In this work,we investigated the methanol steam reforming(MSR)reaction(CH_(3)OH+H_(2)O→CO_(2)+3H_(2))catalyzed byα-MoC by means of density functional theory calculations.The adsorption behavior of the relevant inter...In this work,we investigated the methanol steam reforming(MSR)reaction(CH_(3)OH+H_(2)O→CO_(2)+3H_(2))catalyzed byα-MoC by means of density functional theory calculations.The adsorption behavior of the relevant intermediates and the kinetics of the elementary steps in the MSR reaction are systematically investigated.The results show that,on theα-MoC(100)surface,the O−H bond cleavage of CH3OH leads to CH3O,which subsequently dehydrogenates to CH_(2)O.Then,the formation of CH_(2)OOH between CH_(2)O and OH is favored over the decomposition to CHO and H.The sequential dehydrogenation of CH_(2)OOH results in a high selectivity for CO_(2).In contrast,the over-strong adsorption of the CH_(2)O intermediate on theα-MoC(111)surface leads to its dehydrogenation to CO product.In addition,we found that OH species,which is produced from the facile water activation,help the O−H bond breaking of intermediates by lowering the reaction energy barrier.This work not only reveals the catalytic role played byα-MoC(100)in the MSR reaction,but also provides theoretical guidance for the design ofα-MoC-based catalysts.展开更多
Electrostatic torsional micromirrors are widely applied in the fields·of micro-optical switches,optical attenuators,optical scanners,and optical displays.In previous lectures,most of the micromirrors were twisted...Electrostatic torsional micromirrors are widely applied in the fields·of micro-optical switches,optical attenuators,optical scanners,and optical displays.In previous lectures,most of the micromirrors were twisted along the urtiaxial or biaxial direction,which limited the range of light reflection.In this·paper,a quasicrystal torsional micromirror that can be deflected in any direction is designed and the dynamic model of the electrostatically driven micromirror is established.The static and dynamic phenomena and pull-in characteristics are analyzed through the numerical solution of the strain gradient theory.The results of three kinds of mirror deflection directions are compared and analyzed.The results show the significant differences in the torsion models with different deflection axis directions.When the deflection angle along the oblique axis reaches 45°,the instability voltage is the smallest.The pull-in instability voltage increases with the increment ofphonon-phason coupling elastic modulus and phason elastic modulus.The perrriittivity of quasicrystal,the strain gradient parameter,and the air damping influence the torsion of the micromirror dynaniic system.A larger pull-in instability voltage generates with the decrease of surface distributed forces.展开更多
基金This work is supported by the National Natural Science Foundation of China(No.21973013)the National Natural Science Foundation of Fujian Province,China(No.2020J02025)the“Chuying Program”for the Top Young Talents of Fujian Province.Numerical computations were performed on Hefei Advanced Computing Center.
文摘In this work,we investigated the methanol steam reforming(MSR)reaction(CH_(3)OH+H_(2)O→CO_(2)+3H_(2))catalyzed byα-MoC by means of density functional theory calculations.The adsorption behavior of the relevant intermediates and the kinetics of the elementary steps in the MSR reaction are systematically investigated.The results show that,on theα-MoC(100)surface,the O−H bond cleavage of CH3OH leads to CH3O,which subsequently dehydrogenates to CH_(2)O.Then,the formation of CH_(2)OOH between CH_(2)O and OH is favored over the decomposition to CHO and H.The sequential dehydrogenation of CH_(2)OOH results in a high selectivity for CO_(2).In contrast,the over-strong adsorption of the CH_(2)O intermediate on theα-MoC(111)surface leads to its dehydrogenation to CO product.In addition,we found that OH species,which is produced from the facile water activation,help the O−H bond breaking of intermediates by lowering the reaction energy barrier.This work not only reveals the catalytic role played byα-MoC(100)in the MSR reaction,but also provides theoretical guidance for the design ofα-MoC-based catalysts.
基金supported by the National Natural Science Foundation of China(Grant Nos.11572191,51701117,and 51779139).
文摘Electrostatic torsional micromirrors are widely applied in the fields·of micro-optical switches,optical attenuators,optical scanners,and optical displays.In previous lectures,most of the micromirrors were twisted along the urtiaxial or biaxial direction,which limited the range of light reflection.In this·paper,a quasicrystal torsional micromirror that can be deflected in any direction is designed and the dynamic model of the electrostatically driven micromirror is established.The static and dynamic phenomena and pull-in characteristics are analyzed through the numerical solution of the strain gradient theory.The results of three kinds of mirror deflection directions are compared and analyzed.The results show the significant differences in the torsion models with different deflection axis directions.When the deflection angle along the oblique axis reaches 45°,the instability voltage is the smallest.The pull-in instability voltage increases with the increment ofphonon-phason coupling elastic modulus and phason elastic modulus.The perrriittivity of quasicrystal,the strain gradient parameter,and the air damping influence the torsion of the micromirror dynaniic system.A larger pull-in instability voltage generates with the decrease of surface distributed forces.
