delocalized electrons

  • 文章类型: Journal Article
    过渡金属二硫属化物(TMDC)的基面由于其低效率的电荷转移动力学而对析氢反应(HER)呈惰性。我们提出了一种策略,用离域电子填充范德华(vdW)层,以使电子从收集器垂直穿透到吸附中间体。以密度泛函理论为指导,我们通过将Cu原子结合到二硫化钽(TaS2)的中间层中来实现这一概念。层间Cu的d轨道的离域电子可以构成垂直方向的电荷转移路径,从而克服了通过vdW间隙的跳跃迁移。TaS2的垂直电导率增加了2个数量级。用芯片上微单元提取TaS2基面HER活性。被离域电子修饰,电流密度增加了20倍,在没有iR补偿的情况下,在-0.4V下达到800mAcm-2的超高值。
    The basal plane of transition metal dichalcogenides (TMDCs) is inert for the hydrogen evolution reaction (HER) due to its low-efficiency charge transfer kinetics. We propose a strategy of filling the van der Waals (vdW) layer with delocalized electrons to enable vertical penetration of electrons from the collector to the adsorption intermediate vertically. Guided by density functional theory, we achieve this concept by incorporating Cu atoms into the interlayers of tantalum disulfide (TaS2). The delocalized electrons of d-orbitals of the interlayered Cu can constitute the charge transfer pathways in the vertical direction, thus overcoming the hopping migration through vdW gaps. The vertical conductivity of TaS2 increased by 2 orders of magnitude. The TaS2 basal plane HER activity was extracted with an on-chip microcell. Modified by the delocalized electrons, the current density increased by 20 times, reaching an ultrahigh value of 800 mA cm-2 at -0.4 V without iR compensation.
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  • 文章类型: Journal Article
    从污水污泥焚烧灰(SSIA)中湿法化学回收磷(P)已经成为解决磷短缺的全球倡议,但是通过在SSIA衍生的提取物中吸附有效地从这些伴随的金属(AM)中分离P仍然难以捉摸。这里,我们设计了水热刺激驱动的热力学和动力学增强,以获得用于AM外壳的阴离子乙二胺四乙酸(EDTA)分子界面,以解决这一难题。首次建立了基于EDTA与AMs配合比的新剂量规则。在140°C水热萃取1小时后,这些获得的SSIA样品的P提取效率达到96.7%或更高,然后通过特殊的镧(La)基纳米吸附剂(在pH〜3.0时具有188.86mgP/g吸附剂)实现了这些EDTA螯合AMs的特殊P螯合。相关的理论计算揭示了四价EDTA分子的这些离域电子促进了释放的AM的封闭,因此,通过侵入晶格边缘的碳酸盐以将La与LaCO5(101)上的单齿单核配位,从而导致H2PO4-形式的P的负吸附能(-408.7kcal/mol)大大增加。这项工作突出了这些常见萃取剂在从各种含磷废物中回收湿化学磷的分子适应前景。进一步维持全球P循环。
    Wet-chemically recovering phosphorus (P) from sewage sludge incineration ash (SSIA) has already become a global initiative to address P deficit, but effectively isolating P from these accompanying metals (AMs) through adsorption in a SSIA-derived extract remains elusive. Here, we devised a hydrothermal stimulus-motivated thermodynamic and kinetic enhancement to gain anionic ethylenediaminetetraacetic acid (EDTA) molecular interfaces for AM enclosure to resolve this conundrum. A new dosage rule based on the EDTA coordination ratio with AMs was established for the first time. Upon hydrothermal extraction at 140 °C for 1 h, the P extraction efficiency reached 96.7% or higher for these obtained SSIA samples, and then exceptional P sequestration from these EDTA-chelated AMs was realized by the peculiar lanthanum (La)-based nanoadsorbent (having 188.86 mg P/g adsorbent at pH ∼ 3.0). Relevant theoretical calculations unraveled that these delocalized electrons of tetravalent EDTA molecules boosted the enclosure of liberated AMs, thereby entailing a substantially increased negative adsorption energy (-408.7 kcal/mol) of P in the form of H2PO4- through intruding lattice-edged carbonates to coordinate La with monodentate mononuclear over LaCO5(1 0 1). This work highlights the prospect of molecular adaptation of these common extractants in wet-chemical P recovery from various P-included wastes, further sustaining global P circularity.
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  • 文章类型: Journal Article
    富锂锰基层状氧化物(LLO)由于其独特的氧氧化还原(OR)化学特性,有望作为锂离子电池(LIBs)的阴极材料,这可以增加额外的容量。然而,由于过渡金属(TM)-氧键弱,LLO面临着与OR过程不稳定性有关的挑战,导致氧损失和不可逆的相变,导致严重的容量和电压衰减。在这里,提出了一种表面和内部结构的协同电子调节策略,以增强氧稳定性。在材料的内部,TM和O原子周围的局部电子可能被周围的Mo原子离域,促进在高电压下形成更强的TM-O键。此外,在表面上,具有孤对电子的高反应性O原子被额外的TM原子钝化,这提供了一个更稳定的TM-O框架。因此,这种策略稳定了氧气并阻碍了TM的迁移,增强了结构演化的可逆性,导致增加的容量和电压保持。这项工作提出了一种有效的方法,通过表面到内部的电子结构调制来增强LLO的性能,同时也有助于更深入地了解它们的氧化还原反应。
    Li-rich Mn-based layered oxides (LLO) hold great promise as cathode materials for lithium-ion batteries (LIBs) due to their unique oxygen redox (OR) chemistry, which enables additional capacity. However, the LLOs face challenges related to the instability of their OR process due to the weak transition metal (TM)-oxygen bond, leading to oxygen loss and irreversible phase transition that results in severe capacity and voltage decay. Herein, a synergistic electronic regulation strategy of surface and interior structures to enhance oxygen stability is proposed. In the interior of the materials, the local electrons around TM and O atoms may be delocalized by surrounding Mo atoms, facilitating the formation of stronger TM─O bonds at high voltages. Besides, on the surface, the highly reactive O atoms with lone pairs of electrons are passivated by additional TM atoms, which provides a more stable TM─O framework. Hence, this strategy stabilizes the oxygen and hinders TM migration, which enhances the reversibility in structural evolution, leading to increased capacity and voltage retention. This work presents an efficient approach to enhance the performance of LLOs through surface-to-interior electronic structure modulation, while also contributing to a deeper understanding of their redox reaction.
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  • 文章类型: Journal Article
    Molecular doping of inorganic semiconductors is a rising topic in the field of organic/inorganic hybrid electronics. However, it is difficult to find dopant molecules which simultaneously exhibit strong reducibility and stability in ambient atmosphere, which are needed for n-type doping of oxide semiconductors. Herein, successful n-type doping of SnO2 is demonstrated by a simple, air-robust, and cost-effective triphenylphosphine oxide molecule. Strikingly, it is discovered that electrons are transferred from the R3P+ O- σ-bond to the peripheral tin atoms other than the directly interacted ones at the surface. That means those electrons are delocalized. The course is verified by multi-photophysical characterizations. This doping effect accounts for the enhancement of conductivity and the decline of work function of SnO2 , which enlarges the built-in field from 0.01 to 0.07 eV and decreases the energy barrier from 0.55 to 0.39 eV at the SnO2 /perovskite interface enabling an increase in the conversion efficiency of perovskite solar cells from 19.01% to 20.69%.
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