The adsorption of CO on different lattice oxygen sites in Cu doped CeO_(2)(111)was studied by DFT method,and the geometrical structure and electronic properties of adsorption systems were analyzed.The results showed t...The adsorption of CO on different lattice oxygen sites in Cu doped CeO_(2)(111)was studied by DFT method,and the geometrical structure and electronic properties of adsorption systems were analyzed.The results showed that CO interacted with lattice oxygen on the first layer formed CO_(2).However,when adsorbed on the second layer lattice oxygen,carbonate species were formed with the participation of first layer lattice oxygens,i.e.,CO co-adsorbed on first and second layer lattice oxygens.For the second layer adsorption,the absolute CO adsorption energy was big on the Oss nearby Cu.This kind of carbonates was thermodynamically stable,and it was attributed to the facilitation of Cu on CO adsorption,manifested by an electron migration behavior from the C 2p orbitals to the Cu 3d orbitals.However,the absolute CO adsorption energy on the Oss away from Cu was small.Compared to the formation of carbonates,the formation CO_(2)had very small absolute adsorption energy,suggesting the formed carbonates on second layer was stable.Further,when CO adsorbed on the systems with a carbonate,the absolute CO adsorption energy was significantly smaller than that of the non-carbonated system,indicating that the formation of carbonates inhibited CO oxidation on Cu/CeO_(2)(111).Therefore,the formation of carbonates was unfavorable for CO oxidation reaction on Cu/CeO_(2)(111).The results of this study provide theoretical support for the negative effect of CO_(2)on ceria-based catalysts.展开更多
Methanol is well-known as liquid sunshine,and the synthesis of methanol from CO_(2) hydrogenation can be an effective path to mitigate the greenhouse effect and convert energy.In this work,the active sites over Cu/CeO...Methanol is well-known as liquid sunshine,and the synthesis of methanol from CO_(2) hydrogenation can be an effective path to mitigate the greenhouse effect and convert energy.In this work,the active sites over Cu/CeO_(2) catalyst on reaction mechanisms of CO_(2) hydrogenation to methanol were studied based on density functional theory calculations.Through the electron density and density of states analysis,the interaction between key intermediates and active sites are elucidated,CO_(2) is more easily activated by CeO_(2),whereas the H_(2) dissociation occurs on Cu clusters.Meanwhile,the Cu cluster exhibit a significant interaction with the carbon atom in some key intermediates,which makes the Cu cluster the primary sites for hydrogenation of carbonate intermediates.Migration of spilled H to interfacial sites facilitates activation of CO_(2),highlighting the importance of interfacial sites in this process.CO_(2) activation to COOH and H-assisted dissociation to CO are the most charge transferring processes,making them more reactive,thus facilitating subsequent reactions towards the reverse water-gas shift(RWGS)reaction and CO-hydrogenation pathways.The dominant pathway for methanol synthesis is CO_(2)→COOH→CO(or CO_(2)+H→CO+OH)→COH→HCOH→H_(2)COH→CH_(3)OH,and the rate-determining steps are CO+H→COH and COH+H→HCOH with energy barriers of 1.26 and 1.27 eV,respectively.展开更多
Conversion of CO_(2)back to hydrocarbons is the most direct way of closing the“carbon cycle”,and its significance is further enlarged if this process is driven by renewable energies such as electricity.However,preci...Conversion of CO_(2)back to hydrocarbons is the most direct way of closing the“carbon cycle”,and its significance is further enlarged if this process is driven by renewable energies such as electricity.However,precisely controlling the product selectivity towards hydrocarbons against the competitive hydrogen evolution remains challenging,especially for Cu-based catalysts.Herein,we report a novel defect engineering strategy,by which Cu-doping-induced oxygen vacancies on CeO_(2)nanorods were effectively created,with adjustable vacancy/Cu ratio.The resulting optimum catalyst shows up to 79%catalytic current density to hydrocarbons(excluding CO),with 49%faradaic efficiency to CH4.Experiments and density functional theory unveil that the ratio between oxygen vacancy and Cu affects significantly the formation of*CHO and activation of H2O,which leads to the following deep hydrogenation to hydrocarbons.These findings may spur new insights for designing and developing more controllable chemical process relevant to CO_(2)utilization.展开更多
基金supported by National Natural Science Foundation of China(22379059)Applied Basic Research Program Project of Liaoning Province(2023JH2/101300224)+4 种基金Service Local Project of the Education Department of Liaoning Province(Enlisting and Leading)(LJKFZ20220201)General Project of the Educational Department of Liaoning Province(LJKMZ20220728)supported by Talent Scientific Research Fund of Liaoning Petrochemical University(2019-XJJL-028)Collaborative Innovation Project of Beijing-Tianjin-Hebei(Tianjin)(22PTXTHZ00020)Basic scientific research project of Liaoning Provincial Department of Education(LJ212410148019)。
文摘The adsorption of CO on different lattice oxygen sites in Cu doped CeO_(2)(111)was studied by DFT method,and the geometrical structure and electronic properties of adsorption systems were analyzed.The results showed that CO interacted with lattice oxygen on the first layer formed CO_(2).However,when adsorbed on the second layer lattice oxygen,carbonate species were formed with the participation of first layer lattice oxygens,i.e.,CO co-adsorbed on first and second layer lattice oxygens.For the second layer adsorption,the absolute CO adsorption energy was big on the Oss nearby Cu.This kind of carbonates was thermodynamically stable,and it was attributed to the facilitation of Cu on CO adsorption,manifested by an electron migration behavior from the C 2p orbitals to the Cu 3d orbitals.However,the absolute CO adsorption energy on the Oss away from Cu was small.Compared to the formation of carbonates,the formation CO_(2)had very small absolute adsorption energy,suggesting the formed carbonates on second layer was stable.Further,when CO adsorbed on the systems with a carbonate,the absolute CO adsorption energy was significantly smaller than that of the non-carbonated system,indicating that the formation of carbonates inhibited CO oxidation on Cu/CeO_(2)(111).Therefore,the formation of carbonates was unfavorable for CO oxidation reaction on Cu/CeO_(2)(111).The results of this study provide theoretical support for the negative effect of CO_(2)on ceria-based catalysts.
基金supported by National Natural Science Foundation of China(No.52476105).
文摘Methanol is well-known as liquid sunshine,and the synthesis of methanol from CO_(2) hydrogenation can be an effective path to mitigate the greenhouse effect and convert energy.In this work,the active sites over Cu/CeO_(2) catalyst on reaction mechanisms of CO_(2) hydrogenation to methanol were studied based on density functional theory calculations.Through the electron density and density of states analysis,the interaction between key intermediates and active sites are elucidated,CO_(2) is more easily activated by CeO_(2),whereas the H_(2) dissociation occurs on Cu clusters.Meanwhile,the Cu cluster exhibit a significant interaction with the carbon atom in some key intermediates,which makes the Cu cluster the primary sites for hydrogenation of carbonate intermediates.Migration of spilled H to interfacial sites facilitates activation of CO_(2),highlighting the importance of interfacial sites in this process.CO_(2) activation to COOH and H-assisted dissociation to CO are the most charge transferring processes,making them more reactive,thus facilitating subsequent reactions towards the reverse water-gas shift(RWGS)reaction and CO-hydrogenation pathways.The dominant pathway for methanol synthesis is CO_(2)→COOH→CO(or CO_(2)+H→CO+OH)→COH→HCOH→H_(2)COH→CH_(3)OH,and the rate-determining steps are CO+H→COH and COH+H→HCOH with energy barriers of 1.26 and 1.27 eV,respectively.
基金National Natural Science Foundation of China(21968020,22302222)Natural Science Foundation of Inner Mongolia(2022MS02011)+3 种基金China Postdoctoral Science Foundation under Grant Number(2024T170965,2023M743641)Science and Technology Projects of China Northern Rare Earth(BFXT-2022-D-0023)Science and Technology Department of Shanxi Province(202303021222409)Education Department of Inner Mongolia Autonomous Region(NJZZ23094,NJYT23039)。
文摘Conversion of CO_(2)back to hydrocarbons is the most direct way of closing the“carbon cycle”,and its significance is further enlarged if this process is driven by renewable energies such as electricity.However,precisely controlling the product selectivity towards hydrocarbons against the competitive hydrogen evolution remains challenging,especially for Cu-based catalysts.Herein,we report a novel defect engineering strategy,by which Cu-doping-induced oxygen vacancies on CeO_(2)nanorods were effectively created,with adjustable vacancy/Cu ratio.The resulting optimum catalyst shows up to 79%catalytic current density to hydrocarbons(excluding CO),with 49%faradaic efficiency to CH4.Experiments and density functional theory unveil that the ratio between oxygen vacancy and Cu affects significantly the formation of*CHO and activation of H2O,which leads to the following deep hydrogenation to hydrocarbons.These findings may spur new insights for designing and developing more controllable chemical process relevant to CO_(2)utilization.
