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Dual single-atom Ce-Ti/MnO2 catalyst enhances low-temperature NH3-SCR performance with high H2O and SO2 resistance
No full textMn-based catalysts have exhibited promising performance in low-temperature selective catalytic reduction of NOx with NH3 (NH3-SCR). However, challenges such as H2O- or SO2-induced poisoning to these catalysts still remain. Herein, we report an efficient strategy to prepare the dual single-atom Ce-Ti/MnO2 catalyst via ball-milling and calcination processes to address these issues. Ce-Ti/MnO2 showed better catalytic performance with a higher NO conversion and enhanced H2O- and SO2-resistance at a low-temperature window (100-150 degrees C) than the MnO2, single-atom Ce/MnO2, and Ti/MnO2 catalysts. The in situ infrared Fourier transform spectroscopy analysis confirmed there is no competitive adsorption between NOx and H2O over the Ce-Ti/MnO2 catalyst. The calculation results showed that the synergistic interaction of the neighboring Ce-Ti dual atoms as sacrificial sites weakens the ability of the active Mn sites for binding SO2 and H2O but enhances their binding to NH3. The insight obtained in this work deepens the understanding of catalysis for NH3-SCR. The synthesis strategy developed in this work is easily scaled up to commercialization and applicable to preparing other MnO2-based single-atom catalysts
Dual single-atom Ce-Ti/MnO2 catalyst enhances low-temperature NH3-SCR performance with high H2O and SO2 resistance
No full textMn-based catalysts have exhibited promising performance in low-temperature selective catalytic reduction of NOx with NH3 (NH3-SCR). However, challenges such as H2O- or SO2-induced poisoning to these catalysts still remain. Herein, we report an efficient strategy to prepare the dual single-atom Ce-Ti/MnO2 catalyst via ball-milling and calcination processes to address these issues. Ce-Ti/MnO2 showed better catalytic performance with a higher NO conversion and enhanced H2O- and SO2-resistance at a low-temperature window (100-150 degrees C) than the MnO2, single-atom Ce/MnO2, and Ti/MnO2 catalysts. The in situ infrared Fourier transform spectroscopy analysis confirmed there is no competitive adsorption between NOx and H2O over the Ce-Ti/MnO2 catalyst. The calculation results showed that the synergistic interaction of the neighboring Ce-Ti dual atoms as sacrificial sites weakens the ability of the active Mn sites for binding SO2 and H2O but enhances their binding to NH3. The insight obtained in this work deepens the understanding of catalysis for NH3-SCR. The synthesis strategy developed in this work is easily scaled up to commercialization and applicable to preparing other MnO2-based single-atom catalysts
Two-dimensional ionic liquids with an anomalous stepwise melting process and ultrahigh CO2 adsorption capacity
No full textUltrathin ionic liquid (IL) films have shown wide applications in the chemistry and materials fields. However, the structure feature and quantitative controlling mechanism of thin IL films have rarely been reported to date. Here, computational simulations combined with scanning tunnel microscope experiments are used to quantify the structure and function of the thinnest possible IL films, two-dimensional (2D) ILs, which consist of 2D ordered mono-ionic IL structures. Interestingly, the 2D ILs exhibit anomalous stepwise melting processes, involving localized rotated, out-of-plane flipped, and fully disordered states, which are different from 3D ILs. Meanwhile, a theoretical model and temperature-surface phase diagram are constructed to evaluate the critical stepwise melting behaviors. Furthermore, the 2D ILs also possess ultrahigh CO2 adsorption capabilities and structural robustness during the CO2 adsorption -desorption process. These findings are promising for the rational design of an IL-solid interface for CO2-capture-fixation chemistry and related applications
Effects of high current density on the characteristics of zinc films electroplated in ethaline electrolyte
No full textZinc coatings on Cu substrates were successfully electroplated from choline chloride (ChCl) with ethylene glycol (EG) based deep eutectic solvent with the current density varied from 10 to 40 mA cm(-2) in air atmosphere at a temperature of 343 K. The effects of current density on the microstructure and corrosion performance were investigated in this paper. Smooth zinc coatings were obtained at the current density of 10 mA cm(-2) with a current efficiency of over 90 %. With the increase in current density, there was a declining trend in the current efficiency and the surface quality of zinc coatings. Although there was no diffusion layer between the coating and substrates, all the zinc coatings still bonded well with the copper substrates. Compared with the smooth zinc coating electroplated at 10 mA cm(-2), the zinc coating obtained at 40 mA cm(-2) exhibited a better corrosion resistance in 3.5 wt.% NaCl aqueous solution due to the dense packing of the large number of flake zinc grains
Role of transition metals in catalyst designs for oxygen evolution reaction: A comprehensive review
No full textWith the increasing demand for sustainable energy, human beings put forward higher requirements for the preparation of clean energy. Electrocatalytic water splitting has become a promising way to solve the energy crisis because of the characteristics of high efficiency and cleanliness. The catalyst of oxygen evolution reaction (OER), an important part of electrocatalytic water splitting, plays a critical role in water splitting. Transition metals (TMs) are generally used as active sites to realize high-efficiency electrocatalytic in the water. To better understand the role of TMs in the OER catalysts. This review focused on the relationship between TMs and OER catalyst activity. The mechanism of synthesis strategy in different types of TMs-based catalysts was also summarized. The challenges and prospects of developing economic and efficient TMs-based OER catalysts were discussed. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved
Tuning interfacial ion distribution to improve energy density of supercapacitors
No full textSupercapacitors as energy carriers have the advantages of high-power efficiency and long-term stability. An improvement of their energy density promises a solution to make up for the weakness of secondary batteries at a high rate of applications. Here we report an attempt to improve the energy density of supercapacitor by tuning ions arrangement at the electrode-electrolyte interface. Upon the theoretical analysis with classical density functional theory (CDFT), we find that the capacitance of the supercapacitor is maximized at a mediate con-centration of electrolytes, i.e., 1.0 M, where ions accumulate near the electrode surface and display a few multilayered oscillatory distributions. Further, by adjusting the dielectric constant of electrolyte solution and the electrode surface voltage, the interfacial ion distribution is tuned to optimize the energy density of super -capacitors. The theoretical results are corroborated by designed experiments, confirming the role of interfacial ion distribution in specific capacitance. This study shows that an appropriate interfacial ion distribution is beneficial to obtaining high capacitance, highlighting an unusual solution to improve the energy density of supercapacitors
Ab Initio Study of Structure and Transport Properties of Warm Dense Nitric Oxide
No full textThe structure, equation of state and transport properties of warm dense nitric oxide (NO) were investigated in wide density and temperature ranges by ab initio molecular dynamics simulations. Both the Perdew-Burke-Ernzerhof (PBE) and the strongly constrained and appropriately normed functional with revised Vydrov-van Voorhis nonlocal correlation (SCAN-rVV10) functionals were used in the simulations, and the pressures predicted by the SCAN-rVV10 functional were found to be systematically lower than those predicted using PBE and experimental data along the shock Hugoniot curve. Along the Hugoniot curve, as density increased, we found that the system transformed towards a mixture of atomic nitrogen and oxygen liquids with molecular NO that remained present up to the highest densities explored. The electrical conductivity along Hugoniot indicated that nonmetal to metal transition had taken place. We also calculated the electrical and thermal conductivities of nitric oxide in the warm dense matter regime, and used them to compute the Lorentz number. In addition, we also report the electronic density of states
A novel synthetic method of porous and nanoflower-like Al2O3/MoS2 catalyst for reduction of SO2 to elemental sulfur
No full textMoS2 nanoflowers are favored for their potential in the production of elemental sulfur due to abundant surface area and good catalytic performance for reducing SO2. A novel synthetic strategy of porous Al2O3 supported on the MoS2 with nanoflower structure was proposed. The effects of preparation concentration, calcination atmosphere, and Al2O3 contents on the growth of catalysts with nanoflower structure were systematically studied via X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and Brunauer-Emmett-Teller (BET). The surface area was increased to 295.502 m(2)/g and the amount of Lewis acid on the surface of the Al2O3/MoS2 catalyst was increased by adjusting the ratio of Al/Mo. The porous and nanoflower structures of Al2O3/MoS2 catalysts promoted the sulfur selectivity without inhibiting the catalytic performance of MoS2. The conversion of SO2 and the selectivity of sulfur were 100% and 92% after 100 h life evaluation