A standard in-beam y-spectroscopy experiment for ^188Pt is performed via the ^176yb（^18O, 6n） reaction at beam energies of 88 and 95 MeV, and the level scheme for ^188Pt is established. Prolate and oblate shape coex...A standard in-beam y-spectroscopy experiment for ^188Pt is performed via the ^176yb（^18O, 6n） reaction at beam energies of 88 and 95 MeV, and the level scheme for ^188Pt is established. Prolate and oblate shape coexistence has been demonstrated to occur in ^188Pt by applying the projected shell model. The rotation Mignment of i13/2 neutrons drives the yrast sequence changing suddenly from prolate to oblate shape at angular momentum 1Oh, indicating likely a new type of shape phase transition along the yrast fine in ^188Pt.展开更多
The study of the hydrogen evolution reaction(HER)aimed to reach a deeper understanding of the parameters that control the rate of this reaction is of great importance given the technical relevance of hydrogen producti...The study of the hydrogen evolution reaction(HER)aimed to reach a deeper understanding of the parameters that control the rate of this reaction is of great importance given the technical relevance of hydrogen production as an energy vector in the so-called hydrogen economy.In previous works,laser-induced temperature jump(LITJ)experiments on Pt(111)modified with Ni(OH)_(2)in alkaline media have revealed the importance of the interfacial electric field in the rate of the HER.It was hypothesised that small amounts of Ni(OH)_(2)cause a decrease of the electric field because of a negative shift of the pzfc toward the onset of the hydrogen evolution.In this work,to test the validity of this hypothesis,the study has been extended to Pt(111)surfaces modified with Fe(OH)_(2).The modified surfaces have been studied voltammetrically,and the voltammetric charges have been analysed.The voltammograms show a peak in the hydrogen evolution region that suggest the transformation in the adlayer from Fe(II)to Fe(0).In agreement with the coulometric analysis,the voltammetric features in the OH adsorption region would be related with the oxidation to the+3 valence state.The results obtained with LITJ method reflect the existence of a strong interaction of the Fe oxophilic species with the water molecules,shifting the potential of maximum entropy away from the onset of the HER.Hence,the most catalytic surface is the one with the lowest Fe coverage.展开更多
Platinum/Carbon XC72R （Pt/C） nanocomposite was synthesized in-situ by polyol method. Precursor of hexahydrated chloroplatinic acid H2PtCI6-6H2O was reduced by EG （ethylene glycol） so as to form Pt nanoparticles wh...Platinum/Carbon XC72R （Pt/C） nanocomposite was synthesized in-situ by polyol method. Precursor of hexahydrated chloroplatinic acid H2PtCI6-6H2O was reduced by EG （ethylene glycol） so as to form Pt nanoparticles which were deposited on the surface of carbon. Pt/C composites （treated or untreated carbon） were synthesized at pH - 6.5 and pH = 11. The XRD pattern of Pt/C showed peaks assigned to the crystalline structure of Pt and carbon. TEM images showed that Pt nanoparticles on carbon were ultrafine spheres and the particles obtained sizes from 2 to 6 nm which are mostly concentrated on size of 3 nm. The electrocatalytic activity of Pt/C catalysts toward methanol oxidation was examined by CV （cyclic voltammetry）. Pt/treated XC72R （pH = 11） at potential （0.69 V） exhibited better electroactivity （628 mA/mg Pt）.展开更多
Platinum(Pt)is an efficient catalyst for hydrogen evolution reaction(HER)and oxygen reduction reaction(ORR),but the debate of the relevance between the Pt particle size and its electrocatalytic activity still exist.Th...Platinum(Pt)is an efficient catalyst for hydrogen evolution reaction(HER)and oxygen reduction reaction(ORR),but the debate of the relevance between the Pt particle size and its electrocatalytic activity still exist.The strong metal–support interaction(SMSI)between the metal and carrier causes the charge transfer and mass transport from the support to the metal.Herein,Pt species(0.5 wt.%)with various particle sizes supported on carbon nanotubes(CNTs)have been synthesized by a photo-reduction method.The^1.5 nm-sized Pt catalyst shows much higher HER performance than the counterparts in all pH solutions,and the mass activity of it is even 23–36 times that of Pt/C.While for ORR,the^3 nm-sized Pt catalyst exhibits the optimal performance,and the mass activity is 3 times and even 16 times that of Pt/C in acidic and alkaline media,respectively.The high HER and ORR performances of the^1.5 nm-and^3 nm-sized Pt catalysts benefit from the SMSI between Pt and the CNTs matrix and the higher ratio of face sites to edge sites,which is meaningful for the design of efficient electrocatalysts for renewable energy application.展开更多
Highly crystalline graphitic nanocarbons （GNC） have been prepared by the wet-air treatment of hydrothermally- derived graphitic porous carbon. The materials were characterized by scanning electron microscopy, X-ray ...Highly crystalline graphitic nanocarbons （GNC） have been prepared by the wet-air treatment of hydrothermally- derived graphitic porous carbon. The materials were characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and electrochemical methods. The experimental results revealed that the treatment temperature has a significant effect on the morphology and degree of graphitic crystallinity. When GNC was treated at 450 ~C under a wet-air atmosphere, the product （GNC-450） consisted of aggregates of silkworm-shaped carbon nanoparticles with enhanced graphitic characteristics. GNC-450 was evaluated as a catalyst support in the electro-oxidation of methanol. The Pt/GNC-450 catalyst contained smaller Pt particles and had a higher electrochemically active surface area than a commercial carbon black-supported Pt catalyst. In the electro-oxidation of methanol, the Pt/GNC-450 catalyst showed the highest performance among the Pt catalysts examined in this study. The superior catalytic performance appears to be closely related to the enhanced graphitic characteristics with highly dispersed Pt nanoparticles on the graphitic layers, which have a positive effect on the electrochemical performance.展开更多
基金received financial supports from Innovation Seedling Projects of Zigong City (2017CXM02)Key R&D Program of Sichuan Province (2017GZ0391)National Key Research and Development Program (2016YFE0102600)
基金Supported by the Major State Basic Research Programme of China 2007CB815001, the National Natural Science Foundation of China under Grant No 10775158, and the Chinese Academy of Sciences.
文摘A standard in-beam y-spectroscopy experiment for ^188Pt is performed via the ^176yb（^18O, 6n） reaction at beam energies of 88 and 95 MeV, and the level scheme for ^188Pt is established. Prolate and oblate shape coexistence has been demonstrated to occur in ^188Pt by applying the projected shell model. The rotation Mignment of i13/2 neutrons drives the yrast sequence changing suddenly from prolate to oblate shape at angular momentum 1Oh, indicating likely a new type of shape phase transition along the yrast fine in ^188Pt.
基金funded by Ministerio de Ciencia e Innovación (Spain) (PID2019-105653GB-I00)Generalitat Valenciana (Spain) (PROMETEO/2020/063)。
文摘The study of the hydrogen evolution reaction(HER)aimed to reach a deeper understanding of the parameters that control the rate of this reaction is of great importance given the technical relevance of hydrogen production as an energy vector in the so-called hydrogen economy.In previous works,laser-induced temperature jump(LITJ)experiments on Pt(111)modified with Ni(OH)_(2)in alkaline media have revealed the importance of the interfacial electric field in the rate of the HER.It was hypothesised that small amounts of Ni(OH)_(2)cause a decrease of the electric field because of a negative shift of the pzfc toward the onset of the hydrogen evolution.In this work,to test the validity of this hypothesis,the study has been extended to Pt(111)surfaces modified with Fe(OH)_(2).The modified surfaces have been studied voltammetrically,and the voltammetric charges have been analysed.The voltammograms show a peak in the hydrogen evolution region that suggest the transformation in the adlayer from Fe(II)to Fe(0).In agreement with the coulometric analysis,the voltammetric features in the OH adsorption region would be related with the oxidation to the+3 valence state.The results obtained with LITJ method reflect the existence of a strong interaction of the Fe oxophilic species with the water molecules,shifting the potential of maximum entropy away from the onset of the HER.Hence,the most catalytic surface is the one with the lowest Fe coverage.
文摘Platinum/Carbon XC72R （Pt/C） nanocomposite was synthesized in-situ by polyol method. Precursor of hexahydrated chloroplatinic acid H2PtCI6-6H2O was reduced by EG （ethylene glycol） so as to form Pt nanoparticles which were deposited on the surface of carbon. Pt/C composites （treated or untreated carbon） were synthesized at pH - 6.5 and pH = 11. The XRD pattern of Pt/C showed peaks assigned to the crystalline structure of Pt and carbon. TEM images showed that Pt nanoparticles on carbon were ultrafine spheres and the particles obtained sizes from 2 to 6 nm which are mostly concentrated on size of 3 nm. The electrocatalytic activity of Pt/C catalysts toward methanol oxidation was examined by CV （cyclic voltammetry）. Pt/treated XC72R （pH = 11） at potential （0.69 V） exhibited better electroactivity （628 mA/mg Pt）.
基金support from the Natural Science Foundation of Shanghai(19ZR1479400)the State Key Laboratory for Modication of Chemical Fibers and Polymer Materials,Donghua University(KF1818)the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing(Wuhan University of Technology)。
文摘Platinum(Pt)is an efficient catalyst for hydrogen evolution reaction(HER)and oxygen reduction reaction(ORR),but the debate of the relevance between the Pt particle size and its electrocatalytic activity still exist.The strong metal–support interaction(SMSI)between the metal and carrier causes the charge transfer and mass transport from the support to the metal.Herein,Pt species(0.5 wt.%)with various particle sizes supported on carbon nanotubes(CNTs)have been synthesized by a photo-reduction method.The^1.5 nm-sized Pt catalyst shows much higher HER performance than the counterparts in all pH solutions,and the mass activity of it is even 23–36 times that of Pt/C.While for ORR,the^3 nm-sized Pt catalyst exhibits the optimal performance,and the mass activity is 3 times and even 16 times that of Pt/C in acidic and alkaline media,respectively.The high HER and ORR performances of the^1.5 nm-and^3 nm-sized Pt catalysts benefit from the SMSI between Pt and the CNTs matrix and the higher ratio of face sites to edge sites,which is meaningful for the design of efficient electrocatalysts for renewable energy application.
文摘Highly crystalline graphitic nanocarbons （GNC） have been prepared by the wet-air treatment of hydrothermally- derived graphitic porous carbon. The materials were characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and electrochemical methods. The experimental results revealed that the treatment temperature has a significant effect on the morphology and degree of graphitic crystallinity. When GNC was treated at 450 ~C under a wet-air atmosphere, the product （GNC-450） consisted of aggregates of silkworm-shaped carbon nanoparticles with enhanced graphitic characteristics. GNC-450 was evaluated as a catalyst support in the electro-oxidation of methanol. The Pt/GNC-450 catalyst contained smaller Pt particles and had a higher electrochemically active surface area than a commercial carbon black-supported Pt catalyst. In the electro-oxidation of methanol, the Pt/GNC-450 catalyst showed the highest performance among the Pt catalysts examined in this study. The superior catalytic performance appears to be closely related to the enhanced graphitic characteristics with highly dispersed Pt nanoparticles on the graphitic layers, which have a positive effect on the electrochemical performance.
