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Javier Quílez-Bermejo Sergio García-Dalí Ayoub Daouli Andrea Zitolo Rafael L.S. Canevesi Mélanie Emo María T. Izquierdo Michael Badawi Alain Celzard Vanessa Fierro 《Advanced functional materials》2023,33(21):2300405
Single atoms and nanoclusters of Fe, Ni, Co, Cu, and Mn are systematically designed and embedded in a well-defined C1N1-type material that has internal cavities of ≈0.6 nm based on four N atoms. These N atoms serve as perfect anchoring points for the nucleation of small nanoclusters of different metal natures through the creation of metal-nitrogen (TM-N4) bonds. After pyrolysis at 800 °C, TM@CNx-type structures are obtained, where TM is the transition metal and x < 1. Fe@CNx and Co@CNx are the most promising for oxygen reduction reaction and hydrogen evolution reaction, respectively, with a Pt-like performance, and Ni@CNx is the most active for oxygen evolution reaction (OER) with an EOER of 1.59 V versus RHE, far outperforming the commercial IrO2 (EOER = 1.72 V). This systematic and benchmarking study can serve as a basis for the future design of advanced multi-functional electrocatalysts by modulating and combining the metallic nature of nanoclusters and single atoms. 相似文献
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Kexin Wang Junhui Cao Xiaoxuan Yang Xiahan Sang Siyu Yao Rong Xiang Bin Yang Zhongjian Li Thomas O'Carroll Qinghua Zhang Lecheng Lei Gang Wu Yang Hou 《Advanced functional materials》2023,33(16):2212321
Designing hydrogen evolution reaction (HER) electrocatalysts for facilitating its sluggish adsorption kinetics is crucial in generating green hydrogen via sustainable water electrolysis. Herein, a high-performance ultra-low Ruthenium (Ru) catalyst is developed consisting of atomically-layered Ru nanoclusters with adjacent single Ru sites, which executs a bridging-Ru-H activation strategy to kinetically accelerate the HER elementary steps. Owing to its optimal electronic structure and unique adsorption configuration, the hybrid Ru catalyst simultaneously displayed a drastically reduced overpotential of 16 mV at 10 mA cm−2 as well as a low Tafel slope of 35.2 mV dec−1 in alkaline electrolyte. When further coupled with a commercial IrO2 anode catalyst, the ensembled anion-exchange membrane water electrolyzer achievs a current density of 1.0 A cm−2 at a voltage of only 1.70 Vcell. In situ spectroscopic analysis verified that Ru single atom and atomically-layered Ru nanoclusters in the hybrid materials play a critical role in facilitating water dissociation and weakening *H adsorption, respectively. Theoretical calculations further elucidate the underlaying mechanism, suggesting that the dissociated proton at the single atom Ru site orients itself adjacently with Ru nanoclusters in a bridged structure through targeted charge transfer, thus promoting Volmer-Heyrovsky dynamics and boosting the HER activity. 相似文献
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采用固相反应的方法制备粉料,合成了一种新型的(Zr1/2Ti1/2)1x(Nb2/3Mg1/3)xO2 (x=0.05～0.30)高频介质陶瓷。XRD分析确定粉料为单相,其晶相为ZrTiO4结构。瓷片在1 430～1 470℃之间烧结。讨论了收缩率与烧结温度的关系以及介电性能随烧结温度的变化,探讨了不同配比对材料电性能的影响,确定出最佳烧结温度为1 460℃。在1 MHz下测试了材料的介电常数及损耗。相对介电常数在26～34之间。配比为x=0.25的材料,品质因数可达到1×104。 相似文献
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Cheng Ding Xinxin Lu Bo Tao Liuqing Yang Xiaoyong Xu Lanqin Tang Haoqiang Chi Yong Yang Debora Motta Meira Lu Wang Xi Zhu Si Li Yong Zhou Zhigang Zou 《Advanced functional materials》2023,33(35):2302824
Simultaneous optimization on bulk photogenerated-carrier separation and surface atomic arrangement of catalyst is crucial for reactivity of CO2 photo-reduction. Rare studies capture the detail that, better than in-plane regulation, interlayer-spacing regulation may significantly influence the carrier transport of the bulk-catalyst thereby affecting its CO2 photo-reduction in g-C3N4. Herein, through a single atom-assisted thermal-polymerization process, single-atom In-bonded N-atom (Inδ+–N4) in the (002) crystal planes of g-C3N4 is originally constructed. This Inδ+–N4 reduces the (002) interplanar spacing of g-C3N4 by electrostatic adsorption, which significantly enhances the separation of bulk carriers and greatly promotes the reactivity of CO2 photoreduction. The CO2 photo-conversion performance of this resulted single-atom In modified g-C3N4 is significantly superior to other single atom loaded carbon nitride catalysts. Moreover, the Inδ+–N4 enhances the CO2 adsorption on g-C3N4, reduces the *COOH formation energy, and optimizes the reaction path. It achieves a remarkable 398.87 µmol g−1 h−1 yield rate, 0.21% apparent quantum efficiency, and nearly 100% selectivity for CO without any cocatalyst or sacrificial agent. Through d(002) modulation of carbon nitride by single In atom, this study provides a ground-breaking insight for reactivity enhancement from a double-gain view of bulk structural control and surface atomic arrangement for CO2-reduction photocatalysts. 相似文献
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首次报道了通过引入ZnAl2O4缓冲层,以金属源化学气相外延法(MVPE)生长的ZnO晶体质量明显提高.ZnAl2O4缓冲层是通过对溶胶-凝胶法制备的ZnO薄膜进行高温退火而得到的.用双晶X射线衍射仪(DCXRD)对样品进行了θ-2θ和摇摆曲线测量,在ZnAl2O4缓冲层上生长的ZnO厚膜具有高度的择优取向性和良好的晶体质量(摇摆曲线半高宽为342\").用电子扫描显微镜(SEM)观察样品横截面,并测得样品厚度约为10μm. 相似文献
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以新型BaCo0.05Co0.1Bi0.85O3材料为基体,掺杂不同摩尔分数x(MnO2),在840℃下烧结4h制备了NTC厚膜电阻。借助XRD、SEM和直流阻温特性测试仪,研究x(MnO2)对电阻相组成、微结构及电性能的影响。结果表明:所得的NTC厚膜热敏电阻主要物相为具有钙钛矿结构的BaCo0.05Co0.1Bi0.85O3,且表面致密。当x(MnO2)超过5%时,有新相BaMnO3开始沿晶界析出,获得小尺寸晶粒;厚膜电阻的室温电阻率ρ25及B25/85值随x(MnO2)增加而升高;当x(MnO2)为10%时,ρ25从初始的13.5?·mm升高为810.0?·mm,B25/85值从600K升高到2049K。 相似文献
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Hematite (α‐Fe2O3) as a photoanode material for photoelectrochemical (PEC) water splitting suffers from the two problems of poor charge separation and slow water oxidation kinetics. The construction of p–n junction nanostructures by coupling of highly stable Co3O4 in aqueous alkaline environment to Fe2O3 nanorod arrays with delicate energy band positions may be a challenging strategy for efficient PEC water oxidation. It is demonstrated that the designed p‐Co3O4/n‐Fe2O3 junction exhibits superior photocurrent density, fast water oxidation kinetics, and remarkable charge injection and bulk separation efficiency (ηinj and ηsep), attributing to the high catalytic behavior of Co3O4 for the oxygen evolution reaction as well as the induced interfacial electric field that facilitates separation and transportation of charge carriers. In addition, a cocatalyst of cobalt phosphate (Co‐Pi) is introduced, which brings the PEC performance to a high level. The resultant Co‐Pi/Co3O4/Ti:Fe2O3 photoanode shows a photocurrent density of 2.7 mA cm?2 at 1.23 VRHE (V vs reversible hydrogen electrode), 125% higher than that of the Ti:Fe2O3 photoanode. The optimized ηinj and ηsep of 91.6 and 23.0% at 1.23 VRHE are achieved on Co‐Pi/Co3O4/Ti:Fe2O3, respectively, corresponding to the 70 and 43% improvements compared with those of Ti:Fe2O3. Furthermore, Co‐Pi/Co3O4/Ti:Fe2O3 shows a low onset potential of 0.64 VRHE and long‐time PEC stability. 相似文献
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Chong Wang Bohan Li Wanci Shen Feiyu Kang Zheng-Hong Huang Ruitao Lv 《Advanced functional materials》2023,33(18):2214429
Single atomic metal (SAM) doping is reported as an effective strategy to promote the electrochemical property of carbon-based anode materials for high-power sodium-ion batteries (SIBs). However, the effects of SAM with different configurations on solid electrolyte interphase (SEI) and energy storage mechanism of Na+ are not revealed. Herein, Cr single atoms (CrSAs) are reported with controllable configurations (Cr–N4 or Cr–N2) implanted on the N, P co-doped carbon (NPC) anode materials (denoted as CrN4SAs/NPC or CrN2SAs/NPC). The CrN4SAs/NPC anode displays a high specific capacity (318.2 mAh g−1 at 0.05 A g−1) and outstanding rate performance (145.1 mAh g−1 at 5 A g−1), better than those of CrN2SAs/NPC and NPC. The superiority is originated from the difference of SEI and the energy storage mechanism of sodium ions during electrochemical process, which are unveiled through ex situ characterization and theoretical calculation. The full cell assembled with CrN4SAs/NPC anode and Na3V2(PO4)2F3@C cathode displays a high energy density at a high power density. 相似文献
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基于密度泛函理论方法分析研究了一种低自旋反铁磁状态Co基层状复合氧化物Ca2Co2O5的电子学性质。结果表明,其能带中均包括5个子带,其中费米能级附近的能带中的能级数量较多,具有较宽的分布。向上自旋的电子形成半导体型能带,带宽为0.0112 eV,向下自旋的电子形成金属型能带。在费米能级附近,s、p、d电子对其态密度的贡献程度逐渐提高。CaCoO层对总态密度贡献较大,CoO层对总态密度贡献较小。Ca中电子主要在远离费米能的位置形成能带,Co中电子主要在费米能附近形成能带,O中电子主要在-19 eV和费米能形成能带,Co d电子和O p电子贡献这种反铁磁状态层状Co基复合氧化物Ca2Co2O5的电子学性质。 相似文献
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半导体材料Ga2O3是继宽禁带半导体材料SiC/GaN之后新兴的直接带隙超宽禁带氧化物半导体,其禁带宽度为4.5~4.9eV,击穿电场强度高达8MV/cm(是SiC及GaN的2倍以上),物理化学稳定性高,在发展下一代电力电子学和固态微波功率电子学领域具有较大的潜力。自2012年第一只Ga2O3场效应晶体管诞生以来,Ga2O3微电子学的研究呈现快速发展态势。本文综述了β-Ga2O3单晶材料和外延生长技术以及β-Ga2O3二极管和β-Ga2O3场效应管等方面的研究进展,介绍了β-Ga2O3材料和器件的新工艺、新器件结构以及性能测试结果,分析了相关技术难点和创新思路,展望了Ga2O3微电子学未来的发展趋势。 相似文献
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Xue‐Qiang Zhang Xin‐Bing Cheng Xiang Chen Chong Yan Qiang Zhang 《Advanced functional materials》2017,27(10)
Lithium (Li) metal has been considered as an important substitute for the graphite anode to further boost the energy density of Li‐ion batteries. However, Li dendrite growth during Li plating/stripping causes safety concern and poor lifespan of Li metal batteries (LMB). Herein, fluoroethylene carbonate (FEC) additives are used to form a LiF‐rich solid electrolyte interphase (SEI). The FEC‐induced SEI layer is compact and stable, and thus beneficial to obtain a uniform morphology of Li deposits. This uniform and dendrite‐free morphology renders a significantly improved Coulombic efficiency of 98% within 100 cycles in a Li | Cu half‐cell. When the FEC‐protected Li metal anode matches a high‐loading LiNi0.5Co0.2Mn0.3O2 (NMC) cathode (12 mg cm?2), a high initial capacity of 154 mAh g?1 (1.9 mAh cm?2) at 180.0 mA g?1 is obtained. This LMB with conversion‐type Li metal anode and intercalation‐type NMC cathode affords an emerging energy storage system to probe the energy chemistry of Li metal protection and demonstrates the material engineering of batteries with very high energy density. 相似文献
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Small GeO2 single crystal was successfully grown on a polyvinyl chloride (PVC) substrate at room temperature in oversaturate aqueous solution. The oversaturated solution could be prepared at strong acid condition (pH 0) using distilled water, germanium oxide, dilute ammonia, and nitric acid. About 7 μm size of the GeO2 single crystals with quartz‐type structure was obtained by only keeping the PVC plate in the solution for about 10 days when appropriate concentration of the solution was used. The obtained GeO2 single crystals were confirmed to be constructed by {101} and {011} surfaces based on powder X‐ray diffraction pattern and particle morphology observed by scanning electron microscope. 相似文献
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H_2O_2对溶液法制备a-IGZO薄膜光学特性的影响 总被引：1，自引：0，他引：1
基于溶液旋涂法和高压退火工艺制备了a-IGZO薄膜。采用椭圆偏振光谱分析仪以及原子力显微镜研究和分析了H_2O_2对薄膜的表面结构和光学特性的影响。实验结果表明,a-IGZO前驱液中不含H_2O_2的薄膜,退火温度从220℃升高到300℃,薄膜的光学带隙从3.03增加到3.29,而膜表面粗糙层由20.69nm降至4.68nm。在同样的高压退火条件处理下,与前驱液中没加入H_2O_2的薄膜相比,折射率显著增加并明显的降低了薄膜表面粗糙度。退火温度在300℃时,薄膜的光学带隙由3.29eV增大到3.34eV,表面粗糙层由4.68nm减少到2.89nm。因此,H_2O_2可以在相对低温条件下有效降低薄膜内部的有机物残留及微缺陷,形成更加致密的a-IGZO薄膜。证明了利用H_2O_2能够有效降低溶液法制备aIGZO薄膜所需的退火温度。 相似文献
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采用传统固相法制备Zn0.7Co0.3(Ti1-xSnx)Nb2O8(x=0.1,0.15,0.2,0.25,0.3,0.35)微波陶瓷。研究了Sn取代Ti对Zn0.7Co0.3(Ti1-xSnx)Nb2O8微波介质陶瓷的物相结构与介电性能的影响。XRD研究表明,Zn0.7Co0.3(Ti1-xSnx)Nb2O8陶瓷主晶相为ZnTiNb2O8,有极少杂相Zn0.17Ti0.5Nb0.33O2存在;随着Sn含量的增加,陶瓷晶格常数增大,晶胞体积变大,陶瓷密度增大;电子扫描显微镜(SEM)显示随着Sn含量增加陶瓷结构致密;相对介电常数εr逐渐变小,温度系数τf逐渐变小,Q×f值逐渐增大;当Sn含量为0.35时,烧结温度为1 080℃,εr=30.5,Q×f=46 973GHz,τf=-45.4×10-6/℃。 相似文献
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Usman Khan Yuting Luo Lei Tang Changjiu Teng Jiaman Liu Bilu Liu Hui‐Ming Cheng 《Advanced functional materials》2019,29(14)
Atomically thin 2D materials have received intense interest both scientifically and technologically. Bismuth oxyselenide (Bi2O2Se) is a semiconducting 2D material with high electron mobility and good stability, making it promising for high‐performance electronics and optoelectronics. Here, an ambient‐pressure vapor–solid (VS) deposition approach for the growth of millimeter‐size 2D Bi2O2Se single crystal domains with thicknesses down to one monolayer is reported. The VS‐grown 2D Bi2O2Se has good crystalline quality, chemical uniformity, and stoichiometry. Field‐effect transistors (FETs) are fabricated using this material and they show a small contact resistivity of 55.2 Ω cm measured by a transfer line method. Upon light irradiation, a phototransistor based on the Bi2O2Se FETs exhibits a maximum responsivity of 22 100 AW?1, which is a record among currently reported 2D semiconductors and approximately two orders of magnitude higher than monolayer MoS2. The Bi2O2Se phototransistor shows a gate tunable photodetectivity up to 3.4 × 1015 Jones and an on/off ratio up to ≈109, both of which are much higher than phototransistors based on other 2D materials reported so far. The results of this study indicate a method to grow large 2D Bi2O2Se single crystals that have great potential for use in optoelectronic applications. 相似文献
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采用传统电子陶瓷制备方法研究了Co2O3(1.5％～5.0％,质量分数)掺杂的0.965MgTiO3-0.035SrTiO3 ( MST0.035)微波介质陶瓷,分析了Co2O3含量对MST0.035陶瓷的烧结性能、晶相结构、显微形貌以及微波介电性能的影响.结果表明:Co2O3的掺杂促进了MST0.035陶瓷的烧结.随着Co2O3掺杂量的增加,陶瓷介电常数略有下降,谐振频率温度系数以及品质因数增加,同时中间相MgTi2O5逐渐减少直至完全消失.当Co2O3掺杂量为质量分数3.0％时,MST0.035陶瓷的烧结温度由1 380℃降低到1 290℃,其烧结所得的样品具有优良的微波介电性能:谐振频率温度系数τf=-2.53×10-6/℃,高的品质因数Q·f=19 006 GHz和介电常数ε(r)=20.5. 相似文献