Predicted a honeycomb metallic BiC and a direct semiconducting Bi2C monolayer as excellent CO2 adsorbents

We predicted two stable two-dimensional materials of carbon and bismuth elements, namely BiC and Bi₂C monolayers. The stabilities of two monolayers were examined by cohesive energy, Born criteria, firstprinciple MD simulations and phonon spectra, respectively. By including the spin-orbit coupling effects,the Bi C monolayer is a metal and the Bi₂C monolayer possesses a narrow direct（indirect） band gap of 0.403（0.126） e V under the HSE06（GGA-PBE） functional. For the adsorptio...     

Phase-mediated cobalt phosphide with unique core-shell architecture serving as efficient and bifunctional electrocatalyst for hydrogen evolution and oxygen reduction reaction

Hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) have been considered as two critical processes in the field of electrocatalytic water-splitting for hydrogen production and fuel cells. However, the sluggish reaction kinetics of HER and ORR required efficient electrocatalyst such as Pt to promote such process. Transition metal phosphides (TMPs) exhibit great potential to replace noble metal electrocatalysts to accelerate HER and ORR due to their high activity and easy availability. Herein, a highly-efficient bifunctional CoP electrocatalyst for HER and ORR, featuring a unique core-shell structure decorated on nitrogen-doped carbon matrix was designed and constructed via etching a cobalt-based zeolitic imidazolate framework (ZIF-67) with phytic acid (PA) followed by pyrolysis treatment (PA-ZIF-67–900). Experimental results revealed that the pure-phase single-crystalline CoP exhibited outstanding electrocatalytic performance in HER and ORR, superior to Co(PO₃)₂ in PA-ZIF-67–700, hybrid phase of Co(PO₃)₂ and CoP in PA-ZIF-67–800 and Co₂P-doped CoP in PA-ZIF-67–1000. To reach the current density of 10 mA/cm² the as-synthesized CoP required an overpotential of 120 mV for HER in 1 mol/L KOH and half-wave potential of 0.85 V in O₂-saturated 0.1 mol/L KOH. This work present new clue for construction of efficient and bifunctional electrocatalyst in the field of energy conversion and storage     

Electrochemical reaction mechanism of porous Zn2Ti3O8 as a high-performance pseudocapacitive anode for Li-ion batteries

Zn₂Ti₃O₈, as a new type of anode material for lithium-ion batteries, is attracting enormous attention because of its low cost and excellent safety. Though decent capacities have been reported, the electrochemical reaction mechanism of Zn₂Ti₃O₈ has rarely been studied. In this work, a porous Zn₂Ti₃O₈ anode with considerably high capacity (421 mAh/g at 100 mA/g and 209 mAh/g at 5000 mA/g after 1500 cycles) was reported, which is even higher than ever reported titanium-based anodes materials including Li₄Ti₅O₁₂, TiO₂ and Li₂ZnTi₃O₈. Here, for the first time, the accurate theoretical capacity of Zn₂Ti₃O₈ was confirmed to be 266.4 mAh/g. It was also found that both intercalation reaction and pseudocapacitance contribute to the actual capacity of Zn₂Ti₃O₈, making it possibly higher than the theoretical value. Most importantly, the porous structure of Zn₂Ti₃O₈ not only promotes the intercalation reaction, but also induces high pseudocapacitance capacity (225.4 mAh/g), which boosts the reversible capacity. Therefore, it is the outstanding pseudocapacitance capacity of porous Zn₂Ti₃O₈ that accounts for high actual capacity exceeding the theoretical one. This work elucidates the superiorities of porous structure and provides an example in designing high-performance electrodes for lithium-ion batteries.     

Combination of RSM and NSGA-II algorithm for optimization and prediction of thermal conductivity and viscosity of bioglycol/water mixture containing SiO2 nanoparticles

The fluids containing nanoparticles have enhanced thermo-physical characteristics in comparison with conventional fluids without nanoparticles. Thermal conductivity and viscosity are thermo-physical properties that strongly determine heat transfer and momentum. In this study, the response surface method was firstly used to derive an equation for the thermal conductivity and another one for the viscosity of bioglycol/water mixture (20:80) containing silicon dioxide nanoparticles as a function of temperature as well as the volume fraction of silicon dioxide. Then, NSGA-II algorithm was used for the optimization and maximizing thermal conductivity and minimizing the nanofluid viscosity. Different fronts were implemented and 20th iteration number was selected as Pareto front. The highest thermal conductivity (0.576 W/m.K) and the lowest viscosity (0.61 mPa.s) were obtained at temperature on volume concentration of (80 °C and 2%) and (80 °C without nanoparticle) respectively. It was concluded that the optimum thermal conductivity and viscosity of nanofluid could be obtained at maximum temperature (80 °C) or a temperature close to this temperature. An increase in the volume fraction of silicon dioxide led to the enhancement of thermal conductivity but the solution viscosity was also increased. Therefore, the optimum point should be selected based on the system requirement.     

Computational Screening of 3 d Transition Metal Atoms Anchored on Defective Graphene for Efficient Electrocatalytic N2 Fixation

The synthesis of ammonia (NH₃) through the electrochemical reduction of molecular nitrogen (N₂) is a promising strategy for significantly reducing energy consumption compared to traditional industrial processes. Herein, we report the design of a series of monovacancy and divacancy defective graphenes decorated with single 3d transition metal atoms (TM@MVG and TM@DVG; TM=Sc−Zn) as electrocatalysts for the nitrogen-reduction reaction (NRR) aided by density functional theory (DFT) calculations. By comparing energies for N₂ adsorption as well as the free energies associated with *N₂ activation and *N₂H formation, we successfully identified V@MVG, with the lowest potential of −0.63 V, to be an effective catalytic substrate for the NRR in an enzymatic mechanism. Electronic properties, including Bader charges, charge density differences, partial densities of states, and crystal orbital Hamilton populations, are further analyzed in detail. We believe that these results help to explain recent observations in this field and provide guidance for the exploration of efficient electrocatalysts for the NRR.     

Kinetics of glass transition,crystallization and soft magnetic properties of the Fe76.5Nb3B20Cu0.5 glassy alloys

Journal of Thermal Analysis and Calorimetry - Differential scanning calorimetry was used to investigate the non-isothermal crystallization kinetics of the Fe76.5Nb3B20Cu0.5 glassy alloys. The...     

Prediction of stable BC3N2 monolayer from first-principles calculations: Stoichiometry,crystal structure,electronic and adsorption properties

In this paper, a novel BC₃N₂ monolayer has been found with a graphene-like structure using the developed particle swarm optimization algorithm in combination with ab initio calculations. The predicted structure meets the thermodynamical, dynamical, and mechanical stability requirements. Interestingly, the BC₃N₂ plane shows a metallic character. Importantly, BC₃N₂ has an in-plane stiffness comparable to that of graphene. We have also investigated the adsorption characteristics of CO₂ on pristine monolayer and Mo functionalized monolayer using density functional theory. Subsequently, electronic structures of the interacting systems (CO₂ molecule and substrates) have been preliminarily explored. The results show that Mo/BC₃N₂ has a stronger adsorption capacity towards CO₂ comparing with the pristine one, which can provide a reference for the further study of the CO₂ reduction mechanism on the transition metal-functionalized surface as well as the new catalyst’s design.     

Cationic Nonporous Macrocyclic Organic Compounds for Multimedia Iodine Capture

Over the past two decades, progress in chemistry has generated various types of porous materials for removing iodine (¹²⁹I or ¹³¹I) that can be formed during nuclear energy generation or nuclear waste storage. However, most studies for iodine capture are based on the weak host-guest interactions of the porous materials. Here, we present two cationic nonporous macrocyclic organic compounds, namely, MOC-1 and MOC-2 , in which 6I^- and 8I⁻ were as counter anions, for highly efficient iodine capture. MOC-1 and MOC-2 were formed by reacting 1,1′-diamino-4,4′-bipyridylium di-iodide with 1,2-diformylbenzene or 1,3-diformylbenzene, respectively. The presence of a large number of I⁻ anions results in high I₂ affinity with uptake capacities up to 2.15 g ⋅ g⁻¹ for MOC-1 and 2.25 g ⋅ g⁻¹ for MOC-2 .     

Ce-promoted Fe–Cu–ZSM-5 catalyst: SCR-NO activity and hydrothermal stability

Research on Chemical Intermediates - Fe–Cu–ZSM-5 and Ce–Fe–Cu–ZSM-5 solids prepared using solid-state ion exchange method (SSIE) were tested in the NH3–SCR of NO...     

Improving the sensitivity of cellulose fiber-based lateral flow assay by incorporating a water-dissolvable polyvinyl alcohol dam

Cellulose - Lateral flow assay (LFA) is an important point-of-care (POC) test platform due to the associated portability, on-site testing, and low cost for diagnosis of pathogen infections and...