Interdiscipline between optoelectronic materials and mechanical sensors:Recent advances of organic triboluminescent compounds and their applications in sensing

Triboluminescence,also as known as mechanoluminescence,is an attractive optical behavior that means the light emitted from specific organic and inorganic materials when they are subjected to external forces,such as crushing,deformation,cleaving,vibration.Inorganic triboluminescent materials show great potential for applications in sensing,such as stress sensing,damage detection.However,the triboluminescent mechanism of organic materials should be pushed further as well as their application.In this review,we summarized the history of development and possible mechanism of organic triboluminescent materials,and discussed various applications in sensing field.At the same time,inspired by the existing research progress in inorganic triboluminescent materials,we proposed the flourishing development prospects of organic triboluminescent materials in stress sensors,movement monitoring,imaging stress distribution,visualization of crack propagation,structural diagnosis,and other fields.

Synthesis and Properties of High Performance Functional Polyimides Containing Rigid Nonplanar Conjugated Fluorene Moieties

A diamine(WuFDA) containing vertical rigid non-planar conjugated fluorene moiety and low polarizability group(C―F)was designed and synthesized through three steps of reactions(halogenated reaction, Suzuki coupling reaction, and reduction reaction).Four kinds of high performance functional polyimides(WuFPI-6 F, WuFPI-BP, WuFPI-BT, and WuFPI-PM) were thus prepared by the condensation polymerization of WuFDA with four commercial dianhydride 6 FDA, BPDA, BTDA, and PMDA, respectively. The polyimides exhibited low dielectric constant, excellent thermal stability, outstanding solubility, good film-forming property, and mechanical properties. The dielectric constants of the polyimides were in the range of 2.28-2.88(f = 10~4 Hz). The 5% weight-loss temperatures(Td 5%)in nitrogen were in the range of 555-584 °C, and the glass transition temperatures(T_g) were in the range of 408-448 °C. The weight loss of WuFPI-BP maintaining at 450 and 500 °C for half an hour was only 0.33% and 1.26%, respectively. All the WuFPIs could be dissolved in almost all organic solvents, even chloroform. The tensile strength and tensile modulus of these films were in the ranges of 78.6-85.7 MPa and 3.1-3.2 GPa, respectively. In addition, the polyimides displayed light color with special fluorescent and resistive switching(ON-OFF) characteristics; the maximum fluorescence emission was observed at 422-424 nm in NMP solution and at 470-548 nm in film state. The memory devices with the configuration of indium tin oxide/WuFPIs/aluminum(ITO/WuFPIs/Al) exhibited distinct volatile memory characteristics of static random access memory(SRAM), with an ON/OFF current ratio of 10~5-10~6. These functional polyimides showed attractive potential applications in the field of high performance flexible polymer photoelectronic devices or polymer memory devices.

Synthesis and characterization of soluble intrinsic black polyimide with excellent comprehensive properties

Black polyimides(BPIs)have attracted increasing attention owing to their growing demand in optoelectronics.However,commonly used black polyimides doped with black fillers suffer from poor mechanical and electrical properties.To address these issues,a new diamine(2,5-bis(4′-amino-[1,1′-biphenyl]-4-yl)-3,4-bis(4-fluorophenyl)cyclopenta-2,4-dien-1-one,TPCPFPDA)bearing a tetraphenylcyclopentadienone(TPCP)moiety bonded with benzene and fluorine units was synthesized.The diamine was reacted with 4,4′-(hexafluoroisopropylidene)diphthalic anhydride(6FDA)to yield a soluble intrinsic black polyimide(TPCPFPPI).Bonding fluorine(auxochrome group)and benzene units to TPCP can increase the conjugation ofπ-electrons systems and facilitate the movement of electron throughout the bigπbond,respectively.Owing to the structural features,the synthesized TPCPFPPI exhibited complete visible-light absorption with high blackness and opacity.Its cutoff wavelength(λ_(cut))and CIE(Commission Internationale de I′Eclairage)parameter L^(*)were 684 nm and 1.33,respectively.Moreover,TPCPFPPI displayed exceptional electrical,mechanical,and thermal properties as well as excellent solubility.A detailed theoretical calculation was conducted to gain better insight into the electronic properties of the TPCPFPPI.Results showed that the blackness of TPCPFPPI was chiefly attributed to the electron transition from highest occupied molecular orbital(HOMO)to lowest unoccupied molecular orbital(LUMO)in the diamines,where the charges primarily migrated from the aryl groups in the 2-and 5-positions to the cyclopentadienone center.The as-obtained intrinsic BPI(TPCPFPPI),exhibiting both high solubility and outstanding overall properties,has important applications in photo-electronics.

In-situ construction of MnCO_(3)@CNTs nanosheets for high-capacity aqueous zinc ion batteries

Owing to severe agglomeration of manganese carbonate(MnCO_(3))during its synthesis,it exhibits rapid decay cycle performance when used as a cathode material in aqueous zinc ion batteries.To overcome this drawback,we synthesized a MnCO_(3)material with carbon nanotubes(CNTs)(i.e.,MnCO_(3)@CNTs)via a one-step solvothermal method using a hybrid modification strategy.MnCO_(3)nanospheres were grown in-situ on a two-dimensional(2D)plane that was orderly interwoven by tubular single fibers of carbon to form a leaf-like nanosheet structure.The surface area of the MnCO_(3)@CNTs material was enlarged enormously through the special nanosheet structure,and its stability was improved by the supporting structure of the CNTs.As a result,the MnCO_(3)@CNTs exhibited a discharge capacity of 247.6 mAh g^(-1)at a current density of 0.1 A g^(-1).The energy storage mechanism of MnCO_(3)@CNTs was further explored using a series of electrochemical kinetic analyses and ex-situ characterization tests.This modification method not only broadens the application field of MnCO_(3),but also provides the possibility of modifying more cathode materials.

High-loading single cobalt atoms on ultrathin MOF nanosheets for efficient photocatalytic CO_(2) reduction

Based on suitable scaffolds,constructing high-loading single-atom catalysts is a promising strategy to achieve highly efficient catalysis.Herein,using ultrathin metal-organic framework(MOF)nanosheets(2.4±0.5 nm)as the support,single-atom catalysts with high cobalt loading(6.0 wt%)were constructed(denoted as Co-MNSs)by a simple bottom-up synthetic strategy.The catalytic system of Co-MNSs exhibited an outstanding photocatalytic CO_(2)-to-CO evolution rate of 7,041μmol g^(-1)h^(-1)and a selectivity of 86%in aqueous media under visible-light irradiation,which has reached the top level of the reported MOF-based photocatalysts.The control experiments and theoretical calculation revealed that the Co-N_(4)moiety in the MOF nanosheets acted as the active site for the photocatalytic CO_(2)-to-CO conversion.The boosted photocatalytic performance could be ascribed to the high aspect-ratio of layered Co-MNSs providing abundant accessible active sites on their surfaces,which reduced the energy barrier,improved the charge separation efficiency,and also facilitated the adsorption of CO_(2)to form the reactive radicals of*COOH.Our study provides an appealing strategy for constructing high-loading single-atom catalysts and demonstrates the significance of 2D ultrathin MOF nanosheets as the support in boosting CO_(2)photoreduction efficiency.

Template-free synthesis to micro-meso-macroporous hierarchy in nanostructured MIL-101(Cr)with enhanced catalytic activity

Hierarchical porous(HP)materials[1,2],having multimodal pore-size distribution,receive keen attention due to advantages offered by improved diffusion efficiency and mass transport.HP metal-organic frameworks(HPMOFs)is an emerging field focussing on delivering improved performance in catalysis[3,4],adsorption/separation[5,6],sensorics[7]and energy storage[8,9],especially when bulky guest molecules are involved.Micropores usually offer high surface area while mesopores/macropores will significantly enlarge the application as a host material to carry bulky anchoring molecular catalysts,large drug molecules and even nanomaterials.This is indeed an advantage for catalysis reaction or transformation without transportation limitations in a confined space.Some MOFs with the large pore-sizes of over 2 nm diameter are formally micro-/mesoporous in the defectfree crystalline state.Isoreticular expansion[10]allows synthesizing MOF materials with pore sizes of up to 10 nm[11].