Single-atom catalysts have been applied in many processes recently.The difference of their kinetic behavior compared to the traditional heterogeneous catalysts has not been extensively discussed yet.Herein a complete ...Single-atom catalysts have been applied in many processes recently.The difference of their kinetic behavior compared to the traditional heterogeneous catalysts has not been extensively discussed yet.Herein a complete catalytic cycle of CH4 combustion assuming to be confined at isolated single sites of the Co3O4(110)surface is computationally compared with that on multi sites.The macroscopic kinetic behaviors of CH4 combustion on Co3O4(110)is systematically and quantitatively compared between those on the single site and multi sites utilizing kinetic Monte Carlo simulations upon the energetic information from the PBE+U calculation and statistic mechanics.The key factors governing the kinetics of CH4 combustion are disclosed for both the catalytic cycles respectively following the single-site and multi-site mechanisms.It is found that cooperation of multi active sites can promote the activity of complete CH4 combustions substantially in comparison to separated single-site catalyst whereas the confinement of active sites could regulate the selectivity of CH4 oxidation.The quantitative understanding of catalytic mechanism paves the way to improve the activity and selectivity for CH4 oxidation.展开更多
The past decade has seen a sharp increase in machine learning(ML)applications in scientific research.This review introduces the basic constituents of ML,including databases,features,and algorithms,and highlights a few...The past decade has seen a sharp increase in machine learning(ML)applications in scientific research.This review introduces the basic constituents of ML,including databases,features,and algorithms,and highlights a few important achievements in chemistry that have been aided by ML techniques.The described databases include some of the most popular chemical databases for molecules and materials obtained from either experiments or computational calculations.Important two-dimensional(2D)and three-dimensional(3D)features representing the chemical environment of molecules and solids are briefly introduced.Decision tree and deep learning neural network algorithms are overviewed to emphasize their frameworks and typical application scenarios.Three important fields of ML in chemistry are discussed:(1)retrosynthesis,in which ML predicts the likely routes of organic synthesis;(2)atomic simulations,which utilize the ML potential to accelerate potential energy surface sampling;and(3)heterogeneous catalysis,in which ML assists in various aspects of catalytic design,ranging from synthetic condition optimization to reaction mechanism exploration.Finally,a prospect on future ML applications is provided.展开更多
Indium oxide(In_2O_3) has demonstrated to be an effective non-noble metal catalyst for methanol steam reforming reaction(MSR).However, the reaction mechanism of MSR and crucial structure-activity relations determining...Indium oxide(In_2O_3) has demonstrated to be an effective non-noble metal catalyst for methanol steam reforming reaction(MSR).However, the reaction mechanism of MSR and crucial structure-activity relations determining the catalytic performance of In_2O_3 are still not fully understood yet. Using density functional theory(DFT) calculation, we systematically investigate the MSR process over a high-index In_2O_3(211) and a favoured catalytic cycle of MSR is determined. The results show that In_2O_3(211) possesses excellent dehydrogenation and oxidizing ability, on which CH_3 OH can readily adsorb on the In4 c site and be easily activated by the reactive lattice oxygens, resulting in a total oxidation into CO_2 rather than CO, while the H_2 formation through surface H–H coupling limits the overall MSR activity because of the strong H adsorption on the two-coordinated lattice O(O_(2c)). Our analyses show that the relatively inert three-coordinated lattice O(O_(3c)) could play an important catalytic role. To uncover the influence of the local coordination of surface In atoms and lattice O on the catalytic activity, we evaluate the activity trend of several types of In_2O_3 surfaces including(211),(111), and(100) by examining the rate-limiting, which reveals the following activity order:(211)>(111)>(100). These findings provide an in-depth understanding on the MSR reaction mechanism over In_2O_3 catalysts and some basic structure-activity relations at the atomic scale, could facilitate the rational design of In_2O_3-based catalysts for MSR by controlling the local coordination environment of surface active sites.展开更多
To make methane a suitable energy carrier and transport less costly,it is an urgent and challenging task for us to convert methane to liquid under mild conditions efficiently.In this study,we explored partial methane ...To make methane a suitable energy carrier and transport less costly,it is an urgent and challenging task for us to convert methane to liquid under mild conditions efficiently.In this study,we explored partial methane oxidation to methanol by density functional theory(DFT)calculations using a hybrid functional(HSE06)with van der Waals(vdW)interactions.The stabilities of different active sites over SSZ-13 and SAPO-34,two CHA type zeolites,are thoroughly investigated by ab initio molecular dynamics(AIMD)simulations and ab initio thermodynamics analyses.Four possible active sites,namely[CuOHCu]2+,[Cu(OH)2Cu]2+,[CuOCu]2+and[CuOH]+,are identified stable.Methane-to-methanol reaction mechanisms are further studied upon these most stable active sites,among which[CuOCu]2+and[CuOH]+are proved to be reactive.The migration of species among zeolite pores are also discussed,which accounts for the activity on[CuOH]+sites.This concept may represent a more complete picture of catalytic reactions over zeolites in general.展开更多
Nitric oxide(NO_x), as one of the main pollutants, can contribute to a series of environmental problems, and to date the selective catalytic reduction(SCR) of NO_x with NH_3 in the presence of excess of O_2 over the c...Nitric oxide(NO_x), as one of the main pollutants, can contribute to a series of environmental problems, and to date the selective catalytic reduction(SCR) of NO_x with NH_3 in the presence of excess of O_2 over the catalysts has served as one of the most effective methods, in which Mn-based catalysts have been widely studied owing to their excellent low-temperature activity toward NH3-SCR. However, the related structure-activity relation was not satisfactorily explored at the atomic level. By virtue of DFT+U calculations together with microkinetic analysis, we systemically investigate the selective catalytic reduction process of NO with NH_3 over Mn_3 O_4(110), and identify the crucial thermodynamic and kinetic factors that limit the catalytic activity and selectivity.It is found that NH3 prefers to adsorb on the Lewis acid site and then dehydrogenates into NH_2~* assisted by either the two-or three-fold lattice oxygen; NH_2~* would then react with the gaseous NO to form an important intermediate NH_2 NO that prefers to convert into N_2 O rather than N_2 after the sequential dehydrogenation, while the residual H atoms interact with O_2 and left the surface in the form of H_2 O. The rate-determining step is proposed to be the coupling reaction between NH_2~* and gaseous NO.Regarding the complex surface structure of Mn_3 O_4(110),the main active sites are quantitatively revealed to be O_(3 c) and Mn_(4 c).展开更多
Science generally proceeds based on a mutual interaction between theory and experiment： theory can explain experimental phenomena and propose general rules for the design of new experiments while experiment can verif...Science generally proceeds based on a mutual interaction between theory and experiment： theory can explain experimental phenomena and propose general rules for the design of new experiments while experiment can verify theoretical predictions and discover new phenomena to improve theories. Yet, the progress of heterogeneous catalysis mainly relied on experimental advances for a long time. In its early days, heterogeneous catalysis was an empirically applied field,展开更多
The chemical reduction of carbon dioxide(CO2) has always drawn intensive attentions as it can not only remove CO2 which is the primary greenhouse gas but also produce useful fuels. Industrial synthesis of methanol uti...The chemical reduction of carbon dioxide(CO2) has always drawn intensive attentions as it can not only remove CO2 which is the primary greenhouse gas but also produce useful fuels. Industrial synthesis of methanol utilizing copper-based catalysts is a commonly used process for CO2 hydrogenation. Despite extensive efforts on improving its reaction mechanism by identifying the active sites and optimizing the operating temperature and pressure, it is still remains completely unveiled. The selectivities of CO2 electroreduction at copper electrode could mainly be towards carbon monoxide(CO), formic acid(HCOOH), methane(CH4) or ethylene(C2H4), which depends on the chemical potentials of hydrogen controlled by the applied potential. Interestingly, methanol could hardly be produced electrochemically despite utilizing metallic copper as catalysts in both processes. Moreover, the mechanistic researches have also been performed aiming to achieve the higher selectivity towards more desirable higher hydrocarbons. In this work, we review the present proposals of reaction mechanisms of copper catalyzing CO2 reduction in industrial methanol synthesis and electrochemical environment in terms of density functional theory(DFT) calculations, respectively. In addition, the influences of the simulation methods of solvation and electrochemical model at liquid-solid interface on the selectivity are discussed and compared.展开更多
Rational design/screening of more active,more selective,and less expensive catalysts has long been an important target in heterogeneous catalysis [1].In recent decades,the advances of density functional theory (DFT)ca...Rational design/screening of more active,more selective,and less expensive catalysts has long been an important target in heterogeneous catalysis [1].In recent decades,the advances of density functional theory (DFT)calculations allow us to theoretically evaluate the activity of catalysts.As shown in Figure 1(a),kinetics serves as the link between the atomic-scale properties obtained by DFT and turnover frequency (TOF)of catalysts.展开更多
Oxidation state changes under reaction conditions are very common in heterogeneous catalysis. However, due to the limitation of experiment and computational methods, the relation between oxidation state and catalytic ...Oxidation state changes under reaction conditions are very common in heterogeneous catalysis. However, due to the limitation of experiment and computational methods, the relation between oxidation state and catalytic activity is not clear. Herein, we obtain the most stable structures of palladium oxide films with different oxidation states on palladium metal surfaces using density functional theory calculations and a state-of-the-art optimization method, namely the particle swarm optimization. These structures clearly show the process of palladium oxide film formation on metallic surfaces. Using CO oxidation as a model reaction, we find that the activities increase first and then decrease with the increase of oxidation states, peaking at Pd_4O_3. Our findings offer an understanding of the phase transformation and the activity of non-stoichiometric phases.展开更多
The hydrogenation of carbon dioxide(CO2)is one of important processes to effectively convert and utilize CO2,which is also regarded as the key step at the industrial methanol synthesis.Water is likely to play an impor...The hydrogenation of carbon dioxide(CO2)is one of important processes to effectively convert and utilize CO2,which is also regarded as the key step at the industrial methanol synthesis.Water is likely to play an important role in this process,but it still remains elusive.To systematically understand its influence,here we computationally compare the reaction mechanisms of CO2 hydrogenation over the stepped Cu(211)surface between in the absence and presence of water based on microkinetic simulations upon density functional theory(DFT)calculations.The effects of water on each hydrogenation step and the whole activity and selectivity are checked and its physical origin is discussed.It is found that the water could kinetically accelerate the hydrogenation on CO2 to COOH,promoting the reverse water gas shift reaction to produce carbon monoxide(CO).It hardly influences the CO2 hydrogenation to methanol kinetically.In addition,the too high initial partial pressure of water will thermodynamically inhibit the CO2 conversion.展开更多
This Perspective explores the integration of machine learning potentials(MLPs)in the research of heterogeneous catalysis,focusing on their role in identifying in situ active sites and enhancing the understanding of ca...This Perspective explores the integration of machine learning potentials(MLPs)in the research of heterogeneous catalysis,focusing on their role in identifying in situ active sites and enhancing the understanding of catalytic processes.MLPs utilize extensive databases from high-throughput density functional theory(DFT)calculations to train models that predict atomic configurations,energies,and forces with near-DFT accuracy.These capabilities allow MLPs to handle significantly larger systems and extend simulation times beyond the limitations of traditional ab initio methods.Coupled with global optimization algorithms,MLPs enable systematic investigations across vast structural spaces,making substantial contributions to the modeling of catalyst surface structures under reactive conditions.The review aims to provide a broad introduction to recent advancements and practical guidance on employing MLPs and also showcases several exemplary cases of MLP-driven discoveries related to surface structure changes under reactive conditions and the nature of active sites in heterogeneous catalysis.The prevailing challenges faced by this approach are also discussed.展开更多
文摘Single-atom catalysts have been applied in many processes recently.The difference of their kinetic behavior compared to the traditional heterogeneous catalysts has not been extensively discussed yet.Herein a complete catalytic cycle of CH4 combustion assuming to be confined at isolated single sites of the Co3O4(110)surface is computationally compared with that on multi sites.The macroscopic kinetic behaviors of CH4 combustion on Co3O4(110)is systematically and quantitatively compared between those on the single site and multi sites utilizing kinetic Monte Carlo simulations upon the energetic information from the PBE+U calculation and statistic mechanics.The key factors governing the kinetics of CH4 combustion are disclosed for both the catalytic cycles respectively following the single-site and multi-site mechanisms.It is found that cooperation of multi active sites can promote the activity of complete CH4 combustions substantially in comparison to separated single-site catalyst whereas the confinement of active sites could regulate the selectivity of CH4 oxidation.The quantitative understanding of catalytic mechanism paves the way to improve the activity and selectivity for CH4 oxidation.
基金financial support from the National Key Research and Development Program of China(2018YFA0208600)the National Natural Science Foundation of China(12188101,22033003,91945301,91745201,92145302,22122301,and 92061112)the Tencent Foundation for XPLORER PRIZE,and Fundamental Research Funds for the Central Universities(20720220011)。
文摘The past decade has seen a sharp increase in machine learning(ML)applications in scientific research.This review introduces the basic constituents of ML,including databases,features,and algorithms,and highlights a few important achievements in chemistry that have been aided by ML techniques.The described databases include some of the most popular chemical databases for molecules and materials obtained from either experiments or computational calculations.Important two-dimensional(2D)and three-dimensional(3D)features representing the chemical environment of molecules and solids are briefly introduced.Decision tree and deep learning neural network algorithms are overviewed to emphasize their frameworks and typical application scenarios.Three important fields of ML in chemistry are discussed:(1)retrosynthesis,in which ML predicts the likely routes of organic synthesis;(2)atomic simulations,which utilize the ML potential to accelerate potential energy surface sampling;and(3)heterogeneous catalysis,in which ML assists in various aspects of catalytic design,ranging from synthetic condition optimization to reaction mechanism exploration.Finally,a prospect on future ML applications is provided.
基金supported by the National Natural Science Foundation of China(21333003,21622305)Young Elite Scientist Sponsorship Program by China Association for Science and Technology(YESS20150131)+1 种基金"Shu Guang"project supported by Shanghai Municipal Education Commission and Shanghai Education Development Foundation(13SG30)the Fundamental Research Funds for the Central Universities(WJ616007)
文摘Indium oxide(In_2O_3) has demonstrated to be an effective non-noble metal catalyst for methanol steam reforming reaction(MSR).However, the reaction mechanism of MSR and crucial structure-activity relations determining the catalytic performance of In_2O_3 are still not fully understood yet. Using density functional theory(DFT) calculation, we systematically investigate the MSR process over a high-index In_2O_3(211) and a favoured catalytic cycle of MSR is determined. The results show that In_2O_3(211) possesses excellent dehydrogenation and oxidizing ability, on which CH_3 OH can readily adsorb on the In4 c site and be easily activated by the reactive lattice oxygens, resulting in a total oxidation into CO_2 rather than CO, while the H_2 formation through surface H–H coupling limits the overall MSR activity because of the strong H adsorption on the two-coordinated lattice O(O_(2c)). Our analyses show that the relatively inert three-coordinated lattice O(O_(3c)) could play an important catalytic role. To uncover the influence of the local coordination of surface In atoms and lattice O on the catalytic activity, we evaluate the activity trend of several types of In_2O_3 surfaces including(211),(111), and(100) by examining the rate-limiting, which reveals the following activity order:(211)>(111)>(100). These findings provide an in-depth understanding on the MSR reaction mechanism over In_2O_3 catalysts and some basic structure-activity relations at the atomic scale, could facilitate the rational design of In_2O_3-based catalysts for MSR by controlling the local coordination environment of surface active sites.
基金supported by the Queen’s University of Belfast and Chinese Scholarship Council for a Joint Scholarship。
文摘To make methane a suitable energy carrier and transport less costly,it is an urgent and challenging task for us to convert methane to liquid under mild conditions efficiently.In this study,we explored partial methane oxidation to methanol by density functional theory(DFT)calculations using a hybrid functional(HSE06)with van der Waals(vdW)interactions.The stabilities of different active sites over SSZ-13 and SAPO-34,two CHA type zeolites,are thoroughly investigated by ab initio molecular dynamics(AIMD)simulations and ab initio thermodynamics analyses.Four possible active sites,namely[CuOHCu]2+,[Cu(OH)2Cu]2+,[CuOCu]2+and[CuOH]+,are identified stable.Methane-to-methanol reaction mechanisms are further studied upon these most stable active sites,among which[CuOCu]2+and[CuOH]+are proved to be reactive.The migration of species among zeolite pores are also discussed,which accounts for the activity on[CuOH]+sites.This concept may represent a more complete picture of catalytic reactions over zeolites in general.
基金supported by the National Natural Science Foundation of China(21333003,21622305)Young Elite Scientist Sponsorship Program by China Association for Science and Technology(YESS20150131)+1 种基金"Shu Guang"project supported by Shanghai Municipal Education Commission and Shanghai Education Development Foundation(13SG30)the Fundamental Research Funds for the Central Universities(WJ616007)
文摘Nitric oxide(NO_x), as one of the main pollutants, can contribute to a series of environmental problems, and to date the selective catalytic reduction(SCR) of NO_x with NH_3 in the presence of excess of O_2 over the catalysts has served as one of the most effective methods, in which Mn-based catalysts have been widely studied owing to their excellent low-temperature activity toward NH3-SCR. However, the related structure-activity relation was not satisfactorily explored at the atomic level. By virtue of DFT+U calculations together with microkinetic analysis, we systemically investigate the selective catalytic reduction process of NO with NH_3 over Mn_3 O_4(110), and identify the crucial thermodynamic and kinetic factors that limit the catalytic activity and selectivity.It is found that NH3 prefers to adsorb on the Lewis acid site and then dehydrogenates into NH_2~* assisted by either the two-or three-fold lattice oxygen; NH_2~* would then react with the gaseous NO to form an important intermediate NH_2 NO that prefers to convert into N_2 O rather than N_2 after the sequential dehydrogenation, while the residual H atoms interact with O_2 and left the surface in the form of H_2 O. The rate-determining step is proposed to be the coupling reaction between NH_2~* and gaseous NO.Regarding the complex surface structure of Mn_3 O_4(110),the main active sites are quantitatively revealed to be O_(3 c) and Mn_(4 c).
文摘Science generally proceeds based on a mutual interaction between theory and experiment： theory can explain experimental phenomena and propose general rules for the design of new experiments while experiment can verify theoretical predictions and discover new phenomena to improve theories. Yet, the progress of heterogeneous catalysis mainly relied on experimental advances for a long time. In its early days, heterogeneous catalysis was an empirically applied field,
基金supported by the National Natural Science Foundation of China(21333003,21303051)Shanghai Natural Science Foundation(13ZR1453000)the Recruitment Program of Global Experts(B08021)
文摘The chemical reduction of carbon dioxide(CO2) has always drawn intensive attentions as it can not only remove CO2 which is the primary greenhouse gas but also produce useful fuels. Industrial synthesis of methanol utilizing copper-based catalysts is a commonly used process for CO2 hydrogenation. Despite extensive efforts on improving its reaction mechanism by identifying the active sites and optimizing the operating temperature and pressure, it is still remains completely unveiled. The selectivities of CO2 electroreduction at copper electrode could mainly be towards carbon monoxide(CO), formic acid(HCOOH), methane(CH4) or ethylene(C2H4), which depends on the chemical potentials of hydrogen controlled by the applied potential. Interestingly, methanol could hardly be produced electrochemically despite utilizing metallic copper as catalysts in both processes. Moreover, the mechanistic researches have also been performed aiming to achieve the higher selectivity towards more desirable higher hydrocarbons. In this work, we review the present proposals of reaction mechanisms of copper catalyzing CO2 reduction in industrial methanol synthesis and electrochemical environment in terms of density functional theory(DFT) calculations, respectively. In addition, the influences of the simulation methods of solvation and electrochemical model at liquid-solid interface on the selectivity are discussed and compared.
文摘Rational design/screening of more active,more selective,and less expensive catalysts has long been an important target in heterogeneous catalysis [1].In recent decades,the advances of density functional theory (DFT)calculations allow us to theoretically evaluate the activity of catalysts.As shown in Figure 1(a),kinetics serves as the link between the atomic-scale properties obtained by DFT and turnover frequency (TOF)of catalysts.
基金supported by the National Natural Science Foundation of China (21333003)Queens University Belfast for a Ph.D. studentship
文摘Oxidation state changes under reaction conditions are very common in heterogeneous catalysis. However, due to the limitation of experiment and computational methods, the relation between oxidation state and catalytic activity is not clear. Herein, we obtain the most stable structures of palladium oxide films with different oxidation states on palladium metal surfaces using density functional theory calculations and a state-of-the-art optimization method, namely the particle swarm optimization. These structures clearly show the process of palladium oxide film formation on metallic surfaces. Using CO oxidation as a model reaction, we find that the activities increase first and then decrease with the increase of oxidation states, peaking at Pd_4O_3. Our findings offer an understanding of the phase transformation and the activity of non-stoichiometric phases.
基金supported by the National Key Research and Development Program of China(2018YFA0208600)the National Natural Science Foundation of China(21673072,21333003,91845111)Program of Shanghai Subject Chief Scientist(17XD1401400)
文摘The hydrogenation of carbon dioxide(CO2)is one of important processes to effectively convert and utilize CO2,which is also regarded as the key step at the industrial methanol synthesis.Water is likely to play an important role in this process,but it still remains elusive.To systematically understand its influence,here we computationally compare the reaction mechanisms of CO2 hydrogenation over the stepped Cu(211)surface between in the absence and presence of water based on microkinetic simulations upon density functional theory(DFT)calculations.The effects of water on each hydrogenation step and the whole activity and selectivity are checked and its physical origin is discussed.It is found that the water could kinetically accelerate the hydrogenation on CO2 to COOH,promoting the reverse water gas shift reaction to produce carbon monoxide(CO).It hardly influences the CO2 hydrogenation to methanol kinetically.In addition,the too high initial partial pressure of water will thermodynamically inhibit the CO2 conversion.
基金the NKRDPC(2021YFA1500700)and NSFC(92045303).X.C.is grateful for financial support from ShanghaiTech University.
文摘This Perspective explores the integration of machine learning potentials(MLPs)in the research of heterogeneous catalysis,focusing on their role in identifying in situ active sites and enhancing the understanding of catalytic processes.MLPs utilize extensive databases from high-throughput density functional theory(DFT)calculations to train models that predict atomic configurations,energies,and forces with near-DFT accuracy.These capabilities allow MLPs to handle significantly larger systems and extend simulation times beyond the limitations of traditional ab initio methods.Coupled with global optimization algorithms,MLPs enable systematic investigations across vast structural spaces,making substantial contributions to the modeling of catalyst surface structures under reactive conditions.The review aims to provide a broad introduction to recent advancements and practical guidance on employing MLPs and also showcases several exemplary cases of MLP-driven discoveries related to surface structure changes under reactive conditions and the nature of active sites in heterogeneous catalysis.The prevailing challenges faced by this approach are also discussed.
