Crystallization Control of N,N′-Dioctyl Perylene Diimide by Amphiphilic Block Copolymers Containing poly(3-Hexylthiophene) and Polyethylene Glycol

The preparation of micron- to nanometer-sized functional materials with well-defined shapes and packing is a key process to their applications. There are many ways to control the crystal growth of organic semiconductors. Adding polymer additives has been proven a robust strategy to optimize semiconductor crystal structure and the corresponding optoelectronic properties. We have found that poly(3-hexylthiophene) (P3HT) can effectively regulate the crystallization behavior of N,N′-dioctyl perylene diimide (C8PDI). In this study, we combined P3HT and polyethylene glycol (PEG) to amphiphilic block copolymers and studied the crystallization modification effect of these block copolymers. It is found that the crystallization modification effect of the block copolymers is retained and gradually enhanced with P3HT content. The length of C8PDI crystals were well controlled from 2 to 0.4 μm, and the width from 210 to 35 nm. On the other hand, due to the water solubility of PEG block, crystalline PEG-b-P3HT/C8PDI micelles in water were successfully prepared, and this water phase colloid could be stable for more than 2 weeks, which provides a new way to prepare pollution-free aqueous organic semiconductor inks for printing electronic devices

Dense platinum/nickel oxide heterointerfaces with abundant oxygen vacancies enable ampere-level current density ultrastable hydrogen evolution in alkaline

Platinum (Pt) remains the benchmark electrocatalyst for alkaline hydrogen evolution reaction (HER), but its industry-scale hydrogen production is severely hampered by the lack of well-designed durable Pt-based materials that can operate at ampere-level current densities. Herein, based on the original oxide layer and parallel convex structure on the surface of nickel foam (NF), a 3D quasi-parallel architecture consisting of dense Pt nanoparticles (NPs) immobilized oxygen vacancy-rich NiOx heterojunctions (Pt/NiOx-OV) as an alkaline HER catalyst is developed. A combined experimental and theoretical studies manifest that anchoring Pt NPs on NiOx-OV leads to electron-rich Pt species with altered density of states (DOS) distribution, which can efficiently optimize the d-band center and the adsorption of reaction intermediates as well as enhance the water dissociation ability. The as-prepared catalyst exhibits extraordinary HER performance with a low overpotential of 19.4 mV at 10 mA cm−2, a mass activity 16.3-fold higher than that of 20% Pt/C, and a long durability of more than 100 h at 1000 mA cm−2. Furthermore, the assembled alkaline electrolyzer combined with NiFe-layered double hydroxide requires extremely low voltage of 1.776 V to attain 1000 mA cm−2, and can operate stably for more than 400 h, which is rarely achieved

Insights into the Jahn-Teller effect in layered oxide cathode materials for potassium-ion batteries

Potassium-ion batteries (PIBs) have attracted increasing interest as promising alternatives to lithium-ion batteries (LIBs) in large-scale electrical energy storage systems due to the potential price advantages, abundant availability of potassium resources, and low standard redox potential of potassium. However, the pursuit of suitable cathode materials that exhibit desirable characteristics such as voltage platforms, high capacity, and long cycling stability is of utmost importance. Recently, layered transition-metal oxides for PIBs offer great potential due to their high theoretical capacity, suitable voltage range, and eco-friendliness. Nevertheless, the progress of KxMO2 cathodes in PIBs faces obstacles due to the detrimental effects of structural disorder and irreversible phase transitions caused by the Jahn-Teller effect. This review provides a brief description of the origin and mechanism of the Jahn-Teller effect, accompanied by the proposed principles to mitigate this phenomenon. In particular, the current status of KxMO2 cathodes for PIBs, is summarized highlighting the challenges posed by the Jahn-Teller effect. Furthermore, promising strategies, such as composition modulation, synthesis approaches, and surface modification, are proposed to alleviate and suppress the Jahn-Teller effect. These strategies offer valuable insights into the prospects of innovative cathode materials and provide a foundation for future research in the field of PIBs

Synergistically boosting the elementary reactions over multiheterogeneous ordered macroporous Mo2C/NC-Ru for highly efficient alkaline hydrogen evolution

Simultaneously enhancing the reaction kinetics, mass transport, and gas release during alkaline hydrogen evolution reaction (HER) is critical to minimizing the reaction polarization resistance, but remains a big challenge. Through rational design of a hierarchical multiheterogeneous three-dimensionally (3D) ordered macroporous Mo2C-embedded nitrogen-doped carbon with ultrafine Ru nanoclusters anchored on its surface (OMS Mo2C/NC-Ru), we realize both electronic and morphologic engineering of the catalyst to maximize the electrocatalysis performance. The formed Ru-NC heterostructure shows regulative electronic states and optimized adsorption energy with the intermediate H*, and the Mo2C-NC heterostructure accelerates the Volmer reaction due to the strong water dissociation ability as confirmed by theoretical calculations. Consequently, superior HER activity in alkaline solution with an extremely low overpotential of 15.5 mV at 10 mA cm−2 with the mass activity more than 17 times higher than that of the benchmark Pt/C, an ultrasmall Tafel slope of 22.7 mV dec−1, and excellent electrocatalytic durability were achieved, attributing to the enhanced mass transport and favorable gas release process endowed from the unique OMS Mo2C/NC-Ru structure. By oxidizing OMS Mo2C/NC-Ru into OMS MoO3-RuO2 catalyst, it can also be applied as efficient oxygen evolution electrocatalyst, enabling the construction of a quasi-symmetric electrolyzer for overall water splitting. Such a device's performance surpassed the state-of-the-art Pt/C || RuO2 electrolyzer. This study provides instructive guidance for designing 3D-ordered macroporous multicomponent catalysts for efficient catalytic applications

Single-atom tailoring of Li2S to Form Li2S2 for building better lithium-sulfur batteries

The Li2S-based cathodes to couple with Li-free anodes are regarded as a commercially available approach to overcome the safety risk of lithium metal anodes. However, the passivated Li2S instinct leads to a high activation potential in the initial charging process, and the notorious shuttle effect of polysulfide is inevitable upon cell cycling. Here we create a single atom tailoring strategy by comproportionation reactions (Li2S + 1/8S8 = Li2S2) to form the Li2S2 materials without any complex manufacturing process or additives, where the Li2S2 cell enables a lower potential barrier and allows for the 3.0 V activation voltage without any other material modification. Meanwhile, the polar conducting material TaB2 is introduced to restrain the migration of polysulfides, and provide fast redox reaction kinetics. With those ingenious tailoring of cell designs, the Li2S2-TaB2 cell (Li2S2: 88 wt%) exhibits high areal capacity (4.6 mAh/cm2 at 6.0 mg/cm2 Li2S2 loading), excellent cycling stability (500 cycles at 1.6 mA/cm2)

Electrodeposition of a dendrite‐free 3D Al anode for improving cycling of an aluminum–graphite battery

Aluminum–metal batteries show great potential as next-generation energy storage due to their abundant resources and intrinsic safety. However, the crucial limitations of metallic Al anodes, such as dendrite and corrosion problems in conventional aluminum–metal batteries, remain challenging and elusive. Here, we report a novel electrodeposition strategy to prepare an optimized 3D Al anode on carbon cloth with an uniform deposition morphology, low local current density, and mitigatory volume change. The symmetrical cells with the 3D Al anode show superior stable cycling (>450 h) and low-voltage hysteresis (~170 mV) at 0.5 mA cm −2. High reversibility (~99.7%) is achieved for the Al plating/stripping. The graphite | | Al-4/CC full batteries show a long lifespan of 800 cycles with 54 mAh g −1 capacity at a high current density of 1000 mA g −1, benefiting from the high capacitive-controlled distribution. This study proposes a novel strategy to design 3D Al anodes for metallic-Al-based batteries by eliminating the problems of planar Al anodes and realizing the potential applications of aluminum–graphite batteries

Zinc-doping strategy on P2-type Mn-based layered oxide cathode for high-performance potassium-ion batteries

Mn-based layered oxide is extensively investigated as a promising cathode material for potassium-ion batteries due to its high theoretical capacity and natural abundance of manganese. However, the Jahn–Teller distortion caused by high-spin Mn3+(t2g3eg1) destabilizes the host structure and reduces the cycling stability. Here, K0.02Na0.55Mn0.70Ni0.25Zn0.05O2 (denoted as KNMNO-Z) is reported to inhibit the Jahn–Teller effect and reduce the irreversible phase transition. Through the implementation of a Zn-doping strategy, higher Mn valence is achieved in the KNMNO-Z electrode, resulting in a reduction of Mn3+ amount and subsequently leading to an improvement in cyclic stability. Specifically, after 1000 cycles, a high retention rate of 97% is observed. Density functional theory calculations reveals that low-valence Zn2+ ions substituting the transition metal position of Mn regulated the electronic structure around the Mn-O bonding, thereby alleviating the anisotropic coupling between oxidized O2− and Mn4+ and improving the structural stability. K0.02Na0.55Mn0.70Ni0.25Zn0.05O2 provided an initial discharge capacity of 57 mAh g−1 at 100 mA g−1 and a decay rate of only 0.003% per cycle, indicating that the Zn-doped strategy is effective for developing high-performance Mn-based layered oxide cathode materials in PIBs

In situ tailored strategy to remove capping agents from copper sulfide for building better lithium–sulfur batteries

Capping agents are frequently used in the chemical synthesis of materials, to precisely tailor the size, shape, and composition, with the expectation of high-performance catalysis. However, the adsorbed capping agents also serve as a physical barrier to restrict the interaction between reactants and catalytically active sites on the material surface. In this article, an in situ tailored interface strategy is introduced for effectively removing capping agents (long-chain oleylamine) from the surface of copper sulfide, to maximize the catalytic activity. The interface long-chain molecules of oleylamine are replaced by the inorganic S2- ion via a facile stirring approach without harsh processing conditions or the need for additional non-commercial materials. The as-cleaned copper sulfide shows greatly enhanced activity toward lithium-sulfur batteries, with an impressive current rate, excellent cycling stability, and great rate capability. These "clean surface"strategies using interface engineering provide a significant insight into the structure-activity relationships to support advancements in electrocatalysis technology in lithium-sulfur batteries. This journal i

Interfacial “double-terminal binding sites” catalysts synergistically boosting the electrocatalytic Li2S redox for durable lithium-sulfur batteries

Catalytic conversion of polysulfides emerges as a promising approach to improve the kinetics and mitigate polysulfide shuttling in lithium-sulfur (Li-S) batteries, especially under conditions of high sulfur loading and lean electrolyte. Herein, we present a separator architecture that incorporates double-terminal binding (DTB) sites within a nitrogen-doped carbon framework, consisting of polar Co0.85Se and Co clusters (Co/Co0.85Se@NC), to enhance the durability of Li-S batteries. The uniformly dispersed clusters of polar Co0.85Se and Co offer abundant active sites for lithium polysulfides (LiPSs), enabling efficient LiPS conversion while also serving as anchors through a combination of chemical interactions. Density functional theory calculations, along with in situ Raman and X-ray diffraction characterizations, reveal that the DTB effect strengthens the binding energy to polysulfides and lowers the energy barriers of polysulfide redox reactions. Li-S batteries utilizing the Co/Co0.85Se@NC-modified separator demonstrate exceptional cycling stability (0.042% per cycle over 1000 cycles at 2 C) and rate capability (849 mAh g-1 at 3 C), as well as deliver an impressive areal capacity of 10.0 mAh cm-2 even in challenging conditions with a high sulfur loading (10.7 mg cm-2) and lean electrolyte environments (5.8 μL mg-1). The DTB site strategy offers valuable insights into the development of high-performance Li-S batteries

Fundamentally manipulating the electronic structure of polar bifunctional catalysts for lithium-sulfur batteries: Heterojunction design versus doping engineering

Heterogeneous structures and doping strategies have been intensively used to manipulate the catalytic conversion of polysulfides to enhance reaction kinetics and suppress the shuttle effect in lithium-sulfur (Li-S) batteries. However, understanding how to select suitable strategies for engineering the electronic structure of polar catalysts is lacking. Here, a comparative investigation between heterogeneous structures and doping strategies is conducted to assess their impact on the modulation of the electronic structures and their effectiveness in catalyzing the conversion of polysulfides. These findings reveal that Co0.125Zn0.875Se, with metal-cation dopants, exhibits superior performance compared to CoSe2/ZnSe heterogeneous structures. The incorporation of low Co2+ dopants induces the subtle lattice strain in Co0.125Zn0.875Se, resulting in the increased exposure of active sites. As a result, Co0.125Zn0.875Se demonstrates enhanced electron accumulation on surface Se sites, improved charge carrier mobility, and optimized both p-band and d-band centers. The Li-S cells employing Co0.125Zn0.875Se catalyst demonstrate significantly improved capacity (1261.3 mAh g−1 at 0.5 C) and cycle stability (0.048% capacity delay rate within 1000 cycles at 2 C). This study provides valuable guidance for the modulation of the electronic structure of typical polar catalysts, serving as a design directive to tailor the catalytic activity of advanced Li-S catalysts