Showing papers by "Hong Liu published in 2021"

Development of Conductive Hydrogels for Fabricating Flexible Strain Sensors.

Abstract: Conductive hydrogels can be prepared by incorporating various conductive materials into polymeric network hydrogels. In recent years, conductive hydrogels have been developed and applied in the field of strain sensors owing to their unique properties, such as electrical conductivity, mechanical properties, self-healing, and anti-freezing properties. These remarkable properties allow conductive hydrogel-based strain sensors to show excellent performance for identifying external stimuli and detecting human body movement, even at subzero temperatures. This review summarizes the properties of conductive hydrogels and their application in the fabrication of strain sensors working in different modes. Finally, a brief prospectus for the development of conductive hydrogels in the future is provided.

An Ultrarobust and High-Performance Rotational Hydrodynamic Triboelectric Nanogenerator Enabled by Automatic Mode Switching and Charge Excitation.

Abstract: The triboelectric nanogenerator (TENG) is an emerging technology for ambient mechanical energy harvesting, which provides a possibility to realize wild environment monitoring by self-powered sensing systems. However, TENGs are limited in some practical applications as a result of their low output performance (low charge density) and mechanical durability (material abrasion). Herein, an ultrarobust and high-performance rotational TENG enabled by automatic mode switching (contact mode at low speed and noncontact at high speed) and charge excitation is proposed. It displays excellent stability, maintaining 94% electrical output after 72 000 cycles, much higher than that of the normal contact-mode TENG (30%). Due to its high electrical stability and large electrical output, this TENG powers 944 green light-emitting diodes to brightness in series. Furthermore, by harvesting water-flow energy, various commercial capacitors can be charged quickly, and a self-powered fire alarm and self-powered temperature and humidity detection are realized. This work provides an ideal scheme for enhancing the mechanical durability, broadening the range of working frequency, and improving the electrical output of TENGs. In addition, the high-performance hydrodynamic TENG demonstrated in this work will have great applications for Internet of Things in remote areas.

Micro-Nano Processing of Active Layers in Flexible Tactile Sensors via Template Methods: A Review

Abstract: Template methods are regarded as an important method for micro-nano processing in the active layer of flexible tactile sensors. These template methods use physical/chemical processes to introduce micro-nano structures on the active layer, which improves many properties including sensitivity, response/recovery time, and detection limit. However, since the processing process and applicable conditions of the template method have not yet formed a perfect system, the development and commercialization of flexible tactile sensors based on the template method are still at a relatively slow stage. Despite the above obstacles, advances in microelectronics, materials science, nanoscience, and other disciplines have laid the foundation for various template methods, enabling the continuous development of flexible tactile sensors. Therefore, a comprehensive and systematic review of flexible tactile sensors based on the template method is needed to further promote progress in this field. Here, the unique advantages and shortcomings of various template methods are summarized in detail and discuss the research progress and challenges in this field. It is believed that this review will have a significant impact on many fields of flexible electronics, which is beneficial to promote the cross-integration of multiple fields and accelerate the development of flexible electronic devices.

Applications of 2D-Layered Palladium Diselenide and Its van der Waals Heterostructures in Electronics and Optoelectronics

Abstract: The rapid development of two-dimensional (2D) transition-metal dichalcogenides has been possible owing to their special structures and remarkable properties. In particular, palladium diselenide (PdSe2) with a novel pentagonal structure and unique physical characteristics have recently attracted extensive research interest. Consequently, tremendous research progress has been achieved regarding the physics, chemistry, and electronics of PdSe2. Accordingly, in this review, we recapitulate and summarize the most recent research on PdSe2, including its structure, properties, synthesis, and applications. First, a mechanical exfoliation method to obtain PdSe2 nanosheets is introduced, and large-area synthesis strategies are explained with respect to chemical vapor deposition and metal selenization. Next, the electronic and optoelectronic properties of PdSe2 and related heterostructures, such as field-effect transistors, photodetectors, sensors, and thermoelectric devices, are discussed. Subsequently, the integration of systems into infrared image sensors on the basis of PdSe2 van der Waals heterostructures is explored. Finally, future opportunities are highlighted to serve as a general guide for physicists, chemists, materials scientists, and engineers. Therefore, this comprehensive review may shed light on the research conducted by the 2D material community.

Structures of Gi-bound metabotropic glutamate receptors mGlu2 and mGlu4

Abstract: The metabotropic glutamate receptors (mGlus) have key roles in modulating cell excitability and synaptic transmission in response to glutamate (the main excitatory neurotransmitter in the central nervous system)1. It has previously been suggested that only one receptor subunit within an mGlu homodimer is responsible for coupling to G protein during receptor activation2. However, the molecular mechanism that underlies the asymmetric signalling of mGlus remains unknown. Here we report two cryo-electron microscopy structures of human mGlu2 and mGlu4 bound to heterotrimeric Gi protein. The structures reveal a G-protein-binding site formed by three intracellular loops and helices III and IV that is distinct from the corresponding binding site in all of the other G-protein-coupled receptor (GPCR) structures. Furthermore, we observed an asymmetric dimer interface of the transmembrane domain of the receptor in the two mGlu–Gi structures. We confirmed that the asymmetric dimerization is crucial for receptor activation, which was supported by functional data; this dimerization may provide a molecular basis for the asymmetric signal transduction of mGlus. These findings offer insights into receptor signalling of class C GPCRs. Cryo-electron microscopy structures of mGlu2 and mGlu4 bound to heterotrimeric Gi protein shed light on the molecular basis of asymmetric signal transduction by metabotropic glutamate receptors.

Multi-interface collaboration of graphene cross-linked NiS-NiS2-Ni3S4 polymorph foam towards robust hydrogen evolution in alkaline electrolyte

Abstract: Electrocatalytic hydrogen production in alkaline media is extensively adopted in industry. Unfortunately, further performance improvement is severely impeded by the retarded kinetics, which requires the fine regulation of water dissociation, hydrogen recombination, and hydroxyl desorption. Herein, we develop a multi-interface engineering strategy to make an elaborate balance for the alkaline hydrogen evolution reaction (HER) kinetics. The graphene cross-linked three-phase nickel sulfide (NiS-NiS2-Ni3S4) polymorph foam (G-NNNF) was constructed through hydrothermal sulfidation of graphene wrapped nickel foam as a three-dimensional (3D) scaffold template. The G-NNNF exhibits superior catalytic activity toward HER in alkaline electrolyte, which only requires an overpotential of 68 mV to drive 10 mA·cm−2 and is better than most of the recently reported metal sulfides catalysts. Density functional theory (DFT) calculations verify the interfaces between nickel sulfides (NiS/NiS2/Ni3S4) and cross-linked graphene can endow the electrocatalyst with preferable hydrogen adsorption as well as metallic nature. In addition, the electron transfer from Ni3S4/NiS2 to NiS results in the electron accumulation on NiS and the hole accumulation on Ni3S4/NiS2, respectively. The electron accumulation on NiS favors the optimization of the H* adsorption, whereas the hole accumulation on Ni3S4 is beneficial for the adsorption of H2O. The work about multi-interface collaboration pushes forward the frontier of excellent polymorph catalysts design.

Structures of human mGlu2 and mGlu7 homo- and heterodimers

Abstract: The metabotropic glutamate receptors (mGlus) are involved in the modulation of synaptic transmission and neuronal excitability in the central nervous system1. These receptors probably exist as both homo- and heterodimers that have unique pharmacological and functional properties2–4. Here we report four cryo-electron microscopy structures of the human mGlu subtypes mGlu2 and mGlu7, including inactive mGlu2 and mGlu7 homodimers; mGlu2 homodimer bound to an agonist and a positive allosteric modulator; and inactive mGlu2–mGlu7 heterodimer. We observed a subtype-dependent dimerization mode for these mGlus, as a unique dimer interface that is mediated by helix IV (and that is important for limiting receptor activity) exists only in the inactive mGlu2 structure. The structures provide molecular details of the inter- and intra-subunit conformational changes that are required for receptor activation, which distinguish class C G-protein-coupled receptors from those in classes A and B. Furthermore, our structure and functional studies of the mGlu2–mGlu7 heterodimer suggest that the mGlu7 subunit has a dominant role in controlling dimeric association and G-protein activation in the heterodimer. These insights into mGlu homo- and heterodimers highlight the complex landscape of mGlu dimerization and activation. Cryo-electron microscopy structures of homo- and heterodimers of mGlu2 and mGlu7 provide insights into their dimerization modes and the subunit conformational changes that characterize the activation of these class C G-protein-coupled receptors.

Precisely engineering the electronic structure of active sites boosts the activity of iron-nickel selenide on nickel foam for highly efficient and stable overall water splitting

Abstract: The development of efficient and stable electrocatalysts to speed up the sluggish kinetics of water splitting has long been being the frontier of energy conversion research. Herein, we report a highly efficient electrocatalyst of P-Ni0.75Fe0.25Se2 prepared on nickel foam for overall water splitting. The optimal P-Ni0.75Fe0.25Se2 electrode exhibits an extremely low overpotential of 156 mV at 10 mA cm−2 and 226 mV at 300 mA cm−2 for oxygen evolution reaction (OER) and the highly efficient activity remains stable for up to 1000 h at 300 mA cm−2. More importantly, the water-alkali electrolyzer of P-Ni0.75Fe0.25Se2 || MoNi4/MoO2 requires only 1.45 V and 1.82 V to reach current densities of 10 and 300 mA cm−2, respectively, outperforming that of RuO2 || MoNi4/MoO2. Systematically theoretical and experimental results reveal that P doping can independently modulate the electronic structure of Fe without affecting Ni, optimize the adsorption strength of OER intermediates at active sites and consequently facilitate the OER kinetics.

Multi-interfacial engineering of hierarchical CoNi2S4/WS2/Co9S8 hybrid frameworks for robust all-pH electrocatalytic hydrogen evolution

Abstract: Water dissociation, hydroxyl desorption, and hydrogen recombination are three major prerequisites for all-pH hydrogen evolution reaction (HER). Herein, a multi-interfacial engineering in hierarchical CoNi2S4/WS2/Co9S8 (NiCoWS) hybrid frameworks was developed. The NiCoWS is composed of highly exposed active sites and abundant heterogeneous interfaces. The NiCoWS exhibits small overpotentials of 70 mV, 61 mV, and 146 mV at 10 mA cm−2 in alkaline, acid, and neutral medium, respectively, for HER. The robust performance of NiCoWS should originate from the collective synergy of special morphological, electronic, and interfacial structures. The hierarchical nanosheet framework can facilitate the transport of charge/mass as well as the exposure of more active interface sites. Density functional theory (DFT) calculations verify that the multi-interfacial engineering in NiCoWS can endow the electrocatalyst with enhanced electrical conductivity and favorable adsorption energies of H*, H2O* and H…OH*.

Attomolar-Level Ultrasensitive and Multiplex microRNA Detection Enabled by a Nanomaterial Locally Assembled Microfluidic Biochip for Cancer Diagnosis.

Abstract: Non-invasive early diagnosis is of great significance in disease pathologic development and subsequent medical treatments, and microRNA (miRNA) detection has attracted critical attention in early cancer screening and diagnosis. High-throughput, sensitive, economic, and fast miRNA sensing platforms are necessary to realize the low-concentration miRNA detection in clinical diagnosis and biological studies. Here, we developed an attomolar-level ultrasensitive, rapid, and multiple-miRNA simultaneous detection platform enabled by nanomaterial locally assembled microfluidic biochips. This platform presents a large linear detection regime of 1 aM-10 nM, an ultralow detection limit of 0.146 aM with no amplification, a short detection time of 35 min with multiplex miRNA sensing capability, and a small sample volume consumption of 2 μL. The detection results of five miRNAs in real samples from breast cancer patients and healthy humans indicate its excellent capacity for practical applications in early cancer diagnosis. The proposed ultrasensitive, rapid, and multiple-miRNA detection microfluidic biochip platform is a universal miRNA detection approach and an important and valuable tool in early cancer screening and diagnosis as well as biological studies.

Constructing van der Waals Heterogeneous Photocatalysts Based on Atomically Thin Carbon Nitride Sheets and Graphdiyne for Highly Efficient Photocatalytic Conversion of CO2 into CO.

Abstract: Atomically thin two-dimensional (2D) carbon nitride sheets (CNs) are attracting attention in the field of photocatalytic CO2 reduction. Because of the rapid recombination of photogenerated electron-hole pairs and limited more active sites, the photocatalytic efficiency of CNs cannot meet the actual requirements. Here, atomically thin 2D/2D van der Waals heterostructures of metal-free graphdiyne (GDY)/CNs are fabricated through a simple electrostatic self-assembly method. Experimental characterizations along with first-principles calculations show that the introduction of GDY in CNs promoted the transport of photogenerated carriers in the melon chain, thus suppressing the recombination of photogenerated electron-hole pairs. Both in situ FTIR measurements and DFT calculation confirm that the introduced GDY served as the CO2 adsorption site and enhanced the CO2 adsorption capacity of the CNs/GDY heterostructure. Thanks to the 2D/2D van der Waals heterojunction, the optimized CNs/GDY enhances significantly the CO generation rate up to 95.8 μmol g-1 that is 19.2-fold higher than that of CNs. This work provides a viable approach for the design of metal-free van der Waals heterostructure-based photocatalysts with high catalytic activity.

Design, Synthesis, and Biological Evaluation of Peptidomimetic Aldehydes as Broad-Spectrum Inhibitors against Enterovirus and SARS-CoV-2.

Abstract: A novel series of peptidomimetic aldehydes was designed and synthesized to target 3C protease (3Cpro) of enterovirus 71 (EV71). Most of the compounds exhibited high antiviral activity, and among them, compound 18p demonstrated potent enzyme inhibitory activity and broad-spectrum antiviral activity on a panel of enteroviruses and rhinoviruses. The crystal structure of EV71 3Cpro in complex with 18p determined at a resolution of 1.2 A revealed that 18p covalently linked to the catalytic Cys147 with an aldehyde group. In addition, these compounds also exhibited good inhibitory activity against the 3CLpro and the replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), especially compound 18p (IC50 = 0.034 μM, EC50 = 0.29 μM). According to our previous work, these compounds have no reasons for concern regarding acute toxicity. Compared with AG7088, compound 18p also exhibited good pharmacokinetic properties and more potent anticoronavirus activity, making it an excellent lead for further development.

Laser patterned and bifunctional Ni@N-doped carbon nanotubes as electrocatalyst and photothermal conversion layer for water splitting driven by thermoelectric device

Abstract: For efficient conversion from solar energy to hydrogen energy, the integrated system between light absorbing unit and water splitting unit is in the spotlight. Herein, we presented a bifunctional Ni@NCNTs/NF-L as both photothermal conversion layer integrated with thermoelectric generator (TE) and efficient hydrogen evolution reaction (HER) electrocatalyst to reducing the potential, realizing the integration system for overall water splitting. The Ni nanoparticles embedded into N-doped carbon nanotubes (Ni@NCNTs/NF-L) with various patterns are prepared by controllable laser processing and gas-solid calcination reaction. Furthermore, iron nickel oxides nanoparticles on NiFe alloys foil (NiFe-L) are obtained by laser ablation, which are applied for the oxygen evolution reaction (OER) electrode to establish two electrode electrolyzer of (−) Ni@NCNTs/NF-L/TE // NiFe-L (+) for overall water splitting. Integrating with one TE, the voltage of water splitting at the current-density of 50 mA cm−2 reduced from 1.947 V to 1.213 V under the standard AM 1.5 G illumination. The integrated thermoelectric device plays a doubtless role to realize solar energy driving overall water splitting with integration and patterning fabrication in large-scale.

Solution-Grown Chloride Perovskite Crystal of Red Afterglow.

Abstract: Oxide-based afterglow materials were usually produced through high-temperature treatment (> 1000 °C), which brought both considerable energy consumption and safety risk to manufacturer. Here, we report the growth of a halide-based double perovskite, Cs 2 Na x Ag 1-x InCl 6 :y%Mn, via a facile hydrothermal reaction at 180 °C. Through a co-doping strategy of both Na + and Mn 2+ , the as-prepared crystals exhibited a red afterglow featuring a high color purity (~ 100%) and a long duration time (> 5400 s), three orders of magnitude longer than those solution-processed organic afterglow crystals. The energy transfer (ET) process between self-trapped excitons (STE) and activators was investigated through time-resolved spectroscopy, which suggested an ET efficiency up to 41%. Importantly, the nominal concentration of dopants, especially in the case of Na + , was found a useful tool to control both energy level and number distribution of traps. Cryogenic afterglow measurements suggested that the afterglow phenomenon was likely governed by thermal-activated exciton diffusion and electron tunneling process. Our work provided a convenient access to a new class of afterglow materials with low lattice energy, representing a paradigm for low-temperature synthesis of afterglow crystals.

In Situ Electrochemical Transformation Reaction of Ammonium-Anchored Heptavanadate Cathode for Long-Life Aqueous Zinc-Ion Batteries.

Abstract: Rechargeable aqueous zinc-ion batteries (ZIBs) are promising portable and large-scale grid energy storage devices, as they are safe and economical. However, developing suitable ZIB cathode material...