Electrospun membrane of bismuth vanadate-polyvinylidene fluoride nanofibers for efficient piezo-photocatalysis applications.

The fabrication of a Poly (vinylidene fluoride) membrane (PVDF) and ceramic-assisted bismuth vanadate-polyvinylidene fluoride (BiVO4-PVDF) composite membrane was achieved through the utilization of the electrospinning technique. The composition and structure of the fabricated membranes were characterized by X-ray powder diffraction, Raman analysis, scanning electron microscopy, Thermo gravimetric analyzer, Fourier transform infrared spectroscopy, and UV-Vis spectroscopy techniques. The prepared polymeric membranes were then utilized for catalytic investigation and to explore, how structure affects catalytic activity using 5 mg/L, 10 mL methylene blue (MB) dye solution. Ultrasonication, visible light irradiation, and the combination were used to study piezocatalysis, photocatalysis, and piezo-photocatalysis, moreover, degradation intermediates were also explored using scavengers. Electrospun BiVO4-PVDF (BV-PVDF) composite has been found to have better piezocatalytic and photocatalytic properties than PVDF. The experimental findings reveal that the composite of BiVO4-PVDF demonstrates the highest efficiency in dye degradation, achieving a maximum degradation rate of 61% within a processing time of 180 min. The rate of degradation was calculated to be 0.0047 min-1, indicating a promising potential for the composite in the field of dye degradation.

Review on Multicatalytic Behavior of Ba0.85Ca0.15Ti0.9Zr0.1O3 Ceramic.

Ferroelectric materials are known to possess multicatalytic abilities that are nowadays utilized for removing organic pollutants from water via piezocatalysis, photocatalysis, piezo-photocatalysis, and pyrocatalysis processes. The Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZTO) ceramic is one such ferroelectric composition that has been extensively studied for electrical and electronic applications. Furthermore, the BCZTO ceramic has also shown remarkable multicatalytic performance in water-cleaning applications. The present review explores the potentiality of BCZTO for water-cleaning and bacterial-killing applications. It also highlights the fundamentals of ferroelectric ceramics, the importance of electric poling, and the principles underlying piezocatalysis, photocatalysis, and pyrocatalysis processes in addition to the multicatalytic capability of ferroelectric BCZTO ceramic.

Ball-milling synthesized Bi2VO5.5 for piezo-photocatalytic assessment.

The mechanochemical ball milling followed by heating at 650 °C for 5 h successfully produced the single-phase Bi2VO5.5 powder. Catalytic activity for methylene blue dye degradation was investigated. Raman spectroscopy and X-ray diffraction were used to confirm the phase formation. The sample's charge carrier transportation behavior was ascertained using time-dependent photocurrent analysis. The piezo-photocatalysis experiment yielded a 63% degradation efficiency for the ball-milled Bi2VO5.5 sample. The pseudo-first-order kinetics of the piezo-photocatalytic dye degradation are discerned, and the significant k value of 0.00529 min-1 is achieved. The scavenger test declares the h+ radical is the predominant active species during the piezo-photocatalysis experiment. Vigna radiata seeds were used in a phytotoxicity test to evaluate the germination index. The mechanochemical activation method facilitates reactions by lowering reaction temperature and time. The effect of improved piezo-photocatalytic efficiency on the ball-milled Bi2VO5.5 powder is an unexplored area, and we have attempted to investigate it. Here, ball-milled Bi2VO5.5 powder achieved improved dye degradation performance.

Cotton functionalized with polyethylene glycol and graphene oxide for dual thermoregulating and UV-protection applications.

A thermoregulating smart textile based on phase change material (PCM) polyethylene glycol (PEG) was prepared by chemically grafting carboxyl-terminated PEG onto cotton. Further deposits of graphene oxide (GO) nanosheets were made on the PEG grafted cotton (PEG-g-Cotton) to improve the thermal conductivity of the fabric and to block harmful UV radiation. The GO-PEG-g-Cotton was characterized by Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and field emission-scanning electron microscopy (FE-SEM). With an enthalpy of 37 and 36 J/g, respectively, the DSC data revealed that the functionalized cotton's melting and crystallization maxima occurred at 58 °C and 40 °C, respectively. The thermogravimetric analysis (TGA) presented that GO-PEG-g-Cotton was thermally more stable in comparison to pure cotton. The thermal conductivity of PEG-g-Cotton increased to 0.52 W/m K after GO deposition, while pure cotton conductivity was measured as 0.045 W/m K. The improvement in the UV protection factor (UPF) of GO-PEG-g-Cotton was observed indicating excellent UV blocking. This temperature-regulating smart cotton offers a high thermal energy storage capability, better thermal conductivity, thermal stability, and excellent UV protection.

CaCu3Ti4O12 nanoparticle-loaded cotton fabric for dual photocatalytic antibacterial and dye degradation applications.

CaCu3Ti4O12 (CCTO) nanoparticles (NPs) were screen printed on pristine cotton fabric. The CCTO-coated fabric was characterized using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), Raman, X-ray diffraction (XRD), x-ray photoelectron spectrometer (XPS), and field emission-scanning electron microscopy (FE-SEM). The modified fabric photocatalytic antibacterial and dye-degradation abilities were assessed. After 2 h of bacterial contact, unwashed CCTO-embedded cotton reduced E. coli and S. aureus by 95.1% and 94.3%, respectively. After 20 washing cycles, the modified fabric was able to eliminate S. aureus and E. coli by more than 85%. The cloth coated with CCTO-NPs degraded the methylene blue (MB) dye by 82% in 4 h, as opposed to the pure cotton's 11% degradation rate. The embedding of CCTO-NPs onto the cotton surface had minimal effect on fabric intrinsic properties like tensile strength, abrasion resistance, and water-vapor permeability.

Enhancing the Performance of Piezoelectric Wind Energy Harvester Using Curve-Shaped Attachments on the Bluff Body.

This paper presents a piezoelectric wind energy harvester that operates by a galloping mechanism with different shaped attachments attached to a bluff body. A comparison is made between harvesters that consist of different shaped attachments on a bluff body; these include triangular, circular, square, Y-shaped, and curve-shaped attachments. Simulation of the pressure field and the velocity field variation around the different shaped bluff bodies is performed and it is found that a high pressure difference creates a high lift force on the bluff body with curve-shaped attachments. A theoretical model based on a galloping mechanism is presented, which is verified by experiments. It is observed that the proposed harvester with curve-shaped attachments provides the best performance, where the harvester with a curve-shaped attachments provides the highest voltage and power output compared to the other shaped harvesters examined in this study. This paper provides a new concept for improving the power performance of the piezoelectric wind energy harvesters with modifications made on the bluff body.

Mechanochemical Synthesis of Bi2VO5.5 for Improved Photocatalytic Dye Degradation.

A single-phase Bi2VO5.5 powder is formed effectively through a mechanochemical ball milling approach at 650 °C in 5 h and its photocatalytic performance on methylene blue dye is explored. X-ray diffraction and Raman spectroscopy analytical instruments are utilized to confirm the phase formation. The evident presence of irregular-shaped grains is affirmed using a scanning electron microscope. To ascertain the chemical condition of the components present, the Bi2VO5.5 powdered sample undergo an X-Ray photoelectron spectroscopy investigation. The sample is analyzed using a time-dependent photocurrent to discern its charge carrier transportation behavior. A photocatalytic study using Bi2VO5.5 powder produced through the mechanochemical ball milling method has not been explored till now. The efficacy of the ball-milled Bi2VO5.5 powder to attain enhanced photocatalytic efficiency which hasn't been investigated till now, is explored. The ball-milled Bi2VO5.5 sample achieved 70% degradation efficiency when performing the photocatalysis investigation. The photocatalytic dye degradation discerns pseudo-first-order kinetics and achieves a notable k value of 0.00636 min-1. The scavenger test indicates that h+ radicals are the prominent active species during the photocatalysis experiment. The germination index is determined by conducting a phytotoxicity test with the use of Vigna radiata seeds. Here ball-milled Bi2VO5.5 powder attains enhanced dye degradation efficiency.

Comparative Study of the Effective Properties of 0-3 and Gyroid Triply Periodic Minimal Surface Cement-Piezocomposites.

In the present numerical simulation work, effective elastic and piezoelectric properties are calculated and a comparative study is conducted on a cement matrix-based piezocomposite with 0-3 and gyroid triply periodic minimal surface (TPMS) inclusions. The present study compares the effective properties of different piezoelectric materials having two different types of connectivity of the inclusions namely, 0-3 inclusions where the inclusions are physically separated from each other and are embedded within the matrix and the second one is TPMS inclusions having interpenetrating phase type connectivity. Effective properties are calculated for four different materials at five different volume fractions namely, 10%, 15%, 20%, 25%, and 30% volume fractions of inclusion by volume. In terms of effective properties and direct piezoelectric effect, TPMS piezocomposite is found to perform better compared to 0-3 piezocomposite. Lead-free piezoelectric material 0.5Ba(Ca0.8Zr0.2)O3 - 0.5(Ba0.7Ca0.3)TiO3 demonstrates better performance compared to all other material inclusions studied. The present study attempts to highlight improved piezoelectric effective properties of lead-free material-based piezocomposites with TPMS inclusions.

Effect of Poling on Photocatalysis, Piezocatalysis, and Photo-Piezo Catalysis Performance of BaBi4Ti4O15 Ceramics.

This study focuses on analyzing the poling effect of BaBi4Ti4O15 (BBT) on the basis of photo and piezo-catalysis performance. BBT powder is prepared via a solid state reaction followed by calcination at 950 °C for 4 h. BBT is characterized by an X-ray diffractometer, scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The optical bandgap of BBT is evaluated with the help of Tauc's plot and found to be 3.29 eV, which comes in the photon energy range of ultra-violet radiation. BBT powder is poled by using Corona poling in the presence of 2 kV mm-1 of electric field. An aqueous solution of methyl blue (MB) dye in the presence of UV radiation is used to evaluate the photo/piezocatalysis performance. Photocatalysis, piezocatalysis, and photo-piezo catalysis degradation efficiencies of poled and unpoled BBT powder are tested for 120 min of UV light irradiation. Photo-piezocatalysis shows degradation efficiencies of 62% and 40% for poled and unpoled BBT powder, respectively. Poling of BBT powder shows significant enhancement in degradation performance of MB dye in aqueous solution. Scavenger tests are also performed to identify reactive species.

Negative Poisson's ratio polyethylene matrix and 0.5Ba(Zr0.2 Ti0.8) O3-0.5(Ba0.7 Ca0.3)TiO3 based piezocomposite for sensing and energy harvesting applications.

Finite element studies were conducted on 0.5Ba(Zr0.2 Ti0.8) O3-0.5(Ba0.7 Ca0.3)TiO3 (BCZT) piezoelectric particles embedded in polyethylene matrix to create a piezocomposite having a positive and negative Poisson's ratio of -0.32 and 0.2. Polyethylene with a positive Poisson's ratio is referred to as non-auxetic while those with negative Poisson's ratio are referred to as auxetic or inherently auxetic. The effective elastic and piezoelectric properties were calculated at volume fractions of (4%, 8% to 24%) to study their sensing and harvesting performance. This study compared lead-free auxetic 0-3 piezocomposite for sensing and energy harvesting with non-auxetic one. Inherently auxetic piezocomposites have been studied for their elastic and piezoelectric properties and improved mechanical coupling, but their sensing and energy harvesting capabilities and behavior patterns have not been explored in previous literatures. The effect of Poisson's ratio ranging between -0.9 to 0.4 on the sensing and energy harvesting performance of an inherently auxetic lead free piezocomposite composite with BCZT inclusions has also not been studied before, motivating the author to conduct the present study. Auxetic piezocomposite demonstrated an overall improvement in performance in terms of higher sensing voltage and harvested power. The study was repeated at a constant volume fraction of 24% for a range of Poisson's ratio varied between -0.9 to 0.4. Enhanced performance was observed at the extreme negative end of the Poisson's ratio spectrum. This paper demonstrates the potential improvements by exploiting auxetic matrices in future piezocomposite sensors and energy harvesters.

Effect of Poling on Multicatalytic Performance of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Sr0.3)TiO3 Ferroelectric Ceramic for Dye Degradation.

Ferroelectric materials with a spontaneous polarization are proven to be potential multicatalysts in water remediation applications. The composition of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Sr0.3)TiO3 (BST-BZT) was examined for photocatalysis, piezocatalysis, and piezo-photocatalysis processes by degrading an azo dye named methylene blue (MB). Generally, dis-aligned dipoles restrict the catalytic activities due to which the BST-BZT powder sample was poled by the corona poling technique. Coupled piezocatalysis and photocatalysis process, i.e., the piezo-photocatalysis process has shown maximum dye degradation. There was a significant improvement in degradation efficiency by using a poled BST-BZT sample compared to the unpoled sample in all processes, thus the results suggest an extensive scope of poled ferroelectric ceramic powder in the catalysis field.

Sonophotocatalytic Dye Degradation Using rGO-BiVO4 Composites.

Reduced graphene oxide (rGO)/bismuth vanadate BiVO4 composites are fabricated with varied rGO amounts (0, 1, 2, and 3 wt%) through the synergetic effects of ultrasonication, photoinduced reduction, and hydrothermal methods, and the materials are tested as tools for sonophotocatalytic methylene blue (MB) dye degradation. The effect of rGO content on the sonophotocatalytic dye degradation capabilities of the composites are explored. Characterization of the proposed materials is done through transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transformation infrared spectroscopy as well as scanning electron microscopy. The coexistence of BiVO4 and rGO is confirmed using Raman spectroscopy and XRD. TEM confirms the existence of interfaces between rGO and BiVO4 and XPS affirms the existence of varied elemental oxidation states. In order to investigate the charge carriers transportation, time-dependent photocurrent responses of BiVO4 and 2 wt%- rGO/BiVO4 are done under visible light irradiation. The sonophotocatalytic MB dye degradation in an aqueous medium displays promising enhancement with rGO doping in rGO/BiVO4 composite. The 2 wt%- rGO/BiVO4 sample exhibits ≈52% MB dye degradation efficiency as compared to pure BiVO4 (≈25%) in 180 min of the sonophotocatalysis experiment. Phytotoxicity analysis through germination index is done using vigna radiata seeds.

Flexible Ag@LiNbO3/PVDF Composite Film for Piezocatalytic Dye/Pharmaceutical Degradation and Bacterial Disinfection.

A flexible poly(vinylidene difluoride) (PVDF) composite film embedding LiNbO3 ceramics decorated with silver nanoparticles (Ag NPs) has been synthesized using the solvent casting method. The polar ß-phase, Ag NPs, and LiNbO3 phases were confirmed in the composite film using various characterization methods. The composite film showed promising degradation of cationic and anionic dyes using piezocatalysis under ultrasonication. Moreover, this composite film also effectively degraded two model pharmaceutical pollutants named tetracycline and ciprofloxacin using piezocatalysis under ultrasonication. In addition to this, this composite film piezocatalytically removed more than 99.999% of Escherichia coli and 96.65% of Staphylococcus aureus bacteria within 180 min of sonication. The piezocatalytic performance of the PVDF composite film embedding Ag-loaded LiNbO3 in all three applications was superior to that obtained in the case of the PVDF film embedding LiNbO3 and the bare PVDF film. This demonstrates the pronounced effect of Ag NPs in the increase of piezocatalytic activity in the composite film.

Ag-nanoparticles-loaded Ba0.85Ca0.15Ti0.9Zr0.1O3 for multicatalytic dye degradation.

Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZTO) ferroelectric ceramic loaded with Ag nanoparticles (NPs) was explored for its photo/piezocatalytic performance. The presence of Ag loading on BCZTO ceramic was confirmed using electron microscopes. X-ray photoelectron spectroscopy revealed the metallic chemical state of Ag NPs loaded on the surface of BCZTO ceramic. The absorbance spectrum of the Ag-loaded BCZTO sample showed a visible light absorption hump due to the phenomenon of surface plasmonic resonance. During the photocatalysis process, the [Formula: see text]99% of rhodamine B (RB) dye was degraded in aqueous solution using the Ag-loaded BCZTO sample, showing its promising photocatalysis activity. During the piezocatalysis process, the [Formula: see text]95% of RB dye was degraded using the Ag-loaded BCZTO sample, showing its promising piezocatalytic activity. The ·OH radical species were found responsible for the photocatalytic and piezocatalytic performance. The photo/piezocatalytic performance was found to be consistent over five cycles, indicating promising reusability of the Ag-loaded BCZTO sample.

Ag nanoparticles loadedBa0.85Ca0.15Ti0.9Zr0.1O3for multicatalytic dye degradation.

Ba0.85Ca0.15Ti0.9Zr0.1O3(BCZTO) ferroelectric ceramic loaded with Ag nanoparticles (NPs) was explored for their photo/piezocatalytic performance. The presence of Ag loading on BCZTO ceramic was confirmed using the electron microscopes. X-ray photoelectron spectroscopy revealed the metallic chemical state of Ag NPs loaded on the surface of BCZTO ceramic. The absorbance spectrum of the Ag loaded BCZTO sample showed visible light absorption hump due to the phenomenon of surface plasmonic resonance (SPR). During the photocatalysis process, the ~99% of rhodamine B (RB) dye was degraded in aqueous solution using Ag loaded BCZTO sample showing its promising photocatalysis activity. During piezocatalysis process, the ~95% of RB dye was degraded using Ag loaded BCZTO sample showing its promising piezocatalytic activity. The •OH radical species were found responsible behind the photocatalytic and piezocatalytic performance. The photo/piezocatalytic performance was found to be consistent over five cycles indicating promising reusability of Ag loaded BCZTO sample.

Solar Energy Harvesting using Candle-Soot-Coated Thermoelectric Materials.

This article reports the thermoelectric-based solar energy harvesting. The effect of candle soot (CS) coating on solar energy harvesting potential of thermoelectric modules is studied. To compare the performance, uncoated/coated modules are exposed to solar radiations (through Fresnel lens) and the other side is kept at lower temperature using continuous water flow. Substantial enhancements in electrical outputs are observed due to CS coating on the upper surface of the thermoelectric module. The open-circuit voltage and short-circuit current across coated module improve more than six times in comparison to the uncoated module with maximum voltage and current reaching up to 1.5 V and 14 mA. Similarly, the generator can deliver a maximum power of 10 mW across a resistance of 50 Ω. Results indicate that the CS coating is an effective technique to improve the performance of thermoelectric materials for running sensors and other low-power electronic devices.

TiO2@C core@shell nanocomposites: A single precursor synthesis of photocatalyst for efficient solar water treatment.

This study reports the facile synthesis of highly photoactive TiO2@C core@shell nanocomposites through a single alkoxide precursor. TiO2 and carbon-based hybrid nanomaterials are popular photocatalysts owing to their abundance, low toxicity, and high stability, making them strong candidates for practical solar water-treatment applications. However, synthesis of such nanomaterials is often a multi-step process and requires careful control of the external carbon source for producing the desired morphology. In this regard, this study reports the synthesis of well-dispersed TiO2@C nanocomposites without the need of an external carbon source. The resulting photocatalyst was employed for treatment of various water-borne pollutants including several dyes, pharmaceuticals, and pathogens. Rapid mineralization of pollutants could be achieved even with low amounts of catalyst, with the performance well exceeding that of pristine TiO2 and P25 Degussa. Results indicate that incorporation of C increases visible-light absorption and greatly improves the separation of photogenerated charge carriers. Given the facile synthesis and the wide scope of operation, the proposed catalyst could be a significant step towards practical photocatalytic solar water-treatment.

Diesel Exhaust Emission Soot Coated Pyroelectric Materials for Improved Thermal Energy Harvesting.

Pyroelectric performance is significantly improved using a coating of diesel exhaust soot. Coated pyroelectric sample (lead zirconate titanate) is exposed to a temporal temperature gradient. Under the application of infrared (IR) heating for a given temperature gradient, the maximum open circuit voltage improves more than four times, electric current across a resistance of 10 ohm improves more than six times, and the stored energy in 10 µF capacitor is enhanced by 17 times. These results are important from two aspects: 1) utilization of waste diesel exhaust soot and 2) improving energy harvesting performance of pyroelectric materials.

Diesel soot coated non-woven fabric for oil-water separation and adsorption applications.

The diesel soot (DS) coated non-woven fabric was studied for oil-water separation along with the adsorption of dyes, detergents, and pharmaceuticals. The DS coated non-woven fabric showed more than 95% separation efficiency and consistent repeatable performance during oil-water separation experiment. In addition to this, the DS coated non-woven fabric of 17.2 cm2 area successfully adsorbed ~85%, 97%, and 100% methylene blue (MB) dye, ciprofloxacin, and detergent, respectively from their respective solutions within 30 min, which was not possible using uncoated non-woven fabric. The DS coated non-woven fabric was found to be hydrophobic with the contact angle of 140° which was almost invariant upto 60 °C. Hence, the DS coated non-woven fabric showed promising performance in the oil-water separation and adsorption applications.

Vibration induced refrigeration using ferroelectric materials.

This article aims to propose a cantilever based cooling device employing non-axis symmetric placement of bulk ferroelectric patches. Ambient mechanical vibrations produce large stresses in cantilevers resulting in elastocaloric effect associated with ferroelectrics. Further, design allows cascading of several cantilevers to achieve large cooling response. A finite element analysis of the system was performed using material properties of bulk 0.50Ba(Zr0.2Ti0.8)O3-0.50(Ba0.7Ca0.3)TiO3. An individual element could produce a peak elastocaloric effect of 0.02 K (324 K); whereas the proposed system could achieve a temperature drop of 0.2 K within 50 seconds (10 elements, 1.5 Hz). Furthermore, net cooling can be further improved about ~2 K (using 10 cantilevers) for a starting temperature of 358 K. This study shows that elastocaloric effect in ferroelectric materials is capable of converting waste mechanical vibration into refrigeration effect which is not reported so far.