碳化铁θ-Fe_(3)C作为费托反应活性相之一,其氧化造成了催化剂的严重失活。探究氧原子在碳化铁晶面的吸附及移除机理有助于理解氧化过程,为提高催化剂的稳定性提供参考。本工作通过理论计算研究了低覆盖度下氧原子在θ-Fe_(3)C不同晶面...碳化铁θ-Fe_(3)C作为费托反应活性相之一,其氧化造成了催化剂的严重失活。探究氧原子在碳化铁晶面的吸附及移除机理有助于理解氧化过程,为提高催化剂的稳定性提供参考。本工作通过理论计算研究了低覆盖度下氧原子在θ-Fe_(3)C不同晶面的吸附,其在(110)晶面吸附最强,(001)晶面次之,(011)晶面吸附最弱,即(110)容易氧化。原子热力学研究表明,增大H_(2)O分压或降低温度有利于氧原子吸附,容易造成表面氧化。此外,在典型费托反应条件下(110)晶面氧原子的覆盖度最高,进一步证明该晶面易氧化,与低覆盖度吸附结果一致。对移除路径进行计算得出,(011)晶面吸附氧原子直接与CO反应以CO_(2)方式移除能垒较低(0.84 eV);(001)与(110)晶面吸附氧原子主要通过OH歧化以H_(2)O方式移除,但后者形成O−H键需要克服的能垒更高(1.72 vs 1.47 eV)。展开更多
We study the binding of molecular oxygen to a （5, 0） single walled SiC nanotube, by means of density functional calculations. The center of a hexagon of silicon and carbon atoms in sites on SiCNT surfaces is the mos...We study the binding of molecular oxygen to a （5, 0） single walled SiC nanotube, by means of density functional calculations. The center of a hexagon of silicon and carbon atoms in sites on SiCNT surfaces is the most stable adsorption site for 02 molecule, with a binding energy of -38.22 eV and an average Si-O binding distance of 1.698 A. We have also tested the stability of the 02-adsorbed SiCNT/CNT with ab initio molecular dynamics simulation which have been carried out at room temperature. Furthermore, the adsorption of 02 on the single walled carbon nanotubes has been investigated. Our first-principles calculations predict that the 02 adsorptive capability of silicon carbide nanotubes is much better than that of carbon nanotubes. This might have potential for gas detection and energy storage.展开更多
Organic chelating reagent influences upon the redox adsorption of activated carbon fiber towards Au3+ were systematically investigated. The experimental results indicated that the presence of organic chelating reagent...Organic chelating reagent influences upon the redox adsorption of activated carbon fiber towards Au3+ were systematically investigated. The experimental results indicated that the presence of organic chelating reagent on activated carbon fiber strongly affects adsorption capacity of activated carbon fiber towards Au3+. The reduction-adsorption amount of Au3+ increased three times by the presence of 8-quinolinol. Furthermore, The reduction-adsorption amount of Au3+ depended on the pH value of adsorption and temperature.展开更多
The dynamic adsorption of possible intermediates on single-atom catalysts(SACs)under working condition plays a key role in the electrocatalytic performance by the oxygen evolution reaction(OER),and therefore the perfo...The dynamic adsorption of possible intermediates on single-atom catalysts(SACs)under working condition plays a key role in the electrocatalytic performance by the oxygen evolution reaction(OER),and therefore the performance of the dynamic adsorption should be fully considered in the theoretical screening of potential SACs.Based on density functional theory calculations,the OER performance of 27 types of C_(2)N-supported single transition metal atoms(TM@C_(2)N)is systematically investigated without and with considering the dynamic adsorption of possible intermediates.Without considering dynamic adsorption,only Rh@C_(2)N and Ni@C_(2)N are screened out as good catalysts.However,by further considering the dynamic adsorption configurations of possible intermediates,more promising TM@C_(2)N SACs including Fe(Co,Ni,Ru,Rh,Ir)@C_(2)N toward the OER are screened out.The presence of the intermediates(*HO,*O)on SACs could shift their d band center toward lower energy level,which makes the interaction between the adsorbate and SACs moderate and thus enhances their OER performance.The present work is instructive for further screening and designing of efficient single-atom catalysts for the oxygen evolution reaction.展开更多
By using the first-principles calculations,we have systematically investigated the adsorption of atomic oxygen on Cu(111) surface for a wide range of coverages Θ(from 0.11 to 1.00 ML) and adsorption sites.We found th...By using the first-principles calculations,we have systematically investigated the adsorption of atomic oxygen on Cu(111) surface for a wide range of coverages Θ(from 0.11 to 1.00 ML) and adsorption sites.We found that the fcc-hollow site is the most stable site for oxygen adsorption.The adsorption energy decreases with increasing oxygen coverage due to the increasing repulsive interaction in the overlayer O adatoms.Except for coverage of 1.00 ML,the oxygen-induced lateral relaxations and bucklings are found in the outermost three Cu layers,and the hillock-like as well as ridge-like bucklings are also found for Θ=0.25 ML and Θ=0.75 ML as well as Θ=0.50 ML,respectively.With an increasing oxygen coverage,the work function increases and the surface dipole moment decreases.Electron transfer from the first layer Cu atoms to O adatoms indicates the O-Cu bond having some degree of ionic character,while the hybridization between O 2p and Cu 3d orbitals implies that it also has some degree of covalence character.Moreover,with the increasing oxygen coverage,more Cu 3d and O 2p states are empty thus weakening the binding of O/Cu(111) system,but increase in the PDOS at the Fermi level.This implies an enhancement in the metallic character of the O/Cu(111) system.展开更多
By using first-principles calculations,we have systematically investigated the structural stability and electronic properties of a single oxygen atom adsorbed on the surface of foursquare Cu nanowires for a wide range...By using first-principles calculations,we have systematically investigated the structural stability and electronic properties of a single oxygen atom adsorbed on the surface of foursquare Cu nanowires for a wide range of adsorption sites.In view of binding energy maximization,we found that the long bridge site at the edge of the Cu nanowires is the most stable site for oxygen adsorption,which is always slightly energetically favorable compared with the hollow site at the surface.The electron transferring from Cu atoms to O adatom and a significant polarization indicate the O-Cu chemical bond,showing some degree of ionic character.In addition,the hybridization between O-2p and Cu-3d states implies the O-Cu bond which also shows some degree of covalence character.The main factors which affect the oxygen preferred adsorption site are analyzed from the local geometrical configurations and electronic properties.展开更多
文摘碳化铁θ-Fe_(3)C作为费托反应活性相之一,其氧化造成了催化剂的严重失活。探究氧原子在碳化铁晶面的吸附及移除机理有助于理解氧化过程,为提高催化剂的稳定性提供参考。本工作通过理论计算研究了低覆盖度下氧原子在θ-Fe_(3)C不同晶面的吸附,其在(110)晶面吸附最强,(001)晶面次之,(011)晶面吸附最弱,即(110)容易氧化。原子热力学研究表明,增大H_(2)O分压或降低温度有利于氧原子吸附,容易造成表面氧化。此外,在典型费托反应条件下(110)晶面氧原子的覆盖度最高,进一步证明该晶面易氧化,与低覆盖度吸附结果一致。对移除路径进行计算得出,(011)晶面吸附氧原子直接与CO反应以CO_(2)方式移除能垒较低(0.84 eV);(001)与(110)晶面吸附氧原子主要通过OH歧化以H_(2)O方式移除,但后者形成O−H键需要克服的能垒更高(1.72 vs 1.47 eV)。
文摘We study the binding of molecular oxygen to a （5, 0） single walled SiC nanotube, by means of density functional calculations. The center of a hexagon of silicon and carbon atoms in sites on SiCNT surfaces is the most stable adsorption site for 02 molecule, with a binding energy of -38.22 eV and an average Si-O binding distance of 1.698 A. We have also tested the stability of the 02-adsorbed SiCNT/CNT with ab initio molecular dynamics simulation which have been carried out at room temperature. Furthermore, the adsorption of 02 on the single walled carbon nanotubes has been investigated. Our first-principles calculations predict that the 02 adsorptive capability of silicon carbide nanotubes is much better than that of carbon nanotubes. This might have potential for gas detection and energy storage.
基金Chinese Ministry of Education Doctor Fund No.: 2000055804.
文摘Organic chelating reagent influences upon the redox adsorption of activated carbon fiber towards Au3+ were systematically investigated. The experimental results indicated that the presence of organic chelating reagent on activated carbon fiber strongly affects adsorption capacity of activated carbon fiber towards Au3+. The reduction-adsorption amount of Au3+ increased three times by the presence of 8-quinolinol. Furthermore, The reduction-adsorption amount of Au3+ depended on the pH value of adsorption and temperature.
基金This work is supported by the National Key Research and Development Program(No.2018YFA0208600)the National Natural Science Foundation of Chi-na(No.U19A2015,No.22102167)+2 种基金CAS Project for Young Scientists in Basic Research(YSBR-051)Wenhua Zhang is supported by USTC Tang Scholarship and State Scholarship Fund(202206345005)The calculations were performed at the Super-computing Center of University of Science and Technology of China(USTCSCC).
文摘The dynamic adsorption of possible intermediates on single-atom catalysts(SACs)under working condition plays a key role in the electrocatalytic performance by the oxygen evolution reaction(OER),and therefore the performance of the dynamic adsorption should be fully considered in the theoretical screening of potential SACs.Based on density functional theory calculations,the OER performance of 27 types of C_(2)N-supported single transition metal atoms(TM@C_(2)N)is systematically investigated without and with considering the dynamic adsorption of possible intermediates.Without considering dynamic adsorption,only Rh@C_(2)N and Ni@C_(2)N are screened out as good catalysts.However,by further considering the dynamic adsorption configurations of possible intermediates,more promising TM@C_(2)N SACs including Fe(Co,Ni,Ru,Rh,Ir)@C_(2)N toward the OER are screened out.The presence of the intermediates(*HO,*O)on SACs could shift their d band center toward lower energy level,which makes the interaction between the adsorbate and SACs moderate and thus enhances their OER performance.The present work is instructive for further screening and designing of efficient single-atom catalysts for the oxygen evolution reaction.
基金supported by the National Natural Science Foundation of China (Grant No. 51071098)the State Key Development for Basic Research of China (Grant No. 2010CB631002)
文摘By using the first-principles calculations,we have systematically investigated the adsorption of atomic oxygen on Cu(111) surface for a wide range of coverages Θ(from 0.11 to 1.00 ML) and adsorption sites.We found that the fcc-hollow site is the most stable site for oxygen adsorption.The adsorption energy decreases with increasing oxygen coverage due to the increasing repulsive interaction in the overlayer O adatoms.Except for coverage of 1.00 ML,the oxygen-induced lateral relaxations and bucklings are found in the outermost three Cu layers,and the hillock-like as well as ridge-like bucklings are also found for Θ=0.25 ML and Θ=0.75 ML as well as Θ=0.50 ML,respectively.With an increasing oxygen coverage,the work function increases and the surface dipole moment decreases.Electron transfer from the first layer Cu atoms to O adatoms indicates the O-Cu bond having some degree of ionic character,while the hybridization between O 2p and Cu 3d orbitals implies that it also has some degree of covalence character.Moreover,with the increasing oxygen coverage,more Cu 3d and O 2p states are empty thus weakening the binding of O/Cu(111) system,but increase in the PDOS at the Fermi level.This implies an enhancement in the metallic character of the O/Cu(111) system.
基金supported by the National Natural Science Foundation of China (Grant No. 51071098)the State Key Development for Basic Research of China (Grant No. 2010CB631002)
文摘By using first-principles calculations,we have systematically investigated the structural stability and electronic properties of a single oxygen atom adsorbed on the surface of foursquare Cu nanowires for a wide range of adsorption sites.In view of binding energy maximization,we found that the long bridge site at the edge of the Cu nanowires is the most stable site for oxygen adsorption,which is always slightly energetically favorable compared with the hollow site at the surface.The electron transferring from Cu atoms to O adatom and a significant polarization indicate the O-Cu chemical bond,showing some degree of ionic character.In addition,the hybridization between O-2p and Cu-3d states implies the O-Cu bond which also shows some degree of covalence character.The main factors which affect the oxygen preferred adsorption site are analyzed from the local geometrical configurations and electronic properties.
