Covalent organic frameworks (COFs) are promising for catalysis, sensing, gas storage, adsorption, optoelectricity, etc. owning to the unprecedented combination of large surface area, high ...crystallinity, tunable pore size, and unique molecular architecture. Although COFs are in their initial research stage, progress has been made in the design and synthesis of COF‐based electrocatalysis for the oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, and CO2 reduction in energy conversion and fuel generation. Design principles are also established for some of the COF materials toward rational design and rapid screening of the best electrocatalysts for a specific application. Herein, the recent advances in the design and synthesis of COF‐based catalysts for clean energy conversion and storage are presented. Future research directions and perspectives are also being discussed for the development of efficient COF‐based electrocatalysts.
Covalent organic frameworks (COFs) are promising for catalysis, sensing, gas storage, etc., owing to their large surface area, high crystallinity, tunable pore sizes, and unique molecular architecture. Recent advances in the design and synthesis of COF‐based catalysts for clean energy conversion and storage are presented. Design principles and future research directions for development of efficient COF‐based electrocatalysts are also discussed.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Covalent organic frameworks (COFs), an emerging class of framework materials linked by covalent bonds, hold potential for various applications such as efficient electrocatalysts, photovoltaics, and ...sensors. To rationally design COF‐based electrocatalysts for oxygen reduction and evolution reactions in fuel cells and metal‐air batteries, activity descriptors, derived from orbital energy and bonding structures, are identified with the first‐principle calculations for the COFs, which correlate COF structures with their catalytic activities. The calculations also predict that alkaline‐earth metal‐porphyrin COFs could catalyze the direct production of H2O2, a green oxidizer and an energy carrier. These predictions are supported by experimental data, and the design principles derived from the descriptors provide an approach for rational design of new electrocatalysts for both clean energy conversion and green oxidizer production.
Covalent organic frameworks (COFs) hold potential for various applications. To rationally design COF‐based electrocatalysts, activity descriptors are identified with the first‐principle calculations. The calculations also predict that alkaline‐earth metal‐porphyrin COFs could catalyze direct production of H2O2, a green oxidizer. The design principles provide an approach for rational design of new electrocatalysts for both clean energy conversion and green oxidizer production.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Carbon nanomaterials are promising metal‐free catalysts for energy conversion and storage, but the catalysts are usually developed via traditional trial‐and‐error methods. To rationally design and ...accelerate the search for the highly efficient catalysts, it is necessary to establish design principles for the carbon‐based catalysts. Here, theoretical analysis and material design of metal‐free carbon nanomaterials as efficient photo‐/electrocatalysts to facilitate the critical chemical reactions in clean and sustainable energy technologies are reviewed. These reactions include the oxygen reduction reaction in fuel cells, the oxygen evolution reaction in metal–air batteries, the iodine reduction reaction in dye‐sensitized solar cells, the hydrogen evolution reaction in water splitting, and the carbon dioxide reduction in artificial photosynthesis. Basic catalytic principles, computationally guided design approaches and intrinsic descriptors, catalytic material design strategies, and future directions are discussed for the rational design and synthesis of highly efficient carbon‐based catalysts for clean energy technologies.
The theoretical analysis and material design of metal‐free carbon nanomaterials as efficient photo‐/electrocatalysts to facilitate critical chemical reactions in clean energy technologies are considered. Basic catalytic principles, computationally guided design approaches and descriptors, material design strategies, and future directions are discussed for the rational design and synthesis of highly efficient catalysts for clean energy conversion and storage.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
All-inorganic CsPbI
perovskite quantum dots have received substantial research interest for photovoltaic applications because of higher efficiency compared to solar cells using other quantum dots ...materials and the various exciting properties that perovskites have to offer. These quantum dot devices also exhibit good mechanical stability amongst various thin-film photovoltaic technologies. We demonstrate higher mechanical endurance of quantum dot films compared to bulk thin film and highlight the importance of further research on high-performance and flexible optoelectronic devices using nanoscale grains as an advantage. Specifically, we develop a hybrid interfacial architecture consisting of CsPbI
quantum dot/PCBM heterojunction, enabling an energy cascade for efficient charge transfer and mechanical adhesion. The champion CsPbI
quantum dot solar cell has an efficiency of 15.1% (stabilized power output of 14.61%), which is among the highest report to date. Building on this strategy, we further demonstrate a highest efficiency of 12.3% in flexible quantum dot photovoltaics.
Grains and grain boundaries play key roles in determining halide perovskite‐based optoelectronic device performance. Halide perovskite monocrystalline solids with large grains, smaller grain ...boundaries, and uniform surface morphology improve charge transfer and collection, suppress recombination loss, and thus are highly favorable for developing efficient solar cells. To date, strategies of synthesizing high‐quality thin monocrystals (TMCs) for solar cell applications are still limited. Here, by combining the antisolvent vapor‐assisted crystallization and space‐confinement strategies, high‐quality millimeter sized TMCs of methylammonium lead iodide (MAPbI3) perovskites with controlled thickness from tens of nanometers to several micrometers have been fabricated. The solar cells based on these MAPbI3 TMCs show power conversion efficiency (PCE) of 20.1% which is significantly improved compared to their polycrystalline counterparts (PCE) of 17.3%. The MAPbI3 TMCs show large grain size, uniform surface morphology, high hole mobility (up to 142 cm2 V−1 s−1), as well as low trap (defect) densities. These properties suggest that TMCs can effectively suppress the radiative and nonradiative recombination loss, thus provide a promising way for maximizing the efficiency of perovskite solar cells.
Solar cells based on 300 nm thick MAPbI3 perovskite monocrystal are prepared, which show 3% enhancement in power conversion efficiency (PCE) compared to their polycrystalline counterparts. The suppressed charge recombination loss due to the reduction of grains and grain boundaries is believed to be the main reason for the PCE improvement.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Spinal cord injury (SCI) is a severely disabling central nervous system injury with complex pathological mechanisms that leads to sensory and motor dysfunction. The current treatment for SCI is aimed ...at symptomatic symptom relief rather than the pathological causes. Several studies have reported that signaling pathways play a key role in SCI pathological processes and neuronal recovery mechanisms. The PI3K/Akt signaling pathway is an important pathway closely related to the pathological process of SCI, and activation of this pathway can delay the inflammatory response, prevent glial scar formation, and promote neurological function recovery. Activation of this pathway can promote the recovery of neurological function after SCI by reducing cell apoptosis. Based on the role of the PI3K/Akt pathway in SCI, it may be a potential therapeutic target. This review highlights the role of activating or inhibiting the PI3K/Akt signaling pathway in SCI-induced inflammatory response, apoptosis, autophagy, and glial scar formation. We also summarize the latest evidence on treating SCI by targeting the PI3K/Akt pathway, discuss the shortcomings and deficiencies of PI3K/Akt research in the field of SCI, and identify potential challenges in developing these clinical therapeutic SCI strategies, and provide appropriate solutions.
•This paper reviews the recent literature on PI3K/Akt signaling pathway and spinal cord injury.•According to the role of PI3K/Akt pathway in spinal cord injury, the role of PI3K/Akt pathway on SCI field was summarized.•It is concluded that PI3K/Akt pathway may be a potential therapeutic target for spinal cord injury.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A new TENGs based on PVDF-ZnO NWs/nylon-ZnO NWs was constructed with highly polar crystalline β-phase by electrospinning.•The maximum power density of ZnO NWs incorporated PVDF/nylon 11 ...triboelectric nanogenerator reached as high as 3.0 W/m2.•A potent and sustainable power source for portable electronic devices was demonstrated.
Triboelectric nanogenerator (TENG) is a novel energy harvester technology which attracted a great deal of attention in the area of self-powering electronic devices due to its high output power density. In this investigation, zinc oxide nanowires (ZnO NWs) were incorporated into the electrospun polyvinylidene fluoride (PVDF) and nylon 11 nanofibers to construct new TENGs based on PVDF-ZnO NWs/nylon-ZnO NWs. This study showed that ZnO NWs were aligned along the fiber axis during electrospinning. The cooperative and mutual alignment of polymer chains with ZnO NWs were also achieved in the fibers because of electrospinning, which promoted formation of the highly polar crystalline β-phase of PVDF and δ’-phase of nylon. The maximum power density of ZnO NWs incorporated PVDF/nylon 11 triboelectric nanogenerator reached as high as 3.0 W/m2 under an external load of 10–20 MΩ. The fabricated TENG with improved output performance can be directly used to lightening of more than 100 LEDs. Incorporation of ZnO NWs also improved both thermal stability and mechanical properties, such as tensile strength and elastic modulus of PVDF and nylon 11 fibrous membranes. This work disclosed a potent and sustainable power source for portable electronic devices.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Scaling up to a large number of qubits with high-precision control is essential in the demonstrations of quantum computational advantage to exponentially outpace the classical hardware and ...algorithmic improvements. Here, we develop a two-dimensional programmable superconducting quantum processor, Zuchongzhi, which is composed of 66 functional qubits in a tunable coupling architecture. To characterize the performance of the whole system, we perform random quantum circuits sampling for benchmarking, up to a system size of 56 qubits and 20 cycles. The computational cost of the classical simulation of this task is estimated to be 2–3 orders of magnitude higher than the previous work on 53-qubit Sycamore processor Nature 574, 505 (2019). We estimate that the sampling task finished by Zuchongzhi in about 1.2 h will take the most powerful supercomputer at least 8 yr. Our work establishes an unambiguous quantum computational advantage that is infeasible for classical computation in a reasonable amount of time. The high-precision and programmable quantum computing platform opens a new door to explore novel many-body phenomena and implement complex quantum algorithms.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM
This paper investigates the transmission energy minimization problem for the two-user downlink with strictly heterogeneous latency constraints. To cope with the latency constraints and to explicitly ...specify the trade-off between blocklength (latency) and reliability the normal approximation of the capacity of finite blocklength codes (FBCs) is adopted, in contrast to the classical Shannon capacity formula. We first consider the non-orthogonal multiple access (NOMA) based transmission scheme. However, due to heterogeneous latency constraints and channel conditions at receivers, the conventional successive interference cancellation may be infeasible. We thus study the problem by considering heterogeneous receiver conditions under different interference mitigation schemes and solve the corresponding NOMA design problems. It is shown that, though the energy function is not convex and does not have closed form expression, the studied NOMA problems can be globally solved semi-analytically and with low complexity. Moreover, we propose a hybrid transmission scheme that combines the time division multiple access (TDMA) and NOMA. Specifically, the hybrid scheme can judiciously perform bit and time allocation and take TDMA and NOMA as two special instances. To handle the more challenging hybrid design problem, we propose a concave approximation of the FBC rate/capacity formula, by which we obtain computationally efficient and high-quality solutions. Simulation results show that the hybrid scheme can achieve considerable transmission energy saving compared with both pure NOMA and TDMA schemes.
A phosphorus allotrope that has not been observed so far, ring‐shaped phosphorus consisting of alternate P8 and P2 structural units, has been assembled inside multi‐walled carbon nanotube ...nanoreactors with inner diameters of 5–8 nm by a chemical vapor transport and reaction of red phosphorus at 500 °C. The ring‐shaped nanostructures with surrounding graphene walls are stable under ambient conditions. The nanostructures were characterized by high‐resolution transmission electron microscopy, scanning transmission electron microscopy, energy‐dispersive X‐ray spectroscopy, Raman scattering, attenuated total reflectance Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy.
Ring‐shaped phosphorus: A new phosphorus allotrope, ring‐shaped phosphorus, has been synthesized within nanoreactors of carbon nanotubes by a vapor‐phase reaction. The self‐assembled ring‐shaped phosphorus nanostructures, consisting of sequential P8 and P2 structural units, within carbon nanotubes (inside diameter 5–8 nm) are stable under ambient conditions.
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