Publications by authors named "Dingshan Yu"

56 Publications

Octupolar Acrylonitrile-Bridged 2D-Conjugated Polymers Enable Bright Far-Red Emission with Intense Two-Photon Absorption via Alkoxylation Chemistry.

Small 2021 09 28;17(36):e2100955. Epub 2021 Jul 28.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, School of Chemistry, Sun Yat-sen University, Guangzhou, Guangdong Province, 510275, China.

Herein, alkoxylation chemistry is introduced as a "one-stone-three-birds" solution for exploring a new family of highly-fluorescent octupolar 2D-conjugated organic polymers/frameworks (OCOPs/OCOFs) combining far-red emission, high fluorescence quantum yield (QY), and strong two-photon absorption (TPA). Both alkoxy-substituted OCOP and OCOF comprising acrylonitrile-bridged strongly-coupled donor3-(acceptor core) chromophores densely packed in either disordered or ordered forms, exhibit significantly redshifted emission. They produce high QY of 22.2% and 27.8% in tetrahydrofuran, large TPA cross section of 600 and 1124 GM, and 2-3 folds and 15-30 folds that of non-alkoxylate amorphous counterpart respectively. Combined theoretical and experimental studies reveal unique "one-stone-three-birds" role of the alkoxylation in realizing red-shifted-emission, improved QY and TPA enabled by inducing steric hindrance effect for weakened π-π stacking, and triggering p-π conjugation effect for electronically engineering octupolar chromophores, while the crystalline engineering enables enforced coplanarity conformation and improved π-electron delocalization for further improved QY and TPA. The robust and biocompatible pentoxy-substituted polymer can be used not only as metal-free red-emissive phosphor for efficient warm white light-emitting diodes, but also as efficient two-photon fluorescence probes for bio-imaging.
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http://dx.doi.org/10.1002/smll.202100955DOI Listing
September 2021

Enhancing Chain Mobility of Ultrahigh Molecular Weight Polyethylene by Regulating Residence Time under a Consecutive Elongational Flow for Improved Processability.

Polymers (Basel) 2021 Jun 30;13(13). Epub 2021 Jun 30.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education and Key Laboratory of High Performance Polymer-based Composites of Guangdong Province, School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China.

Improving the processability of ultrahigh molecular weight polyethylene (UHMWPE) and understanding the effect of the polymeric chain mobility has long been a challenging task. Herein, we show that UHMWPE without any processing aids can be processed at a lower temperature of 180 °C compared to conventional processing temperatures (~250 °C) under a continuous elongational flow (CEF) by using an eccentric rotor extruder (ERE). By probing the effect of the residence time of UHMWPE samples under a CEF on the morphology, rheological behavior and molecular orientation, we find that the long polymer chains of UHMWPE are apt to orientate under a consecutive volume elongational deformation, thereby leading to a higher residual stress for the extruded sample. Meanwhile, the residence time of samples can regulate the polymeric chain mobility, giving rise to the simultaneous decrease of the melting defects and residual stress as well as Hermans orientation function with increasing residence time from 0 to 60 s. This also engenders the enhanced diffusion of UHMWPE segments, resulting in a defect-free morphology and higher entanglement with lower crystallinity but without causing obvious thermal oxidative degradation of UHMWPE. This interesting result could originate from the fast chain entanglement and particle welding enabled by a desirably short residence time, which could be explained by the empirical, entropy-driven melting explosion mechanism.
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http://dx.doi.org/10.3390/polym13132192DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8271948PMC
June 2021

Elongational Flow Field Processed Ultrahigh Molecular Weight Polyethylene/Polypropylene Blends with Distinct Interlayer Phase for Enhanced Tribological Properties.

Polymers (Basel) 2021 Jun 10;13(12). Epub 2021 Jun 10.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China.

Herein, we produced a series of ultrahigh molecular weight polyethylene/polypropylene (UHMWPE/PP) blends by elongational-flow-field dominated eccentric rotor extruder (ERE) and shear-flow-field dominated twin screw extruder (TSE) respectively and presented a detailed comparative study on microstructures and tribological properties of UHMWPE/PP by different processing modes. Compared with the shear flow field in TSE, the elongational flow field in ERE facilitates the dispersion of PP in the UHMWPE matrix and promotes the interdiffusion of UHMWPE and PP molecular chains. For the first time, we discovered the presence of the interlayer phase in blends with different processing modes by using Raman mapping inspection. The elongational flow field introduces strong interaction to enable excellent compatibility of UHMWPE and PP and induces more pronounced interlayer phase with respect to the shear flow field, eventually endowing UHMWPE/PP with improved wear resistance. The optimized UHMWPE/PP (85/15) blend processed by ERE displayed higher tensile strength (25.3 MPa), higher elongation at break (341.77%) and lower wear loss of ERE-85/15 (1.5 mg) compared to the blend created by TSE. By systematically investigating the microstructures and mechanical properties of blends, we found that with increased content of PP, the wear mechanism of blends varies from abrasive wear, fatigue wear, to adhesion wear as the dominant mechanism for two processing modes.
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http://dx.doi.org/10.3390/polym13121933DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8230468PMC
June 2021

Programmable Invisible Photonic Patterns with Rapid Response Based on Two-Dimensional Colloidal Crystals.

Polymers (Basel) 2021 Jun 10;13(12). Epub 2021 Jun 10.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China.

The development of invisible patterns via programmable patterning can lead to promising applications in optical encryption. This study reports a facile method for building responsive photonic crystal patterns. Commercially printed patterns were used as a mask to induce invisible patterns revealed by wetting. The masked areas exhibit different swelling kinetics, leading to strong structural colors in the masked area and transparent features in the unmasked area. The contrast could disappear through different wetting behavior, providing a unique and reversible wetting feature. This programmable printing is expected to become an environmentally friendly technique for scalable invisible optical anti-counterfeiting technology.
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http://dx.doi.org/10.3390/polym13121926DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8226874PMC
June 2021

Recent Advances in Elongational Flow Dominated Polymer Processing Technologies.

Polymers (Basel) 2021 May 29;13(11). Epub 2021 May 29.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education and Key Laboratory of High-Performance Polymer-based Composites of Guangdong Province, School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China.

The continuous development of plasticizing conveying methods and devices has been carried out to meet the needs of the polymer processing industry. As compared to the conventional shear-flow-dominated plasticizing and conveying techniques, a new method for processing polymers based on elongational flow was proposed. This new method and the related devices such as vane extruders, eccentric rotor extruders and so on, exhibited multiple advantages including shorter processing time, higher mixing effectiveness, improved product performance and better adaptability to various material systems. The development of new techniques in the field of polymer material processing has opened up a broad space for the development of new plastic products, improved product performance and reduced processing costs. In this review, recent advances concerning the processing techniques based on elongational flow are summarized, and the broad applications in polymer processing as well as some future opportunities and challenges in this vibrant area are elucidated in detail.
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http://dx.doi.org/10.3390/polym13111792DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8199109PMC
May 2021

Preparation of Flame-Retardant Polyurethane and Its Applications in the Leather Industry.

Polymers (Basel) 2021 May 25;13(11). Epub 2021 May 25.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China.

As a novel polymer, polyurethane (PU) has been widely applied in leather, synthetic leather, and textiles due to its excellent overall performance. Nevertheless, conventional PU is flammable and its combustion is accompanied by severe melting and dripping, which then generates hazardous fumes and gases. This defect limits PU applications in various fields, including the leather industry. Hence, the development of environmentally friendly, flame-retardant PU is of great significance both theoretically and practically. Currently, phosphorus-nitrogen (P-N) reactive flame-retardant is a hot topic in the field of flame-retardant PU. Based on this, the preparation and flame-retardant mechanism of flame-retardant PU, as well as the current status of flame-retardant PU in the leather industry were reviewed.
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http://dx.doi.org/10.3390/polym13111730DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8198486PMC
May 2021

Capturing Visible Light in Low-Band-Gap C N-Derived Responsive Bifunctional Air Electrodes for Solar Energy Conversion and Storage.

Angew Chem Int Ed Engl 2021 Aug 30;60(32):17615-17621. Epub 2021 Jun 30.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, China.

We report facile synthesis of low-band-gap mesoporous C N particles and their use as responsive bifunctional oxygen catalysts for visible-light-sensitive (VLS) rechargeable Zn-air battery (RZAB) and polymer-air battery (RPAB). Compared to widely studied g-C N , C N shows a smaller band gap of 1.99 eV, with a larger photocurrent response, and it can function as visible-light-harvesting antenna and bifunctional oxygen reduction/evolution (ORR/OER) catalysts, enabling effective photocoupling to tune oxygen catalysis. The C N-enabled VLS-RZAB displays a low charge voltage of 1.35 V under visible light, which is below the theoretical RZAB voltage of 1.65 V, corresponding to a high energy efficiency of 97.78 %. Pairing a C N cathode with a polymer anode also endows an VLS-RPAB with light-boosted charge performance. It is revealed that the ORR and OER active sites in C N are separate carbon sites near pyrazine-nitrogen atoms and photogenerated energetic holes can activate OER for improved reaction kinetics.
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http://dx.doi.org/10.1002/anie.202104790DOI Listing
August 2021

Redox Donor-Acceptor Conjugated Microporous Polymers as Ultralong-Lived Organic Anodes for Rechargeable Air Batteries.

Angew Chem Int Ed Engl 2021 Apr 22;60(18):10164-10171. Epub 2021 Mar 22.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Key Laboratory of High Performance Polymer-based Composites of Guangdong Province, School of Chemistry, Sun Yat-sen University, Guangzhou, 510275, China.

Herein, we explore a new redox donor-acceptor conjugated microporous polymer (AQ-CMP) by utilizing anthraquinone and benzene as linkers via C-C linkages and demonstrate the first use of CMP as ultralong-lived anodes for rechargeable air batteries. AQ-CMP features an interconnected octupole network, which affords not only favorable electronic structure for enhanced electron transport and n-doping activity compared to linear counterpart, but also high density of active sites for maximizing the formula-weight-based redox capability. This coupled with highly cross-linked and porous structure endows AQ-CMP with a specific capacity of 202 mAh g (96 % of theoretical capacity) at 2 Ag and ≈100 % capacity retention over 60000 charge/discharge cycles. The assembled CMP-air full cell shows a stable and high capacity with full capacity recovery after only refreshing cathodes, while the decoupled electrolyte and cathode design boosts the discharge voltage and voltage efficiency to ≈1 V and 87.5 %.
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http://dx.doi.org/10.1002/anie.202016746DOI Listing
April 2021

Author Correction: Scalable synthesis of hierarchically structured carbon nanotube-graphene fibres for capacitive energy storage.

Nat Nanotechnol 2020 Sep;15(9):811

School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore, 637459, Singapore.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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http://dx.doi.org/10.1038/s41565-020-0718-1DOI Listing
September 2020

Alkene-Linked Covalent Organic Frameworks Boosting Photocatalytic Hydrogen Evolution by Efficient Charge Separation and Transfer in the Presence of Sacrificial Electron Donors.

Adv Sci (Weinh) 2020 Jun 6;7(12):1902988. Epub 2020 May 6.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education Key Laboratory of High Performance Polymer‒based Composites of Guangdong Province School of Chemistry Sun Yat-sen University Guangzhou 510275 China.

Covalent organic frameworks (COFs) are potential photocatalysts for artificial photosynthesis but they are much less explored for photocatalytic hydrogen evolution (PHE). COFs, while intriguing due to crystallinity, tunability, and porosity, tend to have low apparent quantum efficiency (AQE) and little is explored on atomistic structure-performance correlation. Here, adopting triphenylbenzene knots and phenyl linkers as a proof of concept, three structurally related COFs with different linkages are constructed to achieve a tunable COF platform and probe the effect of the linkage chemistry on PHE. Cyano-substituted alkene-linked COF (COF-alkene) yields a stable 2330 µmol h g PHE rate, much superior to imine- and imide-linked counterparts (<40 µmol h g) under visible light irradiation. Impressively, COF-alkene achieves an AQE of 6.7% at 420 nm. Combined femtosecond transient absorption spectroscopy and theoretical calculation disclose the critical role of cyano-substituted alkene linkages toward high efficiency of charge separation and transfer in the presence of sacrificial electron donors-the decisive key to the superior PHE performance. Such alkene linkages can also be extended to design a series of high-performance polymeric photocatalysts, highlighting a general design idea for efficient PHE.
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http://dx.doi.org/10.1002/advs.201902988DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7312270PMC
June 2020

Humidity and Pressure Dual-Responsive Metal-Water Batteries Enabled by Three-In-One All-Polymer Cathodes for Smart Self-Powered Systems.

ACS Appl Mater Interfaces 2020 May 13;12(21):23853-23859. Epub 2020 May 13.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China.

A conceptually new class of humidity and pressure dual-responsive smart metal-water batteries (SMWBs) is presented, which displays self-tunable energy release and intriguing perceptibility of human respiration and environmental pressure. This battery is enabled by the direct contact of a metal ( Mg or Zn) anode and a well-designed all-polymer dual-sensitive moisture electrode (DSME) made from semiconductive polymer ( polypyrrole)-wrapped 3D macroporous polyurethane sponge, without additional electrolytes and separator. A DSME is cost-effective, easily scalable, compressible, and able to act as a moisture carrier, a hydrogen evolution catalyst, and a pressure and humidity dual-sensitive unit simultaneously. Unique three-in-one integration in the DSME enables favorable modulation of electron/mass transport or redox reactions in the SMWB upon different stimulations. Thus, the assembled SMWB not only delivers good discharge performance with smart energy management but also serves as a reliable self-powered bifunctional responsor for the real-time monitoring of respiration and the perceptibility of pressure. Based on various active metal-polymer pairs (Mg/Zn polypyrrole/polyaniline), we also developed a series of dual-responsive batteries, demonstrating a general design idea.
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http://dx.doi.org/10.1021/acsami.0c03426DOI Listing
May 2020

Integrated Photo-Responsive Batteries for Solar Energy Harnessing: Recent Advances, Challenges, and Opportunities.

Chempluschem 2020 Apr;85(4):599

Key Laboratory for Polymeric Composite, and Functional Materials of Ministry of Education, Key Laboratory of High Performance Polymer-based Composites of, Guangdong Province, School of Chemistry, Sun Yat-sen University, Guangzhou, 510275, P. R. China.

Invited for this month's cover is the group of Prof. Dingshan Yu from Sun Yat-sen University, China. The Front Cover shows an integrated photo-responsive battery with the simplest two-electrode configuration powering a vehicle under light illumination. The Taiji diagram shows the working principle of this device, which combines photoexcited electrons (e ) and/or holes (h ) with various redox species of the batteries during charging and/or discharging processes to realize the harnessing of solar energy. Read the full text of the Minireview at 10.1002/cplu.201900608.
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http://dx.doi.org/10.1002/cplu.202000041DOI Listing
April 2020

Polyaniline/Pure Carbon Assemblies as Efficient Self-standing Metal-free Oxygen Electrodes in Alkaline Media for Zn-Air Batteries.

Chem Asian J 2020 May 16;15(10):1544-1548. Epub 2020 Apr 16.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education Key Laboratory of High Performance Polymer-based Composites of Guangdong Province School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, P. R. China.

A facile design and fabrication of self-standing metal-free polyaniline (PANI)@carbon nanotubes (CNTs) composite membrane was initially proposed by straightforward noncovalent wrapping the polymer around pure CNTs. Without introduction of extra heteroatoms into CNTs, the optimized [email protected] composite exhibits a much better electrocatalytic performance for oxygen evolution reaction (OER) than pure CNTs via favorable interfacial modification with PANI to largely expose the active sites of on the surface of pure CNTs. Besides, it displays good oxygen reduction reaction (ORR) performance. When directly utilized as bifunctional air electrode without extra additive agents, the composite membrane-enabled rechargeable Zn-air batteries not only deliver a high peak power density (201.9 W g ) and a large energy density (850.3 Wh kg ), but also present robust cycling performance for 216 cycles with a high energy efficiency of 57.8%.
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http://dx.doi.org/10.1002/asia.202000179DOI Listing
May 2020

Versatile, Aqueous Soluble CN Quantum Dots with Enriched Active Edges and Oxygenated Groups.

J Am Chem Soc 2020 Mar 1;142(10):4621-4630. Epub 2020 Mar 1.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Key Laboratory of High Performance Polymer-based Composites of Guangdong Province, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, People's Republic of China.

CN has emerged as a new family of promising two-dimensional (2D) layered frameworks in both fundamental studies and potential applications. Transforming bulk CN into zero-dimensional quantum dots (QDs) could induce unique quantum confinement and edge effects that produce improved or new properties. Despite their appealing potential, CNQDs remain unexplored, and their intriguing properties and a fundamental understanding of their prominent edge effects are still not well understood. Here, we report the first synthesis of water-soluble CNQDs via a top-down approach without any foreign stabilizer and exploit their linear/nonlinear optical properties and unique edge-preferential electrocatalytic activity toward polysulfides for versatile applications. The resultant dispersant-free CNQDs with an average size of less than 5 nm feature rich oxygen-carrying groups and active edges, not only enabling excellent dispersion in water but also creating interesting multifunctionality. They can emit not only blue one-photon luminescence (OPL) under ultraviolet (UV) excitation but also green two-photon luminescence (TPL) with a wide near-infrared (NIR) excitation range of 750-900 nm, enabling their use as a new fluorescent ink. Interestingly, when CNQDs are introduced to modify commercial separators, they can function as new metal-free catalysts to boost polysulfide redox kinetics and endow Li-S batteries with excellent cycling stability, high rate capability, and large areal capacity (7.0 mA h cm) at a high sulfur loading of 8.0 mg cm. Detailed theoretical and experimental results indicate that the edge of CN is more favorable for trapping and catalyzing the polysulfide conversion than the terrace and that the synergy between the active edges and oxygenated groups enriched in CNQDs remarkably improves polysulfide immobilization and catalytic conversion.
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http://dx.doi.org/10.1021/jacs.9b11169DOI Listing
March 2020

Integrated Photo-Responsive Batteries for Solar Energy Harnessing: Recent Advances, Challenges, and Opportunities.

Chempluschem 2020 Apr 16;85(4):600-612. Epub 2020 Jan 16.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Key Laboratory of High Performance Polymer-based Composites of Guangdong Province School of Chemistry, Sun Yat-sen University, Guangzhou, 510275, P. R. China.

Photo-responsive batteries that enable the effective combination of solar harvesting and energy conversion/storage functionalities render a potential solution to achieve the large-scale utilization of unlimited and cost-effective solar energy and alleviate the limits of conventional energy storage devices. The internal integration of photo-responsive electrodes into rechargeable batteries with the simplest two-electrode configuration is regarded as a reliable and appealing strategy for highly-efficient and low-cost utilization of solar energy by simplifying the device architecture and improving the energy efficiency. This progress report provides a brief review on photo-responsive batteries with integrated two-electrode configuration that can achieve solar energy conversion/storage in one single device. The basic device architecture, operating principles and practical performance of various photo-responsive systems based on solar energy harvesting in various batteries including Li ion batteries, Li-S batteries, Li-I batteries, dual-liquid redox batteries, Li-O batteries, non-Li anode-O /air batteries are summarized and discussed. Finally, the future opportunities and challenges regarding the two-electrode photo-responsive batteries are proposed.
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http://dx.doi.org/10.1002/cplu.201900608DOI Listing
April 2020

Donor-Acceptor Nanocarbon Ensembles to Boost Metal-Free All-pH Hydrogen Evolution Catalysis by Combined Surface and Dual Electronic Modulation.

Angew Chem Int Ed Engl 2019 Nov 17;58(45):16217-16222. Epub 2019 Sep 17.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Key Laboratory of High Performance Polymer-based Composites of Guangdong Province, School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, China.

A combined surface and dual electronic modulation strategy is used to realize metal-free all-pH catalysis towards the hydrogen evolution reaction (HER) by coupling a N-doped carbon framework (MHCF, electron acceptors) derived from MOFs with higher-Fermi-level pure carbon nanotubes (CNTs, electron donors), followed by surface modification with carboxyl-group-rich polymers. Although the three constituents are inactive, as-assembled ternary membranes yield superior HER performance with low overpotentials and high durability (≤5 % activity loss over 100 h) at all pH values. The C adjacent to pyrrolic N in MHCF is the most active site and the induced directional interfacial electron transfer from CNTs to MHCF coupled with N-driven intramolecular electron transfer in MHCF optimizes Gibbs free energy for hydrogen adsorption (ΔG ) near zero, while the polymer modulation enables local H enrichment in acidic media and enhanced water adsorption and activation in neutral and basic media.
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http://dx.doi.org/10.1002/anie.201907826DOI Listing
November 2019

A Dissipative Particle Dynamics Study of Flow Behaviors in Ultra High Molecular Weight Polyethylene/Polyamide 6 Blends Based on Souza-Martins Method.

Polymers (Basel) 2019 Jul 31;11(8). Epub 2019 Jul 31.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education and Key Laboratory of High Performance Polymer-based Composites of Guangdong Province, School of Chemistry, Sun Yat-Sen University, Guangzhou510275, China.

This paper presents our study on the use of dissipative particle dynamics (DPD) simulations to discover the flow behavior in ultra high molecular weight polyethylene/polyamide 6 (UHMWPE/PA6) blends associated with extensional-shear coupled flow, based on the Souza-Martins method, for the first time. By way of simulations, we aimed at investigating the mesoscopic morphology and alignment behavior in response to extensional-shear coupled flow, in comparison with simple shear flow and simple extensional flow. Our results reveal that the aggregation of polymers is noticeable under zero flow, as expected. Within the considered range of extensional-shear coupled rates, the morphology transforms from micelle-like clusters to a chain-like network structure by increasing coupled rates from 0.01 to 2.0. Furthermore, it shows a linear distribution along the flow direction at a high coupled rate. It can be concluded that the flow behaviors in UHMWPE/PA6 blends are significantly impacted by extensional-shear coupled rates. The orientation behavior induced by extensional-shear coupled flow is more obvious than shear flow, even though flow variations and mass fractions yield less effects on the distribution behaviors of UHMWPE/PA6 blends. The DPD results are verified by mean square displacement (MSD) as a function of simulation time and relative concentration distribution along Z direction.
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http://dx.doi.org/10.3390/polym11081275DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6722510PMC
July 2019

Isolated Square-Planar Copper Center in Boron Imidazolate Nanocages for Photocatalytic Reduction of CO to CO.

Angew Chem Int Ed Engl 2019 Aug 18;58(34):11752-11756. Epub 2019 Jul 18.

State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, P. R. China.

Photocatalytic reduction of CO to value-added fuel has been considered to be a promising strategy to reduce global warming and shortage of energy. Rational design and synthesis of catalysts to maximumly expose the active sites is the key to activate CO molecules and determine the reaction selectivity. Herein, we synthesize a well-defined copper-based boron imidazolate cage (BIF-29) with six exposed mononuclear copper centers for the photocatalytic reduction of CO . Theoretical calculations show a single Cu site including weak coordinated water delivers a new state in the conduction band near the Fermi level and stabilizes the *COOH intermediate. Steady-state and time-resolved fluorescence spectra show these Cu sites promote the separation of electron-hole pairs and electron transfer. As a result, the cage achieves solar-driven reduction of CO to CO with an evolution rate of 3334 μmol g  h and a high selectivity of 82.6 %.
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http://dx.doi.org/10.1002/anie.201905869DOI Listing
August 2019

Tactile UV- and Solar-Light Multi-Sensing Rechargeable Batteries with Smart Self-Conditioned Charge and Discharge.

Angew Chem Int Ed Engl 2019 Jul 27;58(27):9248-9253. Epub 2019 May 27.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, China.

A tactile, UV- and solar-light multi-sensing smart rechargeable Zn-air battery (SRZAB) with excellent cell performance, self-conditioned charge/discharge, and reliable environmental responsivity is made by using multi-scale conjugated block-copolymer-carbon nanotube-polyurethane foam assemblies as both a self-standing air electrode and a sensing unit. Multiscale engineering fully exploits the multi-synergy among components to endow the newly designed metal-free multi-sensing air electrode (MSAE) with bifunctional oxygen reduction and evolution activities, pressure sensitivity, and photothermal and photoelectric conversion functions in a single electrode, enabling effective regulation of interface properties, electronic/ionic transport, or redox reactions in SRZAB upon various stimulations and establishing multiple working principles. MSAE-driven SRZAB can be used as compressible power sources, self-powered pressure and optical sensors and light-to-electrochemical energy systems.
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http://dx.doi.org/10.1002/anie.201903805DOI Listing
July 2019

Orientation and Dispersion Evolution of Carbon Nanotubes in Ultra High Molecular Weight Polyethylene Composites under Extensional-Shear Coupled Flow: A Dissipative Particle Dynamics Study.

Polymers (Basel) 2019 Jan 17;11(1). Epub 2019 Jan 17.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education and Key Laboratory of High Performance Polymer⁻based Composites of Guangdong Province, School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China.

The property of carbon nanotubes (CNTs)-based composites are significantly dependent on the orientation and dispersion evolution of CNTs in the polymer matrix. In this work, the dissipative particle dynamics (DPD) simulations are employed to discover the orientation and dispersion evolution of CNTs in ultra⁻high molecular weight polyethylene (UHMWPE) under extensional⁻shear coupled flow conditions for the first time. In this paper, we investigate the roles of the increasing extensional-shear coupled rate in morphology of CNTs/UHMWPE composites by varying CNTs concentration and observe that the system under consideration lies in the same evolution morphologies. When comparing our results for various morphologies, we notice that the orientation is affected more significantly by changing the extensional-shear coupled rates. A good alignment appears with an increase of extensional-shear coupled rates, which transform it into ordered morphology. In addition, a higher extensional-shear coupled rate does not necessarily contribute to better dispersion even though CNTs concentration varies, as shown by the mean square displacement (MSD) and the relative concentration distribution functions of CNTs in CNTs/UHMWPE composites.
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http://dx.doi.org/10.3390/polym11010154DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6401708PMC
January 2019

Ultrathin Black Phosphorus-on-Nitrogen Doped Graphene for Efficient Overall Water Splitting: Dual Modulation Roles of Directional Interfacial Charge Transfer.

J Am Chem Soc 2019 Mar 12;141(12):4972-4979. Epub 2019 Mar 12.

Department of Macromolecule Science and Engineering , Case Western Reserve University , Cleveland , Ohio 44106 , United States.

Few-layered exfoliated black phosphorus (EBP) has attracted surging interest for electronics, optoelectronics, and catalysis. As compared to excellent progress in electronic and optoelectronic applications, very few reports are available for electrocatalysis by metal-free EBPs. Herein, we couple solution-processable ultrathin EBP nanosheets with higher Fermi level of N-doped graphene (NG) into a new metal-free 2D/2D heterostructure ([email protected]) with well-designed interfaces and unique electronic configuration, as efficient and durable bifunctional catalysts toward hydrogen evolution and oxygen evolution reactions (HER/OER) for overall water splitting in alkaline media. By rational interface engineering, the synergy of EBP and NG is fully exploited, which not only improves the stability of EBP, but also effectively modulates electronic structures of each component to boost their intrinsic activities. Specifically, due to the lower Fermi level of EBP relative to NG, their electronic interaction induces directional interfacial electron transfer, which not only enriches the electron density over EBP and optimizes H adsorption/desorption to promote HER, but also introduces abundant positively charged carbon sites on NG and provides favorable formation of key OER intermediates (OOH*) to improve OER energetics. Thus, despite that pure EBP or NG alone has poor or negligible activity, [email protected] achieves remarkably enhanced bifunctional HER/OER activities, along with an excellent durability. This endows an optimized electrolyzer using [email protected] as anode and cathode with a low cell voltage of 1.54 V at 10 mA cm, which is smaller than that of the costly integrated Pt/[email protected] couple (1.60 V).
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http://dx.doi.org/10.1021/jacs.9b00154DOI Listing
March 2019

In Situ Activating Strategy to Significantly Boost Oxygen Electrocatalysis of Commercial Carbon Cloth for Flexible and Rechargeable Zn-Air Batteries.

Adv Sci (Weinh) 2018 Dec 18;5(12):1800760. Epub 2018 Oct 18.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education Key Laboratory of High Performance Polymer-Based Composites of Guangdong Province School of Chemistry Sun Yat-Sen University Guangzhou 510275 China.

An in situ strategy to simultaneously boost oxygen reduction and oxygen evolution (ORR/OER) activities of commercial carbon textiles is reported and the direct use of such ubiquitous raw material as low-cost, efficient, robust, self-supporting, and bifunctional air electrodes in rechargeable Zn-air batteries is demonstrated. This strategy not only furnishes carbon textiles with a large surface area and hierarchical meso-microporosity, but also enables efficient dual-doping of N and S into carbon skeletons while retaining high conductivity and stable monolithic structures. Thus, although original carbon textile has rather poor catalytic activity, the activated textiles without loading other active materials yield effective ORR/OER bifunctionality and stability with a much lower reversible overpotential (0.87 V) than those of Pt/C (1.10 V) and RuO (1.02 V) and many reported metal-free bifunctional catalysts. Importantly, they can concurrently function as current collectors and as ORR/OER catalysts for rechargeable aqueous and flexible solid-state Zn-air batteries, showing excellent cell performance, long lifetime, and high flexibility.
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http://dx.doi.org/10.1002/advs.201800760DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6299824PMC
December 2018

Self-Assembled Graphene-Based Architectures and Their Applications.

Adv Sci (Weinh) 2018 02 30;5(2):1700626. Epub 2017 Nov 30.

Liquid Crystal Institute and Chemical Physics Interdisciplinary Program Kent State University Kent OH 44242 USA.

Due to unique planar structures and remarkable thermal, electronic, and mechanical properties, chemically modified graphenes (CMGs) such as graphene oxides, reduced graphene oxides, and the related derivatives are recognized as the attractive building blocks for "bottom-up" nanotechnology, while self-assembly of CMGs has emerged as one of the most promising approaches to construct advanced functional materials/systems based on graphene. By virtue of a variety of noncovalent forces like hydrogen bonding, van der Waals interaction, metal-to-ligand bonds, electrostatic attraction, hydrophobic-hydrophilic interactions, and π-π interactions, the CMGs bearing various functional groups are highly desirable for the assemblies with themselves and a variety of organic and/or inorganic species which can yield various hierarchical nanostructures and macroscopic composites endowed with unique structures, properties, and functions for widespread technological applications such as electronics, optoelectronics, electrocatalysis/photocatalysis, environment, and energy storage and conversion. In this review, significant recent advances concerning the self-assembly of CMGs are summarized, and the broad applications of self-assembled graphene-based materials as well as some future opportunities and challenges in this vibrant area are elucidated.
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http://dx.doi.org/10.1002/advs.201700626DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5827106PMC
February 2018

Effective Dual Polysulfide Rejection by a Tannic Acid/Fe Complex-Coated Separator in Lithium-Sulfur Batteries.

ACS Appl Mater Interfaces 2018 Apr 5;10(15):12708-12715. Epub 2018 Apr 5.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Key Laboratory of High Performance Polymer-Based Composites of Guangdong Province, The Key Lab of Low-Carbon Chem & Energy Conservation of Guangdong Province, School of Chemistry , Sun Yat-sen University , Guangzhou 510275 , China.

The solubility behaviour of polysulfides in electrolyte solutions is a major bottleneck prior to the practical application of the lithium-sulfur battery. To address this issue, we fabricate a tannic acid/Fe complex-coated polypropylene (PP) separator (TA/Fe-PP separator) via a simple, fast, and green method. Benefiting from dual-confinement effects based on Lewis acid-base interactions between Fe and polysulfides as well as the dipole-dipole interactions between rich phenol groups and polysulfides, the migration of polysulfides is effectively suppressed. Meanwhile, the porous structure of the PP separator is not destroyed by an additional coating layer. Thus, the TA/Fe-PP separator can retain rapid lithium ion transport, eventually leading to a significant improvement in both the discharge capacity and rate performance of the corresponding lithium-sulfur cells. The cell with the TA/Fe-PP separator presents a low capacity fade of 0.06% per cycle over 1000 cycles at 2.0 C, along with a high Coulombic efficiency of >97% over 300 cycles at 0.5 C. With respect to the one with the bare PP separator, the cell with the TA/Fe-PP separator exhibits a 1.7-fold increase in the discharge capacity at 3.0 C. The proposed simple and economical approach shows great potential in constructing advanced separators to retard the shuttle effect of polysulfides for lithium-sulfur batteries.
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http://dx.doi.org/10.1021/acsami.8b01189DOI Listing
April 2018

Cross-Linked Graphitic Carbon Nitride with Photonic Crystal Structure for Efficient Visible-Light-Driven Photocatalysis.

ACS Appl Mater Interfaces 2017 Dec 18;9(51):44503-44511. Epub 2017 Dec 18.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Guangdong Engineering Technology Research Center for High-Performance Organic and Polymer Photoelectric Functional Films, School of Chemistry, Sun Yat-sen University , Guangzhou 510275, China.

Highly cross-linked graphitic carbon nitride has been prepared by a thermal copolymerization of dicyanodiamide with tetramethylammonium salts. The cross-linking can be evidenced by (i) increased C/N ratio without new carbon species, (ii) decreased specific surface area, and (iii) Tyndall effect after dissolution in concentrated sulfuric acid. The cross-linked graphitic carbon nitride with photonic crystal structure has highly efficient photocatalytic activity for water splitting under visible light due to the synergistic enhancement by the greatly suppressed photoluminescence, red-shifted absorption edges, strong inner reflections, and effective PCs stop band overlaps. It exhibits an enhanced photodegradation kinetic of methyl orange and a high visible-light-driven hydrogen-evolution rate of 166.9 μmol h (25 times higher than that of the pristine graphitic carbon nitride counterpart). This work presents a facile method for designing and developing high-performance graphitic carbon nitride photocatalysts, providing a broad range of application prospects in the fields of electronics and energy conversion.
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http://dx.doi.org/10.1021/acsami.7b14359DOI Listing
December 2017

Bioinspired Mesoporous Chiral Nematic Graphitic Carbon Nitride Photocatalysts modulated by Polarized Light.

ChemSusChem 2018 01 14;11(1):114-119. Epub 2017 Dec 14.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Guangdong Engineering Technology Research Center for High-performance Organic and Polymer Photoelectric Functional Films, School of Chemistry, Sun Yat-sen University, Guangzhou, 510275, P. R. China.

Endowing materials with chirality and exploring the responses of the material under circularly polarized light (CPL) can enable further insight into the physical and chemical properties of the semiconductors to be gained, thus expanding on optoelectronic applications. Herein a bioinspired mesoporous chiral nematic graphitic carbon nitride (g-C N ) for efficient hydrogen evolution with polarized light modulation based on chiral nematic cellulose nanocrystal films prepared through silica templating is described. The mesoporous nematic chiral g-C N exhibits an ultrahigh hydrogen evolution rate of 219.9 μmol h (for 20 mg catalyst), corresponding to a high enhancement factor of 55 when compared to the bulk g-C N under λ>420 nm irradiation. Furthermore, the chiral g-C N material exhibits unique photocatalytic activity modulated by CPL within the absorption region. This CPL-assisted photocatalytic regulation strategy holds great promise for a wide range of applications including optical devices, asymmetric photocatalysis, and chiral recognition/separation.
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http://dx.doi.org/10.1002/cssc.201701984DOI Listing
January 2018

A General Electrode Design Strategy for Flexible Fiber Micro-Pseudocapacitors Combining Ultrahigh Energy and Power Delivery.

Adv Sci (Weinh) 2017 08 3;4(8):1700003. Epub 2017 Mar 3.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Key Laboratory of High Performance Polymer-based Composites of Guangdong Province School of Chemistry Sun Yat-sen University Guangzhou 510275 China.

Herein, a general strategy is proposed to boost the energy storage capability of pseudocapacitive materials (i.e., MnO) to their theoretical limits in unconventional 1D fiber configuration by rationally designing bicontinuous porous Ni [email protected] wire "sheath-core" metallic scaffold as a versatile host. As a proof of concept, the 1D metallic scaffold supported-MnO fiber electrode is demonstrated. The proposed "sheath" design not only affords large electrode surface area with ordered macropores for large electrolyte-ion accessibility and high electroactive material loading, but also renders interconnected porous metallic skeleton for efficient electronic and ionic transport, while the metallic "core" functions as an extra current collector to promote long-distance electron transport and electron collection. Benefiting from all these merits, the optimized fiber electrode yields unprecedented specific areal capacitance of 1303.6 mF cm (1278 F g based on MnO, approaching the theoretical value of 1370 F g) in liquid KOH and 847.22 mF cm in polyvinyl alcohol (PVA)/KOH gel electrolyte, 2-350 times of previously reported fiber electrodes. The solid-state fiber micro-pseudocapacitors simultaneously achieve remarkable areal energy and power densities of 18.83 µWh cm and 16.33 mW cm, greatly exceeding the existing symmetric fiber supercapacitors, together with long cycle life and high rate capability.
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http://dx.doi.org/10.1002/advs.201700003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5566233PMC
August 2017

One-Pot Large-Scale Synthesis of Carbon Quantum Dots: Efficient Cathode Interlayers for Polymer Solar Cells.

ACS Appl Mater Interfaces 2017 May 20;9(17):14953-14959. Epub 2017 Apr 20.

Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education of China, Guangdong Engineering Technology Research Center for High-performance Organic and Polymer Photoelectric Functional Films, Guangdong Provincial Key Laboratory for High Performance Resin-based Composites, School of Chemistry, Sun Yat-sen University , Guangzhou 510275, P. R. China.

Cathode interlayers (CILs) with low-cost, low-toxicity, and excellent cathode modification ability are necessary for the large-scale industrialization of polymer solar cells (PSCs). In this contribution, we demonstrated one-pot synthesized carbon quantum dots (C-dots) with high production to serve as efficient CIL for inverted PSCs. The C-dots were synthesized by a facile, economical microwave pyrolysis in a household microwave oven within 7 min. Ultraviolet photoelectron spectroscopy (UPS) studies showed that the C-dots possessed the ability to form a dipole at the interface, resulting in the decrease of the work function (WF) of cathode. External quantum efficiency (EQE) measurements and 2D excitation-emission topographical maps revealed that the C-dots down-shifted the high energy near-ultraviolet light to low energy visible light to generate more photocurrent. Remarkably improvement of power conversion efficiency (PCE) was attained by incorporation of C-dots as CIL. The PCE was boosted up from 4.14% to 8.13% with C-dots as CIL, which is one of the best efficiency for i-PSCs used carbon based materials as interlayers. These results demonstrated that C-dots can be a potential candidate for future low cost and large area PSCs producing.
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http://dx.doi.org/10.1021/acsami.7b00282DOI Listing
May 2017

Graphene Oxide Quantum Dots Covalently Functionalized PVDF Membrane with Significantly-Enhanced Bactericidal and Antibiofouling Performances.

Sci Rep 2016 Feb 2;6:20142. Epub 2016 Feb 2.

School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore.

Covalent bonding of graphene oxide quantum dots (GOQDs) onto amino modified polyvinylidene fluoride (PVDF) membrane has generated a new type of nano-carbon functionalized membrane with significantly enhanced antibacterial and antibiofouling properties. A continuous filtration test using E. coli containing feedwater shows that the relative flux drop over GOQDs modified PVDF is 23%, which is significantly lower than those over pristine PVDF (86%) and GO-sheet modified PVDF (62%) after 10 h of filtration. The presence of GOQD coating layer effectively inactivates E. coli and S. aureus cells, and prevents the biofilm formation on the membrane surface, producing excellent antimicrobial activity and potentially antibiofouling capability, more superior than those of previously reported two-dimensional GO sheets and one-dimensional CNTs modified membranes. The distinctive antimicrobial and antibiofouling performances could be attributed to the unique structure and uniform dispersion of GOQDs, enabling the exposure of a larger fraction of active edges and facilitating the formation of oxidation stress. Furthermore, GOQDs modified membrane possesses satisfying long-term stability and durability due to the strong covalent interaction between PVDF and GOQDs. This study opens up a new synthetic avenue in the fabrication of efficient surface-functionalized polymer membranes for potential waste water treatment and biomolecules separation.
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http://dx.doi.org/10.1038/srep20142DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4735848PMC
February 2016
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