Structure-performance Relationship Research Articles

Influence of Chemical Structures on E-Beam Lithography Performance of Polysilsesquioxanes.

Hydrogenated silsesquioxane (HSQ) is a key inorganic electron beam resist, celebrated for its sub-10 nm resolution and etching resistance, but it faces challenges with stability and sensitivity. Our innovative study has comprehensively assessed the lithographic performance of three functionalized polysilsesquioxane (PSQ) resist series─olefins, halogenated alkanes, and alkanes─under electron beam lithography (EBL). We discovered that the addition of olefin groups, such as in the HMP-30 formulation with 30% propyl acrylate, remarkably increased the sensitivity to 0.6 μC/cm2. The inclusion of halogenated aromatic and hydrogen-substituted methyl groups further enhanced sensitivity and contrast, with HClBN-50 achieving a 22.9 nm resolution pattern. At the same time, the storage of PSQ resists was significantly improved compared to commercial HSQ with increasing alkane group content. Crucially, our research has unveiled the lithography reaction mechanism, highlighting how group encapsulation and steric hindrance influence PSQ performance. This insight is groundbreaking, offering a deeper understanding of the molecular structure-performance relationship and laying the groundwork for developing next-generation electron beam resists with superior sensitivity, resolution, and contrast for microelectronics manufacturing.

Electronic Structure Regulated Carbon-Based Single-Atom Catalysts for Highly Efficient and Stable Electrocatalysis.

Single-atom-catalysts (SACs) with atomically dispersed sites on carbon substrates have attained great advancements in electrocatalysis regarding maximum atomic utilization, unique chemical properties, and high catalytic performance. Precisely regulating the electronic structure of single-atom sites offers a rational strategy to optimize reaction processes associated with the activation of reactive intermediates with enhanced electrocatalytic activities of SACs. Although several approaches are proposed in terms of charge transfer, band structure, orbital occupancy, and the spin state, the principles for how electronic structure controls the intrinsic electrocatalytic activity of SACs have not been sufficiently investigated. Herein, strategies for regulating the electronic structure of carbon-based SACs are first summarized, including nonmetal heteroatom doping, coordination number regulating, defect engineering, strain designing, and dual-metal-sites scheming. Second, the impacts of electronic structure on the activation behaviors of reactive intermediates and the electrocatalytic activities of water splitting, oxygen reduction reaction, and CO2/N2 electroreduction reactions are thoroughly discussed. The electronic structure-performance relationships are meticulously understood by combining key characterization techniques with density functional theory (DFT)calculations. Finally, a conclusion of this paper and insights into the challenges and future prospects in this field are proposed. This review highlights the understanding of electronic structure-correlated electrocatalytic activity for SACs and guides their progress in electrochemical applications.

Impact of Inverse Manganese Promotion on Silica-Supported Cobalt Catalysts for Long-Chain Hydrocarbons via Fischer–Tropsch Synthesis

One of the challenges in Fischer–Tropsch synthesis (FTS) is the high reduction temperatures, which cause sintering and the formation of silicates. These lead to pore blockages and the coverage of active metals, particularly in conventional catalyst promotion. To address the challenge, this article investigates the effects of the preparation method, specifically the inverse promotion of SiO2-supported Co catalysts with manganese (Mn), and their reduction in H2 for FTS. The catalysts were prepared using stepwise incipient wetness impregnation of a cobalt nitrate precursor into a promoted silica support. The properties of the catalysts were characterized using XRD, XPS, TPR, and BET techniques. The structure–performance relationship of the inversely promoted catalysts in FTS was studied using a fixed-bed reactor to obtain the best performing catalysts for heavy hydrocarbons (C5+). XRD and XPS results indicated that Co3O4 is the dominant cobalt phase in oxidized catalysts. It was found that with increase in Mn loading, the reduction temperature increased in the following sequence 10%Co/SiO2 < 10%Co/0.25%Mn-SiO2 < 10%Co/0.5%Mn-SiO2 < 10%Co/3.0%Mn-SiO2. The catalyst with the lowest Mn loading, 10%Co/0.25%Mn-SiO2, exhibited higher C5+ selectivity, which can be attributed to less MSI and higher reducibility. This catalyst showed the lowest CH4 selectivity possibly due to lower H2 uptake and higher CO chemisorption.

Advanced Organic–Inorganic Hybrid Materials for Optoelectronic Applications

AbstractResearch on organic–inorganic hybrid materials (OIHMs) has experienced explosive growth in the past decades. The diversity of organic components allows for the introduction of various spatial scales, functional groups, and polarities, while inorganic components provide higher hardness, heat resistance, and stability, their flexible combination facilitates the formation of diverse structures. Furthermore, simple and cost‐effective synthesis methods, such as room temperature solution processes and mechanochemical techniques, enable precise control over the materials' properties at different scales, thus achieving adjustable structure–performance relationships. This review will discuss the recent research progress of OIHMs within the field of optoelectronics and related optoelectronic device applications. According to the dimension of inorganic components and the nature of organic–inorganic interface, this review divides OIHMs into four structural categories. The ongoing research has revealed diverse applications for OIHMs in the fields of solar cells, light‐emitting devices, detectors, and memristors. As an outlook, the potential of perovskite and 0D metal halide materials, which are currently the most studied, for enhancing optoelectronic performance and stability is discussed.

Chemically Engineering Multiple Active Sites in N, P, O-Tridoped Carbocatalyst: Unveiling Structure–Performance Relationship for Efficient Electrochemical Production of Hydrogen Peroxide

Chemically Engineering Multiple Active Sites in N, P, O-Tridoped Carbocatalyst: Unveiling Structure–Performance Relationship for Efficient Electrochemical Production of Hydrogen Peroxide

Construction of La1−xSrxNiO3/g-C3N4 type-Z heterojunctions with enhanced visible-light photocatalytic degradation of organic pollutants

Lanthanum nickelate (LaNiO3), known for its high visible-light absorption, is a promising photocatalyst for water purification. However, the low conduction band position and high photogenerated carrier complexation rate of pure LaNiO3 limit its photocatalytic activity. To address this issue, we investigated the synergistic effects of doping and constructing heterojunctions. A La0.9Sr0.1NiO3 (20%)/g-C3N4 (L2CN8) heterojunction was successfully created. In addition, various characterisation techniques were then employed to analyse the structure–performance relationships of these heterojunction photocatalysts in degrading organic dyes. Results revealed that at a 10% Sr doping level, the oxygen vacancy content was 0.68, which is significantly higher than that of LaNiO3 (0.05). The increased number of oxygen vacancies enhanced the electron capture ability and improved the separation efficiency of photogenerated carriers. Furthermore, the optimised L2CN8 (20 mg) achieved 81.2% and 73.8% removal of methylene blue (50.0 mL, 10 mg L−1) and tetracycline (50.0 mL, 10 mg L−1) under simulated visible-light irradiation (λ > 420 nm). Furthermore, an active species capture experiment confirmed the significant role of superoxide radicals (·O2−) in the degradation process. Based on these experimental findings, we proposed a rational Z-type charge transfer mechanism. This study holds great importance for water pollution control and environmental protection.

Towards Understanding and Control of Thermal Processes in Lithium-Ion Batteries

Despite lithium-ion batteries (LIBs) being state-of-the-art commercial rechargeable batteries, there are still significant challenges. For example, heat generation during cycling can lead to performance degradation and safety issues1-2. During the process of charging and discharging, the heat that is generated from the chemical reactions taking placing is ideally distributed uniformly in space, to dissipate out the cell easily. However, in practice, heat generation tends to be heterogeneous throughout the battery, leading to localized overheating3. This phenomenon can result in e.g. decomposition of the solid-state electrolyte interphase (SEI) layer, triggering electrode reactions with the electrolyte and degradation of the electrolyte (producing combustible gases) and even melting of the separator4. Hence, comprehending the origins of temperature generation and its heterogeneity is crucial.To address this challenge, operando X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) are applied to monitor the structural changes in the electrode materials during charge and discharge, while simultaneous temperature measurements are conducted using a thermal camera, as such obtaining spatial resolved structure/temperature/performance relationships. We have focused on state-of-the-art nickel rich NMC (Nickel Manganese Cobalt Oxide) versus graphite batteries and by comparing the structural changes of the electrode materials during cycling in ‘hot’ versus ‘cool’ areas of the electrode and battery, we were able to establish a structure-temperature relationships, on top of the electrochemical structure-performance relationships and as such unravel “heat-generation” process and reactions. The real-time temperature distribution was compared to the computational models using COMSOL, and insights in thermal processes and their possible control measures could be obtained.References Lain, M. & Kendrick, E. Understanding the limitations of lithium-ion batteries at high rates. Journal of Power Sources. Volume 493, 229690 (2021).Ma, S., et al. Temperature effect and thermal impact in lithium-ion batteries: A review. Progress in Natural Science: Materials International. Volume 28, Issue 6, Pages 653-666 (2018).Rafael, M., et al. Operando Radiography and Multimodal Analysis of Lithium–Sulfur Pouch Cells—Electrolyte Dependent Morphology Evolution at the Cathode. Adv. Energy Mater. 2103432 (2022).Joris, J., et al. A comprehensive review of future thermal management systems for battery electrified vehicles. Journal of Energy Storage 31, 101551(2020).

Pore Network Modelling of a Lithium Ion Battery Cathode as a Tool for Microstructure Optimization

Lithium ion batteries (LIBs) have become the battery of choice, owning almost 90% of the energy storage market [1]. They boast excellent power and energy density, but performance decreases at high discharge rates limiting their use in large scale applications [2]. With the availability of graphite and silicon materials as anode, the anode in a lithium-ion battery is already well optimized and research has focused primarily on the development of cathode materials with high rate-capacity. A LIB cathode is a porous material comprised of electrolyte, active material, and carbon binder phases. The electrolyte facilitates the migration and diffusion of lithium ions from the anode, through a porous separator, and to the active material where lithium ions intercalate, and electronic current is produced as the battery discharges. A carbon binder phase is also dispersed to enhance the electrical conductivity of the cathode and may even contain micropores that can increase current density [3]. The porous microstructure of a LIB cathode thereby plays an important role in controlling the movement of lithium ions and accessibility of active material effecting both discharge rate and capacity of LIBs. Therefore, tailoring the cathode microstructure provides a route for LIB cathode optimization. Pore scale models that resolve the electrolyte, active material, and carbon binder phases in a cathode can be used for this purpose. Pore scale models offer unique advantages compared to experimental studies in that they can test a wide variety of microstructures, even ones that are not yet realized, in a relatively short time frame. Typical battery models are continuum models that do not resolve the pore space and instead use effective properties determined from experiment. Pore scale models do not use effective properties saving experimental effort but are disadvantageous in that they are computationally very expensive requiring a fine mesh on a highly resolved volumetric image. Of the pore-scale modeling options, pore network modelling (PNM) is an especially efficient approach that discretizes the microstructure into pores and throats where pores are the computational nodes and throats are constrictions connecting pores [4]. In the literature, there is only one known pore network model of a LIB cathode, but it is an isothermal model that does not consider the effect of heat generation from electrochemical reactions [5]. While this model was effective at predicting discharge performance at low currents, predicting the voltage for galvanostatic discharge at high currents proved to be difficult, possibly because of assumed isothermal behaviour. Therefore, this work is focused on the development of a non-isothermal pore network model of a LIB cathode undergoing galvanostatic discharge. The complete set of partial differential equations and their discretization’s for modelling lithium transport, ionic or electronic charge transport, as well as heat transfer in all three phases of a LIB cathode is presented along with the numerical framework used for solving the coupled physics. This framework and discretized set of equations are demonstrated on a pore network extracted from an X-ray tomography image of a NMC532 cathode. Post-processing of the extracted network is done to apply novel interphase nodes between active material and electrolyte phases to provide sites for lithium intercalation to occur. The pore network model is written in Python using OpenPNM, an open-source pore network modelling package [6].[1] S. Zavahir et al., “A review on lithium recovery using electrochemical capturing systems,” Desalination, vol. 500, Mar. 2021, doi: 10.1016/j.desal.2020.114883.[2] R. Wagner, N. Preschitschek, S. Passerini, J. Leker, and M. Winter, “Current research trends and prospects among the various materials and designs used in lithium-based batteries,” J Appl Electrochem, vol. 43, no. 5, pp. 481–496, May 2013, doi: 10.1007/S10800-013-0533-6/FIGURES/10.[3] Z. A. Khan et al., “Probing the Structure-Performance Relationship of Lithium-Ion Battery Cathodes Using Pore-Networks Extracted from Three-Phase Tomograms,” J Electrochem Soc, 2020, doi: 10.1149/1945-7111/ab7bd8.[4] M. McKague, H. Fathiannasab, M. Agnaou, M. A. Sadeghi, and J. Gostick, “Extending pore network models to include electrical double layer effects in micropores for studying capacitive deionization,” Desalination, vol. 535, 2022, doi: 10.1016/j.desal.2022.115784.[5] Z. A. Khan, M. Agnaou, M. A. Sadeghi, A. Elkamel, and J. T. Gostick, “Pore Network Modelling of Galvanostatic Discharge Behaviour of Lithium-Ion Battery Cathodes,” J Electrochem Soc, vol. 168, no. 7, Jul. 2021, doi: 10.1149/1945-7111/ac120c.[6] J. Gostick et al., “OpenPNM: A Pore Network Modeling Package,” Comput Sci Eng, vol. 18, no. 4, pp. 60–74, Jul. 2016, doi: 10.1109/MCSE.2016.49. Figure 1

Spinel oxide modified FeCoNi alloy composites prepared with one-step pyrolytic reduction as bifunctional catalyst for ORR/OER

The development of low-cost and highly efficient bifunctional electrocatalysts for oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) is a challenging topic in the fuel cells and metal-air batteries field. Herein, a noble metal-free composite consisting of nano-FeCoNi alloy and spinel oxide was successfully prepared through a simple one-step pyrolytic reduction strategy as identified by XRD, TEM, HRTEM, XPS, and other techniques. The effect of the reduction temperatures (700, 850, and 950 °C) on the composite structure as well as its OER/ORR performances was further investigated. It was observed that FeCoNi@Mn2AlO4 was harvested at the temperature of 700 °C, while FeCoNi@MnAl2O4 was finally formed when the reduction temperature was 850 °C and 950 °C. The composites showed comparable electrocatalytic performance to Pt/C in ORR as well as RuO2 in OER. Moreover, all three catalysts showed great potential for bifunctional catalysis while FeCoNi@MnAl2O4-850 with a ΔEgap of 0.75 V, FeCoNi@MnAl2O4-950 with a ΔEgap of 0.77 V, and FeCoNi@Mn2AlO4-700 with a ΔEgap of 0.83 V. Density functional theory (DFT) computations further confirmed the synergistic effect between FeCoNi and MnAl2O4. This work provides a facile approach to prepare an alternative bifunctional composite electrocatalyst for ORR/OER with deep understanding on the structure-performance relationship.

Lignin data bank: A key to clarifying aromatic structure–performance relationships

Lignin data bank: A key to clarifying aromatic structure–performance relationships

The morphologic dependence of MnO2 electrodes in capacitive deionization process

Manganese dioxide (MnO2) materials are one of promising cathode candidates for capacitive deionization (CDI) applications, with their morphology significantly impacting the performance of the electrode material itself. Therefore, this study systematically investigates the structure-performance relationships and the micro-interface ion storage mechanisms of four morphologies of MnO2 (1D nanorods (NNMO), nanowires (NWMO), 3D microspheres (MMO), and hollow urchin-like spheres (HUMO)) in relation to their capacitive deionization performance with typical heavy metal ions (Cd2+) through experimental and theoretical calculations. In terms of pore morphology, capacitance significantly increases with increasing surface curvature of materials, demonstrating a clear pore structure-dependent characteristic. NNMO, with the smallest pore size, has much lower surface capacitance (∼0.15 μF cm−2) than other materials (∼0.33 μF cm−2). As pore size increases, the capacitance distribution difference driven by pore structure size gradually disappears. Regarding surface and interface characteristics, high-energy crystal facets facilitate electron transfer ({310}>{200}≈{211}>{100}) and increase the proportion of surface active sites (Osur), thus promoting CDI absorption kinetics. During the capacitive deionization process, the pore structure (∼77 %) and surface-interface characteristics (∼23 %) exhibit highly coupled features and the driving force for interfacial ion storage among the four materials is in the order of HUMO>MMO>NWMO>NNMO. This work elucidates the morphology-dependent capacitive processes of MnO2 nanomaterials, enhancing the understanding of structure- electrochemical process at the nanoscale but also providing effective guidance for the design and development of practical, high-performance CDI electrode materials.

Unleashing the Potential of Single-Atom Nanozymes: Catalysts for the Future.

Single-atom nanozymes (SANs) have become a breakthrough in atomically precise catalysis, which relies on the catalytic active site formed by the single-atom itself. From this angle, SANs and their advantages compared to natural enzymes as well as spaces for their application are emphasized. The SANs have outstanding control over their catalytic activities; this is compared with bulk materials and natural enzymes. The structure of the SANs has very promising potential for the next generation of biosensing and biomedical devices and environmental remediation. Although their capabilities are high, difficulties still arise. The specificity, scalability, biosafety, and catalysis mechanisms raise additional issues that require further research. We build up a vision of the perspectives of the better implementation of SANs, which are designed for diagnostic purposes, improving industrial technologies, and creating new sustainable technologies in the food processing industry. AI and machine learning systems may clarify the structure-performance relationship of SANs for improved material and process selectivity. The future of SANs is very promising, and by addressing these challenges and leveraging advancements in artificial intelligence and materials science, SANs have the potential to become powerful tools for a sustainable future.

Recent Advances in Revealing the Electrocatalytic Mechanism for Hydrogen Energy Conversion System.

In light of the intensifying global energy crisis and the mounting demand for environmental protection, it is of vital importance to develop advanced hydrogen energy conversion systems. Electrolysis cells for hydrogen production and fuel cell devices for hydrogen utilization are indispensable in hydrogen energy conversion. As one of the electrolysis cells, water splitting involves two electrochemical reactions, hydrogen evolution reaction and oxygen evolution reaction. And oxygen reduction reaction coupled with hydrogen oxidation reaction, represent the core electrocatalytic reactions in fuel cell devices. However, the inherent complexity and the lack of a clear understanding of the structure-performance relationship of these electrocatalytic reactions, have posed significant challenges to the advancement of research in this field. In this work, the recent development in revealing the mechanism of electrocatalytic reactions in hydrogen energy conversion systems is reviewed, including in situ characterization and theoretical calculation. First, the working principles and applications of operando measurements in unveiling the reaction mechanism are systematically introduced. Then the application of theoretical calculations in the design of catalysts and the investigation of the reaction mechanism are discussed. Furthermore, the challenges and opportunities are also summarized and discussed for paving the development of hydrogen energy conversion systems.

Cu-substituted Na0.75Ni0.17Cu0.08Mn0.75O2 cathode with suppressing P2-O2 phase transition and air-stable for high-performance sodium-ion batteries

P2-Na0.75Ni0.25Mn0.75O2 cathode material with high specific capacity and high operating voltage is favored by researchers. However, the complex phase transition (P2-O2) at high voltage and the rapid capacity decay caused by Na+/vacancy ordering seriously restrict its application. In this study, a series of Cu-substituted P2-type Na0.75Ni0.25-xCuxMn0.75O2 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) cathodes are synthesized. The Na0.75Ni0.17Cu0.08Mn0.75O2 cathode achieves a high initial discharge capacity of 133.6 mAh g−1 and remains 80.5 % of this capacity after 150 cycles at 0.1C, outperforming the performance of other compositions. Investigations into the superior electrochemical performance of Na0.75Ni0.17Cu0.08Mn0.75O2 through a multi-technique approach, including in-situ X-ray diffraction (XRD), ex-situ X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT), elucidate the underlying mechanisms. The results show that the introduction of Cu2+ in Na0.75Ni0.25Mn0.75O2 can successfully regulate the ratio of Naf/Nae, with enhanced cell performance when Na+ occupies more Nae sites compared to Naf sites. In-situ XRD confirms that the Cu substitution for Ni stabilizes the P2 structure during the charge–discharge process and inhibits the unfavorable P2-O2 phase transition at high voltage. In addition, Cu-substituted cathode materials exhibit a good effect on improving air stability, attributed to the higher Cu2+/Cu3+ redox potential. This unique substitution mechanism offers a novel perspective for understanding the structure-performance relationship of P2-type cathode materials and provides important support for the design of air-stable, high-performance cathode materials.

Construction of Porous Aromatic Frameworks with Specifically Designed Motifs for Charge Storage and Transport.

ConspectusPorous frameworks possess high porosity and adjustable functions. The two features conjointly create sufficient interfaces for matter exchange and energy transfer within the skeletons. For crystalline porous frameworks, including metal organic frameworks (MOFs) and covalent organic frameworks (COFs), their long-range ordered structures indeed play an important role in managing versatile physicochemical behaviors such as electron transfer or band gap engineering. It is now feasible to predict their functions based on the unveiled structures and structure-performance relationships. In contrast, porous organic frameworks (POFs) represent a member of the porous solid family with no long-range regularity. For the case of POFs, the randomly packed building units and their disordered connections hinder the electronic structural consistency throughout the entire networks. However, many investigations have demonstrated that the functions of POFs could also be designed and originated from their local motifs.In this Account, we will first provide an overview of the design and synthesis principles for porous aromatic frameworks (PAFs), which are a typical family of POFs with high porosity and exceptional stability. Specifically, the functions achieved by the specific design and synthesis of in-framework motifs will be demonstrated. This strategy is particularly intuitive to introduce desired functions to PAFs, owing to the exceptional tolerance of PAFs to harsh chemical treatments and synthetic conditions. The local structures can be either obtained by selecting suitable building units, sometimes with the aid of computational screening, or emerge as the product of coupling reactions during the synthetic process. Radical PAFs can be obtained by incorporating a persistent radical molecule as a building unit, and the rigid and porous framework may facilitate the formation of radical species by trapping spins in the organic network, which could avoid the delocalizing and recombining processes. Alternatively, radical motifs can also be formed during the formation of the framework linkages. The coupling reaction plays an important role in the construction of functional motifs like diacetylene. The highly porous, radical PAFs showed significant performance as anodes of lithium-ion batteries. To improve the charge transport within the framework, the building units and their connecting manner were cohesively considered, and the framework with a fully conjugated backbone was built up. In another case, the explicit product of the cross-coupling reaction ensured the precise assembly of two building units with electron donating and accepting abilities; therefore, the moving direction of photogenerated electrons was rationally controlled. Constructing a fully conjugated backbone or rationally designing a D-A system for charge transfer in porous frameworks introduced exciting properties for photovoltaic and photocatalysis, and their highly porous, stable frameworks improved their functional applications for perovskite solar cells and chemical productions. These investigations shed light on the designable combination of intrinsic functional motifs with highly porous organic frameworks for effective energy storage and conversion.

Tracking the dynamics of catalytic Pt/CeO2 active sites during water-gas-shift reaction

Understanding the atomistic structure of the active site during catalytic reactions is of paramount importance in both fundamental studies and practical applications, but such studies are challenging due to the complexity of heterogeneous systems. Here, we use Pt/CeO2 as an example to study the dynamic nature of active sites during the water-gas-shift reaction (WGSR) by combining multiple in situ characterization tools. We show that the different concentrations of interfacial Ptδ+ – O – Ce4+ moieties at Pt/CeO2 interfaces are responsible for the rank of catalytic performance of Pt/CeO2 catalysts: Pt/CeO2-rod > Pt/CeO2-cube > Pt/CeO2-oct. For all the catalysts, metallic Pt is formed during the WGSR, leading to the transformation of the active sites to Pt0 – Ov – Ce3+ and interface reconstruction. These findings shed light on the nature of the active site for the WGSR on Pt/CeO2 and highlight the importance of combining complementary in situ techniques for establishing structure-performance relationships.

Hexa-atom Pt Catalyst Fabricated by a Ligand Engineering Strategy for Efficient Hydrogen Oxidation Reaction.

Atomically precise supported nanocluster catalysts (APSNCs), which feature exact atomic composition, well-defined structures, and unique catalytic properties, offer an exceptional platform for understanding the structure-performance relationship at the atomic level. However, fabricating APSNCs with precisely controlled and uniform metal atom numbers, as well as maintaining a stable structure, remains a significant challenge due to uncontrollable dispersion and easy aggregation during synthetic and catalytic processes. Herein, we developed an effective ligand engineering strategy to construct a Pt6 nanocluster catalyst stabilized on oxidized carbon nanotubes (Pt6/OCNT). The structural analysis revealed that Pt6 nanoclusters in Pt6/OCNT were fully exposed and exhibited a planar structure. Furthermore, the obtained Pt6/OCNT exhibited outstanding acidic HOR performances with a high mass activity of 18.37 A·mgpt-1 along with excellent stability during a 24 h constant operation and good CO tolerance, surpassing those of the commercial Pt/C. Density functional theory (DFT) calculations demonstrated that the unique geometric and electronic structures of Pt6 nanoclusters on OCNT altered the hydrogen adsorption energies on catalytic sites and thus lowered the HOR theoretical overpotential. This work presents a new prospect for designing and synthesizing advanced APSNCs for efficient energy electrocatalysis.

Isoporous Membranes by the Symmetric Triblock Copolymer: A Strategy to Improve the Mechanical Strength without Sharply Changing the Pore Size and Permselectivity.

Isoporous membranes produced from diblock copolymers commonly display a poor mechanical property that shows many negative impacts on their separation application. It is theoretically predicted that dense films produced from symmetric triblock copolymers show much stronger mechanical properties than those of homologous diblock copolymers. However, to the best of our knowledge, symmetric triblock copolymers have rarely been fabricated into isoporous membranes before, and a full understanding of separation as well as mechanical properties of membranes prepared from triblock copolymers and homologous diblock copolymers has not been conducted, either. In this work, a cleavable symmetric triblock copolymer with polystyrene as the side block and poly(4-vinylpyridine) (P4VP) as the middle block was synthesized and designed by the RAFT polymerization using the symmetric chain transfer agent, which located at the center of polymer chains and could be removed to produce homologous diblock copolymers with half-length while having the same composition as that found in triblock copolymers. The self-assembly of these two copolymers in thin films and casting solutions was first investigated, observing that they displayed similar self-organized structures under these two conditions. When fabricated into isoporous membranes, they showed similar pore sizes (5-7% difference) and comparable rejection performance (∼10% difference). However, isoporous membranes produced from triblock copolymers showed significantly improved mechanical strength and higher toughness (2-10 times larger) as evidenced by the compacting resistance, strain-stress determination, and nanoindentation testing, suggesting the unique and novel structure-performance relationship in the isoporous membranes produced from symmetric triblock copolymers. The above finding will guide the way to fabricate mechanically robust isoporous membranes without notably changing the separation performance from rarely used symmetric triblock copolymers, which can be synthesized by the controlled polymerization as facilely as that found for diblock copolymers.

Metal ionic liquid-based hybrid membranes for ammonia separation through moderate interaction sites and cooperative transport channels

The combination ionic liquids (ILs) with membranes is a potential method for direct NH3 separation. In particular, ILs can modulate the interactions with NH3 and construct pathways in membranes for preferential NH3 transport, which is expected to overcome the trade-off effect and achieve a desirable separation performance. In this work, four metal ILs (MILs) with different metal centres and hydrogen bond donating ability, including [2-Mim][Li(NTf2)2], [Eim][Li(NTf2)2], [Bmim]2[Co(NCS)4], and [Bim]2[Co(NCS)4], were incorporated into sulfonated block copolymers to prepare MIL-based hybrid membranes for NH3 separation. The investigation of structure–performance relationships suggested that the interaction sites and transport channels could be tuned by the MIL type, which greatly affects the NH3 separation performance of the membranes. The Nexar/2-Mim-Li-10 membrane exhibits NH3 permeability of 735.6 Barrer with NH3/N2 selectivity of 844.5 and NH3/H2 selectivity of 154.7, which is higher than other MIL-based hybrid membranes owing to self-assembled transport channels and moderate complexation. Increasing the MIL content and feed pressure significantly improved NH3 separation performance.

Unveiling the structure-performance of MoO3/La2O2CO3 for ultra-deep aerobic oxidative desulfurization of diesel

The production of clean fuel via the aerobic oxidative desulfurization (ODS) technique is a potential substitute due to its moderate reaction conditions and outstanding catalytic efficiency. However, the relationship between the catalyst structure and the catalytic performance for sulfur-containing compounds with high steric hindrance effect in this process remains unclear hitherto. Herein, a series of MoO3/La2O2CO3 catalysts with various MoO3 particle sizes were carefully designed and prepared through a facile citric acid-assisted hydrothermal strategy. The structures of the loaded Mo-based catalysts were analyzed by series characterization methods, and their structure-performance relationships were investigated for catalytic ODS of 4,6-dimethyldibenzothiophene (4,6-DMDBT). The results revealed that the particle size of MoO3 significantly influenced the redox properties, reactive oxygen species, and ODS performances of MoO3/La2O2CO3 catalysts. With the decrease of MoO3 crystal size from 15.8 nm to 5.3 nm, the ODS performances of MoO3/La2O2CO3 catalysts considerably increased. Among them, MoO3/La2O2CO3-3 exhibited the best ODS activity with complete 4,6-DMDBT conversion within 2.5 h at 130 °C because of its appropriate MoO3 size and the lowest apparent activation energy (Ea). Nevertheless, further downsizing the crystal size of MoO3 to 2.8 nm resulted in a significant increase in the Ea, which dramatically suppressed the catalytic ODS performance of the corresponding MoO3/La2O2CO3-4 catalyst instead. It therefore reveals for the first time that there is a balance between the geometry and the catalytic efficiency of MoO3/La2O2CO3 catalysts for catalytic ODS of 4,6-DMDBT with high steric hindrance effect, which could provide insight for developing advanced ODS catalysts in the future.