In an effort to provide visualization and understanding to the electronic ‘‘push effect' of axial ligands on the catalytic activity of cobalt macrocyclic molecules, we design a simple model system involving an[5...In an effort to provide visualization and understanding to the electronic ‘‘push effect' of axial ligands on the catalytic activity of cobalt macrocyclic molecules, we design a simple model system involving an[5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin]cobalt(II)(TMMPCo) monolayer axially-coordinated on thiol ligand modified Au electrode and explore the activity of the axial-ligand coordinated TMPPCo toward oxygen reduction reaction(ORR) in acidic medium. Three different ligands, with a decreasing order of coordinating ability as: 4-mercaptopyridine(MPy) > 4-aminothiolphenol(APT) > 4-mercaptobenzonitrile(MBN) are used and a maximum difference in ORR onset potential of 80 mV is observed between the MPy(highest onset potential) and MBN systems(lowest onset potential). The ORR activity of TMPPCo increases with the increase in binding strength of the axial ligand. A detailed mechanism study reveals that ORR on the three ligand coordinated TMPPCo systems shares the same2-electron mechanism with H2 O2 as the terminal product. Theoretical calculation into the structure of the ligand coordinated cobalt porphyrins uncovers the variation in atomic charge of the Co(II) center and altered frontier molecular orbital distribution among the three ligand systems. Both properties have great influence on the back-bonding formation between the Co(II) center and O2 molecules, which has been suggested to be critical toward the O2 adsorption and subsequent activation process.展开更多
正如创新是发展的动力,绿色创新是绿色化转型和高质量发展的动力。文章基于Web of Science和CNKI数据库中1990—2019年经济地理学领域的绿色创新研究相关文献,借助CiteSpace软件,运用文献计量分析法回顾分析了国内外相关文献资料,系统...正如创新是发展的动力,绿色创新是绿色化转型和高质量发展的动力。文章基于Web of Science和CNKI数据库中1990—2019年经济地理学领域的绿色创新研究相关文献,借助CiteSpace软件,运用文献计量分析法回顾分析了国内外相关文献资料,系统梳理了绿色创新研究的理论发展脉络和热点主题,明晰了研究前沿及学术争议,旨在为国内绿色创新的理论体系建设寻求突破。研究发现经济地理学视角下的绿色创新研究有如下特点:①研究脉络主要经历了从关注绿色创新本身的内涵和特征,发展到重视外部影响、驱动效应以及跨区域知识互动与绿色创新的关系研究,再到如今围绕绿色创新的企业间和城市间创新网络特征及其空间演化特征研究;②研究视角主要关注微观企业层面和城市层面的知识联系和空间影响;③研究热点主要包括绿色创新的双重溢出效应、三重底线、多重驱动效应及路径依赖等;④研究范式侧重于地理区位影响、流空间结网演化、创新系统协同。文章提出未来绿色创新研究方向:一是探究不同立场下对绿色创新投入的平衡点,使得绿色创新最大程度上同时符合政策逻辑和市场逻辑;二是探讨基于多维邻近性的政策推/拉效应下绿色创新的影响;三是立足于中国当下绿色发展战略背景和“双碳”目标,探索高效、相宜的中国特色绿色创新体系。展开更多
基金supported by the National Key Research and Development Program of China (2017YFA0206500)the National Natural Science Foundation of China (21635004, 21675079)
文摘In an effort to provide visualization and understanding to the electronic ‘‘push effect' of axial ligands on the catalytic activity of cobalt macrocyclic molecules, we design a simple model system involving an[5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin]cobalt(II)(TMMPCo) monolayer axially-coordinated on thiol ligand modified Au electrode and explore the activity of the axial-ligand coordinated TMPPCo toward oxygen reduction reaction(ORR) in acidic medium. Three different ligands, with a decreasing order of coordinating ability as: 4-mercaptopyridine(MPy) > 4-aminothiolphenol(APT) > 4-mercaptobenzonitrile(MBN) are used and a maximum difference in ORR onset potential of 80 mV is observed between the MPy(highest onset potential) and MBN systems(lowest onset potential). The ORR activity of TMPPCo increases with the increase in binding strength of the axial ligand. A detailed mechanism study reveals that ORR on the three ligand coordinated TMPPCo systems shares the same2-electron mechanism with H2 O2 as the terminal product. Theoretical calculation into the structure of the ligand coordinated cobalt porphyrins uncovers the variation in atomic charge of the Co(II) center and altered frontier molecular orbital distribution among the three ligand systems. Both properties have great influence on the back-bonding formation between the Co(II) center and O2 molecules, which has been suggested to be critical toward the O2 adsorption and subsequent activation process.
文摘正如创新是发展的动力,绿色创新是绿色化转型和高质量发展的动力。文章基于Web of Science和CNKI数据库中1990—2019年经济地理学领域的绿色创新研究相关文献,借助CiteSpace软件,运用文献计量分析法回顾分析了国内外相关文献资料,系统梳理了绿色创新研究的理论发展脉络和热点主题,明晰了研究前沿及学术争议,旨在为国内绿色创新的理论体系建设寻求突破。研究发现经济地理学视角下的绿色创新研究有如下特点:①研究脉络主要经历了从关注绿色创新本身的内涵和特征,发展到重视外部影响、驱动效应以及跨区域知识互动与绿色创新的关系研究,再到如今围绕绿色创新的企业间和城市间创新网络特征及其空间演化特征研究;②研究视角主要关注微观企业层面和城市层面的知识联系和空间影响;③研究热点主要包括绿色创新的双重溢出效应、三重底线、多重驱动效应及路径依赖等;④研究范式侧重于地理区位影响、流空间结网演化、创新系统协同。文章提出未来绿色创新研究方向:一是探究不同立场下对绿色创新投入的平衡点,使得绿色创新最大程度上同时符合政策逻辑和市场逻辑;二是探讨基于多维邻近性的政策推/拉效应下绿色创新的影响;三是立足于中国当下绿色发展战略背景和“双碳”目标,探索高效、相宜的中国特色绿色创新体系。
