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Triboelectric nanogenerators (TENG) with great performance and biodegradability are desired for the expansion of novel medical devices and wearable electronics. The present study aims at the preparation of natural silk in the form of silk fibroin (SF) film for utilization in TENG and further improving its output efficiency by embedding organic-piezoelectric gamma-glycine (γ-gly) amino acid to be a hybrid-organic piezoelectric/triboelectric nanogenerator (HO-P/TENG). The attenuated total reflectance infrared spectroscopy (ATR-IR) results demonstrated the N-H, C = O, and C-N bonding for SF and SF/γ-gly, confirming its dominant effect with a strong electron-donating tendency from those amino groups. The scanning electron microscope (SEM) and synchrotron radiation X-ray tomographic microscopy (SR-XTM) images show good dispersibility of incorporated γ-gly on the surface and also inside the SF matrix relating to its content to improve the electrical performance homogeneously. By fabricating the device in the vertical contact-separation mode, the present SF/γ-gly HO-P/TENG at 15 wt% provides the maximum output voltage (VOC) and current (ISC) of 81 V and 121 μA with a maximum output power (Pmax) of 205 μW at the external load resistance of 5 MΩ. This SF-based HO-P/TENG has the advantage of being cost-effective with simple fabrication, demonstrating great promise for practical uses. [ABSTRACT FROM AUTHOR]

Surface charge density is a key factor that greatly enhances the performance of a natural-based triboelectric nanogenerator (TENG), which is essential for future sustainable sensing and harvesting devices. This work introduced a conductive interlayer between a main frictional layer and electrode. This approach can suppress the charge recombination rate and improve the amount of charges produced during the triboelectrification process. Bacterial cellulose (BC) film was selected as a main frictional layer for the TENG. A conductive nanomaterial, i.e. silver flake, was incorporated into the BC film as an intermediate layer for enhancing TENG performance. As firstly reported, the maximum electrical outputs for the multi-layer BC structure could be found when using silver flake/BC composite (ratio 1:5) as an intermediate layer, which has 122 V and 8.2 µA of output voltage and current, respectively. This is higher than the output voltage and current of a single layer BC TENG by approximately 3 and 8 times, respectively. The maximum output power of ∼440 µW is achieved by connecting with a load resistor of ∼10 MΩ. This demonstrates an efficient strategy for designing a high performance energy harvester by adding an intermediate layer for the target of practical purposes in sustainable systems. [ABSTRACT FROM AUTHOR]

Polydopamine/Ag (PDA/Ag) nanoparticles were synthesized for methylene blue (MB) removal from aqueous solution as a model dye. These particles were prepared in a modified literature procedure in which polydopamine (PDA) nanoparticles were first prepared via the oxidative polymerization of dopamine (DA) under alkaline conditions in the presence of oxygen. Subsequently, nanoparticulate PDA/Ag was accessed from direct reduction of silver precursor [Ag(NH3)2]+ ions by catechol amino groups in the PDA structure to form Ag nanoparticles (AgNPs) fixed on the PDA surface. Confirmation of the formation of the PDA and PDA/Ag nanoparticles, plus characterization of their surface morphologies was achieved. In the MB adsorption studies, the various factors affecting the dye adsorption and thermodynamic parameters were investigated in detail. This adsorption process can be described well by the Langmuir model. In order to gain a deeper molecular insight into this process, we investigated some possible local model structures of PDA/Ag nanoparticles and MB interaction with these structures using density functional theory (DFT) calculations. The results indicated that the adsorption energies (Eads) of MB on the PDA/Ag nanoparticles were higher than the Eads of MB on PDA nanoparticles, which was consistent with the experimental results. Our results provide a significant new finding for the role of Ag nanoparticles in the MB adsorption process on PDA/Ag nanoparticles. Readily accessible nanoparticulate PDA/Ag was shown to be a highly effective adsorbent for MB from aqueous solution and thus has significant potential for applications in wastewater dye removal. [ABSTRACT FROM AUTHOR]

Alkali-activated cement (AAC) produced with metakaolin and black rice husk ash was investigated. The characteristics, physical properties, and thermal properties were investigated. Porosity assessments were carried out using synchrotron radiation X-ray tomographic microscopy (XTM). The results revealed that the concentration of NaOH solution and Na2SiO3 solution was the key parameter which affected the morphology and properties of AAC. Particle-structures and prolonged structures were formed when using NaOH as an activator. However, stacked plate-like structures were observed when using Na2SiO3 together with NaOH. The amorphous phases of N-A-S-H gel and geopolymer were formed. XTM profiles showed that the pore volume decreased with increasing NaOH solution concentration and Na2SiO3 contents. The 3D images illustrated that the pore structures were occupied by pores less than 50 µm in size. Pore connections within the range of 0–50 µm were the main parameter which controlled the thermal and physical properties. [ABSTRACT FROM AUTHOR]

Owing to their structural advantages over bulk polymers, porous 3D substrates possess immense potential in triboelectric energy generation. This work reports the effective effort to fabricate the porous structure of polydimethylsiloxane, also known as the sponge-PDMS, by a simple template method. The sodium chloride salt from commodity product is used to create the 300 μm size of pores within the PDMS elastomeric layers, turning affects to the mechanical deformability of the triboelectric nanogenerator (TENG). The inner face of those pores is composited with the PVDF-HFP particles as a piezoelectric fillers. The presence of those fillers can be confirmed and their distribution within porous PDMS is 3D visualized by the synchrotron radiation X-ray tomography. The spatial distribution of the PVDF-HFP made it possible to fabricate the piezo-embedded macroporous TENG with high output power of 7.84 μW, giving over 2-fold enhancement, compared with the sponge-PDMS and even more when compared with the flat PDMS film under the same mechanical force. [ABSTRACT FROM AUTHOR]

The flexible piezoelectric nanocomposites based on lead magnesium niobate titanate [Pb(Mg1/3Nb2/3)0.65Ti0.35O3; PMNT] particles in polydimethylsiloxane (PDMS) matrix were fabricated and characterized. PMNT powders are synthesized using the columbite precursor method. PMNT/PDMS flexible nanocomposites are then prepared by spin casting technique, where a small amount of carbon nanotubes (CNTs) is added into the PMNT/PDMS composite to enhance cross-links between PMNT particles and PDMS matrix. The phase and microstructure of the nanocomposite are investigated by using X-ray diffraction and scanning electron microscope (SEM). The electromechanical behavior is evaluated by using an autonomous pneumatic actuator. The flexible composite, occupying approximately 300 mm2, is capable of generating an open-circuit voltage (Voc) of 2.83 ± 0.24 V and a short-circuit current (Isc) signal of 0.33 ± 0.01 µA across 10 Ω resistor under mechanical load of 300 N. The generated electrical charges are 29026 pC. The relative dielectric constant is measured at 10 kHz and found to be 6.76 ± 1.15. The piezoelectric PMNT/PDMS composite can potentially be used in a variety of applications such as wearable sensors, actuators, and energy harvesting for converting kinetic energy into useful electrical energy. [ABSTRACT FROM AUTHOR]

The 0.93PZN-0.07BT ceramics containing 0.5 wt% AuNPs sintering was carried out for 3 – 5 h at various temperatures ranging from 1100 to 1150°C. The effect of AuNPs on 0.93PZN-0.07BT local structure and dielectric properties were investigated. The AuK-edge XANES spectrum indicated that AuNPs are not substituted into 0.93PZN-0.07BT structure. The dielectric constants and dielectric loss of 0.93PZN-0.07BT ceramics containing 0.5 wt% AuNPs after sintering at 1050°C for 3–5 h are higher and lower than that of 0.93PZN-0.07BT ceramics without AuNPs after sintering at 1100°C for 3–5 h, respectively, which can be described by assuming the connectivity series between the ceramics and the metal phases. In addition, Curie temperature shifting of 0.93PZN-0.07BT ceramics containing 0.5 wt% AuNPs due to the higher degree of chemical heterogeneity caused by the AuNPs addition. Therefore, the including of AuNPs into 0.93PZN-0.07BT ceramics can be improving dielectric properties with lower temperature and shorter time in sintering process. [ABSTRACT FROM PUBLISHER]