利用溶剂热法,在N,N-二甲基甲酰胺(DMF)溶剂中共同还原乙酰丙酮铂(Pt(acac)2)和乙酰丙酮铜(Cu(acac)_2)制备PtCu八面体合金催化剂.PtCu_2八面体表现出明显的晶格收缩、较高比例的非氧化态Pt单质和较高的电子结合能,进而表现出较弱的含...利用溶剂热法,在N,N-二甲基甲酰胺(DMF)溶剂中共同还原乙酰丙酮铂(Pt(acac)2)和乙酰丙酮铜(Cu(acac)_2)制备PtCu八面体合金催化剂.PtCu_2八面体表现出明显的晶格收缩、较高比例的非氧化态Pt单质和较高的电子结合能,进而表现出较弱的含氧物种吸附强度和较低的d带中心位置.系统研究结构导向剂对PtCu合金形貌影响.在半电池测试中,由于PtCu_2具有均匀分散的规则八面体形貌结构,导致在0.9 V vs.RHE处氧还原(ORR)的质量比活性和面积比活性分别是Pt/C(JM)的6.3和27.2倍,并在加速衰减测试后其ORR的质量比活性仍达到Pt/C(JM)的4.5倍.展开更多
Dynamical mode locking phenomena in incommensurate structures of the dc- and ac-driven overdamped FrenkelKontorova model are studied by molecular-dynamics simulations.It is found that the Shapiro steps exhibit signifi...Dynamical mode locking phenomena in incommensurate structures of the dc- and ac-driven overdamped FrenkelKontorova model are studied by molecular-dynamics simulations.It is found that the Shapiro steps exhibit significantly different amplitude and frequency dependences from the ones observed in the commensurate structures.The step widths still oscillate with the amplitude,but the form is no longer Bessel-like,i.e.,the anomaly appears in our simulations.The same type of anomalies is also exhibited by the critical depinning force.The oscillatory behavior and the anomalies are also revealed in the ((F),Fac) phase diagram where three phases are observed.These oscillations are directly correlated with the existence and the stability of interference phenomena in real systems.展开更多
文摘利用溶剂热法,在N,N-二甲基甲酰胺(DMF)溶剂中共同还原乙酰丙酮铂(Pt(acac)2)和乙酰丙酮铜(Cu(acac)_2)制备PtCu八面体合金催化剂.PtCu_2八面体表现出明显的晶格收缩、较高比例的非氧化态Pt单质和较高的电子结合能,进而表现出较弱的含氧物种吸附强度和较低的d带中心位置.系统研究结构导向剂对PtCu合金形貌影响.在半电池测试中,由于PtCu_2具有均匀分散的规则八面体形貌结构,导致在0.9 V vs.RHE处氧还原(ORR)的质量比活性和面积比活性分别是Pt/C(JM)的6.3和27.2倍,并在加速衰减测试后其ORR的质量比活性仍达到Pt/C(JM)的4.5倍.
基金Supported by the National Natural Science Foundation of China under Grant Nos 91026005 and 11105054the Foundation for Distinguished Young Talents in Higher Education of Guangdong Province under Grant No LYM10065the Domestic Visiting Scholars Program of the Doctoral Candidates of Northwest Normal University of China.
文摘Dynamical mode locking phenomena in incommensurate structures of the dc- and ac-driven overdamped FrenkelKontorova model are studied by molecular-dynamics simulations.It is found that the Shapiro steps exhibit significantly different amplitude and frequency dependences from the ones observed in the commensurate structures.The step widths still oscillate with the amplitude,but the form is no longer Bessel-like,i.e.,the anomaly appears in our simulations.The same type of anomalies is also exhibited by the critical depinning force.The oscillatory behavior and the anomalies are also revealed in the ((F),Fac) phase diagram where three phases are observed.These oscillations are directly correlated with the existence and the stability of interference phenomena in real systems.
