The electrochemical nitrogen reduction reaction (NRR) is an attractive pathway for producing ammonia under ambient conditions. The development of efficient catalysts for nitrogen fixation in electrochemical NRRs has become increasingly important, but it remains challenging due to the need to address the issues of activity and selectivity. Herein, using density functional theory (DFT), we explore ten kinds of triple transition metal atoms (M3 = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) anchored on the C2N monolayer (M3-C2N) as NRR electrocatalysts. The negative binding energies of M3 clusters on C2N mean that the triple transition metal clusters can be stably anchored on the N6 cavity of the C2N structure. As the first step of the NRR, the adsorption configurations of N2 show that the N2 on M3-C2N catalysts can be stably adsorbed in a side-on mode, except for Zn3-C2N. Moreover, the extended N-N bond length and electronic structure indicate that the N2 molecule has been fully activated on the M3-C2N surface. The results of limiting potential screen out the four M3-C2N catalysts (Co3-C2N, Cr3-C2N, Fe3-C2N, and Ni3-C2N) that have a superior electrochemical NRR performance, and the corresponding values are −0.61 V, −0.67 V, −0.63 V, and −0.66 V, respectively, which are smaller than those on Ru(0001). In addition, the detailed NRR mechanism studied shows that the alternating and enzymatic mechanisms of association pathways on Co3-C2N, Cr3-C2N, Fe3-C2N, and Ni3-C2N are more energetically favorable. In the end, the catalytic selectivity for NRR on M3-C2N is investigated through the performance of a hydrogen evolution reaction (HER) on them. We find that Co3-C2N, Cr3-C2N, Fe3-C2N, and Ni3-C2N catalysts possess a high catalytic activity for NRR and exhibit a strong capability of suppressing the competitive HER. Our findings provide a new strategy for designing NRR catalysts with high catalytic activity and selectivity.

The topological anomalous Hall effect and the anomalous Nernst effect are of great interest for the development of spintronic devices for energy-efficient data storage and energy harvesting. Using first-principles calculations, we have studied the anomalous Hall conductivity (AHC) and anomalous Nernst conductivity (ANC) of six ferromagnetic compounds Co 3 Al, Fe 3 Ge, Fe 3 Pt, Ni 3 Ga, Ni 3 In, and Rh 3 Cr belonging to the cubic Cu 3 Au structure. A large AHC of 1973 S cm −1 is obtained for Fe 3 Pt. Parallel to the large AHC, a giant ANC of −5.41 A mK −1 and −4.18 A mK −1 is observed for Ni 3 In and Co 3 Al, respectively. Finally, we found that AHC and ANC can be adjusted by switching the magnetization direction.

In recent years, clean and sustainable energy generation by photocatalytic water splitting has gained enormous attention from researchers. Two-dimensional Cd-based structures play a central role in the research of semiconductor-based photocatalysis. Here, a few layers of cadmium monochalcogenides (CdX; X=S, Se, and Te) are theoretically investigated using density functional theory (DFT). For their potential applicability in photocatalysis, it is proposed that they are exfoliated from the wurtzite structure with an electronic gap that depends on the thickness of the proposed systems. Our calculations address a long-standing doubt about the stabilities of free-standing CdX monolayers (ML). Induced buckling removes the acoustic instabilities in 2D planar hexagonal CdX structures (due to interlayer interactions) that depend on the number of neighboring atomic layers present. All studied (and stable) systems have an electronic gap of >1.68 eV, calculated with hybrid functionals (HSE06). A band-edge alignment plot about the water's oxidation-reduction potential is constructed, and a potential energy surface is constructed for the hydrogen evolution reaction. Our calculations suggest that the chalcogenide site is most favorable for hydrogen adsorption, and the energy barrier falls within the experimentally achievable limits.

The long-range interaction between two identical solitons in strongly nonlocal nonlinear media with the sine-oscillation response function is studied. It is found that the two solitons may attract each other, repel each other, or keep in parallel in the initial stage. The behavior of the soliton interactions depends periodically on the separation between solitons; it is essentially controlled by the superposition of the periodic light-induced nonlinear refractive index. The different versions of the soliton interactions can be interchanged by adjusting the separation between solitons.

刚体是考虑了物体大小的理想模型.刚体在一定的支撑物上无滑滚动时,刚体与支撑物的接触会造成对刚体运动的限制.本文提出用定解问题思想研究刚体运动,将刚体视为一个有大小的系统,"无滑滚动条件"理解为系统的边界条件,求解刚体运动的定解问题即可获得刚体运动信息,揭示"无滑滚动条件"的本质.

论文给出了一端外力激励下弦振动的适定性定解问题描述及其解,讨论定解条件的匹配性问题.

随着互联网与移动技术的发展,微信逐渐成为人们必不可少的即时通讯软件.在教育信息化2.0的时代背景下,构建了高校物理实验室的微信公众平台,并应用在实验仪器设备管理、教学资源共享、开放创新、安全教育、资讯通告、师生互动以及统计分析等方面,为高校实验的教学管理提供了新模式,弥补了传统实验教学与实验室安全管理的不足,有效地提高了教学与管理效率,提升了教师的教学热情与学生自主学习的积极性.

当今大学生的自我认知模糊不清晰,不能准确定位.本文主要分析了体育舞蹈对学生体型、身体素质、审美能力、社会交往及适应能力等方面认知的影响,得出体育舞蹈对提高大学生的认知水平有一定的积极作用.

花鼓舞是一项传统的民间文化娱乐活动,近年来,演变成一种极具观赏与健身于一体的群众性活动.在对于秭归花鼓舞进行探究分析中,本文采用文献资料法、专家访谈法、实体考察法,从秭归花鼓舞的多元化特征入手,深入分析秭归花鼓舞的推广价值,旨在为"秭归花鼓舞"的继承与发展打下扎实的基础,并丰富我国中华民族民间传统文化.

本文采用文献资料法、问卷调查法、统计分析法等方法,通过对湖北文理学院选修体育舞蹈俱乐部的同学现状进行调查分析,对学生在学习体育舞蹈课程后的结果反馈进行分析总结,并提出让体育舞蹈更好的在湖北文理学院体育俱乐部发展的建议.

本文运用文献资料法、问卷调查法、逻辑分析法等研究方法,运用SWOT模型对体育舞蹈进入高校体育课堂的优势、劣势、机会和威胁进行分析,并对体育舞蹈进入高校体育课堂提出合理化建议.

实验室低值易耗品管理是高校实验室管理的一个重要组成部分.目前高校实验室低值易耗品经费逐年增加,而低值易耗品管理中存在品种多、效率低和易浪费、申报程序繁琐、购买周期长等问题.为了提高实验室低值易耗品的管理效率,针对实验室低值易耗品的特点,总结分析了当前高校实验室低值易耗品管理中存在的问题,提出实验室低值易耗品的管理对策,为高校规范实验耗材的管理提供参考.

文章基于共振原理,将三线摆和单摆结合起来,利用共振状态下的单摆周期等效于三线摆的周期,将单摆的周期公式代入三线摆求转动惯量的理论推导式中,消掉重力加速度g,达到计算不用考虑g值的目的.

随着社会的进步与发展,骑行以一种新的方式出现在人们的生活中.本文以川藏线骑行者为研究对象,通过比较分析法、参与观察法、网络游记统计调查法、文献综述法,对各广大驴友的骑行动机进行研究分析,从而提出相应地有建设性的建议来促进户外骑行运动的发展.

It expounds the contents of the examination in college physical experiment,analyzes the necessity of the reform in the examination method,and introduces the implementation of the reform of the examination mode of college physical experiment in my college.Practice shows that:After the reform of the examination mode is conducive to improving the students' ability to innovate,experimental thinking,scientific experimental ability and other comprehensive ability.

分析了J-FG3-D型金属线胀系数测定仪器设计上的缺陷,并进行了改进.改进后的实验效果很好,提高了实验的精度,节约了成本.

近些年随着我国高校军事教学的快速发展,军事训练已经成为绝大多数的高校提高大学生思想道德、意志品格、身体素质和对国家认同的有效措施.而目前关于军事训练项目对高校体育生的意义的研究较少,因此,该论文通过文献资料法、访谈法和逻辑分析法对军事训练项目对高校体育生的影响进行调查分析,旨在更好地突出军事训练项目的必要性与价值.

From the Schr?dinger equation of quantum mechanics,introducing quantum momentum op-erator using comparing the expression of classical momentum:the mean value of momentum operator e-quals mass times the rate of change of position coordinate.This method was applied to the curve, geometry momentum was obtained naturally.So,the momentum operator in quantum mechanics is not a basic assumption.

Based on spatial interaction theory,this paper illustrates the characteristics of integrated space and effect on space interaction of urban and rural sports. According to the related essential factors and interactive mechanism be-tween urban and rural sports space,this paper puts forward five aspects for integrated development of urban and rural sports space,which are basic unit,sports spatial community,space connection channel,space combination mode and suitable policy.

本文采用问卷调查、文献资料和数理统计等方法，深入了解湖北文理学院大学生体育消费现状及影响因素；从大学生的体育消费意识、体育消费水平、体育消费结构和体育消费行为等方面进行分析，为积极推动“运动校园”建设、提高高校体育文化水平、丰富大学生的生活提供科学有效的理论参考。