Simultaneous photocatalytic degradation and SERS detection of tetracycline with self-sustainable and recyclable ternary PI/TiO_(2)/Ag flexible microfibers

Facile and efficient photocatalysts using sunlight,as well as fast and sensitive surface-enhanced Raman spectroscopy(SERS)substrates,are urgently needed for practical degradation of tetracycline(TC).To meet these requirements,a new paradigm for PI/TiO_(2)/Ag organic‒inorganic ternary flexible microfibers based on semiconducting titanium dioxide(TiO_(2)),the noble metal silver(Ag)and the conjugated polymer polyimide(PI)was developed by engineering a simple method.Under sunlight,the photocatalytic characteristics of the PI/TiO_(2)/Ag flexible microfibers containing varying amounts of Ag quantum dots(QDs)were evaluated with photocatalytic degradation of TC in aqueous solution.The results demonstrated that the amount of Ag affected the photocatalytic activity.Among the tested samples,PI/TiO_(2)/Ag-0.07(93.1%)exhibited a higher photocatalytic degradation rate than PI/TiO_(2)(25.7%),PI/TiO_(2)/Ag-0.05(77.7%),and PI/TiO_(2)/Ag-0.09(63.3%).This observation and evaluation conducted in the present work strongly indicated a charge transfer mechanism.Moreover,the PI/TiO_(2)/Ag-0.07 flexible microfibers exhibited highly sensitive SERS detection,as demonstrated by the observation of the Raman peaks for TC even at an extremely low concentration of 10–10 moles per liter.The excellent photocatalytic performance and SERS detection capability of the PI/TiO_(2)/Ag flexible microfibers arose from the Schottky barrier formed between Ag and TiO_(2)and also from the outstanding plasmonic resonance and visible light absorptivity of Ag,along with immobilization by the PI.The successful synthesis of PI/TiO_(2)/Ag flexible microfibers holds significant promise for sensitive detection and efficient photocatalytic degradation of antibiotics.

Monitoring the charge-transfer process in a Nd-doped semiconductor based on photoluminescence and SERS technology

Surface-enhanced Raman scattering(SERS)and photoluminescence(PL)are important photoexcitation spectroscopy techniques;however,understanding how to analyze and modulate the relationship between SERS and PL is rather important for enhancing SERS,having a great effect on practical applications.In this work,a charge-transfer(CT)mechanism is proposed to investigate the change and relationships between SERS and PL.Analyzing the change in PL and SERS before and after the adsorption of the probe molecules on Nd-doped ZnO indicates that the unique optical characteristics of Nd^(3+) ions increase the SERS signal.On the other hand,the observed SERS can be used to explain the cause of PL background reduction.This study demonstrates that modulating the interaction between the probe molecules and the substrate can not only enhance Raman scattering but also reduce the SERS background.Our work also provides a guideline for the investigation of CT as well as a new method for exploring fluorescence quenching.

Self-sustainable and recyclable ternary Au@Cu2O–Ag nanocomposites:application in ultrasensitive SERS detection and highly efficient photocatalysis of organic dyes under visible light

Ternary noble metal–semiconductor nanocomposites(NCs)with core–shell–satellite nanostructures have received widespread attention due to their outstanding performance in detecting pollutants through surface-enhanced Raman scattering(SERS)and photodegradation of organic pollutants.In this work,ternary Au@Cu2O–Ag NCs were designed and prepared by a galvanic replacement method.The effect of different amounts of Ag nanocrystals adsorbed on the surfaces of Au@Cu2O on the SERS activity was investigated based on the SERS detection of 4-mercaptobenzoic acid(4-MBA)reporter molecules.Based on electromagnetic field simulations and photoluminescence(PL)results,a possible SERS enhancement mechanism was proposed and discussed.Moreover,Au@Cu2O–Ag NCs served as SERS substrates,and highly sensitive SERS detection of malachite green(MG)with a detection limit as low as 10−9 M was achieved.In addition,Au@Cu2O–Ag NCs were recycled due to their superior self-cleaning ability and could catalyze the degradation of MG driven by visible light.This work demonstrates a wide range of possibilities for the integration of recyclable SERS detection and photodegradation of organic dyes and promotes the development of green testing techniques.

Conjugated ladder-type polymers with multielectron reactions as high-capacity organic anode materials for lithium-ion batteries

Ladder-type conjugated polymers(LCPs)have attracted extensive attention in rechargeable lithium-ion batteries(LIBs)due to their inherent stability,poor solubility,tunable structure,and strongπ-πintermolecular interactions.Herein,we describe the synthesis of two heteroatom nitrogen/oxygen-rich LCPs(TABQ-NTCDA,named TNL,and TABQPMDA,named TPL)by the polycondensation reaction of tetromino-benzoquinone(TABQ)and aromatic dianhydride.Benefiting from the rigid backbone,the large conjugated skeleton and the heteroatom-driven superlithiation process in polycyclic aromatic systems,heteroatom nitrogen/oxygen-rich LCPs acting as organic anode materials for LIBs display high specific capacity and long-term cycle stability.In particular,TNL displays a high reversible capacity of 1063.5 mA h g^(-1) at 0.05 A g^(-1),good cyclic performance with a capacity retention of 75.2% after 1000 cycles at 1 A g^(-1),and excellent rate capability of 260.6 mA h g^(-1) even at 2 A g^(-1).In addition,the superlithiation storage mechanism was further confirmed by theoretical calculations,suggesting multiple active sites of C=O,C=N,and aromatic rings for lithium-ion storage.Furthermore,a full cell is also assembled by pairing a TNL anode with a LiCoO_(2) cathode,indicating the feasibility of practical application.

Upgraded antisolvent engineering enables 2D@3D quasi core-shell perovskite for achieving stable and 21.6%efficiency solar cells

Perovskite solar cells(PSCs)have become a promising alternative to sustainable energy due to their high power conversion efficiency(PCE)and low-cost processing.However,the practical applications of PSCs are still limited by the trade-off between high performance and poor stability under operation.Here,a2D@3D perovskite with quasi core-shell architecture linking the superiorities of both two-dimensional(2D)and three-dimensional(3D)perovskite is prepared through a novel upgraded antisolvent approach.The basic properties as well as the phase distribution and the charge transport behavior of the 2D@3D perovskite were systematically elucidated.A high PCE of 21.60%for 2D@3D PSCs is achieved due to the enhanced surface and grain boundaries passivation,improved energy level alignment and efficient holes transport.The 2D@3D perovskite device without encapsulation shows significantly improved stability at the room temperature(90%of initial PCE for 45 d with a relative humidity of 50%±5%)and relative thermal conditions(83%of initial PCE for 200 h under 85℃).Compared with traditional 3D PSCs,it proved that such 2D@3D perovskite configuration is an effective architecture for enhancing efficiency and improving stability and therefore will facilitate the further industrialization of PSCs.