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The present study outlines the preparation of a ternary nanocomposite film comprising of polyaniline doped with camphor sulfonic acid (PANI), reduced graphene oxide (rGO), and graphitic carbon nitride (g-C 3 N 4 ), and delves into its thermoelectric performance. PANI is known to possess high electrical conductivity ( σ ) and poor thermal conductivity ( κ ). However, its potential for thermoelectric applications is constrained by the low value of the Seebeck coefficient ( S ). The incorporation of g-C 3 N 4 in PANI has been demonstrated to result in an improvement of the Seebeck coefficient. Furthermore, the addition of rGO to the PANI/g-C 3 N 4 sample counteracts the decrease in electrical conductivity. The PANI/g-C 3 N 4 /rGO ternary nanocomposite film exhibits an enhanced Seebeck coefficient of ∼2.2 times when compared to the PANI sample. The Seebeck coefficient of the PANI/g-C 3 N 4 /rGO nanocomposite is enhanced by the energy filtering effect that occurs at the interfaces between g-C 3 N 4 /PANI and PANI/rGO. The π - π interaction between the PANI chains and rGO is responsible for the increased electrical conductivity resulting from the well-ordered polymer chain arrangement on the g-C 3 N 4 and rGO surfaces. The ternary nanocomposite sample demonstrated a synergistic improvement in both electrical conductivity and Seebeck coefficient, resulting in a remarkable ∼4.6-fold increment in power factor and an ∼4.3-fold enhancement in the figure of merit ( zT ), as compared to the pristine PANI film., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

The emergence of piezoelectric nanogenerators (PENGs) presents a promising alternative to supply energy demands within the realms of portable and miniaturized devices. In this article, the role of 2D transition metal dichalcogenide tungsten sulfide (WS 2 ) and conductive rGO sheets as filler materials inside the polyvinylidene fluoride (PVDF) matrix on piezoelectric performances has been investigated extensively. The strong electrostatic interaction between C-F and C-H monomer bonds of PVDF interacted with the large surface area of the WS 2 nanosheets, increasing the electroactive polar phases and resulting in enhanced ferroelectricity in the PVDF/WS 2 nanocomposite. Further, the inclusion of rGO sheets in the PVDF/WS 2 composite allows mobile charge carriers to move freely through the conductive network provided by the rGO basal planes, which improves the internal polarization of the PVDF/WS 2 /rGO nanocomposites and increases the electrical performance of the PENGs. The PVDF/WS 2 /0.3rGO nanocomposite-based PENG exhibits maximum piezoresponses with ∼8.1 times enhancements in the output power density than the bare PVDF-based PENG. The mechanism behind the enhanced piezoresponses in the PVDF/WS 2 /rGO nanocomposites has been discussed., (© 2024 IOP Publishing Ltd.)

In this paper, we have demonstrated a novel design of a liquid-solid interface triboelectric nanogenerator based on a ZnO- polyvinylidene fluoride (PVDF) flexible ferroelectric film that employs both piezoelectric and triboelectric properties to produce more electricity from water droplets. The present device gives an output voltage of ∼1.32 V and a short-circuit current of ∼0.32 μ A from the conventional liquid-solid triboelectric nanogenerator (LSTENG), while an additional open-circuit voltage of ∼2.72 mV and short-circuit current of ∼20 nA is generated from the piezoelectric effect. The mechanism for generating energy in both the piezoelectric and triboelectric components is also discussed. Furthermore, we explored the effect of ions in water on the performance of the LSTENG, and the results were confirmed by Kelvin probe force microscopy measurements. The current work reveals a new LSTENG design and the benefit of employing a ferroelectric polymer as the contacting material rather than other non-piezoelectric materials for the LSTENG., (© 2021 IOP Publishing Ltd.)

Bismuth sulfide (Bi 2 S 3 ) is a promising material for thermoelectric applications owing to its non-toxicity and high abundance of bismuth (Bi) and sulfur (S) elements on earth. However, its low electrical conductivity drastically reduces the value of the figure of merit ( ZT ). In this work, we have synthesized three-dimensional (3D) hierarchical Bi 2 S 3 nanoflowers (NFs) by the hydrothermal route and further incorporated them with conducting polymer polyaniline (PANI) by simple chemisorption method. We have investigated the thermoelectric properties of the as-prepared Bi 2 S 3 NFs and PANI/Bi 2 S 3 nanocomposite samples and it is demonstrated that the incorporation of the PANI matrix with the 3D hierarchical Bi 2 S 3 NFs provides a conducting substrate for the easy transport of the electrons and reduces the barrier height at the interface, resulting in ∼62% increment in the electrical conductivity as compared to Bi 2 S 3 NFs. Moreover, a decrement in the thermal conductivity of the PANI/Bi 2 S 3 nanocomposite is observed as compared to pristine Bi 2 S 3 NFs due to the increased phonon scattering at the interfaces facilitated by the hierarchical morphology of the NFs. Furthermore, an increment in the electrical conductivity and simultaneous decrement in the thermal conductivity results in an overall ∼20% increment in the figure of merit ( ZT ) for PANI/Bi 2 S 3 nanocomposite as compared to pristine Bi 2 S 3 NFs. The work highlights an effective strategy of coupling 3D hierarchical metal chalcogenide with conducting polymer for optimizing their thermoelectric properties., (© 2021 IOP Publishing Ltd.)

We report on the resistive memory effects of a Ag/CoFe 2 O 4 /Pt device and a deterministic conversion between volatile and nonvolatile resistive switching (RS) memory through the tuning of current compliance (I CC ). For the smaller I CC (10 -4 A) the device exhibits volatile RS behavior with an atomically sized conducting filament showing the quantum conductance. For an intermediate I CC (10 -2 A) nonvolatile bipolar RS behavior is observed, which could originate from the formation and rupture of filament consisting of Ag ions. The high resistance state (HRS) of the device shows a semiconducting conduction mechanism, whereas the low resistance state (LRS) was found to be Ohmic in nature. The temperature dependent resistance studies and magnetization studies indicated that the electrochemical metallization plays a dominant role in the resistive switching process for volatile and nonvolatile modes through the formation of Ag conducting filaments. For higher I CC (10 -1 A) the device permanently switches to LRS. The irreversible RS memory behaviors, observed for higher I CC , could be attributed to the formation of a thick and stable conducting channel formed of oxygen vacancies and Ag ions. The compliance current controlled resistive switching modes with a large memory window make the present device a potential candidate to pave the way for future resistive switching devices.

Hierarchical nanoflowers (NFs) of zinc oxide (ZnO) have been synthesized in the hexagonal wurtzite structure by a facile hydrothermal method. Polyaniline (PANI) has been prepared by the chemical oxidative polymerization method and incorporated with ZnO NFs by the chemisorption method. The potential of the synthesized nanostructures has been demonstrated for efficient photocatalytic degradation of methylene blue (MB) and photoelectrochemical water splitting. The PANI/ZnO nanocomposite has exhibited the enhanced photocatalytic activity which is ∼9 fold higher in comparison to pristine ZnO NFs and enhanced photocurrent density which is ∼16 fold higher than the ZnO photoanode. Importantly, ∼4 fold increment in the incident photon-to-current conversion efficiency (IPCE) is exhibited by PANI/ZnO, than that of ZnO photoanode. The remarkably enhanced photocatalytic and photoelectrochemical performance of PANI/ZnO nanocomposite is attributed to the availability of more interfacial sites facilitated by the hierarchical ZnO NFs, improved overall photoresponse due to its photosensitization with PANI and the resulting type-II heterojunction between them, which helps in the efficient separation of photogenerated charge carriers at the interface. A plausible reaction mechanism for the substantially improved performance of nanostructured PANI/ZnO towards MB degradation and water splitting has also been elucidated.

Sodium niobate nanofibers (NaNbO 3 -NF) have been synthesized using a hydrothermal technique and further coupled with visible light responsive graphitic carbon nitride (g-C 3 N 4 ) nanosheets in different concentration ratios of 2:1 (2-CN), 4:1 (4-CN) and 8:1 (8-CN). A significant improvement in the photoelectrochemical (PEC) performance of the g-C 3 N 4 /NaNbO 3 -NF (4-CN) nanostructured photoanode compared to the bare NaNbO 3 photoanode is observed. A current density of 12.55 mA cm -2 at 1 V with respect to the Ag/AgCl reference electrode is achieved for the g-C 3 N 4 /NaNbO 3 -NF (4-CN) photoanode, which is ∼3 times higher than the NaNbO 3 -NF photoanode. Also, compared to NaNbO 3 -NF, the g-C 3 N 4 /NaNbO 3 -NF (4-CN) nanocomposite photoanode showed ∼3 times improvement in the incident photon-to-current conversion efficiency. The improvement in the PEC performance of visible light active g-C 3 N 4 /NaNbO 3 -NF (4-CN) nanocomposite is attributed to the improved photoresponse of NaNbO 3 -NF due to the coupling of g-C 3 N 4 and the formation of a type-II heterojunction between them leading to the enhanced separation of the photogenerated charge carriers. A possible reaction mechanism for the improved PEC water splitting performance has been proposed for the g-C 3 N 4 /NaNbO 3 -NF (4-CN) photoanode.

In this report, we investigate the effect of graphene nanofillers on the thermoelectric properties of Bi 2 Te 3 nanosheets and demonstrate the role of interface for enhancing the overall figure of merit (ZT) ∼ 53%. The enhancement in the ZT is obtained due to an increase in the electrical conductivity (∼111%) and decrease in the thermal conductivity (∼12%) resulting from increased conducting channels and phonon scattering, respectively at the interfaces between graphene and Bi 2 Te 3 nanosheets. A detailed analysis of the thermal conductivity reveals ∼4 times decrease in the lattice thermal conductivity in contrast to ∼2 times increase in the electronic thermal conductivity after the addition of graphene. Kelvin probe measurements have also been carried which reveals presence of low potential barrier at the interface between graphene and Bi 2 Te 3 nanosheets which assist the flow of charge carriers thereby, increasing the mobility of the carriers. Thus, our results reveals a significant decrease in the lattice thermal conductivity (due to the formation of interfaces) and increase in the electron mobility (due to conducting paths at the interfaces) strongly participate in deciding observed enhancement in the thermoelectric figure of merit.