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[Polymers and Polymeric Composites: A Reference Series] Functional Polymers || Organic-Inorganic Hybrid Materials and Their Applications
摘要： The organic-inorganic composites in addition to providing new alternate materials represent a class that exhibit novel, astonishing features, and their properties can be tailored to suit a particular application. These are developed by combinations of two or more materials that differ in form or composition on a macroscale. The matrix and the filler are two indispensable components of a composite. In this chapter, synthetic routes, viz., sol-gel, blending, and emulsion polymerization, classification, and application of organic-inorganic composites as ion-selective membrane electrodes has been discussed. The ion-selective electrodes provide simple, reliable, low cost, on-spot methods for the detection of heavy metal ions. The field of hybrid materials is vast open and promising and newer possibilities to improve their application are to be explored.
关键词： Selectivity,Sol-gel synthesis,Composite,Ion-selective membrane electrode
更新于2025-09-09 09:28:46
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Shape Controllable Synthesis of Silver Particles by Selecting the Crystallization Routes
摘要： Classic crystallization describes a burst nucleation followed by a layer-by-layer atom deposition. The non-classic crystallization refers to particle mediated crystallization process. Different crystallization routes lead to the formation of diverse structured materials. Here we report a rational synthesis of silver particles by selecting the crystallization routes. Silver particles were synthesized by a solution reduction approach. The crystallization routes were regulated by adding amino acids to stabilize silver ions which leads to the decrease of the reduction rate. Without amino acids, silver dendrites were largely formed. With the addition of amino acids, flower-like (low concentration of amino acids) and spherical silver (high concentration of amino acid) particles were synthesized. Three kinds of amino acids were tested and the similar results were obtained. The time-dependent characterization on the evolution of silver particles showed that silver dendrites were formed by the classic atom deposition while the other two morphologies were formed by the combination of classic and non-classic crystallization. The silver particles synthesized were evaluated for ethylene epoxidation and the dendritic particles demonstrated a high selectivity.
关键词： catalytic selectivity,silver particles,reaction kinetics,shape control,crystallization
更新于2025-09-09 09:28:46
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Nitric Oxide Detector Based on WO <sub/>3</sub> -1wt%In <sub/>2</sub> O <sub/>3</sub> -1wt%Nb <sub/>2</sub> O <sub/>5</sub> with State-of-the-Art Selectivity and ppb-Level Sensitivity
摘要： Fast, sensitive, and precise detection of nitric oxide (NO) is critical to many applications in environmental monitoring and early disease diagnosis via respiratory testing. An effective detection system requires a sensor to detect NO gas at the parts per billion (ppb) level, and this system should possess a high degree of anti-interference selectivity. To achieve these targets, a series of gas sensor thin films based on intrinsic WO3, one-additive-doped WO3 (prepared by doping In2O3 or Nb2O5), and two-additive-doped WO3 (synthesized by doping with In2O3 and Nb2O5) oxides were successfully grown. By analyzing the properties of sensitivity, selectivity, responsiveness, and recovery time of the gas sensors, we found that WO3-1wt%In2O3-1wt%Nb2O5 has overwhelming advantages over intrinsic WO3, WO3-In2O3, and WO3-Nb2O5. A sensing response value of 2.4 was observed for NO concentrations as low as 20 ppb from the WO3-1wt%In2O3-1wt%Nb2O5 sensor. With 100 ppb NO gas, the WO3-1wt%In2O3-1wt%Nb2O5 sensor achieved a high response of 56.1 at 70 °C, which is a state-of-the-art performance for NO detection at low working temperature settings. WO3-1wt%In2O3-1wt%Nb2O5 also yields significantly improved selectivity and stability over intrinsic WO3, WO3-In2O3, and WO3-Nb2O5. Studies on the sensing mechanism show that the grain size, rather than the n?n heterostructure effect, plays a dominant role in the observed results. By decreasing the grain size so that it is close to the thickness of the space-charge layer, the sensing response is enhanced. Although room remains to further improve the sensing properties, the performance of WO3-1wt%In2O3-1wt%Nb2O5 is sufficient for implementation in low-content NO detection devices.
关键词： codoping,high selectivity,NO gas sensor,limit of detection (LOD),ppb-level response,pulsed laser deposition (PLD)
更新于2025-09-09 09:28:46
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Ultrathin Bi4O5Br2 nanosheets for selective photocatalytic CO2 conversion into CO
摘要： The ultrathin two-dimensional materials with the unique catalytic performance attract extensive interests of researchers. In this paper, ultrathin Bi4O5Br2 nanosheet (Bi4O5Br2-UN) is synthesized through precursor method by controlling the mole ratio of Bi(NO3)3·5H2O and cetyltrimethyl ammonium bromide. The ultrathin structure of Bi4O5Br2-UN was con?rmed by X-ray di?raction, atomic force miscroscopy and high-resolution transmission electron microscopy. UV–vis light irradiation, Bi4O5Br2-UN display excellent selective photocatalytic activity for CO2 conversion, which also was proved by isotope experiment. After 2 h reaction, the CO generation over Bi4O5Br2-UN reached 63.13 μmol g?1, which is about 2.3 times higher than that of bulk Bi4O5Br2 (27.56 μmol g?1). Additionally, the CO selectivity of Bi4O5Br2-UN is more than 99.5% in the whole catalytic process. The enhanced CO2 adsorption, suitable band position and improved charge separation induce the outstanding photocatalytic performance of Bi4O5Br2-UN. The photocatalytic mechanism of CO2 conversion with Bi4O5Br2-UN was analyzed by the in situ Fourier transform infrared spectrometry (FT-IR).
关键词： Bi4O5Br2,CO2 conversion,Photocatalysis,Selectivity,Ultrathin
更新于2025-09-09 09:28:46
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Nanodisc decorated W-WOx suspended nanowire: A highly sensitive and selective H2S sensor
摘要： In this work we report room temperature synthesis of plasma oxidized, suspended tungsten-tungsten oxide (W-WOx) core-shell nanowire for sensing ppb level H2S. The electric field modulation at the W-WOx interface of the core-shell nanowire strongly influences the sensing performance and brings down the operating temperature all the way down to 50°C, compared to completely oxidized (WOx) nanowire. The optimum interface ratio (W/WOx) of the nanowire shows response of 90.4% (1 ppm) with 6 months of response stability and excellent selectivity. The limit of detection of 10 ppb with response and recovery time of 4 s and 46 s respectively is achieved. To enhance the response further, we utilize nanostructuring on top of nanowire, using nanodiscs of 20 nm, 50 nm and 100 nm diameter and 10 nm height. The nanowire with nanodiscs of 20 nm diameter shows the high repeatable response of 12529% (1 ppm) at 150°C and fast response and recovery times of 12 s and 19 s with detection limit of 0.5 ppb. As we switch from unpatterned to patterned nanowire the observed change in H2S sensing characteristics, indicates that the core-shell nanowire behaviour makes a transition from p-type to n-type. Extensive material characterization is done using UV-Vis spectroscopy, XPS and TEM.
关键词： plasma oxidation,selectivity,Core-shell nanowire,nanodiscs,suspended
更新于2025-09-09 09:28:46
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A MINIATURIZED BANDPASS FREQUENCY SELECTIVE SURFACE WITH HIGH SELECTIVITY BASE ON SLOT COUPLING
摘要： A Ku-band bandpass frequency selective surface (FSS) with high selectivity and miniaturization is proposed in this paper. We use two metallic strips and one slot to design the frequency selective surface structure which contains both electrical and magnetic couplings. A metallic via is introduced in the FSS element for miniaturization. With the via inserted at the end of the metallic strip, the FSS unit size is reduced to half compared to that without via inserted. To investigate the operating principle of the slot-coupled FSS, an equivalent-circuit model is given and analysed using the odd- and even-mode method. The constructed out-of-phase signal path causes two transmission zeros (TZs) near the skirts of the narrow pass band, thereby enhancing the selectivity. A prototype of the proposed FSS operating at 16 GHz is fabricated and measured. The measured results agree well with the full-wave and circuit simulation results, thus verifying the FSS design.
关键词： slot coupling,Ku-band,bandpass frequency selective surface,metallic via,high selectivity,equivalent-circuit model,transmission zeros,miniaturization
更新于2025-09-09 09:28:46
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Development of Graphene Based Photocatalysts for CO2 Reduction to C1 Chemicals: A brief Overview
摘要： Transformation of CO2, a notorious greenhouse gas, to solar fuels is a promising strategy to alleviate the issues of global warming, environmental pollution, and climatic changes. Additionally, the CO2 conversion to useful chemicals/ fuels also possess a great potential to well match the energy demand in a sustainable manner. Hence, such exceptional benefits of harnessing CO2, by capitalizing sunlight, to valuable chemicals/fuels through photocatalysis, as one of the effective approach in the respective domain, have triggered great interest among researchers and scientific community. In this regard, utilization of customary and standard photocatalytic materials, specifically metal oxides like TiO2, are modified to provide enhanced performance, which is usually restricted due to limited intrinsic optical and physicochemical properties. To overcome such a critical issue of limited performance, several strategies like metals and non-metals doping, hetero-junctions, composites and nanostructures formation of photocatalytic materials have been investigated. Recently, with the invention of graphene and its derivatives, graphene based photocatalytic materials have been a topic of great interest, specifically for photocatalysts development and photocatalysis application. Graphene and its derivatives, due to their extraordinary physiochemical and electrical properties like high surface area, stability, anticorrosion capacity, photosensitizer, and excellent conductivity, can knock out the performance limiting constraints faced by traditional photocatalysts. Thus, Graphene based photocatalysts can be a feasible strategy to break new grounds in the field of photocatalytic CO2 reduction (PCCR) to useful chemicals/ fuels, i.e. conversion of sunlight to fuels. Herein, a summarized overview is presented for the latest development in graphene-based photocatalysts, focusing various strategies and researches being investigated in relation to the, utility of graphene and its derivatives for solar fuels generation, particularly C1 chemicals like CO, CH4, CH3OH, and insights to their role in improving efficacy of photocatalysts.
关键词： Photocatalytic activity,Photocatalytic CO2 reduction,Solar fuels,Product Selectivity,Graphene based photocatalysts
更新于2025-09-09 09:28:46
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Organic field effect transistors (OFETs) in environmental sensing and health monitoring: A review
摘要： Organic field effect transistors (OFETs) have been the focus of sensing application research over the last two decades. In comparison to their inorganic counterparts, OFETs have multiple advantages, such as low-cost manufacturing, large area coverage, flexibility and readily tunable electronic material properties. To date, various organic semiconductors (OSCs), both polymers and small molecules, have been extensively researched for the purpose of developing the active channel layers in OFETs, enhancing their sensitivity and selectivity. However, OFET devices still need to be optimized to demonstrate reliable performance at the device level and in sensing applications. This review begins with an introduction of the OFETs with an emphasis on their geometry, materials (OSCs), fabrication process, and data analysis. After this, multiple applications are discussed and the progress regarding sensing elements and precisions is highlighted. In the end, the challenges and possible future directions of OFET arrays in embedded sensing platforms are presented.
关键词： stability,bi-layer,selectivity,biosensor,sensitivity,composites,OFETs,gamma irradiation,VOCs
更新于2025-09-09 09:28:46
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Selectivity map for molecular beam epitaxy of advanced III-V quantum nanowire networks
摘要： Selective area growth is a promising technique to enable fabrication of scalable III-V nanowire networks required to test proposals for Majorana-based quantum computing devices. However, the contours of the growth parameter window resulting in selective growth remain undefined. Herein, we present a set of experimental techniques which unambiguously establish the parameter space window resulting in selective III-V nanowire networks growth by molecular beam epitaxy. Selectivity maps are constructed for both GaAs and InAs compounds based on in situ characterization of growth kinetics on GaAs(001) substrates, where the difference in group III adatom desorption rates between the III-V surface and the amorphous mask area is identified as the primary mechanism governing selectivity. The broad applicability of this method is demonstrated by successful realization of high quality InAs and GaAs nanowire networks on GaAs, InP, and InAs substrates of both (001) and (111)B orientations as well as homoepitaxial InSb nanowire networks. Finally, phase coherence in Aharonov-Bohm ring experiments validates the potential of these crystals for nanoelectronics and quantum transport applications. This work should enable faster and better nanoscale crystal engineering over a range of compound semiconductors for improved device performance.
关键词： GaAs,selectivity,selective area growth,epitaxy,InAs,III-V nanowire,molecular beam epitaxy
更新于2025-09-09 09:28:46
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BANDPASS FILTERS WITH IMPROVED SELECTIVITY BASED ON DUAL-MODE RING RESONATORS
摘要： Two novel microstrip bandpass ?lters with improved selectivity based on dual-mode ring resonators are proposed. Tow and four transmission zeros close to the passband are realized to improve the selectivity for the passband. Sixth-order passband is realized with two open/shorted stubs and a dual-mode ring resonator. The transmission zeros near the passband can be adjusted conveniently by changing the characteristic impedances of the coupled lines. For demonstration, two planar bandpass ?lters (3-dB bandwidths 20.9%, 20.2%) are designed and fabricated.
关键词： dual-mode ring resonators,transmission zeros,microstrip bandpass filters,selectivity
更新于2025-09-04 15:30:14