior(over 500 h at 1 mA cm^?2),high Coulombic efficiency(99.2%at 2 mA cm^?2 after 100 cycles)and reduced redox barrier.Moreover,it is also found that the Zn corrosion can be effectively retarded through diminishing the potential discrepancy on Zn surface.Such a separator engineering also saliently promotes the overall performance of Zn|MnO2 full cells,which deliver nearly 100%capacity retention after 2000 cycles at 4 A g^?1 and high power density over 10 kW kg^?1.This work provides a feasible route to the high-performance Zn anodes for ZBs.     

Immobilization of trophic anaerobic acetogen for semi-continuous syngas fermentation

The massive consumption of fossil energy forces people to find new sources of energy. Syngas fermentation has become a hot research field as its high potential in renewable energy production and sustainable development. In this study, trophic anaerobic acetogen Morella thermoacetica was successfully immobilized by calcium alginate embedding method. The ability of the immobilized cells on production of acetic acid through syngas fermentation was compared in both airlift and bubble column bioreactors. The bubble column bioreactor was selected as the better type of bioreactor. The production of acetic acid reached 32.3 g·L^-1 in bubble column bioreactor with a space-time yield of 2.13 g·L^-1·d^-1. The immobilized acetogen could be efficiently reused without significant lag period, even if exposed to air for a short time. A semi-continuous syngas fermentation was performed using immobilized cells, with an average space-time acetic acid yield of 3.20 g·L^-1·d^-1. After 30 days of fermentation, no significant decrease of the acetic acid production rate was observed.     

Catalytic hydrogenation performance of ZIF-8 carbide for electrochemical reduction of carbon dioxide

The conversion of CO₂ electrocatalytic hydrogenation into energy-rich fuel is considered to be the most effective way to carbon recycle. Nitrogen-doping carbonized ZIF-8 is proposed as carrier of the earth-rich Sn catalyst to overcome the limit of electron transfer and CO₂ adsorption capacity of Sn. Hierarchically porous structure of Sn doped carbonized ZIF-8 is controlled by hydrothermal and carbonization conditions, which induces much higher specific surface area than that of the commercial Sn nanoparticle (1003.174 vs. 7.410 m²·g^-1). The shift of nitrogen peaks in X-ray Photoelectron Spectroscopy spectra indicates interaction between ZIF-8 and Sn, which induces the shift of electron cloud from Sn to the chemical nitrogen to enhance conductivity and regulate electron transfer from catalyst to CO₂. Lower mass transfer resistance and Warburg resistance are investigated through EIS, which significantly improves the catalytic activity for CO₂ reduction reaction (CO₂RR). Onset potential of the reaction is reduced from -0.74 V to less than -0.54 V vs. RHE. The total Faraday efficiency of HCOOH and CO reaches 68.9% at -1.14 V vs. RHE, which is much higher than that of the commercial Sn (45.0%) and some other Sn-based catalyst reported in the literature.     

Kinetic study for the oxidation of cyclohexanol and cyclohexanone with nitric acid to adipic acid

The adipic acid is an important intermediate in the production of nylon, polyurethane and polyester resins. The industrial approach for preparing adipic acid is through the liquid catalytic oxidation of KA oil with nitric acid. In this work, a comprehensive model is developed for this reaction based on the kinetic study conducted in a continuous flow tubular reactor. The kinetic model fits well with the experimental results across the experimental conditions, and the average relative error between the calculated and experimental values is 5.7%. Results show that there was an induction period at the early stage of reaction. Moreover, it is found that at temperature range of 328-358 K, the formation rate of adipic acid strongly dependents on the temperature and nitric acid concentration. The developed model is used to predict the yield of adipic acid at 359-368 K. The work in this study could provide much knowledge for industrial tubular reactor design.     

Contact fatigue life prediction of a bevel gear under spectrum loading

Rolling contact fatigue (RCF) issues, such as pitting, might occur on bevel gears because load fluctuation induces considerable subsurface stress amplitudes. Such issues can dramatically affect the service life of associated machines. An accurate geometry model of a hypoid gear utilized in the main reducer of a heavy-duty vehicle is developed in this study with the commercial gear design software MASTA. Multiaxial stress–strain states are simulated with the finite element method, and the RCF life is predicted using the Brown–Miller–Morrow fatigue criterion. The patterns of fatigue life on the tooth surface are simulated under various loading levels, and the RCF S–N curve is numerically generated. Moreover, a typical torque–time history on the driven axle is described, followed by the construction of program load spectrum with the rain flow method and the Goodman mean stress equation. The effects of various fatigue damage accumulation rules on fatigue life are compared and discussed in detail. Predicted results reveal that the Miner linear rule provides the most optimistic result among the three selected rules, and the Manson bilinear rule produces the most conservative result.     

Study of the mechanisms of streamline-adjustment-assisted heterogeneous combination flooding for enhanced oil recovery for post-polymer-flooded reservoirs

Streamline-adjustment-assisted heterogeneous combination flooding is a new technology for enhanced oil recovery for postpolymer- flooded reservoirs. In this work, we first carried out a series of 2D visualization experiments for different chemical flooding scenarios after polymer flooding. Then, we explored the synergistic mechanisms of streamline-adjustment-assisted heterogeneous combination flooding for enhanced oil recovery and the contribution of each component. Test results show that for single heterogeneous combination flooding, the residual oil in the main streamline area after polymer flooding is ready to be driven, but it is difficult to be recovered in the non-main streamline area. Due to the effect of drainage and synergism, the streamline-adjustment-assisted heterogeneous combination flooding diverts the injected chemical agent from the main streamline area to the non-main streamline area, which consequently expands the active area of chemical flooding. Based on the results from the single-factor contribution of the quantitative analysis, the contribution of temporary plugging and profile control of branched preformed particle gels ranks in the first place and followed by the polymer profile control and the effect of streamline adjustment. On the contrary, the surfactant contributes the least to enhance the efficiency of oil displacement.     

Acid-induced topological morphology modulation of graphitic carbon nitride homojunctions as advanced metal-free catalysts for OER and pollutant degradation

Topological morphology that dominates the surface electronic properties of nanostructures plays a key role in producing desired materials for versatile functions and applications in many fields,but its modula-tion for specific functions remains a big challenge.Herein,we report an acid-induced method to prepare S-doped graphitic carbon nitride/graphitic carbon nitride(S-CN/CN)homojunction by simply pyrolyzing a supramolecular precursor synthesized from melamine and H2SO4.The topological morphology and electronic structure of CN homojunction can be easily adjusted only by changing the ratio of raw materi-als.Moreover,the topological morphology of S-CN/CN homojunction can be further adjusted from hollow cocoon to 2D nanosheets by changing the annealing conditions.The optimized S-CN/CN homojunction shows highly efficient in charge transfer and separation and exhibits superior OER activity and high abil-ity to degrade organic pollutants.Impressively,S-CN/CN nanosheets only demand low overpotential of 301 mV to drive a current density of 10 mAcm-2 in 1 M KOH media,and the corresponding Tafel slope is only 57.71 mV/dec,which is superior to the most advanced precious metal IrO2 catalyst.Moreover,under visible light irradiation,its photodegradation kinetic rate of RhB is 2.38,which is 47.6 times higher than that of bulk CN.This work provides useful guidance for designing and developing efficient multifunctional metal-free catalysts.