Search

Increasing the collision frequency between gas molecules and photocatalysts can enhance the removal efficiency of volatile organic compounds (VOCs) and particulate matter (PM) in air. In this study, we propose an Electrostatic-Photocatalytic air purification system, containing Tesla valve, triboelectric nanogenerator (TENG), and photocatalysis parts. The incorporation of Ag@ZnO nanorod array (Ag@ZnO-NR) photocatalysts into the internal baffles of the Tesla valve pipeline effectively enhances the collision probability between air pollutant molecules and photocatalysts, and thus facilitating the removal efficiency of pollutants. Additionally, the high-voltage electricity (∼9.0 kV) generated by the TENG facilitates the separation of electron-hole pairs in the photocatalyst, leading to increased production of superoxide radicals (O •−2), hydroxyl radicals ( • OH), and holes (h+), thereby enhancing the photocatalytic efficiency. In a 1.8 L space system, we achieved an approximately 97 % removal efficiency for toluene within 130 minutes and a similar efficiency for formaldehyde (∼200 ppm) within 175 minutes. Additionally, the PM 2.5 concentration rapidly decreased from 999 μg·m−3 to 42 μg·m−3 within 6 minutes, alongside with a significantly faster pollutant removal rate compared to conventional methods. By integrating Tesla valves, TENG, and photocatalysis, this combined system presents an efficient and promising approach for addressing indoor air pollution, with potential applications across various settings. [Display omitted] • The electrostatic-photocatalytic air purifier combines Tesla valves with photocatalysis. • The Tesla valve structure enhances the photocatalytic degradation rate of VOCs. • High voltage generated by TENG boosts adsorption and photocatalytic efficiency. • The synergistic effect of electrostatic adsorption and photocatalysis is explored. [ABSTRACT FROM AUTHOR]

Ammonia synthesis through nitrate reduction can mitigate nitrate pollution and fulfill energy demands. However, the process still has limitations because it is a complex eight-electron reduction process with a high energy barrier. Herein, Cu2+, which is a highly electronegative element, was successfully integrated into NH 2 –MIL-125 (Cu–NM) using an in situ solvothermal method. This incorporation regulates the band structure of MOFs, promoting the generation and directional transfer of photogenerated charges. Furthermore, it enhances the electron density of the Cu active sites, effectively improving the catalytic activity of the catalyst s for ammonia synthesis. Density functional theory (DFT) calculations and in situ characterization further confirmed that Cu doping induces p–d hybridization between Cu 3d and NO 3 − O 2p orbitals. This facilitates the formation of a more stable bidentate mode adsorption structure for nitrates (NO 3 −) on the Cu sites, reducing the activation energy barrier of the active intermediates. Consequently, Cu–NM exhibited a high ammonia yield of 32.8 mg g cat −1.h−1 and high selectivity of 94.8%, outperforming the catalysts reported in previous studies. This study provides valuable insights into the advancement of highly active photocatalysts for nitrate reduction and ammonia production. [Display omitted] • Cu doping restructuring the directional charges transfer of Ti-O-Cu in NH 2 -UiO-66 via of Ti-O-Cu and enhanced electron transfer from ligands to metal. • Cu doping induces p-d hybridization between Cu 3d orbitals and NO 3 - O 2p orbitals, facilitating the formation of a more stable bidentate mode adsorption structure for NO 3 - on Cu sites. • Cu-NM exhibited a high ammonia yield of 32.8 mg g cat -1·h-1 with remarkable selectivity of 94.8%. [ABSTRACT FROM AUTHOR]

The development of sustainable, energy-free dissolution methods is crucial for gold recycling. For the first time, we have achieved the dissolution of gold through a triboelectric nanogenerator (TENG). With 1 wt% Au/SiO 2 as the research subject in KI solution, the gold dissolution efficiency can reach 100 % in three hours driven by R-TENG. However, by using a direct current (DC) source with 25 mA and 5 V, the gold dissolution efficiency is only 85 % after the same operation time. Meanwhile, to achieve the same 85 % gold dissolution rate, the total charge consumed from TENG is only 1.6 % of that from the DC source, indicating an ultrahigh charge utilization rate. Thus, the side reactions such as water splitting and the formation of the iodine oxide film in KI aqueous solution can be avoided by using TENG, which blocks the adhesion on the anode and facilitates the reaction. The amount of gold extracted from the waste central processing units (CPU) board (4 × 4 cm) by the solution method could reach 6 mg/piece. Hence, TENGs provide a new direction for the recovery of other metals in secondary resources and many other applications in the direction of electrochemistry can be also inspired. [Display omitted] • For the first time, we have achieved the dissolution of gold through a triboelectric nanogenerator (TENG). • To achieve the same gold dissolution efficiency, the total charge consumed by the DC source is 63 times that of the TENG. • Gold can be successfully extracted from secondary resources such as CPU, gold ore driven by R-TENG. • R-TENG drives the dissolution of gold in KI solution to avoid side reactions and the formation of iodine oxide film. [ABSTRACT FROM AUTHOR]

Water is an important resource for building different energy systems towards diversified applications. In this paper, a novel hybrid nanogenerator is proposed based on a water-wave triboelectric nanogenerator (TENG) and evaporation generator, which opens up a more effective approach to fully utilize the energy from water. This hybrid nanogenerator can solve the problem of insufficient output of water wave TENGs in calm water. The optimized peak power of water-wave TENG can reach 0.62 mW under simulated waves frequency of 2.5 Hz, while a capacitor of 0.33 µF can be charged to 15 V by TENG within 80 s in actual water waves. The evaporation generator based on wood block can continuously generate direct currents during the spontaneous evaporation of water. The solar-vapor conversion efficiency of evaporation generator can reach 84.2%, while the evaporation generator can provide a maximum current density of 3.2 μA·cm−2 and a maximum output power density of 1.4 mW·m−2 with a matching load of 10 kΩ (23 ℃, 30% RH). To demonstrate the application capability of the evaporation generator, we design a multi-stage boost circuit coupled with the pulse charging method, which can increase the voltage output and effectively reduce the charging time. The proposed hybrid nanogenerator provides a promising way for collecting both water wave and steam evaporation energy, effectively broadening methods for energy harvesting by TENGs. [Display omitted] • Hybrid nanogenerator for harvesting wave and evaporation energy is proposed for the first time. • The current density of the evaporation generator can be increased to 3.2 μA·cm−2. • The multi-stage boost circuit is designed to increase the voltage output. • It can still generate energy based on evaporation when water wave is stabilized. [ABSTRACT FROM AUTHOR]

Piezo-catalysis induced by piezoelectric polarization has been proven to be a powerful technology for potential applications in the energy and environment. It is generally accepted that piezo-catalysis derived the easily deformation from the piezoelectric materials with one or two dimensions. In this study, piezoelectric materials lead zirconate titanate (PZT) with a spherical morphology was synthesized, which is used to explore whether the widely accepted principle that is one or two-dimensional structure is necessary in the piezo-catalysis process is exclusive. We would like to clarify the relationship between deformation and piezoelectric catalytic performance. In addition, a key fundamental problem that has not yet been fully solved whether the charges of the reaction are from polarized charges or free charges. We investigate the role of polarization charges and free charges in piezoelectric catalysis by doping the piezoelectric material. It is hoped that the study of this work will re-understand and explain the mechanism of piezoelectric catalytic reaction. [ABSTRACT FROM AUTHOR]

The biodegradable triboelectric nanogenerators (TENGs) for monitoring human physiological signals have attracted immensely attention in recent years. In this work, a water-soluble TENG (WS-TENG) is manufactured by using biodegradable recycled papers and water-soluble graphite electrode. The cellulose nanocrystal (CNC) in the papers is extracted and further mixed with methylcellulose (MC) to form a CNC/MC film, which can serve as the positive electrification material and form a TENG device with the common MC film as the negative electrification material. This low-cost, light weight and biodegradable WS-TENG that can be directly washed away by water is developed as a bandage sensor. Unlike traditional gauze sensors, the water-insoluble parts of our cellulose-based can be easily separated from water for reuse. The variation of the output voltage of WS-TENG between 0 V and 2 V can accurately distinguish various respiratory states, which is enough to be used as a real-time physiological signal monitoring sensor. This fully water-soluble device can serve as an advanced medical sensor and expand the application of TENG in health care monitoring field. [Display omitted] • It is proposed for the first time to recycle paper-based materials for a fully biodegradable water-soluble WS-TENG. • The CNC/MC film has excellent triboelectric properties and can be completely degraded in the natural environment. • WS-TENG can serve as a bandage sensor for real-time monitoring human respiration and physiological signals. [ABSTRACT FROM AUTHOR]

Abstract: A novel crystalline Bi2Ti2O7 in uniform porous microspheres was synthesized by aerosol-spray assisted surfactant self-assembly which displayed strong optical response in visible region owing to the narrow energy gap. During photodegradation of p-chlorophenol and rhodamine B under visible light irradiation, this photocatalyst was more active than the Bi2Ti2O7 obtained via chemical solution decomposition, apparently owing to the larger surface area and higher crystallization degree which might promote the reactant adsorption and inhibit the charge carrier recombination. The as-prepared Bi2Ti2O7 crystal also showed much higher activity than the Bi-doped TiO2 owing to the low recombination rate between photoelectrons and holes, corresponding to the higher quantum efficiency. Besides, the Bi2Ti2O7 crystal was strongly durable and could be used repetitively for more than nine times without significant deactivation, which could be attributed to the high hydrothermal stability against phase transformation and architecture damage. [Copyright &y& Elsevier]

Abstract: Mesoporous Bi x Ti1−x O2 spheres with core–shell chamber were prepared by alcoholysis under solvothermal conditions. The cross-condensation between Ti–OH and Bi–OH ensured complete incorporation of Bi-dopants into TiO2 lattice, though Bi atom is much bigger than Ti. Meanwhile, the aggregation of titania building clusters into spheres and their subsequent reactions including dissolution and re-deposition processes lead to the hollow spheres with tunable interior structure. The Bi-doping induced strong spectral response in visible region owing to the formation of narrow intermediate energy band gaps. Meanwhile, multiple reflections within the sphere interior voids promoted the light absorbance. As a result, the as-prepared Bi x Ti1−x O2 spheres exhibited much higher activity than the undoped TiO2, the Bi2O3/TiO2 obtained by impregnating the TiO2 with Bi(NO3)3 solution, and the Bi x Ti1−x O2 after being ground during photodegradation of p-chlorophenol under visible light irradiation. Meanwhile, the Bi x Ti1−x O2 could be used repetitively for 10 times owing to the high hydrothermal stability and the absence of Bi-leaching. [Copyright &y& Elsevier]

Charge separation and surface chemistry are essential for photocatalytic reaction, which is challenging to manipulate the performance of catalyst. In this work, the effects of ferroelectric and piezoelectricity (piezophototronics) properties on photocatalytic properties were studied in detail by using PbTiO 3 monocrystalline nanoplates (PMNs). Visualization of charge distribution on the surface of PMNs was carried out by noble metal loading and selectivity dependence of crystal surface was revealed by choosing organic molecules with different charge properties. The apparent quantum efficiency (AQE) for photocatalytic water splitting can be promoted to 6.5 times by the ferroelectric/piezoelectricity synergistic modulation of the internal carriers and the interaction with the matrix. This strategy based on the coupling of ferroelectricity and piezoelectricity provides a new idea for the preparation of highly active photocatalysts and the improvement of photocatalytic performance. Image 1 • The interfacial reactions of free charges and charged/non-charged substrates were revealed. • The reaction activity and selectivity are controlled by the polar crystalline facets. • Regulating the crystalline facets polarization has no limitation on substrates and reactions. [ABSTRACT FROM AUTHOR]

Dielectric polymer materials are indispensable for the fabrication of self-powered nanosystem and electronic skin. However, the performance of the device is often seriously degraded due to the contamination of the surface. It is very important to keep the clean of the surface of the device, especially for the application of wearable devices. In this work, triboelectric nanogenerator (TENG) integrated with TiO 2 photocatalysis is developed for realizing the dual functions of energy generation and self-cleaning interface. The friction layer of TENG is sponged polydimethylsiloxane (PDMS) film which is prepared by sacrificial template method with the pore size varied from hundreds of microns to several millimeters. When the interface of TENG is contaminated by organic pollutants, the open circuit voltage (V OC) of the device decrease from 125 V to 88 V. Under the solar illumination for 35 min, the self-cleaning interface can degrade the contaminants attached on the tribo-surface, while V OC raises from 88 V to 115 V after illumination, indicating that 92% of the TENG's output performance can be fully recovered. The photocatalysis-based self-cleaning effect on polymer tribo-material can contribute to the application of TENG towards e-skin and wearable devices. Image 1 • TENG with self-cleaning function can be used for its electrical performance recovery. • Loading photocatalyst onto the surface of TENG device, its performance recovered to 90% under light irradiation. • Due to the diversity of photocatalysts and dielectric materials, it is easy to apply to self-powered nanosystem. [ABSTRACT FROM AUTHOR]

The difficulty of traditional Fenton reaction is the low conversion of Fe3+/Fe2+. The emergence of the photo-Fenton reaction can greatly improve the oxidation efficiency and Fe2+ utilization rate to a certain extent, but this system is more complicated. Here, we used the in-situ iron (Fe) ions doped titanium dioxide (TiO 2) mesocrystals (MST) as a model to study in detail the effect of the catalyst's surface Fe site and oxygen defect on the photo-Fenton reaction. This in-situ doping strategy constructs oxygen vacancies (OVs) on the surface of MST to anchor Fe ions, thereby promoting the circulation of Fe3+/Fe2+. OVs form shallow energy levels in the conduction band of MST, enhancing the separation efficiency of photogenerated electrons and holes. The content of Fe ions can adjust the energy band gap of catalyst, which accelerating the transfer of photogenerated carriers on the surface with visible light. The strong interaction between OVs and Fe ions improves the synergy between photocatalysis and Fenton reaction. Under visible light irradiation, Fex+/MST exhibits efficient degradation of organic pollutants and mineralized intermediates under a wide range of pH conditions. This work provides a potential path to prepare efficient visible light photo-Fenton catalysts. [Display omitted] • A facile method is proposed to prepare Fe(III)-doped TiO 2 mesocrystals. • Abundant oxygen vacancies are formed on the surface of TiO 2 mesocrystals. • Oxygen vacancies (O vs) and Fe ions promote the circulation of Fe3+/Fe2+. • The Fe(III)-doped TiO 2 mesocrystals has excellent degradation performance. [ABSTRACT FROM AUTHOR]

A novel nanocomposite with ZnO nanorod arrays vertically growing on the three-dimensional (3D) Ni foam has been synthesized under hydrothermal conditions, which displays both the piezoelectric and photocatalytic functions. When the solution is stirred by magnetic rotation, fluid eddies are produced within the unique macroporous structure in 3D network, causing deformation of ZnO nanorod to generate piezoelectric field. Meanwhile, UV light irradiation on ZnO semiconductor generates photoelectrons and holes, followed by starting photocatalytic degradation of organic dye pollutants in wastewater. The piezo-induced bias voltage promotes the separation of photoelectrons and holes and thus can inhibit their recombination, leading to the enhanced quantum efficiency (more than 5 times). The photocatalytic activity increased by increasing the stirring rate owing to the enhanced piezoelectric field. [ABSTRACT FROM AUTHOR]