Electrochemical water splitting plays a crucial role in storing sustainable energy into H2 as an ideal fuel,in which the anodic oxygen evolution reaction(OER)is the bottleneck.Currently,Fe-doped NiOOH(Ni_(1−x)Fe_(x)OO...Electrochemical water splitting plays a crucial role in storing sustainable energy into H2 as an ideal fuel,in which the anodic oxygen evolution reaction(OER)is the bottleneck.Currently,Fe-doped NiOOH(Ni_(1−x)Fe_(x)OOH)is a promising OER catalyst under alkaline conditions.However,the specific active sites responsible for their good performances remain debatable.Here,we identify a nickel-oxygen radical(Ni–O·)and an iron-oxo(Fe=O)group as two essential states for adsorbed oxygen.Meanwhile,both thermochemical O–O coupling and electrochemical OER elementary steps are considered on the Ni_(1−x)Fe_(x)OOH catalysts.Sophisticated mechanistic studies with a combined density functional theory simulation and experimental analysis unravel that both the Ni and Fe centers can act as the active sites for the defective Ni_(1−x)Fe_(x)OOH to catalyze OER,depending on the nature of the defect.The presence of Fe can benefit the stabilization of the defective surface and influence the electronic property of the nearby Ni site.This work not only identifies the intrinsic active sites of Ni_(1−x)Fe_(x)OOH,but also illustrates the essential roles of defects in catalysis,which sheds light on the design of more efficient OER catalysts in the future.展开更多
The present study stems from the realization that the general problem relating to the analysis of wind-induced vibrations in suspension bridges still requires significant attention.Sidewalk railings,overhaul tracks,an...The present study stems from the realization that the general problem relating to the analysis of wind-induced vibrations in suspension bridges still requires significant attention.Sidewalk railings,overhaul tracks,and deflectors are known to largely affect such dynamics.Here,the influence of a row of water-filled traffic barriers on the response of a sample suspension bridge is investigated numerically.It is shown that the existence of water barriers causes flow separation and non-negligible vortices with respect to the condition with no water barriers.The vortex shedding frequency at the far end is around 41.30 Hz,relatively close to the real vibration frequency.It is also shown how different incoming angles of attack can change the flow field around the bridge cross-section and the vortex detachment frequency.展开更多
文摘Electrochemical water splitting plays a crucial role in storing sustainable energy into H2 as an ideal fuel,in which the anodic oxygen evolution reaction(OER)is the bottleneck.Currently,Fe-doped NiOOH(Ni_(1−x)Fe_(x)OOH)is a promising OER catalyst under alkaline conditions.However,the specific active sites responsible for their good performances remain debatable.Here,we identify a nickel-oxygen radical(Ni–O·)and an iron-oxo(Fe=O)group as two essential states for adsorbed oxygen.Meanwhile,both thermochemical O–O coupling and electrochemical OER elementary steps are considered on the Ni_(1−x)Fe_(x)OOH catalysts.Sophisticated mechanistic studies with a combined density functional theory simulation and experimental analysis unravel that both the Ni and Fe centers can act as the active sites for the defective Ni_(1−x)Fe_(x)OOH to catalyze OER,depending on the nature of the defect.The presence of Fe can benefit the stabilization of the defective surface and influence the electronic property of the nearby Ni site.This work not only identifies the intrinsic active sites of Ni_(1−x)Fe_(x)OOH,but also illustrates the essential roles of defects in catalysis,which sheds light on the design of more efficient OER catalysts in the future.
文摘The present study stems from the realization that the general problem relating to the analysis of wind-induced vibrations in suspension bridges still requires significant attention.Sidewalk railings,overhaul tracks,and deflectors are known to largely affect such dynamics.Here,the influence of a row of water-filled traffic barriers on the response of a sample suspension bridge is investigated numerically.It is shown that the existence of water barriers causes flow separation and non-negligible vortices with respect to the condition with no water barriers.The vortex shedding frequency at the far end is around 41.30 Hz,relatively close to the real vibration frequency.It is also shown how different incoming angles of attack can change the flow field around the bridge cross-section and the vortex detachment frequency.
