Development of reaction-tailored electrocatalysts is becoming increasingly important as energy and environment are among key issues governing our sustainable future.Electrocatalysts are inherently optimized for applic...Development of reaction-tailored electrocatalysts is becoming increasingly important as energy and environment are among key issues governing our sustainable future.Electrocatalysts are inherently optimized for application towards reactions of interest in renewable energy,such as those involved in water splitting and artificial photosynthesis,owing to its energy efficiency,simple fabrication,and ease of operation.In this view,it is important to secure logical design principles for the synthesis of electrocatalysts for various reactions of interest,and also understand their catalytic mechanisms in the respective reactions for improvements in further iterations.In this review,we introduce several key methods of scanning electrochemical microscopy(SECM)in its applications towards electrocatalysis.A brief history and a handful of seminal works in the SECM field is introduced in advancing the synthetic designs of electrocatalysts and elucidation of the operating mechanism.New developments in nano-sizing of the electrodes in attempts for improved spatial resolution of SECM is also introduced,and the application of nanoelectrodes towards the investigation of formerly inaccessible single catalytic entities is shared.展开更多
An approach of limit state equation for surrounding rock was put forward based on deformation criterion. A method of symmetrical sampling of basic random variables adopted by classical response surface method was mend...An approach of limit state equation for surrounding rock was put forward based on deformation criterion. A method of symmetrical sampling of basic random variables adopted by classical response surface method was mended, and peak value and deflection degree of basic random variables distribution curve were took into account in the mended sampling method. A calculation way of probability moment, based on mended Rosenbluth method, suitable for non-explicit performance function was put forward. The first, second, third and fourth order moments of functional function value were calculated by mended Rosenbluth method through the first, second, third and fourth order moments of basic random variable. A probability density the function（PDF） of functional function was deduced through its first, second, third and fourth moments, the PDF in the new method took the place of the method of quadratic polynomial to approximate real functional function and reliability probability was calculated through integral by the PDF for random variable of functional function value in the new method. The result shows that the improved response surface method can adapt to various statistic distribution types of basic random variables, its calculation process is legible and need not itemtive circulation. In addition, a stability probability of surrounding rock for a tunnel was calculated by the improved method, whose workload is only 30% of classical method and its accuracy is comparative.展开更多
Offshore project risk concerns many influence factors with complex relationship, and traditional methods cannot be used for the evaluation on risk probability. To deal with this problem, a new method was developed by ...Offshore project risk concerns many influence factors with complex relationship, and traditional methods cannot be used for the evaluation on risk probability. To deal with this problem, a new method was developed by the combination of improved technique for order preference by similarity ideal solution method, analytical hierarchy process method and the network response surface method. The risk probability was calculated by adopting network response surface analysis based on the state variable of a known event and its degree of membership.This quantification method was applied to an offshore platform project, Bonan oil and gas field project in Bohai Bay in June 2004.There were 7 sub-projects and each includes 4 risk factors.The values of 28 risk factors, ranging from 10^-6 to 10^-4, were achieved. This precision conforms to the international principle of as low as reasonably practically.The evaluation indicates that the values of comprehensive level of construction group and ability of technical personnel on the spot are relatively high among all risk factors, so these two factors should be paid more attention to in offshore platform construction.展开更多
Ruthenium-based catalyst is one of the most active catalysts for oxygen evolution reaction(OER)in acid media.However,the strong bonding between the Ru sites and oxygen intermediates leads to high overpotential to trig...Ruthenium-based catalyst is one of the most active catalysts for oxygen evolution reaction(OER)in acid media.However,the strong bonding between the Ru sites and oxygen intermediates leads to high overpotential to trigger the OER process.Hence,pyrochlore rare-earth ruthenate(RE_(2)-Ru_(2)O_(7))structures with a series of rare-earth elements(Nd,Sm,Gd,Er,and Yb)were constructed to tune the electronic structure of the Ru sites.Surface structure analysis indicated that the increase of the radius of the rare-earth cations resulted in higher content of defective oxygen(the percentage of the defective oxygen increased from 29.5% to 49.7%) in the RE_(2)Ru_(2)O_(7) structure due to the weakened hybridization of the Ru-O bond.This reduced the valence states of the Ru sites and enlarged the gap between the 4d band center and the Fermi level(E_(F))of Ru,resulting in the weakened adsorption of oxygen intermediates and the improved OER performance in acid media.Among the as-prepared ruthenium pyrochlores,Nd_(2)Ru_(2)O_(7) displayed the lowest OER onset overpotential(210 mV)and Tafel slope(58.48 mV dec^(-1)),as well as 30 times higher intrinsic activity and much higher durability than the state-of-art RuO_(2) catalyst.展开更多
文摘Development of reaction-tailored electrocatalysts is becoming increasingly important as energy and environment are among key issues governing our sustainable future.Electrocatalysts are inherently optimized for application towards reactions of interest in renewable energy,such as those involved in water splitting and artificial photosynthesis,owing to its energy efficiency,simple fabrication,and ease of operation.In this view,it is important to secure logical design principles for the synthesis of electrocatalysts for various reactions of interest,and also understand their catalytic mechanisms in the respective reactions for improvements in further iterations.In this review,we introduce several key methods of scanning electrochemical microscopy(SECM)in its applications towards electrocatalysis.A brief history and a handful of seminal works in the SECM field is introduced in advancing the synthetic designs of electrocatalysts and elucidation of the operating mechanism.New developments in nano-sizing of the electrodes in attempts for improved spatial resolution of SECM is also introduced,and the application of nanoelectrodes towards the investigation of formerly inaccessible single catalytic entities is shared.
基金Project(50378036) supported by the National Natural Science Foundation of China Project (200503) supported by the Foundation ofCommunications Department of Hunan Province, China
文摘An approach of limit state equation for surrounding rock was put forward based on deformation criterion. A method of symmetrical sampling of basic random variables adopted by classical response surface method was mended, and peak value and deflection degree of basic random variables distribution curve were took into account in the mended sampling method. A calculation way of probability moment, based on mended Rosenbluth method, suitable for non-explicit performance function was put forward. The first, second, third and fourth order moments of functional function value were calculated by mended Rosenbluth method through the first, second, third and fourth order moments of basic random variable. A probability density the function（PDF） of functional function was deduced through its first, second, third and fourth moments, the PDF in the new method took the place of the method of quadratic polynomial to approximate real functional function and reliability probability was calculated through integral by the PDF for random variable of functional function value in the new method. The result shows that the improved response surface method can adapt to various statistic distribution types of basic random variables, its calculation process is legible and need not itemtive circulation. In addition, a stability probability of surrounding rock for a tunnel was calculated by the improved method, whose workload is only 30% of classical method and its accuracy is comparative.
文摘Offshore project risk concerns many influence factors with complex relationship, and traditional methods cannot be used for the evaluation on risk probability. To deal with this problem, a new method was developed by the combination of improved technique for order preference by similarity ideal solution method, analytical hierarchy process method and the network response surface method. The risk probability was calculated by adopting network response surface analysis based on the state variable of a known event and its degree of membership.This quantification method was applied to an offshore platform project, Bonan oil and gas field project in Bohai Bay in June 2004.There were 7 sub-projects and each includes 4 risk factors.The values of 28 risk factors, ranging from 10^-6 to 10^-4, were achieved. This precision conforms to the international principle of as low as reasonably practically.The evaluation indicates that the values of comprehensive level of construction group and ability of technical personnel on the spot are relatively high among all risk factors, so these two factors should be paid more attention to in offshore platform construction.
基金supported by the National Key Research and Development Project(2018YFB1502401)the National Natural Science Foundation of China(21771018 and 21875004)+3 种基金the Royal Society and Newton Fund through Newton Advanced Fellowship award(NAF\R1\191294)the Program for Changjiang Scholars and Innovation Research Team in the University(IRT1205)the Fundamental Research Funds for the Central Universitiesthe long-term subsidy mechanism from the Ministry of Finance and the Ministry of Education of China。
文摘Ruthenium-based catalyst is one of the most active catalysts for oxygen evolution reaction(OER)in acid media.However,the strong bonding between the Ru sites and oxygen intermediates leads to high overpotential to trigger the OER process.Hence,pyrochlore rare-earth ruthenate(RE_(2)-Ru_(2)O_(7))structures with a series of rare-earth elements(Nd,Sm,Gd,Er,and Yb)were constructed to tune the electronic structure of the Ru sites.Surface structure analysis indicated that the increase of the radius of the rare-earth cations resulted in higher content of defective oxygen(the percentage of the defective oxygen increased from 29.5% to 49.7%) in the RE_(2)Ru_(2)O_(7) structure due to the weakened hybridization of the Ru-O bond.This reduced the valence states of the Ru sites and enlarged the gap between the 4d band center and the Fermi level(E_(F))of Ru,resulting in the weakened adsorption of oxygen intermediates and the improved OER performance in acid media.Among the as-prepared ruthenium pyrochlores,Nd_(2)Ru_(2)O_(7) displayed the lowest OER onset overpotential(210 mV)and Tafel slope(58.48 mV dec^(-1)),as well as 30 times higher intrinsic activity and much higher durability than the state-of-art RuO_(2) catalyst.
