Latest ArticlesExploring the intrinsic reasons for the dynamic reconstruction of catalysts during electrocatalytic reactions and their impact on activity enhancement still face severe challenges. Herein, the bifunctional catalyst Ru/V-CoO/CP with doping strategy and heterostructure was synthesized for overall water splitting. The Ru/V-CoO exhibits excellent activity for HER and OER with low overpotentials of 49, 147 mV at a current density of 10 mA/cm2 in 1.0 mol/L KOH, respectively. The assembled electrolytic cell just needs voltages of 1.47 and 1.71 V to achieve 10 and 350 mA/cm2 current density under the same conditions and delivers an outstanding stability for over 100 h, which is far superior to the commercial RuO2Pt/C cell. Experimental and theoretical results indicate that the doping of V species and the formation of heterostructures lead to charge redistribution. More importantly, the leaching of V species induces electron transfer form Co to O and then Ru through the Co-O-Ru electron bridge, optimizes the adsorption strength of the key intermediate, thereby reducing the free energy barrier of the rate-determining step and improving catalytic activity. This work proposes an effective strategy of using cation dissolution to induce electron transfer through the electron bridge and thus regulate the electronic structure of catalysts, providing new ideas for the design and development of efficient and stable electrocatalysts.
The exploitation of organic-inorganic hybrid perovskites (OIHPs) as active layer materials for typical sandwich-structured resistive memories has attracted widespread interest due to the property of low power consumption and fast switching. However, the inherent thermal instability of perovskites limits the application of OIHPs-based resistive memories under extreme conditions, while the influence of thermal effects on their resistance change characteristics remains unclear. Herein, a novel 2D <100>-oriented high-temperature resistant OIHP [(BIZ-H)2(PbBr4)]n (BIZ = benzimidazole) is prepared as an active layer material to fabricate FTO/[(BIZ-H)2(PbBr4)]n/Ag resistive memory with excellent thermal reproducibility and stability up to 120 ℃. The increase in temperature leads to a decrease in the PbBr6 octahedral distortion in the crystal structure, an increase in hydrogen bonding between the (BIZ-H)+ cation and the (PbBr4)n2n- layer, and a shortening of the spacing of the inorganic layers, which is found to result in the creation and predominance of thermally activated traps with increasing temperature. This work provides a new direction for the next generation of OIHPs-based resistive memories with high-temperature tolerance.
Unstable electrode/electrolyte interfaces and heterogeneous Zn deposition would reduce the Coulombic efficiency and cycle life of Zn metal batteries (ZMBs). Applying water-in-salt (WIS) electrolytes has proven to be an effective strategy to address the above issues. However, an understanding of the reaction mechanisms on the Zn anode at nanoscale is still elusive. Here we utilize in situ atomic force microscopy to visualize the solid electrolyte interphase (SEI) formation and Zn deposition/dissolution processes in WIS electrolyte and construct relationships between interfacial behavior and electrochemical performance. The formation processes, chemical properties, and structure of the on-site formed SEI are deeply explored. The SEI with a “plum-pudding” model can guide uniform Zn deposition and reversible dissolution. Mechanistic understanding of the interfacial evolution of the SEI layer and Zn deposition/dissolution has been achieved and will benefit the structural optimization and interfacial engineering of ZMBs.
Designing carbon materials with ideal stable hierarchical porous structures and flexible functional properties for efficient and sustainable Zn2+ ion storage still faces great challenges. Herein, the three-dimensional carbon superstructures with spherical nanoflower-like structures were tailor-made by the self-assembly strategy. Specifically, organic polymer units (i.e., organic motifs) were formed by tetrachloro-p-benzoquinone (TBQ) and 2, 6-diamino anthraquinone (DAQ) via a noble-metal-free catalyzed coupling reaction. Subsequently, the organic motifs assemble into spherical nanoflower-like superstructures induced by intermolecular hydrogen bonding and aromatic π-π stacking interactions. Well-designed carbon superstructures can provide a stable backbone that effectively blocks structural stacking and collapse. Meanwhile, the hierarchical porous structures in 3D carbon superstructures provide continuous charge transport pathways to greatly shorten the ion diffusion distance, and as a result, the carbon superstructures-based zinc-ion hybrid capacitors (ZIHCs) provide a capacity of 245 mAh/g at 0.5 A/g, a high energy density of 152 Wh/kg and an ultra-long life of 300, 000 cycles at 20 A/g. The excellent electrochemical performance is also attributed to the corresponding charge storage mechanism, i.e., the alternate binding of Zn2+/CF3SO3− ions. Besides, the high-level N/O motifs improve the surface properties of the carbon superstructures and reduce the ion migration barriers for more efficient charge storage. This paper provides insights into the design of advanced carbon-based cathodes and presents a fundamental understanding of their charge storage mechanisms.
Fluoride-based electrolyte exhibits extraordinarily high oxidative stability in high-voltage lithium metal batteries (h-LMBs) due to the inherent low highest occupied molecular orbital (HOMO) of fluorinated solvents. However, such fascinating properties do not bring long-term cyclability of h-LMBs. One of critical challenges is the interface instability in contacting with the Li metal anode, as fluorinated solvents are highly susceptible to exceptionally reductive metallic Li attributed to its low lowest unoccupied molecular orbital (LUMO), which leads to significant consumption of the fluorinated components upon cycling. Herein, attenuating reductive decomposition of fluorinated electrolytes is proposed to circumvent rapid electrolyte consumption. Specifically, the vinylene carbonate (VC) is selected to tame the reduction decomposition by preferentially forming protective layer on the Li anode. This work, experimentally and computationally, demonstrates the importance of pre-passivation of Li metal anodes at high voltage to attenuate the decomposition of fluoroethylene carbonate (FEC). It is expected to enrich the understanding of how VC attenuate the reactivity of FEC, thereby extending the cycle life of fluorinated electrolytes in high-voltage Li-metal batteries.
Metal phosphosulfides have been recognized as advanced anode materials for sodium/potassium ion batteries due to their high theoretical capacities and the incorporation of the advantage of metal sulfides and phosphates. However, they also suffer from the shortcomings of frustrating cycling stability due to the large volume expansion and unsatisfactory electrical conductivity. Herein, hexapod cobalt phosphosulfide nanodots based nanorods encapsulating into N, P, and S hetero-atoms tri-doped carbon framework (CoP/CoS2@NPSC) have been triumphantly designed and synthesized. The six nanorods constructed hexapod framework and multi-atom doped carbon matrix not only provides more active sites, but also contribute to maintain the structure integrity from avoiding the agglomeration of internal CoP and CoS2 nanodots. The synergistic effect between CoP and CoS2 components, as well as the CoP/CoS2 and the NPSC carbon framework can improve the electrochemical conductivity. Besides, the kinetics analysis demonstrated that N/P/S tri-doping could greatly increase the interlayer distance and introduce enough active sites, which effectively facilitate the transport, adsorption, insertion and diffusion of Na+ and K+. CoP/CoS2@NPSC demonstrated excellent electrochemical properties and battery performances including excellent cycle stability with 404.63 mAh/g at 5.0 A/g around 700 cycles for SIBs and 115.33 mAh/g at 5.0 A/g around 800 cycles for PIBs. This presented strategy establishes a novel and adaptable method for the integration of doped carbon with metal phosphosulfide and guides a new research approach and direction for secondary batteries electrode materials.
Multiple donor-acceptor (D-A) combinations represent a promising category of thermally activated delayed fluorescence (TADF) materials, offering potential for superior efficiency and stability. However, current systems are predominantly composed of limited donor groups, primarily carbazole-based derivatives. In this work, we developed a series of D-A type materials incorporating helical π-expanded carbazole (CzNaph) and 7H-dinaphtho[1,8-bc:1′,8′-ef]azepine (AzNaph), alongside traditional carbazole, ranging from mono- to tetra-substituted configurations (Dn-A). Through systematic investigation of geometric and electronic structures, the number and positioning of multiple donors are confirmed with significant manipulations on charge transfer characteristics and the S1 state via steric effects. Density functional theory (DFT) calculations reveal that varying the number of π-extended donors within the acceptor framework produces emission colors from ultraviolet to red, providing a diverse range of emitters. Furthermore, the reduced reorganization energy of S1 observed in tetra-substituted Cz and CzNaph, as well as MonoAzN, indicates lower structural relaxation, highlighting these materials' potential as stable luminescent candidates. This study underscores the importance of diverse composing units in achieving efficient and stable TADF emitters with multiple and hetero-donor configurations.
The separation of alicyclic ketones and alicyclic alcohols is one of the challenges in the field of petrochemical industry. However, traditional separation methods suffer from excessive energy consumption, complicated operation, and unsatisfactory separation efficiency for substances with similar boiling points. Herein, we offer an innovative method for the separation of alicyclic ketones and alicyclic alcohols employing nonporous adaptive crystals (NACs) of perethylated pillar[5]arene (EtP5) and perethylated pillar[6]arene (EtP6). NACs of EtP5 cannot adsorb either alicyclic ketones or alicyclic alcohols because of the small cavity size of EtP5. By contrast, NACs of EtP6 can separate cyclopentanone from the vapor mixture of cyclopentanone/cyclopentanol (v:v = 1:1) and cyclohexanone from the vapor mixture of cyclohexanone/cyclohexanol (v:v = 1:1) with purities of 99.1% and 100%, respectively. Density functional theory calculations show that the selectivity comes from the thermodynamic stability of the newly formed crystal structure after adsorption of the preferred guest molecule. Moreover, NACs of EtP6 can be reused without losing selectivity and performance.
In most Suzuki–Miyaura carbon-carbon cross-coupling reactions, the borabicyclo[3.3.1]nonane scaffold (9-BBN) only serves as an auxiliary facilitating the transmetalation step and thus is transformed into by-products. There are rare examples where the 9-BBN derivatives serve as the potentially diverse C8 building blocks in cross-coupling reactions. Herein, we report a cobalt-catalyzed migratory carbon-carbon cross-coupling reaction of the in situ formed 9-BBN ate complexes to afford diverse aryl- and alkyl-functionalized cyclooctenes. Preliminary mechanistic studies suggest the oxidation-induced cis-bicyclo[3.3.0]oct-1-ylborane is the key intermediate in this migratory cross-coupling reaction, which promotes the development of other diverse migratory cross-coupling of borate complexes.
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