Nitrogen doped FeS2 nanoparticles for efficient and stable hydrogen evolution reaction

Performance breakthrough of electrocatalysts highly relies on the regulation of internal structures and electronic states.In present work,for the first time,we successfully synthesized nitrogen doped FeS₂ nanoparticles(N-FeS₂)as the electrocatalysts for hydrogen evolution reaction(HER).The band structure and electronic state of FeS₂ are modulated by a nitrogen doping strategy,as confirmed by X-ray photoelectron spectroscopy(XPS),X-ray absorption spectroscopy(XAS)and density functional theory(DFT)calculations.Owing to the band structure and electronic state regulation as well as the weakening of H-S interaction,the designed N-FeS₂ electrocatalyst exhibits superior catalytic performance with a low overpotential(~126 mV at 10 mA cm^-2)and excellent activity stability under alkaline conditions,which is substantially improved as compared with that of the pure FeS₂ counterpart.Our work demonstrates that the modulation of electron state and band structure of an electrocatalyst,which can provide a valuable guidance for designing excellent catalysts for hydrogen evolution reaction and beyond.     

Tailoring the d‐Band Centers Enables Co4N Nanosheets To Be Highly Active for Hydrogen Evolution Catalysis

Endowing materials with specific functions that are not readily available is always of great importance, but extremely challenging. Co₄N, with its beneficial metallic characteristics, has been proved to be highly active for the oxidation of water, while it is notoriously poor for catalyzing the hydrogen evolution reaction (HER), because of its unfavorable d‐band energy level. Herein, we successfully endow Co₄N with prominent HER catalytic capability by tailoring the positions of the d‐band center through transition‐metal doping. The V‐doped Co₄N nanosheets display an overpotential of 37 mV at 10 mA cm^?2, which is substantially better than Co₄N and even close to the benchmark Pt/C catalysts. XANES, UPS, and DFT calculations consistently reveal the enhanced performance is attributed to the downshift of the d‐band center, which helps facilitate the H desorption. This concept could provide valuable insights into the design of other catalysts for HER and beyond.     

Standing Waves of the Coupled Nonlinear Schr ¨odinger Equations

In this paper, we study the existence of standIng waves of the coupled nonlinear Schrodinger equations. The proofs of which rely on the Lyapunov-Schmidt methods and contraction mapping principle are due to F. Weinstein in .     

On Existence of Ground States for Some Elliptic Systems

In this paper we consider the existence of ground states for some 2- coupled nonlinear Schrodinger systems with or without potentials. Under various conditions on the parameters in the equations, we prove the existence of ground states.     

有机分子膜层间相互作用对聚集体的影响

有机材料在分子设计与合成方面具有高度可塑性、灵活性及多样性,易于制成各种功能器件．带有电子给体和受体以及、电子体系的两亲类有机分子具有极高的超分子极化率“‘．利用Langmuir－Blodgett（LB）技术可实现有机材料在纳米尺寸上的分子组装,形成高度有序、非中心对称的LB膜以实现大的宏观二阶非线性极化系数．有机分子在LB膜中常常形成聚集体,而聚集体的存在将显著改变膜的宏观光学特性．根据有机分子间相互作用能的类型,聚集体可以分为J一型和H一型两种,分别表现为它们的吸收或荧光光谱‘”相对于单体发生红移或蓝移．近年来…     

LB膜中混合聚集体的光致荧光特性研究

研究了不同活性分子（半花菁和氐盐）混合聚集体的形成以及紫外光照射对ＬＢ交替多层膜光致荧光（ＰＬ）特性的影响。在半花菁和氐盐混合的ＬＢ膜中,由于不同分子间较强的相互作用使混合膜的荧光光谱较纯半花菁和氐盐分子膜分别发生了蓝移和红移。利用紫外光照射可以使分子的聚集体部分分解甚至破坏分子的结构,导致光致荧光强度明显减弱。     

Lewis酸催化下苯乙酮型苯并吡喃的合成

以2,4-二羟基苯乙酮(1a)为原料,通过O-异戊烯基化和Lewis酸催化分子内关环反应,合成了苯乙酮型苯并吡喃化合物3a.产物结构经UV,IR,1HNMR,13CNMR和元素分析表征,并对反应条件进行了初步探讨.     

非对称耦合量子阱Zn1-xCdxSe/ZnSe的二次谐波产生及其光学各向异性研究

采用反射式二次谐波产生方法对非对称Ⅱ-Ⅵ族耦合量子阱Zn1-xCdxSe/ZnSe的非线性光学特性进行了研究。与衬底相比,非对称量子阱在可见光波段的二次谐波信号增强一个量级以上。测量和比较了室温下量子阱样品与衬底样品的荧光光谱,研究了在入射光和反射光均为p偏振,以及入射光和反射光分别为s偏振和p偏振两种情况下,二次谐波强度随样品旋转方位角的变化关系,可见其有非常明显的二阶非线性一光学各向异性。     

半花菁LB膜的三阶非线性特性

本文利用Z扫描测量技术首次对半花菁LB膜的三阶非线性光学特性进行了研究.实验结果表明,LB多层膜中的半花菁分子具有较高的三阶非线性折射率n²=2.0×10^-8(esu),这主要是半花菁分子中π电子体系的贡献,并且由于532nm在其Q吸收带内,引起三阶非线性的共振增强效应,实验数据与理论拟合结果符合得很好.半花菁LB膜的三阶非线性的响应时间在30ns以内.