9 results on '"Jian-Wei Liu"'
Search Results
2. Microchemical Engineering in a 3D Ordered Channel Enhances Electrocatalysis
- Author
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Wei-Ran Huang, Zhonghuai Hou, Huijun Jiang, Ying-Huan Liu, Guanyin Gao, Zhen He, Shu-Hong Yu, Jian-Wei Liu, Jin-Long Wang, and Qing-Xia Chen
- Subjects
Chemistry ,Kinetics ,General Chemistry ,Electrocatalyst ,Biochemistry ,Redox ,Catalysis ,Reaction rate ,Colloid and Surface Chemistry ,Chemical engineering ,Mass transfer ,Electrode ,Microreactor - Abstract
The kinetics of electrode reactions including mass transfer and surface reaction is essential in electrocatalysis, as it strongly determines the apparent reaction rates, especially on nanostructured electrocatalysts. However, important challenges still remain in optimizing the kinetics of given catalysts with suitable constituents, morphology, and crystalline design to maximize the electrocatalytic performances. We propose a comprehensive kinetic model coupling mass transfer and surface reaction on the nanocatalyst-modified electrode surface to explore and shed light on the kinetic optimization in electrocatalysis. Moreover, a theory-guided microchemical engineering (MCE) strategy has been demonstrated to rationally redesign the catalysts with optimized kinetics. Experimental measurements for methanol oxidation reaction in a 3D ordered channel with tunable channel sizes confirm the calculation prediction. Under the optimized channel size, mass transfer and surface reaction in the channeled microreactor are both well regulated. This MCE strategy will bring about a significant leap forward in structured catalyst design and kinetic modulation.
- Published
- 2021
3. Ordered Nanostructure Enhances Electrocatalytic Performance by Directional Micro-Electric Field
- Author
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Zhen He, Huijun Jiang, Xi-Feng Ren, Jian-Wei Liu, Shu-Hong Yu, Zhonghuai Hou, Qing-Xia Chen, Xiao-Zhuo Qi, Ying-Huan Liu, and Jin-Long Wang
- Subjects
Nanostructure ,Chemistry ,Kinetics ,Nanotechnology ,General Chemistry ,Electrolyte ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Catalysis ,Nanomaterial-based catalyst ,0104 chemical sciences ,Colloid and Surface Chemistry ,Electric field ,Renewable energy system ,Molecule - Abstract
Designing high-efficiency catalyst is at the heart of a transition to future renewable energy systems. Great achievements have been made to optimize thermodynamics to reduce energetic barriers of the catalytic reactions. However, little attention has been paid to design catalysts to improve kinetics to enrich the local concentration of reactant molecules surrounding electrocatalysts. Here, we find that well-designed nanocatalysts with periodic structures can optimize kinetics to accelerate mass-transport from bulk electrolyte to the catalyst surface, leading to the enhanced catalytic performance. This achievement stems from regulation of the surface reactant flux due to the gradient of the microelectric field directing uniformly to the nearest catalyst on ordered pattern, so that all of the reactant molecules are utilized sufficiently for reactions, enabling the boost of the electrocatalytic performance. This novel concept is further confirmed in various catalytic systems and nanoassemblies, such as nanoparticles, nanorods, and nanoflakes.
- Published
- 2019
4. Real-Time Visualization of Solid-Phase Ion Migration Kinetics on Nanowire Monolayer
- Author
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Jianbo Wu, Jian-Wei Liu, Lin Gu, Qinghua Zhang, Zhen He, Ze-Dong Li, Yuyang Lu, Shu-Hong Yu, Yue Lin, Yi Li, Qing-Xia Chen, Li Ge Chang, Jin-Long Wang, Rui Wang, Fenglei Shi, and Yong Ni
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Nanostructure ,Fabrication ,business.industry ,Chemistry ,Nanowire ,Ab initio ,Nanotechnology ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Colloid and Surface Chemistry ,Semiconductor ,Phase (matter) ,Monolayer ,business ,Nanoscopic scale - Abstract
Ion migration has been recognized as a critical step in determining the performance of numerous devices in chemistry, biology, and material science. However, direct visualization and quantitative investigation of solid-phase ion migration among anisotropic nanostructures have been a challenging task. Here, we report an in-situ ChemTEM method to quantitatively investigate the solid-phase ion migration process among coassembled nanowires (NWs). This complicated process was tracked within a NW and between NWs with an obvious nanogap, which was revealed by both phase field simulation and ab initio modeling theoretical evaluation. A migration "bridge" between neighboring NWs was observed. Furthermore, these new observations could be applied to migration of other metal ions on semiconductor NWs. These findings provide critical insights into the solid-phase ion migration kinetics occurring in nanoscale systems with generality and offer an efficient tool to explore other ion migration processes, which will facilitate fabrication of customized and new heteronanostructures in the future.
- Published
- 2020
5. Large Area Co-Assembly of Nanowires for Flexible Transparent Smart Windows
- Author
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Yi-Ruo Lu, Jin-Long Wang, Hui-Hui Li, Shu-Hong Yu, and Jian-Wei Liu
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Fabrication ,Chemistry ,Bend radius ,Nanowire ,Nanotechnology ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochromic devices ,01 natural sciences ,Biochemistry ,Catalysis ,Flexible electronics ,0104 chemical sciences ,Indium tin oxide ,Colloid and Surface Chemistry ,Electrochromism ,Transmittance ,0210 nano-technology - Abstract
Electrochromic devices with controllable color switching, low cost, and energy-saving advantages have been widely used as smart windows, rear-view car mirrors, displays, and so on. However, the devices are seriously limited for flexible electronics as they are traditionally fabricated on indium tin oxide (ITO) substrates which will lose their conductivity after bending cycles (the resistance significantly changed from 200 Ω to 6.56 MΩ when the bending radius was 1.2 cm). Herein, we report a new route for large area coassembly of nanowires (NWs), resulting in the formation of multilayer ordered nanowire (NW) networks with tunable conductivity (7-40 Ω/sq) and transmittance (58-86% at 550 nm) for fabrication of flexible transparent electrochromic devices, showing good stability of electrochromic switching behaviors. The electrochromic performance of the devices can be tuned and is strongly dependent on the structures of the Ag and W18O49 NW assemblies. Unlike the ITO-based electronics, the electrochromic films can be bent to a radius of 1.2 cm for more than 1000 bending cycles without obvious failure of both conductivity (ΔR/R ≈ 8.3%) and electrochromic performance (90% retention), indicating the excellent mechanical flexibility. The present method for large area coassembly of NWs can be extended to fabricate various NW-based flexible devices in the future.
- Published
- 2017
6. Dense CO Adlayers as Enablers of CO Hydrogenation Turnovers on Ru Surfaces
- Author
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David Hibbitts, Enrique Iglesia, and Jian-Wei Liu
- Subjects
Langmuir ,Chemistry ,Infrared ,Analytical chemistry ,Infrared spectroscopy ,02 engineering and technology ,General Chemistry ,Rate equation ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Kinetic energy ,01 natural sciences ,Biochemistry ,Catalysis ,Transition state ,0104 chemical sciences ,Colloid and Surface Chemistry ,Lattice (order) ,0210 nano-technology - Abstract
High CO* coverages lead to rates much higher than Langmuirian treatments predict because co-adsorbate interactions destabilize relevant transition states less than their bound precursors. This is shown here by kinetic and spectroscopic data-interpreted by rate equations modified for thermodynamically nonideal surfaces-and by DFT treatments of CO-covered Ru clusters and lattice models that mimic adlayer densification. At conditions (0.01-1 kPa CO; 500-600 K) which create low CO* coverages (0.3-0.8 ML from in situ infrared spectra), turnover rates are accurately described by Langmuirian models. Infrared bands indicate that adlayers nearly saturate and then gradually densify as pressure increases above 1 kPa CO, and rates become increasingly larger than those predicted from Langmuir treatments (15-fold at 25 kPa and 70-fold at 1 MPa CO). These strong rate enhancements are described here by adapting formalisms for reactions in nonideal and nearly incompressible media (liquids, ultrahigh-pressure gases) to handle the strong co-adsorbate interactions within the nearly incompressible CO* adlayer. These approaches show that rates are enhanced by densifying CO* adlayers because CO hydrogenation has a negative activation area (calculated by DFT), analogous to how increasing pressure enhances rates for liquid-phase reactions with negative activation volumes. Without these co-adsorbate effects and the negative activation area of CO activation, Fischer-Tropsch synthesis would not occur at practical rates. These findings and conceptual frameworks accurately treat dense surface adlayers and are relevant in the general treatment of surface catalysis as it is typically practiced at conditions leading to saturation coverages of reactants or products.
- Published
- 2017
7. One-Pot Colloidal Chemistry Route to Homogeneous and Doped Colloidosomes
- Author
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Xue-Wei Xu, Jian-Wei Liu, Yinglong Yang, Chun-Hua Dong, Ximo Zhang, Shu-Hong Yu, Huai-Ping Cong, Chao Liu, and Xi-Feng Ren
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chemistry.chemical_classification ,Interface and colloid science ,Doping ,Nanotechnology ,General Chemistry ,Biochemistry ,Catalysis ,Colloid and Surface Chemistry ,chemistry ,Quantum dot ,Mechanical stability ,Homogeneous ,Phenol formaldehyde resin ,Nanometre ,Semipermeable membrane - Abstract
Colloidosomes are usually produced from a series of building blocks with different sizes ranging from several nanometers to micrometers or various shapes, such as particles, microrods, and quantum dots. Colloidosomes can possess a variety of characteristics in terms of photics, electrology, mechanical strength, and selective permeability, derived from their building blocks. However, poor mechanical stability and complicated synthesis processes have limited the applications of colloidosomes. Here, we report a new one-pot colloidal chemistry route to synthesize phenol formaldehyde resin (PFR), Ag@PFR, and Au@PFR colloidosomes with high yields. The method can be modified to synthesize different kinds of doped colloidosomes with different components, which will provide a new approach to design colloidosomes with different functions.
- Published
- 2013
8. Mesostructured assemblies of ultrathin superlong tellurium nanowires and their photoconductivity
- Author
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Jian-Wei Liu, Jian-Hua Zhu, Chuan-Ling Zhang, Hai-Wei Liang, and Shu-Hong Yu
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Hydrophobic effect -- Analysis ,Thin films, Multilayered -- Structure ,Thin films, Multilayered -- Chemical properties ,Nanotechnology -- Research ,Tellurium -- Chemical properties ,Tellurium -- Optical properties ,Chemistry - Abstract
The Langmuir-Blodgett technique without any extra hydrophobic pretreatment or functionalization is utilized to produce well-defined periodic mesostructures of hydrophilic ultrathin Te nanowires with aspect ratios of at least [10.sup.4]. The method could also be extended for fabrication of other mesostructured assemblies of ultrathin nanowires or nanotubes.
- Published
- 2010
9. Mesostructured Assemblies of Ultrathin Superlong Tellurium Nanowires and Their Photoconductivity
- Author
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Chuan-Ling Zhang, Shu-Hong Yu, Jian-Hua Zhu, Jian-Wei Liu, and Hai-Wei Liang
- Subjects
Photocurrent ,Fabrication ,Chemistry ,Photoconductivity ,Nanowire ,chemistry.chemical_element ,Nanotechnology ,General Chemistry ,Biochemistry ,Catalysis ,Light intensity ,Colloid and Surface Chemistry ,Monolayer ,Surface modification ,Tellurium - Abstract
Well-defined periodic mesostructures of hydrophilic ultrathin Te nanowires with aspect ratios of at least 10(4) can be produced by the Langmuir-Blodgett technique without any extra hydrophobic pretreatment or functionalization. Packing the arrayed nanowire monolayers will allow construction of nanomesh-like mesostructures or more complex multilayered structures composed of ultrathin nanowires on a planar substrate. The well-organized monolayer of Te nanowires with periodic mesostructures can be readily used as a stamp to transfer such mesostructured nanopatterns to other substrates or can be embedded within a polymer matrix. The mesostructures of ultrathin Te nanowire films show reversibly switched photoelectric properties between the lower- and higher-conductivity states when the light is off and on, and the photocurrent is influenced by the light intensity and the number of mesostructured nanowire monolayer films. This method can be extended for fabrication of other mesostructured assemblies of ultrathin nanowires or nanotubes.
- Published
- 2010
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