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1.
An important challenge facing K-ion batteries lies in exploring earth-abundant and safe cathode materials that can provide high capacity with high migration rate of K ions.Here,we propose a simple and efficient method for searching potential K cathode materials with first principles calculations.Our screening is based on combinations of weight capacity,K ion occupation ratio,volume change per K,and valence limit.With this screening method we predicted a series of potential K ions cathodes with favorable electrochemical performance,such as K2VPO4CO3-like structures with 1 D diffusion channels,3 D channel structures K2CoSiO4,layered materials KCoO2,KCrO2,KVF4 and K5V3F14,and others.These potential cathodes have small volume changes,suitable voltage,and high capacity,with small diffusion barriers.They may be useful in K-ion batteries with high energy density and rate performance.  相似文献   

2.
Artificial base pairs,from the perspective of synthetic biology,are designed to contain the features of modularity,orthogonality,and manipulability.And the development of artificial base pairs has beat endowed with responsibility to understand the biological process,improve the recognition capacity and stability of aptamers,and develop the nucleoside drugs,diagnosis,and drag delivery.In this review,we first gave a concise introduction of artificial base pairs based on their interaction modes including alternative hydrogen bonding,hydrophobic interaction,and metal coordination.Then we displayed the detailed information of artificial base pairs with hydrogen bonding interaction,and analyzed how the changes of their structures affect their functions.Subsequently,we highlighted the applications of functional artificial base pairs in aptamer discovery,diagnosis,and drug delivery.Finally,an insight into the remaining challenges and future perspective of the artificial bases was provided.  相似文献   

3.
Inefficient electrocatalysts and high-power consumption are two thorny problems for electrochemical hydrogen(H2)production from acidic water electrolysis.Herein we report the one-pot precise synthesis of ultrafine Au core-Pt Au alloy shell nanowires(Au@PtxAu UFNWs).Among them,Au@Pt0.077 Au UFNWs exhibit the best performance for formic acid oxidation reaction(FAOR)and hydrogen evolution reaction(HER),which only require applied potentials of 0.29 V and-22.6 m V to achieve a current density of 10 m A cm-2,respectively.The corresponding formic acid electrolyzer realizes the electrochemical H2 production at a voltage of only 0.51 V with 10 m A cm-2 current density.Density functional theory(DFT)calculations reveal that the Au-riched Pt Au alloy structure can facilitates the direct oxidation pathway of FAOR and consequently elevates the FAOR activity of Au@Pt0.077 Au UFNWs.This work provides meaningful insights into the electrochemical H2 production from both the construction of advanced bifunctional electrocatalysts and the replacement of OER.  相似文献   

4.
有中学化学参考资料题:0.10 mol/L的NH4Cl和(NH4)2SO4溶液哪个pH值高?这似乎是个中学生可做的简单题目,仔细考虑不是如此.如果简单地认为盐酸和硫酸都是强酸,而硫酸是二元酸,硫酸铵溶液中铵盐浓度为0.20 mol/L,那么NH4Cl溶液pH高,那是不妥的.硫酸是二元酸,第一个氢离子能完全电离,第二个氢离子部分电离,如此考虑情况怎么样呢?是不是答案发生变化?这要通过计算来说明.  相似文献   

5.
Layered Li-rich Mn-based oxides are promising cathode materials for Li-ion batteries due to their high capacity and high operation voltage.However,their commercial applications are hindered by irreversible capacity loss in the first charge-discharge process,voltage decay during cycling,inefficient cyclability and rate capability.Many attempts have been performed to solve such issues,including the mechanism study and strategies to improve the electrochemical performance.This article provides a brief review and future perspective on the main challenges of the high-capacity Li-rich Mn-based cathodes for Li-ion batteries.  相似文献   

6.
The perovskite transition metal oxide(TMO) has been considered in electrocatalysis for the modern clean energy technologies as its high electrochemical activity and low cost. The atomic scale engineering to the local stoichiometry of single crystal TMO provides a clue of the relation between electronic structure and catalytic performance. Here we report a hydrogen evolution reaction(HER) activity enhancement ~ 1761% of Bi0.85Sr0.15FeO_3 compared to the pure BiFeO_3. By the systemic investigation of the Sr doping level of Bi1-xSr_xFeO_3(BSFO), it is found that the HER enhancement originates from the improvement of ferromagnetism of BSFO without obvious scarification of the ferroelectricity at the room temperature. The multiple ferroic orderings in BSFO are beneficial for HER activity, which offers the strengthen of hybridization of Fe 3d and O2 p orbitals from the view of ferromagnetism, and the assistance of electron drift by spontaneous electric polarization. Our study not only affords the strategy of developing multiple ferroic orderings in TMO, but also facilitates the atomic scale understanding of the improved HER activity.  相似文献   

7.
The aqueous rechargeable Zn-ion batteries based on the safe,low cost and environmental benignity aqueous electrolytes are one of the most compelling candidates for large scale energy storage applications.However,pursuing suitable insertion materials may be a great challenge due to the strong electrostatic interaction between Zn^(2+)and cathode materials.Hence,a novel NaV6O15/V2O5 skin-core heterostructure nanowire is reported via a one-step hydrothermal method and subsequent calcination for high-stable aqueous Zn-ion batteries(ZIBs).The NaV6O15/V2O5 cathode delivers high specific capacity of 390 m Ah/g at 0.3 A/g and outstanding cycling stability of 267 m Ah/g at 5 A/g with high capacity retention over 92.3%after 3000 cycles.The superior electrochemical performances are attributed to the synergistic effect of skin-core heterostructured NaV6O15/V2O5,in which the sheath of NaV6O15 possesses high stability and conductivity,and the V2O5 endows high specific capacity.Besides,the heterojunction structure not only accelerates intercalation kinetics of Zn2+transport but also further consolidates the stability of the layers of V2O5 during the cyclic process.This work provides a new perspective in developing feasible insertion materials for rechargeable aqueous ZIBs.  相似文献   

8.
杨周  张文华 《催化学报》2014,35(7):983-988
正1.Introduction We have recently witnessed a breakthrough in highly effi-cient solar cells, where the organolead halide perovskite, CH3NH3PbI3, was used as an absorber of sunlight. The perov-skite was used to sensitize mesoporous TiO2 films in a solid-state mesoscopic solar cell to deliver a power conversion  相似文献   

9.
李俊生 《化学教育》2007,28(7):61-62
长期以来人们一直认为金属钠保存在煤油中是因为金属钠的密度比煤油的密度大且金属钠和煤油不发生化学反应的缘故,因此在教学中形成一个教师都默认学生也认可的事实,这个事实就是金属钠能保存在煤油中有2点原因:  相似文献   

10.
The effect of electrolytes on the micellar behavior of an amphiphilic drug,chlorpromazine(CPZ)hydroehloride,was studied using cloud point(CP)and dye solubilization techniques.In the presence of KBr,increase because of deprotonation of drug molecules at high pH. The visible absorbance increased(due to dye solubilization)with the increase in pH from 6.5 to 6.9,which indicated micellar growth.At fixed pH(6.7),addition of inorganic salts(KF,KC1,effecfiveness being in the order:F-Na >K ,which Was explained by considering cognizance of their hydrated radii.Compared with anions,their effect was small.Increase in[CPZ]caused micellar growth and hence the CP as well as the visible absorbance increased.The overall behavior Was discussed in terms of electrostatic interactions and micellar growth.  相似文献   

11.
Since the outbreak of novel coronavirus pneumonia (NCP) at the beginning of this year, Chinese government acted immediately and made some regulations to control the epidemic NCP and promote the recovery of society and industry including education. Chinese universities stayed on the online courses without suspension on teaching and learning. Herein, we report online teaching of structural chemistry course based on the teaching mode of online live broadcast platform, online course resources and management platforms ("1 + 2" mode). This may promote online teaching, and take advantage of online live broadcast and massive open online courses, which achieves good teaching and learning experiences on structural chemistry course.  相似文献   

12.
Under the guidance of the "Classes are suspended but teaching and studying is in progress" put forth by the Ministry of Education in response to the epidemic of novel coronavirus pneumonia, colleges and universities responded positively. This article analyzes the problems of online teaching in local universities such as single teaching styles, variated online teaching skills of teachers, teaching concepts need to be changed and inadequate online learning capabilities of students. Strategies for improving the quality of online teaching are introduced from university, teacher and student levels, respectively. Taking the teaching of electrochemical basis as an example, the specific application of online resources and platforms in teaching practice and the results achieved are introduced in detail. It can provide a reference for university teachers to carry out the teaching with online resources.  相似文献   

13.
为应对新型冠状病毒肺炎疫情,教师通过在线直播和线上交互讨论等形式,积极探索有效的线上教学方式,为在家自主学习的学生提供良好的学习体验。本文以"无机化学与化学分析"课程为例,面对疫情期间的特殊性,将以往的"线上线下融合"的混合式教学模式进行相应调整,提供给大家"完全线上"的远程混合式教学案例,以获得实时高效的教学效果。  相似文献   

14.
In the online organic chemistry and laboratory courses, the open or semi open quizzes before class and after class are adopted to explore the "dual quizzes teaching" mode on the network teaching platform. As the progress of "dual quizzes teaching", students' learning weakness, confidence and enthusiasm are improved continuously. Through the analysis of online students' learning data, questionnaire and interactive feedback, the teachers can evaluate the learning situation of the students and regulate instructional content in time. As a result of teaching online, the "dual quizzes teaching" mode has achieved highly positive effect.  相似文献   

15.
由于新型冠状病毒肺炎疫情,高校延期开学。为了实现"停课不停教、停课不停学",需要积极开展在线教学。本文基于超星学习通平台,开展了有机化学课程录播课教学实践,为高校教师网络教学提供一定的参考。  相似文献   

16.
The COVID-19 broke out on a large scale, and online teaching became the first choice for teachers. Avoiding network congestion and ensuring learning effects are the dilemmas faced by online teaching. With the help of the UOOC platform and the Tencent Classroom, taking the "Polymer Structure and Performance" course as a sample, we suggested a new "online asynchronous teaching" model. Among them, the SPOC course is convenient for students to manage their learning time; "Chapter Quiz" and "Student-to-Student Mutual Evaluation" are helpful for students to obtain multi-angle feedback; project tasks are focused on case analysis so that students carry out inquiry-based learning. Overall, the "online asynchronous teaching" model breaks the time and space restrictions on teaching and learning, guarantees the quality of teaching during the epidemic, and lays the foundation for creating a "golden class".  相似文献   

17.
Zhiping Peng 《大学化学》2020,35(5):184-190
In response to the COVID-19 epidemic prevention, the "polymer chemistry" course teaching team actively explored the "learning-centered" online teaching model. The students were guided to active learning by using the rich contents of Chaoxin online teaching platform and multiple online teaching activities. The basic knowledge points, difficulties and emphases of the teaching were highlighted and the real-time communication and Q&A were achieved in combination with the Tencent course live broadcast and QQ learning group. Following the concept of "students as the main body and teachers as the leading", the online teaching of "polymer chemistry" has effectively aroused the students' interest in learning, cultivated the initiative of autonomous learning, organically integrated the ideological and political education, and achieved a good learning outcome.  相似文献   

18.
With the implementation of the basic discipline of "Top Talent Training Program" (the "East Ever Project"), more and more new reforms and attempts are being made in various universities. In the process of innovation and exploration, a new curriculum is being implemented, that is, the "the frontier aspects of disciplines" course. Through investigation and research, we found that many colleges and universities in China are carrying out or trying to carry out such courses, and the students who participated have different benefits. This paper mainly discusses the current situation of the development of the frontier courses of many universities in China, and gives suggestions based on the two courses of Tang Aoqing Honors Program in Science of chemistry in Jilin University. This paper provides reference for other colleges and universities to open such courses.  相似文献   

19.
"学生演示-集体评课-全班实验"三环节教学模式是高师教学论实验课程的主要形式,我们对化学专业教学论实验课程教学现状进行了教学观察和调研,从教学内容的选择、教学组织形式、教学管理形式、课程评价方式等方面进行优化,取得明显的教学效果。这对促进高师院校的化学实验教学改革、培养创新型实验教学能力的师范生有一定的参考价值。  相似文献   

20.
This paper aims at the implementation of the online courses of chemistry majors in Sichuan University in response to the epidemic, and explores a more effective and reasonable way to organize teaching. Based on the investigation and feedback of teachers and students, this paper points out the difficulties and challenges of online teaching at the present stage:the classroom interaction and discussion are not smooth, the online teaching tools and methods are diversified, and the chemistry laboratory courses are not matched. Therefore, the School of Chemistry of Sichuan University will coordinate the online teaching platform, enhance the classroom interaction, and launch the "chemistry virtual simulation experiment teaching center" to ensure the teaching progress and quality during the epidemic prevention and control.  相似文献   

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