The existence of multiple vacancies leads to significant changes in the local atomic structure,which can regulate the electronic structure of the surface and form unsaturated coordination geometries.However,the curren...The existence of multiple vacancies leads to significant changes in the local atomic structure,which can regulate the electronic structure of the surface and form unsaturated coordination geometries.However,the current methods employed to generate multiple vacancies in two-dimensional(2D)layered double hydroxide(LDH)materials are still difficult to achieve to some extent and are primarily limited to monolayer LDH structures.Here,we present an improved method to synthesize NiMoP/Ni_(2)P catalysts with a sponge-like porous structure.Firstly,NiO with dual defects was constructed by subjecting NiMo-LDH/Ni to air calcination.Subsequently,we performed phosphorization treatment and introduced multiple Ni vacancies and O vacancies as defect sites to tune the edge and substrate surfaces of LDH.At the same time,the electronic structure was tuned by adding P heteroatoms.The synergistic effect of porous structure,heterogeneous interfaces,vacancies,doping defects,and amorphous states can greatly enhance the electron transfer effect inside the catalysts,which significantly improves the catalytic ability of the oxygen evolution reaction(OER).Therefore,the overpotential for the oxygen evolution reaction of NiMoP/Ni_(2)P heterointerfaces reaches 270 mV at a current density of 10 mA·cm^(-2)under alkaline conditions,with the catalysts capable of sustaining high current densities even after the durability testing for 35 h.展开更多
Flow?induced vibration plays a positive role on heat transfer enhancement. Meanwhile, it is also a negative factor for fatigue strength. Satisfying the fatigue strength is the primary prerequisite for heat transfer en...Flow?induced vibration plays a positive role on heat transfer enhancement. Meanwhile, it is also a negative factor for fatigue strength. Satisfying the fatigue strength is the primary prerequisite for heat transfer enhancement. This paper numerically studied the flow?induced vibration of planar elastic tube bundle based on a two?way fluid–structure interaction(FSI) calculation. The numerical calculation involved the unsteady, three?dimensional incompressible governing equations solved with finite volume approach and the dynamic balance equation of planar elastic tube bundle solved with finite element method combined with dynamic mesh scheme. The numerical approach was verified by comparing with the published experimental results. Then the vibration trajectory, deformation and stress contour of planar elastic tube bundle were all studied. Results show that the combined movement of planar elastic tube bundle represents the agitation from inside to outside. The vibration of out?of?plane is the main vibration form with the typically sinusoidal behavior because the magnitude of displacement along the out?of?plane direction is the 100 times than the value of in?plane direction. The dangerous point locates in the innermost tube where the equivalent stress can be utilized to study the multiaxial fatigue of planar elastic tube bundle due to the alternating stress concentration. In the velocity range of 0.2-3 m/s, it is inferred that the vibration amplitude plays a role on the stress response and the stress amplitude is susceptible to the fluid velocity. This research paves a way for studying the fatigue strength of planar elastic tube bundle by flow?induced vibration.展开更多
基金supported by the National Natural Science Foundation of China(No.22269010)Jiangxi Provincial Natural Science Foundation(No.20224BAB214021)the Opening Project of National Engineering Research Center for Domestic&Building Ceramics(No.GXZX2302).
文摘The existence of multiple vacancies leads to significant changes in the local atomic structure,which can regulate the electronic structure of the surface and form unsaturated coordination geometries.However,the current methods employed to generate multiple vacancies in two-dimensional(2D)layered double hydroxide(LDH)materials are still difficult to achieve to some extent and are primarily limited to monolayer LDH structures.Here,we present an improved method to synthesize NiMoP/Ni_(2)P catalysts with a sponge-like porous structure.Firstly,NiO with dual defects was constructed by subjecting NiMo-LDH/Ni to air calcination.Subsequently,we performed phosphorization treatment and introduced multiple Ni vacancies and O vacancies as defect sites to tune the edge and substrate surfaces of LDH.At the same time,the electronic structure was tuned by adding P heteroatoms.The synergistic effect of porous structure,heterogeneous interfaces,vacancies,doping defects,and amorphous states can greatly enhance the electron transfer effect inside the catalysts,which significantly improves the catalytic ability of the oxygen evolution reaction(OER).Therefore,the overpotential for the oxygen evolution reaction of NiMoP/Ni_(2)P heterointerfaces reaches 270 mV at a current density of 10 mA·cm^(-2)under alkaline conditions,with the catalysts capable of sustaining high current densities even after the durability testing for 35 h.
基金Supported by National Natural Science Foundation of China(Grant No.51475268)National Basic Research Program of China(973 Program,Grant No.2007CB206903)
文摘Flow?induced vibration plays a positive role on heat transfer enhancement. Meanwhile, it is also a negative factor for fatigue strength. Satisfying the fatigue strength is the primary prerequisite for heat transfer enhancement. This paper numerically studied the flow?induced vibration of planar elastic tube bundle based on a two?way fluid–structure interaction(FSI) calculation. The numerical calculation involved the unsteady, three?dimensional incompressible governing equations solved with finite volume approach and the dynamic balance equation of planar elastic tube bundle solved with finite element method combined with dynamic mesh scheme. The numerical approach was verified by comparing with the published experimental results. Then the vibration trajectory, deformation and stress contour of planar elastic tube bundle were all studied. Results show that the combined movement of planar elastic tube bundle represents the agitation from inside to outside. The vibration of out?of?plane is the main vibration form with the typically sinusoidal behavior because the magnitude of displacement along the out?of?plane direction is the 100 times than the value of in?plane direction. The dangerous point locates in the innermost tube where the equivalent stress can be utilized to study the multiaxial fatigue of planar elastic tube bundle due to the alternating stress concentration. In the velocity range of 0.2-3 m/s, it is inferred that the vibration amplitude plays a role on the stress response and the stress amplitude is susceptible to the fluid velocity. This research paves a way for studying the fatigue strength of planar elastic tube bundle by flow?induced vibration.
