mlsa-iai-msu-lab/ru_sci_bench_zho_cite_reranking huggingface dataset:
超临界流体制备氮化硼纳米片的研究进展

氮化硼纳米片(BNNSs)是一种新型二维纳米材料,具有极好的绝缘导热性能、力学性能、介电性能、化学稳定性和良好的生物相容性,被广泛应用于复合材料增强、导热复合材料、储氢、药物运输、催化载体、量子点等方面,逐渐成为研究的热点。氮化硼主要有六方(h-BN) 、立方(c-BN) 、菱方(r-BN)和纤维矿(w-BN)四种稳定结构,其中h-BN是与石墨相类似的层状结构,但其层间范德华力更强,这也给其剥离带来困难。迄今为止,人们参照石墨烯的制备探究出许多制备氮化硼纳米材料的方法,如微机械剥离法、液相剥离法、化学气相沉积法(CVD)和二次外延生长法等。这些方法虽各有优劣,但在大规模稳定生产晶体结构较为完整的BNNSs且剥离效率较高上均存在不足。采用低成本、高效率、高质量的方法制备出氮化硼纳米片是其产业化的关键。超临界流体兼具气体的扩散性质和液体的溶解能力,自从被引入到石墨烯的制备中取得了一些成果后,许多研究者也将其运用到BNNSs的制备上。目前,利用超临界CO_2在一定的温度和压力下能制备出厚度为2 ~6 nm的BNNSs,且BNNSs的结晶形态与原始的h-BN基本没有太大差异,得到的BNNSs悬浮液的浓度可高达0.24 mg /mL,辅助以剪切、超声波等手段后能有效提高其剥离效率。超临界有机溶剂一般有超临界甲醇、超临界N,N-二甲基甲酰胺,它们不仅能作为插层剂打开片层间距,而且是良好的分散剂,能防止纳米材料再次团聚。超临界有机溶剂能大大简化剥离过程,反应时间只有短短15 min,就能得到2~3层的无明显缺陷的BNNSs,产率约为10%。本文综述了超临界流体制备氮化硼纳米片的方法、原理、研究现状及其表征手法,讨论了提高剥离效率的各种方法及优缺点。超临界流体制备氮化硼纳米片设备单一、条件较易达成、产品质量高,为氮化硼纳米片的工业化生产提供了新的思路。
甘草次酸对乌头碱致大鼠心律失常的拮抗作用

目的:探究甘草次酸拮抗乌头碱致大鼠心律失常的作用机制。方法:将40只大鼠分成正常对照组、模型对照组、胺碘酮56 mg /kg组、甘草次酸50、150 mg /kg组,每组8只,以大鼠Ⅱ导联心电图变化为指标,动态观察用药后大鼠心电图和心率的变化,采用HE染色法评价心肌组织结构的改变,检测大鼠血清肌酸激酶(CK) 、乳酸脱氢酶(LDH) 、脑钠肽(BNP)和心肌组织中Na~+-K~+-ATP酶,钙调蛋白(CaM) 、钙调素依赖性蛋白激酶Ⅱ(CaMK Ⅱ)水平。结果:与正常对照组比较,模型对照组出现明显心率降低,BNP、LDH、CK水平明显升高,甘草次酸50、150 mg /kg组能有效恢复大鼠心率; BNP、CK的释放显著降低(P < 0.01),甘草次酸150 mg /kg组LDH含量明显降低(P < 0.05);与正常对照组比较,模型对照组中Na~+-K~+-ATP酶水平明显降低、CaM和CaMK Ⅱ水平显著升高,甘草次酸150 mg /kg明显升高Na~+-K~+-ATP酶水平,降低CaM和CaMK Ⅱ水平(P < 0.05) 。HE染色结果表明,模型对照组心肌组织疏松,心肌细胞萎缩,排列紊乱,甘草次酸50 mg /kg组可见局部肌纤维坏死、变性,较模型对照组有好转。甘草次酸150 mg /kg组基本无炎症细胞浸润,心肌组织无坏死,变性明显好转,其他无明显病变。结论:甘草主要有效成分甘草次酸对乌头碱所致的大鼠心律失常具有较为明显的减毒作用。
三电平双有源桥变换器的新型控制策略研究

针对三电平双有源桥(TL DAB)变换器在电压不匹配及轻载条件下电流应力大、失去软开关特性、效率低的问题,提出一种基于四电平调制的新型控制策略。该控制策略包含两个控制自由度,分别为三电平桥内移相角和桥间移相角,引入桥内移相角后,三电平桥输出具有一定占空比的四电平电压。通过优化两个控制自由度,使TL DAB变换器在宽电压及全功率范围内具有更小的电流应力和更优的软开关特性,从而提升变换器在电压不匹配及轻载条件下的传输效率。最后,在小功率样机上验证了所提出控制策略的有效性。
外加注入信号的MMC子模块电压波动抑制策略

针对模块化多电平换流器(MMC)子模块(SM)电容电压波动问题,提出一种注入共模电压与环流的MMC SM电压波动抑制策略。首先通过注入共模电压使系统工作在较高调制比状态,然后根据半桥MMC SM的数学模型推导出注入共模电压后的桥臂功率解析式,从减小桥臂功率波动角度提出了一种高、低次环流抑制策略,实现注入共模电压与环流的MMC SM电压波动抑制。实验结果显示该策略可有效减少SM电容电压波动幅值。
沙漠能源生态圈概念、内涵及发展模式

沙漠地区既是中国重要的能源基地,也是生态环境脆弱区和发展落后地区,如何在保护沙漠生态环境的前提下,充分开发利用沙漠丰富资源,同时又带动地区经济发展和改善民生?首先基于生态学、管理学、自然地理学、系统科学等相关理论,结合国内外沙漠能源开发及沙漠治理、生态修复等方面最新研究进展,运用能源互联网思维,构建了包涵沙漠治理、生态修复、脱贫攻坚、乡村振兴、能源建设、经济发展等要素的生态圈结构模型,提出一个合作共赢、基于沙漠能源、以电力为核心的沙漠能源生态圈概念;然后对沙漠能源生态圈内涵及特征进行解析,并从经济、社会、生态三方面对其效益进行阐述;最后,探讨了沙漠能源生态圈发展模式,并从能源、生态、经济、国情、战略五方面阐述了沙漠能源生态圈发展愿景。
喀什地区PM_(10)输送路径及潜在源区

基于HYSPLIT模型和2019年9月至2020年8月喀什地区大气颗粒物逐时数据,利用聚类分析、潜在源贡献因子法(PSCF)和浓度权重轨迹法(CWT)分析喀什地区四季PM_(10)传输路径与潜在源区,揭示研究期间喀什地区不同季节PM_(10)的潜在源分布及其贡献水平。结果表明:喀什地区PM_(10)、PM_(2.5)年均值分别为237.3±268.3、89.3± 82.3 μg·m~(-3),大气颗粒物以PM_(10)为主;喀什地区气流输送路径主要来自中亚西风气流,其次是来自中国新疆南部; PM_(10)秋季主要贡献源区分布在中亚部分地区以及中国新疆南部区域,贡献水平为250-450 μg·m~(-3);冬季主要贡献源区与秋季相似,贡献水平为150-300 μg·m~(-3);春季重点贡献源区主要分布在新疆南部塔克拉玛干沙漠区域,贡献水平为250-500 μg·m~(-3);夏季主要贡献源区与春季相似,贡献水平为150-250 μg·m~(-3)。喀什地区重点防范应是塔克拉玛干沙漠沙尘气溶胶的影响,其次是中亚西风气流携带的大气颗粒物远距离输送。
宁夏旅游经济与生态环境耦合协调过程与格局

实现区域旅游经济与生态环境协调发展是旅游业发展的重要目标,也是实现沙漠旅游主导型省区旅游产业可持续发展的关键。构建沙漠旅游主导型省区旅游经济与生态环境耦合协调评价指标体系,综合运用耦合协调度模型、剪刀差模型以及ArcGIS空间可视化表达方法对2009-2018年宁夏旅游经济与生态环境耦合协调过程与格局进行了分析研究。结果表明:宁夏旅游经济与生态环境发展水平呈逐年增长态势,且各市发展程度差异显著;耦合协调度指数由2009年的0.3121上升至2018年的0.5655,旅游经济与生态环境的关系不断改善,趋向于协调发展,耦合协调程度由低水平失调的旅游经济滞后型发展为高水平协调的生态环境滞后型;宁夏旅游经济与生态环境耦合协调空间格局变化明显,且差异显著;剪刀差整体演化速率较为稳定,波动趋势极为平缓,表明两系统演化速率差异基本保持稳定状态;而耦合度夹角在45°-90°波动变化,表明两系统正处于协调发展阶段。
基于混合阻尼的光伏集群逆变器并网谐振抑制

组串式光伏集群逆变器系统并网后会引发谐振,给系统带来不利影响。为抑制集群并网谐振,建立集群逆变器的数学模型,研究分析了谐振机理与谐振特性,提出一种基于混合阻尼的全局谐振抑制策略。该策略在逆变器电流环中引入电容电流反馈与并网电压比例前馈作为有源阻尼,以削弱并网电流的谐波;在此基础上加入RLC型二阶谐振抑制电路作为无源阻尼,以抑制系统谐振,使集群并网时逆变器输出电流满足并网条件。仿真和实验结果表明,3台组串式光伏集群逆变器采用该策略后,并网电流总谐波畸变率(THD)由10.54%下降至1.97%,有效抑制了并网谐振。
改进开关控制率的PMSM软测控系统

针对工业用表面式永磁同步电机(SPMSM)设计一种滑模观测器(SMO),在转子定向d,q坐标系下建立SMO模型,基于实际电流值和观测电流值差的积分值建立了开关控制率,并基于此设计永磁同步电机(PMSM)控制系统。基于李雅普诺夫稳定性原理证明了该观测器的稳定性,相较于传统SMO降低了稳定性条件且无相位延迟。实验表明,采用基于上述SMO的软测控方法,能够在中高转速范围内实现转子位置的有效估计。基于上述方法的无感控制方法具有广泛的应用价值。
基于高通滤波器的电机驱动系统电磁干扰测试

在电机驱动系统中,脉宽调制(PWM)技术会引起严重的共模(CM)干扰和差模(DM)干扰。为了分析系统电磁兼容的问题,提出了电机驱动系统端口测试的新方法。采用示波器配合电压探头和电流探头进行测试,对所得系统噪声的时域波形进行傅里叶变换后,即为端口噪声的低频分量。根据示波器垂直精度与高频底噪的对应关系,确定目标限值,并设计数字滤波器分析端口各频段时域波形,计算滤波电路所需要的插入损耗,进而完成高通滤波电路的设计,实现抑制低频段噪声幅值、减小示波器的高频底噪的功能。最后通过实测获取了频率0.1~30 MHz的CM电压、CM电流、DM电压、DM电流的频谱信息。
锂离子电池热失控扩展特征及抑制策略研究进展

锂离子电池在能量密度和工作电压等关键工作性能方面具有很大的优势,广泛应用于电化学储能系统中.锂离子电池由于具有能量密度高、电解质易燃、隔膜稳定性低等特性,不可避免地出现热失控等安全问题.若局部区域电池的热失控事件不能有效控制,将导致热失控事件扩展至系统层面,造成严重安全问题.因此,在电池体系未能取得重点突破,本征安全问题不能根本解决时,锂离子电池热失控扩展的有效抑制尤为重要.本文针对锂离子电池热失控扩展问题,首先介绍了热失控触发诱因与机理;然后从电气特征和传热特征两个角度阐述了热失控扩展特征,为热失控扩展的抑制策略设计提供理论支撑;最后在介绍典型单体热失控及其扩展模型基础上,从散热与隔热、相变材料技术、兼顾常规工况的策略三方面对热失控扩展抑制策略的研究现状进行了总结,指出了进一步研究的方向和关键所在,可为锂离子电池系统安全性能的提升提供理论基础和工程应用指导.
microRNA与靶基因相互调控机制的研究进展

microRNA(miRNA)是一类由内源基因编码的长度约22个核苷酸的单链非编码RNA分子,其通过剪切信使RNA或非编码RNA、沉默或激活转录、primary miRNA(pri-miRNA)加工及mRNA翻译,调控几乎所有细胞增殖分化、个体生长发育及内环境稳态.大量研究已对miRNA的生物发生和调控机制进行了清晰阐述.然而,关于miRNA的转换机制,尤其是miRNA在特定条件下的快速变化,仍尚未解决.近年来研究发现,靶基因能以序列依赖性方式调控miRNA的生成和降解,表明miRNA和靶基因之间的调控不是单向的,而是相互调控.本文详细概述靶基因调控miRNA的最新进展,归纳二者相互作用的条件和机制,提出miRNA转换的研究方向,以期为深入研究机体内miRNA与靶基因的相互作用及开发miRNA靶向治疗药物提供理论基础.
功能添加剂和保形包覆改性锂金属负极界面

金属锂负极因其超高的理论比容量和极低的氧化还原电势成为下一代可充电池的"圣杯"负极材料,高能量密度的锂金属电池有望成为后锂离子电池时代最具商业应用潜力的电化学储能系统.但是负极锂枝晶的生长带来了极大的安全隐患,"死锂"的积累和电解质的过度消耗造成了电池循环稳定性的下降,这些严重阻碍了锂金属电池的商业应用.近年来,国内外学者通过电极结构设计、固态电解质、隔膜修饰、保形包覆、添加剂等手段有效抑制了枝晶的生长.本文着重介绍了功能性添加剂和保形包覆两种策略的成功实例,通过在负极-电解质界面处注入富氟成分或引入亲锂性基团以均匀化锂离子流,从而实现稳定且无枝晶的负极循环,为锂金属电池的发展提供有益的见解.
二维材料功能化隔膜在锂电池中的应用

功能化隔膜对于锂二次电池的安全性能和电化学性能有着重要影响.相比于其他改性传统聚烯烃隔膜的材料,二维材料具有超薄的片层结构、高机械强度、高比面积以及可调的表面化学性质等优势.本文综述了不同类型二维材料功能化隔膜在解决锂硫电池中多硫化物的穿梭效应、锂金属电池中负极枝晶生长问题,以及锂离子电池中传统聚烯烃隔膜润湿性和热稳定差等问题的研究进展.最后,讨论了二维材料在锂电池隔膜中面临的机遇和挑战.
拉萨河流域典型区域保护、修复、治理技术示范体系

青藏高原是世界屋脊、亚洲水塔,是地球第三极,是我国重要的生态安全屏障,是地球上最独特的地质-地理-生态单元,是开展地球与生命演化、圈层相互作用及人地关系研究的天然实验室.近50年,青藏高原自然与社会环境发生了剧烈变化,气候变暖幅度约是同期全球平均值的2倍,是全球变暖背景下环境变化不确定性最大的地区;青藏高原生态环境和水循环格局的重大变化,如冰川退缩、冻土退化、冰湖溃决、冰崩、草地退化、泥石流频发等对人类生存环境和经济社会发展造成了重大影响.
锗掺杂/替位锌黄锡矿太阳能电池研究进展

锌黄锡矿(CZTS(e))太阳能电池作为新兴薄膜太阳能电池的代表之一,以其原材料储量丰富、制备工艺简单、环境友好、成本低廉等优势受到广泛关注.为了进一步提升CZTS(e)太阳能电池的器件效率,在光吸收层内引入掺杂或替位元素成为近年来CZTS(e)太阳能电池的重要研究方向.在众多掺杂或替位元素中,锗元素(Ge)对CZTS(e)太阳能电池器件性能(特别是器件的开路电压(V_(oc)))的提升作用极为明显.本文综述了近年来Ge掺杂或替位CZTS(e)太阳能电池(CZTS(e):Ge)的研究进展,重点介绍了CZTS(e)太阳能电池高开路电压损耗(V_(oc) deficit,V_(oc-def))的根源、CZTS(e):Ge太阳能电池的制备方法以及Ge对CZTS(e)太阳能电池器件性能的影响,并对CZTS(e):Ge太阳能电池的未来研究方向进行了展望.
Complete biosynthesis of the potential medicine icaritin by engineered Saccharomyces cerevisiae and Escherichia coli

Icaritin is a prenylflavonoid present in the Chinese herbal medicinal plant Epimedium spp. and is under investigation in a phase III clinical trial for advanced hepatocellular carcinoma. Here, we report the biosynthesis of icaritin from glucose by engineered microbial strains. We initially designed an artificial icaritin biosynthetic pathway by identifying a novel prenyltransferase from the Berberidaceae-family species Epimedium sagittatum (EsPT2) that catalyzes the C8 prenylation of kaempferol to yield 8- prenlykaempferol and a novel methyltransferase GmOMT2 from soybean to transfer a methyl to C4’- OH of 8-prenlykaempferol to produce icaritin. We next introduced 11 heterologous genes and modified 12 native yeast genes to construct a yeast strain capable of producing 8-prenylkaempferol with high efficiency. GmOMT2 was sensitive to low pH and lost its activity when expressed in the yeast cytoplasm. By relocating GmOMT2 into mitochondria (higher pH than cytoplasm) of the 8-prenylkaempferol–producing yeast strain or co-culturing the 8-prenylkaempferol–producing yeast with an Escherichia coli strain expressing GmOMT2, we obtained icaritin yields of 7.2 and 19.7 mg/L, respectively. Beyond the characterizing two previously unknown plant enzymes and conducting the first biosynthesis of icaritin from glucose, we describe two strategies of overcoming the widespread issue of incompatible pH conditions encountered in basic and applied bioproduction research. Our findings will facilitate industrial-scale production of icaritin and other prenylflavonoids.
In situ observation of cracking and self-healing of solid electrolyte interphases during lithium deposition

The growth of lithium (Li) whiskers is detrimental to Li batteries. However, it remains a challenge to directly track Li whisker growth. Here we report in situ observations of electrochemically induced Li deposition under a CO_2 atmosphere inside an environmental transmission electron microscope. We find that the morphology of individual Li deposits is strongly influenced by the competing processes of cracking and self-healing of the solid electrolyte interphase (SEI). When cracking overwhelms self-healing, the directional growth of Li whiskers predominates. In contrast, when self-healing dominates over cracking, the isotropic growth of round Li particles prevails. The Li deposition rate and SEI constituent can be tuned to control the Li morphologies. We reveal a new "weak-spot" mode of Li dendrite growth, which is attributed to the operation of the Bardeen-Herring growth mechanism in the whisker’s cross section. This work has implications for the control of Li dendrite growth in Li batteries.
Rich oxygen vacancies mediated bismuth oxysulfide crystals towards photocatalytic CO_2-to-CH_4 conversion

Oxygen vacancy-rich bismuth oxysulfide(Bi_2O_2S) with layered structure was prepared for efficient photocatalytic CO_2 reduction under visible light irradiation.The existence of rich oxygen vacancies in Bi_2O_2S,which was proven by sufficient characterization,can provide abundant active sites,improve CO_2 adsorption and activation abilities and boost the separation efficiency of photogenerated carriers,as determined by theoretical and experimental analyses.As a result,Bi_2O_2S with rich oxygen vacancies achieves excellent CO_2 conversion with a CH_4 production of 65.8 μmol g~(-1) under 90 min of visible light irradiation,which was 27-fold higher than the pristine Bi_2O_2S.The mechanism of photocatalytic conversion of CO_2 to CH_4 was also determined by in situ FT-IR analyses.This study provides an in-depth understanding of the development of Bi-O-S system photocatalysts through defect engineering for photocatalytic CO_2 reduction.
Fast decomposition of Li_2CO_3/C actuated by singleatom catalysts for Li-CO_2 batteries

Lithium carbon dioxide (Li-CO_2) batteries deliver a theoretical energy density of 1876 W h kg~(-1) in terms of effective utilization of greenhouse gases.This battery system is considered to be an encouraging electrochemical energy storage device and a promising alternative to Li-ion batteries.However,the main drawback of Li-CO_2 batteries is their accumulative discharge product of Li_2CO_3/C,which leads to large overpotential and poor cycling performance.Thus,specific and efficient catalysts must be explored to enhance the decomposition of Li_2CO_3/C.Single-atom catalysts (SACs) are regarded as promising heterogeneous catalysts owing to their maximized utilization of metal atoms and strong interfacial electronic interactions.Herein,single-metal atoms of Fe,Co,and Ni uniformly anchored on N-doped reduced graphene oxide (rGO),designated as Fe_1/N-rGO,Co_1/N-rGO,and Ni_1/N-rGO,respectively,are designed and fabricated to investigate their catalytic activity toward the decomposition of Li_2CO_3/C.Among them,Fe_1/N-rGO delivers a high discharge capacity of 16,835 mA h g~(-1) at 100 mA g~(-1) and maintains stability for more than 170 cycles with a discharge voltage of 2.30 V at 400 mA g~(-1).Therefore,this catalysts are overwhelmingly superior to other types.This work reveals the advances of SACs in Li-CO_2 batteries and offers an effective method for realizing high-performance Li-CO_2 batteries.
Enlarging ion-transfer micropore channels of hierarchical carbon nanocages for ultrahigh energy and power densities

Increasing the energy density of supercapacitor without sacrificing its high power is an everlasting pursuit in energy storage.Using ionic liquid electrolyte with high operating voltage can increase the energy density but usually at the expense of power density due to the large ion size,low ionic conductivity and high viscosity.Herein we demonstrate a simultaneous increase of the energy and power densities with ionic liquid electrolyte (EMIMBF_4) mainly by enlarging the ion-transfer micropore channels of the electrode material,i.e.,the unique hierarchical carbon nanocages (hCNC).Boudouard reaction is adopted to tune the micropore size while remaining the hierarchical framework of hCNC.Meanwhile,the specific surface area,pore volume and conductivity are also increased under optimal activation temperature.Such a unique modification boosts the large-sized ion transfer,leading to the obvious decrease of equivalent series resistance and the dramatic increase of supercapacitive performance thereof.The optimized product exhibits an energy density up to 153.8 W h kg~(-1) at the power density of 1.8 kW kg~(-1),and maintains 54.0 W h kg~(-1) even at an ultrahigh power density of 480.1 kW kg~(-1).This study demonstrates an effective way to explore advanced electrode materials by the fine regulation of micropores and related properties.
High-fire-safety thermoplastic polyester constructed by novel sulfonate with benzimidazole structure

The flammability of thermoplastic polyesters and the subsequent heavy smoke and severe melt drips formed after ignition are the main obstacles hindering their widespread application.In this study,a novel ionic monomer containing sulfonate and benzimidazole was synthesized and incorporated into the main chain of poly(ethylene terephthalate)(PET,used as a model thermoplastic polyester) by melt copolymerization.The synergetic effect of ionic aggregation and carbonization endowed the obtained copolyester with high melt viscosity and excellent char-forming ability at high temperatures.The copolyester having a monomer content of 8 mol.% easily achieved the Underwriters Laboratories Inc 94 (UL-94) V-0 flammability rating without dripping and the limiting oxygen index value reached 33.0 vol.%.In addition,the total smoke production,peak heat release rate,and maximum CO production decreased by 45.2%,60.5%,and 75.0%,respectively,compared with those of PET.In addition,the copolyester was spinnable,and showed greater adsorption efficiency (99.6%) for a cationic dye from solution compared to PET (6.5%),demonstrating the excellent affinity of the copolyester for the cationic dye.The obtained inherently firesafe PET copolyester has great potential for applications in flame retardant textiles,artwork base materials,and decorative materials for transportation applications.
3D interconnected nanoporous Ta_3N_5 films for photoelectrochemical water splitting:thicknesscontrolled synthesis and insights into stability

Solar-driven photoelectrochemical (PEC) water splitting is a promising technology for sustainable hydrogen production,which relies on the development of efficient and stable photoanodes for water oxidation reaction.The thickness and microstructure of semiconductor films are generally crucial to their PEC properties.Herein,three-dimensional(3D) interconnected nanoporous Ta_3N_5 film photoanodes with controlled thickness were successfully fabricated via galvanostatic anodization and NH_3 nitridation.The porous Ta_3N_5 nanoarchitectures (NAs) of 900 nm in thickness showed the highest PEC performance due to the optimal lightharvesting and charge separation.Compared with the holeinduced photocorrosion,the electrochemical oxidation at high anodic potentials resulted in severer performance degradation of Ta_3N_5.Although the surface oxide layer on deteriorated Ta_3N_5 photoanodes could be removed by NH_3 re-treatment,the PEC performance was only partially recovered.As an alternative,anchoring a dual-layer Co(OH)_x/CoOOH co-catalyst shell on the porous Ta_3N_5 NAs demonstrated substantially enhanced PEC performance and stability.Overall,this work provides reference to controllably fabricate 3D nanoporous Ta_3N_5-based photoanodes for efficient and stable PEC water splitting via optimizing the light absorption,hole extraction,charge separation and utilization.
Nickel-doped Co_4N nanowire bundles as efficient electrocatalysts for oxygen evolution reaction

Cost-efficient electrocatalysts composed of earth-abundant elements are highly desired for enhanced oxygen evolution reaction (OER).As a promising candidate,metallic Co_4N already demonstrated electrocatalytic performance relying on specific nanostructures and electronic configurations.Herein,nickel was introduced as the dopant into one-dimensional (1D) hierarchical Co_4N structures,achieving effective electronic regulation of Co_4N toward high OER performance.The amount of Co~(3+) increased after Ni-doping,and the in-situ formed surface oxyhydroxide during OER enhanced the electrocatalytic kinetics.Meanwhile,the 1D hierarchical structure further promoted the performances of Co_4N owing to the high electrical conductivity and abundant activesites on the rough surface.As expected,the optimal Ni-doped Co_4N with a Ni/Co molar ratio of 0.25 provides a small overpotential of 233 mV at a current density of 10 mA cm~(-2),with a low Tafel slope of 61 mV dec~(-1),and high long-term stability in 1.0 mol L~(-1) KOH.Following these results,the enhancement by doping the Co_4N nanowire bundles with Fe and Cu was further evidenced for the OER.
Atomic-level-designed copper atoms on hierarchically porous gold architectures for highefficiency electrochemical CO_2 reduction

Electrochemical CO_2 reduction is a promising technology for solving the CO_2 emission problems and producing value-added products.Here,we report a hierarchically porous Cu1Au single-atom alloy (SAA) as an efficient electrocatalyst for CO_2 reduction.Benefiting from the hierarchically porous architectures with abundant vacancies as well as three-dimensional accessible active sites,the as-prepared nanoporous Cu1Au SAA catalyst shows remarkable CO_2 reduction performance with nearly 100% CO Faraday efficiency in a wide potential range (-0.4 to -0.9 V vs.reversible hydrogen electrode.The in-situ X-ray absorption spectroscopy studies and density functional theory calculations reveal that the Cu-Au interface sites serve as the intrinsic active centers,which can facilitate the activated adsorption of CO_2 and stabilize the *COOH intermediate.
Tailored Sr-Co-free perovskite oxide as an air electrode for high-performance reversible solid oxide cells

Sr-Co containing perovskite oxides are prospective air electrode candidates for reversible solid oxide cells(RSOCs).However,their efficiencies are limited by Sr segregation and the high thermal expansion coefficient (TEC) of Cobased perovskites.Herein,La_(0.6)Ca_(0.4)Fe_(0.8)Ni_(0.2)O_(3-δ) (LCaFN) is tailored as an Sr-Co-free perovskite air electrode for highperformance RSOCs.Compared with La_(0.6)Sr_(0.4)Fe_(0.8)Ni_(0.2)O_(3-δ)(LSFN) and La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) (LSCoF),LCaFN has a high electrical conductivity (297 S cm~(-1)),TEC compatibility (11.2 × 10~(-6) K~(-1)) and improved chemical stability.Moreover,LCaFN has high oxygen reduction reaction (ORR) activity with a low polarization resistance (0.06 Ω cm~2) at 800°C.A single-cell Ni-YSZ/YSZ/gadolinium-doped ceria (GDC)/LCaFN-GDC operated at 800°C yields a maximum power density of 1.08 Wcm~(-2) using H_2 as fuel.In the solid oxide electrolysis cell (SOEC) mode,the cell can achieve a current density of approximately 1.2 A cm~(-2) at 1.3 V with 70% humidity at 800°C.The cell exhibits good reversibility and remains stable in continuous SOEC and solid oxide fuel cell (SOFC) modes.These findings indicate the potential application of LCaFN as an air electrode material for RSOCs.
Microscopic morphology independence in linear absorption cross-section of CsPbBr_3 nanocrystals

Multiple morphologies of colloidal perovskite nanocrystals (NCs) diversify their optical and electronic properties.Among them,the linear absorption cross-section(σ) is a primary parameter to determine their intrinsic photophysical features,and consequently,application potential.Herein,three morphologies of all-inorganic hybrid colloidal perovskite CsPbBr_3 NCs,nanocubes (NBs),nanoplatelets(NLs),and nanowires (NWs),were targeted,and their linear σ values were obtained through femtosecond transient absorption(TA) spectroscopy analysis.At high excitation energy well above the bandgap,the σ per particle of all CsPbBr_3 NCs linearly increased with the particle volume (V_(NC)) regardless of the morphology with the value of σ_(400) = 9.45 × 10~4 cm~(-1) × V_(NC)(cm~2).Density functional theory (DFT) calculation confirmed the negligible influence of shapes on the optical selection rules.The Einstein spontaneous emission coefficients calculated from the σ values define the intrinsic radiative recombination rate.However,reduced size dependence is observed when the excitation energy is close to the bandgap (i.e.,at 460 nm) with the value of σ_(460) = 2.82 × 10~8 cm0.65 × (V_(NC))~(0.45) (cm~2).This should be ascribed to the discrete energy levels as well as lower density of states close to the band edge for perovskite NCs.These results provide in-depth insight into the optical characteristics for perovskite NCs.
One-dimensional Co_9S_8-V_3S_4 heterojunctions as bifunctional electrocatalysts for highly efficient overall water splitting

Development of cost-effective,active and durable electrocatalysts for overall water splitting is still a huge challenge.Herein,we have constructed one-dimensional (1D) cobalt sulfide and vanadium sulfide heterojunction nanowires arranged on carbon cloth (Co_9S_8-V_3S_4/CC) as bifunctional electrocatalysts for the efficient overall water splitting.The 1D wire-structured Co_9S_8-V_3S_4 heterojunctions possess large surface area,plentiful active sites and rapid transport of electrons/reactants and the release of gas.Importantly,the electron transfer from Co_9S_8 to V_3S_4 occurs at the interface due to the strong electronic coupling effect in Co_9S_8-V_3S_4 heterojunction,in which the electron-attracting V_3S_4 (V~(2+)) optimizes the adsorption of H* active species for hydrogen evolution reaction (HER),while the electron-losing Co_9S_8 (Co~(3+)) responds to the enhancement of oxygen evolution reaction(OER) activity.Co_9S_8-V_3S_4/CC exhibits low overpotentials of 85 and 232 mV at 10 mA cm~(-2) and small Tafel slopes of 51 and 59 mV dec~(-1) for HER and OER,respectively.Especially,the electrolyzer with Co_9S_8-V_3S_4/CC as both the anode and cathode requires low onset voltage of 1.35 V and cell voltage of 1.53 V at 10 mA cm~(-2) and exhibits high Faradaic efficiencies and robust stability.It can be driven by a solar cell (1.53 V) for continuous production of hydrogen and oxygen.This study highlights the design of 1D sulfide heterojunction in pursuit of highly efficient electrocatalysts for overall water splitting.
Efficient control of emission and carrier polarity in WS_2 monolayer by indium doping

Substitutional doping of two-dimensional (2D) transition metal dichalcogenides (TMDs) has been recognized as a promising strategy to tune their optoelectronic properties for a wide array of applications.However,controllable doping of TMDs remains a challenging issue due to the natural doping of these materials.Here,we demonstrate the controllable growth of indium-doped p-type WS_2 monolayers with various doping concentrations via chemical vapor deposition(CVD) of a host tungsten (W) source and indium (In) dopant.Scanning transmission electron microscopy confirmed that In atoms successfully substitute the W atoms in the WS_2 lattice.Intriguingly,the photoluminescence of the doped sample experiences strong intensity modulation by the doping concentration,which first increases remarkably with an enhancement factor up to ~35 and then decreases gradually when further increasing the doping concentration.Such a phenomenon is attributed to the progressive change of the exciton to trion ratio as well as the defect concentration in the doped samples.The assignment was further verified by the electric behavior of the fabricated In-doped WS_2 field effect transistors,which changes regularly from n-type to bipolar and finally to p-type behavior with increasing doping concentration.The successful growth of p-type monolayer WS_2 and the dual control of its optical and electrical properties by In doping may provide a promising method to engineer the opto-electronic properties of 2D materials.