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Advanced Materials

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Efficient and Robust Carbon Dioxide Electroreduction Enabled by Atomically Dispersed Snδ+ Sites
Xiaolong Zu, Xiaodong Li, Wei Liu, Yongfu Sun, Jiaqi Xu, Tao Yao, Wensheng Yan, Shan Gao, Chengming Wang, Shiqiang Wei, Yi Xie
Keywords:CO2 electroreduction
Abstracts:Electrocatalytic CO2 reduction at considerably low overpotentials still remains a great challenge. Here, a positively charged single‐atom metal electrocatalyst to largely reduce the overpotentials is designed and hence CO2 electroreduction performance is accelerated. Taking the metal Sn as an example, kilogram‐scale single‐atom Snδ+ on N‐doped graphene is first fabricated by a quick freeze–vacuum drying–calcination method. Synchrotron‐radiation X‐ray absorption fine structure and high‐angle annular dark‐field scanning transmission electron microscopy demonstrate the atomically dispersed Sn atoms are positively charged, which enables CO2 activation and protonation to proceed spontaneously through stabilizing CO2•−* and HCOO−*, affirmed by in situ Fourier transform infrared spectra and Gibbs free energy calculations. Furthermore, N‐doping facilitates the rate‐limiting formate desorption step, verified by the decreased desorption energy from 2.16 to 1.01 eV and the elongated SnHCOO− bond length. As an result, single‐atom Snδ+ on N‐doped graphene exhibits a very low onset overpotential down to 60 mV for formate production and shows a very large turnover frequency up to 11930 h−1, while its electroreduction activity proceeds without deactivation even after 200 h. This work offers a new pathway for manipulating electrocatalytic performance.
Surface and Interface Properties in Thin‐Film Solar Cells: Using Soft X‐rays and Electrons to Unravel the Electronic and Chemical Structure
Lothar Weinhardt, Dirk Hauschild, Clemens Heske
Keywords:chemical structures
Abstracts:Thin‐film solar cells have great potential to overtake the currently dominant silicon‐based solar cell technologies in a strongly growing market. Such thin‐film devices consist of a multilayer structure, for which charge‐carrier transport across interfaces plays a crucial role in minimizing the associated recombination losses and achieving high solar conversion efficiencies. Further development can strongly profit from a high‐level characterization that gives a local, electronic, and chemical picture of the interface properties, which allows for an insight‐driven optimization. Herein, the authors' recent progress of applying a “toolbox” of high‐level laboratory‐ and synchrotron‐based electron and soft X‐ray spectroscopies to characterize the chemical and electronic properties of such applied interfaces is provided. With this toolbox in hand, the activities are paired with those of experts in thin‐film solar cell preparation at the cutting edge of current developments to obtain a deeper understanding of the recent improvements in the field, e.g., by studying the influence of so‐called “post‐deposition treatments”, as well as characterizing the properties of interfaces with alternative buffer layer materials that give superior efficiencies on large, module‐sized areas.
Cr‐Doped FeNi–P Nanoparticles Encapsulated into N‐Doped Carbon Nanotube as a Robust Bifunctional Catalyst for Efficient Overall Water Splitting
Yiqiang Wu, Xu Tao, Yan Qing, Han Xu, Fan Yang, Sha Luo, Cuihua Tian, Ming Liu, Xihong Lu
Keywords:bifunctional catalyst
Abstracts:Exploring high‐efficiency, stable, and cost‐effective bifunctional electrocatalysts for overall water splitting is greatly desirable and challenging. Herein, a newly designed hybrid catalyst with Cr‐doped FeNi–P nanoparticles encapsulated into N‐doped carbon nanotubes (Cr‐doped FeNi–P/NCN) with unprecedented electrocatalytic activity is developed by a simple one‐step heating treatment. The as‐synthesized Cr‐doped FeNi–P/NCN with moderate Cr doping exhibits admirable oxygen evolution reaction and hydrogen evolution reaction activities with overpotentials of 240 and 190 mV to reach a current density of 10 mA cm−2 in 1 m KOH solution. When used in overall water splitting as a bifunctional catalyst, it needs only 1.50 V to give a current density of 10 mA cm−2, which is superior to its typically integrated Pt/C and RuO2 counterparts (1.54 V @ 10 mA cm−2). Density functional theory calculation confirms that Cr doping into a FeNi‐host can effectively alter the relative Gibbs adsorption energy and reduces the theoretical overpotential. Additionally, the synergetic effects between Cr‐doped FeNi–P nanoparticles and NCNs are regarded as significant contributors to accelerate charge transfer and promote electrocatalytic activity in hybrid catalysts.
3D Scaffolds to Study Basic Cell Biology
Marc Hippler, Enrico Domenico Lemma, Sarah Bertels, Eva Blasco, Christopher Barner‐Kowollik, Martin Wegener, Martin Bastmeyer
Keywords:3D scaffolds
Abstracts:Mimicking the properties of the extracellular matrix is crucial for developing in vitro models of the physiological microenvironment of living cells. Among other techniques, 3D direct laser writing (DLW) has emerged as a promising technology for realizing tailored 3D scaffolds for cell biology studies. Here, results based on DLW addressing basic biological issues, e.g., cell‐force measurements and selective 3D cell spreading on functionalized structures are reviewed. Continuous future progress in DLW materials engineering and innovative approaches for scaffold fabrication will enable further applications of DLW in applied biomedical research and tissue engineering.
Elaborately Modified BiVO4 Photoanodes for Solar Water Splitting
Jin Hyun Kim, Jae Sung Lee
Keywords:bismuth vanadate
Abstracts:Photoelectrochemical (PEC) cells for solar‐energy conversion have received immense interest as a promising technology for renewable hydrogen production. Their similarity to natural photosynthesis, utilizing sunlight and water, has provoked intense research for over half a century. Among many potential photocatalysts, BiVO4, with a bandgap of 2.4–2.5 eV, has emerged as a highly promising photoanode material with a good chemical stability, environmental inertness, and low cost. Unfortunately, its charge transport properties are modest, at most a hole diffusion length (Lp) of ≈70 nm. However, recent rapid developments in multiple modification strategies have elevated it to a position as the most promising metal oxide photoanode material. This review summarizes developments in BiVO4 photoanodes in the past 10 years, in which time it has continuously broken its own performance records for PEC water oxidation. Effective modification techniques are discussed, including synthesis of nanostructures/nanopores, external/internal doping, heterojunction fabrication, surface passivation, and cocatalysts. Tandem systems for unassisted solar water splitting and PEC production of value‐added chemicals are also discussed.
Engineered Bacterial Bioreactor for Tumor Therapy via Fenton‐Like Reaction with Localized H2O2 Generation
Jin‐Xuan Fan, Meng‐Yun Peng, He Wang, Hao‐Ran Zheng, Zong‐Lin Liu, Chu‐Xin Li, Xia‐Nan Wang, Xin‐Hua Liu, Si‐Xue Cheng, Xian‐Zheng Zhang
Keywords:bacterial bioreactor
Abstracts:Synthetic biology based on bacteria has been displayed in antitumor therapy and shown good performance. In this study, an engineered bacterium Escherichia coli MG1655 is designed with NDH‐2 enzyme (respiratory chain enzyme II) overexpression (Ec‐pE), which can colonize in tumor regions and increase localized H2O2 generation. Following from this, magnetic Fe3O4 nanoparticles are covalently linked to bacteria to act as a catalyst for a Fenton‐like reaction, which converts H2O2 to toxic hydroxyl radicals (•OH) for tumor therapy. In this constructed bioreactor, the Fenton‐like reaction occurs with sustainably synthesized H2O2 produced by engineered bacteria, and severe tumor apoptosis is induced via the produced toxic •OH. These results show that this bioreactor can achieve effective tumor colonization, and realize a self‐supplied therapeutic Fenton‐like reaction without additional H2O2 provision.
Advances in Polyimide‐Based Materials for Space Applications
Irina Gouzman, Eitan Grossman, Ronen Verker, Nurit Atar, Asaf Bolker, Noam Eliaz
Keywords:additive manufacturing
Abstracts:The space environment raises many challenges for new materials development and ground characterization. These environmental hazards in space include solar radiation, energetic particles, vacuum, micrometeoroids and debris, and space plasma. In low Earth orbits, there is also a significant concentration of highly reactive atomic oxygen (AO). This Progress Report focuses on the development of space‐durable polyimide (PI)‐based materials and nanocomposites and their testing under simulated space environment. Commercial PIs suffer from AO‐induced erosion and surface electric charging. Modified PIs and PI‐based nanocomposites are developed and tested to resist degradation in space. The durability of PIs in AO is successfully increased by addition of polyhedral oligomeric silsesquioxane. Conductive materials are prepared based on composites of PI and either carbon nanotube (CNT) sheets or 3D‐graphene structures. 3D PI structures, which can expand PI space applications, made by either additive manufacturing (AM) or thermoforming, are presented. The selection of AM‐processable engineering polymers in general, and PIs in particular, is relatively limited. Here, innovative preliminary results of a PI‐based material processed by the PolyJet technology are presented.
Synthetic Hilbert Space Engineering of Molecular Qudits: Isotopologue Chemistry
Wolfgang Wernsdorfer, Mario Ruben
Keywords:Hilbert space
Abstracts:One of the most ambitious technological goals is the development of devices working under the laws of quantum mechanics. Among others, an important challenge to be resolved on the way to such breakthrough technology concerns the scalability of the available Hilbert space. Recently, proof‐of‐principle experiments were reported, in which the implementation of quantum algorithms (the Grover's search algorithm, iSWAP‐gate, etc.) in a single‐molecule nuclear spin qudit (with d = 4) known as 159TbPc2 was described, where the nuclear spins of lanthanides are used as a quantum register to execute simple quantum algorithms. In this progress report, the goal of linear and exponential up‐scalability of the available Hilbert space expressed by the qudit‐dimension “d” is addressed by synthesizing lanthanide metal complexes as quantum computing hardware. The synthesis of multinuclear large‐Hilbert‐space complexes has to be carried out under strict control of the nuclear spin degree of freedom leading to isotopologues, whereby electronic coupling between several nuclear spin units will exponentially extend the Hilbert space available for quantum information processing. Thus, improved multilevel spin qudits can be achieved that exhibit an exponentially scalable Hilbert space to enable high‐performance quantum computing and information storage.
Rechargeable Aqueous Electrochromic Batteries Utilizing Ti‐Substituted Tungsten Molybdenum Oxide Based Zn2+ Ion Intercalation Cathodes
Haizeng Li, Liam McRae, Curtis J. Firby, Abdulhakem Y. Elezzabi
Keywords:aqueous zinc‐ion battery
Abstracts:Batteries are used in every facet of human lives. Desirable battery architectures demand high capacity, rechargeability, rapid charging speed, and cycling stability, all within an environmentally friendly platform. Many applications are limited by opaque batteries; thus, new functionalities can be unlocked by introducing transparent battery architectures. This can be achieved by incorporating electrochromic and energy storage functions. Transparent electrochromic batteries enable new applications, including variable optical attenuators, optical switches, addressable displays, touch screen devices, and most importantly smart windows for energy‐efficient buildings. However, this technology is in the incipient state due to limited electrochromic materials having satisfactory optical contrast and capacity. As such, triggering electrochromism via Zn2+ intercalation is advantageous: Zn is abundant, safe, easily processed in aqueous electrolytes and provides two electrons during redox reactions. Here, enhanced Zn2+ intercalation is demonstrated in Ti‐substituted tungsten molybdenum oxide, yielding improved capacity and electrochromic performance. This technique is employed to engineer cathodes exhibiting an areal capacity of 260 mAh m−2 and high optical contrast (76%), utilized in the fabrication of aqueous Zn‐ion electrochromic batteries. Remarkably, these batteries can be charged by external voltages and self‐recharged by spontaneously extracting Zn2+, providing a new technology for practical electrochromic devices.
A Bioinspired Platform for Effective Delivery of Protein Therapeutics to the Central Nervous System
Di Wu, Meng Qin, Duo Xu, Lan Wang, Chaoyong Liu, Jie Ren, George Zhou, Chen Chen, Fengmei Yang, Yanyan Li, Yuan Zhao, Ruyi Huang, Sina Pourtaheri, Chunsheng Kang, Masakazu Kamata, Irvin S. Y. Chen, Zhanlong He, Jing Wen, Wei Chen, Yunfeng Lu
Keywords:blood–brain barrier penetration
Abstracts:Central nervous system (CNS) diseases are the leading cause of morbidity and mortality; their treatment, however, remains constrained by the blood–brain barrier (BBB) that impedes the access of most therapeutics to the brain. A CNS delivery platform for protein therapeutics, which is achieved by encapsulating the proteins within nanocapsules that contain choline and acetylcholine analogues, is reported herein. Mediated by nicotinic acetylcholine receptors and choline transporters, such nanocapsules can effectively penetrate the BBB and deliver the therapeutics to the CNS, as demonstrated in mice and non‐human primates. This universal platform, in general, enables the delivery of any protein therapeutics of interest to the brain, opening a new avenue for the treatment of CNS diseases.
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