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Among mid-temperature thermoelectric materials, PbSe is deemed as a natural replacement of PbTe owing to the much larger abundance of selenium than tellurium. Usually, extra Cu can enter the tetrahedral interstices of PbSe as an effective n-type dopant and significantly enhance its thermoelectric properties; however, anomalously low lattice thermal conductivity as reported due to extra Cu doping gave rise to controversies about the significance of the achieved thermoelectric performance. In this work, we introduced another method of Cu incorporation, i.e., Cu2Se alloying, and systematically discussed its distinction from the method of extra Cu doping. Cu2Se alloying was found to be able to complicate the lattice occupation of Cu in PbSe by introducing CuPb–CuVF pair defects while offering no free electrons. Ultimately, by combining the two methods of Cu incorporation, we achieved a superior peak figure of merit (ZT) value of 1.56 at 773 K and an average ZT value of ∼1.01 at 323–773 K in the composition of PbSe–3% Cu2Se–0.8% Cu. Notably, the enhancements were achieved without any lattice thermal conductivity anomaly as seen in the cases using extra Cu doping alone. [ABSTRACT FROM AUTHOR]

Ruthenium nanoparticle tris(2,2′-bipyridyl)ruthenium(ii) bis(hexafluorophosphate) (Ru(bpy)3(PF6)2, RuNP) was self-assembled on polystyrene (PS) electrospun microfibers. The formation of RuNP is attributed to the sulfonated PS (SPS) microfibers' high adsorptive capability of 94% for Ru(bpy)32+, as well as the strong interaction between the Ru(bpy)32+ and ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMIMPF6). The RuNP/SPS microfibers exhibited an enhanced electrochemiluminescence (ECL) emission, 2.3 times higher than that from Ru(bpy)32+/SPS microfibers and 6.6 times higher than that from Ru(bpy)32+/SPS continuous thin films. It is worthy of note that, as a result of the hydrophobic nature of the RuNP, the transfer of water-insoluble α-naphthol is accelerated, and thus the α-naphthol ECL quenching efficiency is enhanced. An ECL sensor based on the RuNP/SPS microfibers was fabricated and used to detect low concentrations of α-naphthol. The detection limit was of 1.0 nM (S/N ＞ 3), and the linear response ranged from 0 to 18 μM. This sensor has been successfully applied to measure the α-naphthol content in pesticide carbaryl samples. Our work provides a very simple and cost-effective method to fabricate RuNP on polymer microfibers with great potential in the field of chemo/biosensors. [ABSTRACT FROM AUTHOR]

An easy and convenient method for the synthesis of polyaniline (PANI) microtubes was developed using polystyrene (PS) electrospun microfibers as a template. The diameter range of these microtubes was from 0.63 to 2.93 μm. This accuracy was achieved by tuning the template microfiber's diameter. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to study the effect of these microtubes' diameters on their electroactivity. When the diameter is 1.43 μm, the PANI microtube exhibited the maximum electroactivity and a distinguished electrocatalytic oxidation of ascorbic acid (AA). Herein, the PANI microtube was fabricated into an amperometric AA sensor. At the working potential of 0.4 V (vs. SCE), the oxidation current was significantly enhanced by the addition of a low concentration of AA but no such current was observed with other selected small molecules. The AA detection limit was 0.28 μM at the signal-to-noise ratio of 3. A linear relationship was demonstrated between the oxidation current enhancement and the AA concentration ranging from 5.0 μM to 4.7 mM. The detection limit was better than a reported PANI nanotube (1.0 μM), nanofiber (1.7 μM) and nanoparticle (8.3 μM). The high sensitivity could be attributed to the PANI microtube's high conductivity, high electroactivity for the AA electrocatalytic oxidation, as well as its high surface-to-volume ratio resulting in an efficient interaction between the microtube and the AA molecule. A promising application of the PANI microtube-based sensor was offered.

Ruthenium nanoparticle tris(2,2'-bipyridyl)ruthenium(II) bis(hexafluorophosphate) (Ru(bpy)3(PF6)2, RuNP) was self-assembled on polystyrene (PS) electrospun microfibers. The formation of RuNP is attributed to the sulfonated PS (SPS) microfibers' high adsorptive capability of 94% for Ru(bpy)3(2+), as well as the strong interaction between the Ru(bpy)3(2+) and ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMIMPF6). The RuNP/SPS microfibers exhibited an enhanced electrochemiluminescence (ECL) emission, 2.3 times higher than that from Ru(bpy)3(2+)/SPS microfibers and 6.6 times higher than that from Ru(bpy)3(2+)/SPS continuous thin films. It is worthy of note that, as a result of the hydrophobic nature of the RuNP, the transfer of water-insoluble α-naphthol is accelerated, and thus the α-naphthol ECL quenching efficiency is enhanced. An ECL sensor based on the RuNP/SPS microfibers was fabricated and used to detect low concentrations of α-naphthol. The detection limit was of 1.0 nM (S/N > 3), and the linear response ranged from 0 to 18 μM. This sensor has been successfully applied to measure the α-naphthol content in pesticide carbaryl samples. Our work provides a very simple and cost-effective method to fabricate RuNP on polymer microfibers with great potential in the field of chemo/biosensors.

A simple and cost-effective method was reported to synthesize small size (6 nm) gold nanoparticles (AuNPs) on polyacrylonitrile (PAN) electrospun nanofibers (AuNPs/PAN). The formation of AuNPs is attributed to the in situ reduction of Au(III) to Au(0) by 4-(dimethylamino)benzaldehyde doped in the PAN nanofibers. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) confirmed that the AuNPs/PAN nanofibers showed good conductivity. The AuNPs/PAN nanofibers were used to immobilize tris(2,2'-bipyridyl)ruthenium(II) ions (Ru(bpy)(3)(2+)) to form an electrochemiluminescence (ECL) sensor. The AuNPs on the PAN nanofibers exhibited an excellent catalytic effect on the ECL of Ru(bpy)(3)(2+) which could be employed to detect low concentrations of phenolic compounds. The linear response range of the ECL sensor to hydroquinone is 0.55-37 μM with limit of detection of 80 nM (S/N = 3). This sensor has been successfully applied to determine the hydroquinone content in photographic developer samples. Our work provides a very simple and cost-effective method to synthesize AuNPs on polymer nanofibers which shows great potential in the field of electrocatalysis and chemo/biosensors.