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Contact‐electro‐catalysis (CEC) has garnered significant interest as a viable method for degrading organic pollutants. Nevertheless, the current array of catalyst materials for CEC is restricted, and their effectiveness is frequently undermined by environmental influences, resulting in diminished catalytic performance. Herein, a new fluorinated graphite [(CFx)n] catalyst is presented that notably expands the repertoire of available catalyst materials for CEC. It is demonstrated that the (CFx)n catalyst maintains high catalytic activity under nonilluminated conditions and exhibits excellent stability under high‐temperature conditions, surpassing traditional organic polymer CEC catalysts. Furthermore, DFT (density functional theory) calculations reveal the key factors affecting catalytic performance. An in‐depth analysis of the influence of temperature on CEC efficiency is also conducted. The cyclic tests verify that the (CFx)n powders sustain a catalytic efficacy of over 95% and proficiently decompose various organic pollutants, underscoring its promise for large‐scale treatment systems targeting organic pollutants. These results carry significant implications for the progression of CEC technology in environmental remediation efforts and offer valuable direction for the enhancement of catalyst efficiency and stability. [ABSTRACT FROM AUTHOR]

Contact Electro‐Catalysis (CEC) using commercial dielectric materials in contact‐separation cycles with water can trigger interfacial electron transfer and induce the generation of reactive oxygen species (ROS). However, the inherent hydrophobicity of commercial dielectric materials limits the effective reaction sites, and the generated ROS inevitably undergo self‐combination to form hydrogen peroxide (H2O2). In typical CEC systems, H2O2 does not further decompose into ROS, leading to suboptimal reaction rates. Addressing the generation and activation of H2O2 is therefore crucial for advancing CEC. Here, we synthesized a catalyst by loading the dielectric material polytetrafluoroethylene (PTFE) onto ZSM‐5 (PTFE/ZSM‐5, PZ for short), achieving uniform dispersion of the catalyst in water for the first time. The introduction of an FeIII‐initiated self‐cycling Fenton system (SF‐CEC), with the synergistic effects of O2 activation and FeIII‐activated H2O2, further enhanced ROS generation. In the FeIII‐initiated SF‐CEC system, the synergistic effects of ROS and protonated azo dyes enabled nearly 99 % degradation of azo dyes within 10 minutes, a sixfold improvement compared to the CEC system. This represents the fastest degradation rate of methyl orange dye induced by ultrasound to date. Without extra oxidants, this system enabled stable dissolution of precious metals in weakly acidic solutions at room temperature, achieving 80 % gold dissolution within 2 hours, 2.5 times faster than similar CEC systems. This study also corrects the unfavorable perception of CEC applications under acidic conditions, providing new insights for the fields of dye degradation and precious metal recovery. [ABSTRACT FROM AUTHOR]

Contact‐electrification at solid–liquid interfaces (SL‐CE) and contact‐electro‐catalysis (CEC) are two blooming research areas with promising applications in sustainable energy, sensing, and chemical processes. However, prior research has neglected the impact of electronic defects on the ability of high‐performance tribo‐materials, like fluorinated polymers, to perform SL‐CE/CEC. Here, through first‐principle calculations, the addition of surface functional groups to fluorinated ethylene propylene (FEP) enables the tuning of its molecular orbitals' positions, and displacing deep‐level defect states from the HOMO‐LUMO gap is shown. Thereafter, FEP films are modified accordingly by plasma etching; resulting in a significant performance improvement of up to 202% (charge) in SL‐CE experiments, and up to 398% (kinetic rate) in CEC dye degradation. This study provides a theoretical and experimental framework to design high‐performance materials for SL‐CE and CEC, and insights into their physical mechanisms and defect passivation, which are all fundamental for the advancement of these fields. [ABSTRACT FROM AUTHOR]

The conversion of methane under ambient conditions has attracted significant attention. Although advancements have been made using active oxygen species from photo‐ and electro‐ chemical processes, challenges such as complex catalyst design, costly oxidants, and unwanted byproducts remain. This study exploits the concept of contact‐electro‐catalysis, initiating chemical reactions through charge exchange at a solid–liquid interface, to report a novel process for directly converting methane under ambient conditions. Utilizing the electrification of commercially available Fluorinated Ethylene Propylene (FEP) with water under ultrasound, we demonstrate how this interaction promote the activation of methane and oxygen molecules. Our results show that the yield of HCHO and CH3OH can reach 467.5 and 151.2 μmol ⋅ gcat−1, respectively. We utilized electron paramagnetic resonance (EPR) to confirm the evolution of hydroxyl radicals (⋅OH) and superoxide radicals (⋅OOH). Isotope mass spectrometry (MS) was employed to analyze the elemental origin of CH3OH, which can be further oxidized to HCHO. Additionally, we conducted density functional theory (DFT) simulations to assess the reaction energies of FEP with H2O, O2, and CH4 under these conditions. The implications of this methodology, with its potential applicability to a wider array of gas‐phase catalytic reactions, underscore a significant advance in catalysis. [ABSTRACT FROM AUTHOR]

Perfluoroalkyl substances (PFASs) are persistent and toxic to human health. It is demanding for high‐efficient and green technologies to remove PFASs from water. In this study, a novel PFAS treatment technology was developed, utilizing polytetrafluoroethylene (PTFE) particles (1–5 μm) as the catalyst and a low frequency ultrasound (US, 40 kHz, 0.3 W/cm2) for activation. Remarkably, this system can induce near‐complete defluorination for different structured PFASs. The underlying mechanism relies on contact electrification between PTFE and water, which induces cumulative electrons on PTFE surface, and creates a high surface voltage (tens of volts). Such high surface voltage can generate abundant reactive oxygen species (ROS, i.e. O2⋅−, HO⋅, etc.) and a strong interfacial electrostatic field (IEF of 109~1010 V/m). Consequently, the strong IEF significantly activates PFAS molecules and reduces the energy barrier of O2⋅− nucleophilic reaction. Simultaneously, the co‐existence of surface electrons (PTFE*(e−)) and HO⋅ enables synergetic reduction and oxidation of PFAS and its intermediates, leading to enhanced and thorough defluorination. The US/PTFE method shows compelling advantages of low energy consumption, zero chemical input, and few harmful intermediates. It offers a new and promising solution for effectively treating the PFAS‐contaminated drinking water. [ABSTRACT FROM AUTHOR]

Chemical functional groups on solid surfaces greatly influence contact electrification (CE) at water-solid interfaces. Previous studies of their effects mainly swapped materials or bonded related molecules to a substrate, introducing other factors of influence. This work aims at unambiguously demonstrating the role of functional groups in water-polymer CE. We study the contribution of functional groups, by using ion coupled plasma etching to modify a high-density polyethylene (HDPE) film, a polymer with a naturally quasi-null charge transfer ability. Fluoride (HDPE−F) and hydroxyl (HDPE−OH) functional groups are generated and endowed HDPE with charge withdrawing ability. HDPE−F withdraws 2.5–2.7 times more charges than HDPE−OH. Concurrently, the surface charges accumulated generate electrostatic forces, altering the droplets motion. This phenomenon provides another approach to study CE, helping to evaluate the contribution of electrons to solid-liquid CE. Finally, employing HDPE−F to perform contact-electro-catalysis shows its activity is 2.4 times higher than that of commercial fluorinated films. [ABSTRACT FROM AUTHOR]

The treatment of organic pollutants in wastewater is becoming a great challenge for social development. Herein, a novel contact-piezoelectric bi-catalysis of a ZnO@ PVDF composite membrane was prepared by electrospinning technology. The obtained ZnO@PVDF composite membranes is superior to the pure PVDF membrane in decomposing methyl orange (MO) under ultrasonication at room temperature, which is mainly attributed to the synergy effect of the contact-electro-catalysis of dielectric PVDF, as well as the piezoelectric catalysis of tetrapodal ZnO and the β-phase of PVDF. The heterostructure of the piezoelectric-ZnO@dielectric-PVDF composite is beneficial in reducing the electron/hole pair recombination. As compared to the pure PVDF membrane, the catalytic degradation efficiency of the ZnO@PVDF composite membrane was improved by 444.23% under ultrasonication. Moreover, the reusability and stability of the composite membrane are comparable to those of the traditional powdered catalyst. This work offers a promising strategy for improving the pollutant degradation by combining contact-electro-catalysis with piezoelectric catalysis. [ABSTRACT FROM AUTHOR]

Frequent cyanobacterial blooms pose a serious threat to the aquatic ecosystem and human health, so developing an efficient algae removal method is a long-term goal for bloom management. Current technologies for algal bloom control need urgent improvement in terms of algicide recovery, eco-friendliness and cost. Here we propose a contact-electro-catalytic method, using polytetrafluoroethylene (PTFE) film as a reusable catalyst. This contact-electro-catalytic approach involves the generation of reactive oxygen species (e.g., O 2 •–, HO•, 1O 2 and H 2 O 2) through water-PTFE contact electrification under the low-frequency ultrasonic waves, facilitating the inactivation of algae. The removal rate of the cyanobacterium Microcystis aeruginosa (M. aeruginosa) exposured to the water-PTFE contact-electro-catalytic system is almost five times greater than that of ultrasound alone after 5 h. A mechanistic investigation revealed that the contact-electro-catalytic system damaged the photosynthetic activity, antioxidant system and membrane integrity of the cells. Additionally, LC-MS metabolomic analysis indicated that this system caused substantial significant disruptions in the TCA cycle, amino acid metabolism, purine metabolism and phospholipid metabolism. Three-dimensional fluorescence spectroscopy suggested contact-electro-catalysis could further availably degrade the organic matter. We anticipate that this method can provide an eco-friendly, highly efficient and economic approach for effective control of harmful algal blooms. [Display omitted] ● Water-PTFE contact-electro-catalysis showed superior inactivation efficiency for algal cells than ultrasound alone. ● Ultrasound can induce PTFE film to generate aqueous reactive oxygen species. ● The contact-electro-catalytic inactivation mechanism of algae is proposed. ● PTFE film as a catalyst can be successfully reused without secondary pollution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fluorocarbon polymers mediated contact-electro-catalysis under ultrasound firstly activated PMS (FCPs/PMS/US) • The FCPs/PMS/US performed efficiently in eliminating emerging pollutants. • The main reactive oxidative species in FCPs/PMS/US was singlet oxygen. • −F density of FCPs determined electron transfer and degradation performance. Peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) have been extensively investigated for environmental pollutants remediation. Moreover, systematic exploration of catalysts with the high-efficient, cost-effective, and environment-durable properties has been usually recognized as the crucial pathway to boost PMS activation and enhance pollutants degradation. Herein, we demonstrated that the inert fluorocarbon polymers (FCPs) mediated contact-electro-catalysis (CEC) under ultrasound can be utilized to activate PMS (FCPs/PMS/US) for high-efficient degradation and detoxication of emerging pollutants (EPs). The catalytic EPs degradation process was dominant with 1O 2 pathway, accompanied by radical pathways (•OH, SO 4 •−, and O 2 •−). Density functional theory calculations and correlation analysis provided strong evidence for the fluorine (–F) density-dependent electron transfer among H 2 O-FCPs-electron acceptors, which determined the generation of reactive oxidative species and EPs degradation rate in FCPs/PMS/US. Consequently, fluorinated ethylene propylene (FEP) with the highest –F density exhibited higher degradation rate of sulfadiazine (k obs = 0.043 min−1, at an FEP dosage of 0.25 g·L−1) compared to polytetrafluoroethylene and polyvinylidene fluoride. Besides, the FCPs/PMS/US system showed excellent stability, durability, and promising applicability for high-salinity seawater remediation, with the electrical energy per log order of 0.53 kWh·m−3. This study provided a novel route for PMS activation and stimulates further exploration of CEC for environmental remediation. [ABSTRACT FROM AUTHOR]

Energy and environmental challenges stand as pivotal issues in contemporary society. This study presents a novel solid-liquid-solid contact-electro-catalytic (CEC) approach based on n-type and p-type silicon wafers for the degradation of organic dyes such as methylene blue, rhodamine B, eriochrome black T and crystal violet. Notably, under indoor light conditions, the degradation efficiency of 5 ppm methylene blue can achieve an exceptional 96.25 % within a brief 18-min-friction treatment. Our investigation elucidates that the catalytic mechanism arises from the synergistic interplay between electron transitions induced by the tribovoltaic effect and electron transfer facilitated by CEC. Furthermore, the solid-liquid-solid CEC exhibits remarkable attributes such as complete recyclability and reusability, thereby opening new avenues for advancements in solid-liquid-solid CEC research. [Display omitted] • A novel contact-electro-catalytic method based tribovoltaic effect is proposed. • Electron transfer and transition jointly promote the generation of free radicals. • This method could effectively utilize mechanical energy. • Methylene blue molecules can also be degraded in the dark. [ABSTRACT FROM AUTHOR]

The complex of heavy metals and organic acids leads to high difficulty in heavy metals separation by traditional technologies. Meanwhile, alkaline precipitation commonly used in industry causes the great consumption of resources and extra pollution. Herein, the effective decomplexation of Cu(Ⅱ)-EDTA and synchronous recycling of Cu2+ were realized by contact-electro-catalysis (CEC) coupled with capacitive deionization (CDI) innovatively. In particular, fluorinated ethylene propylene (FEP) as dielectric powders could generate reactive oxygen species under ultrasonic stimulation, realizing continuous deaminization and decarboxylation of Cu(Ⅱ)-EDTA and accelerating the totally breakage of Cu-O and Cu-N bonds. Additionally, the degradation pathway and intermediates evolution of Cu(Ⅱ)-EDTA were investigated using various characterization methods. It was confirmed that decarboxylation predominantly governed the degradation process of Cu(Ⅱ)-EDTA in CEC. During the course of treatment, the degradation ratio of Cu(Ⅱ)-EDTA reached 86.4 % within 150 min. Impressively, this strategy had satisfactory applicability to other metal combinations and excellent cycle stability. Subsequently, the released Cu ions were captured by CuSe cathode electrode through CDI. This research elucidated the degradation mechanism of persistent organic pollutant during CEC, and provided a novel approach for efficiently treating industrial wastewater containing metal complexes and advancing the exploitation and utilization of new technologies for metal recovery. [Display omitted] • The reactive oxygen species were generated in CEC without extra oxidants. • FEP as dielectric powders could effectively degrade Cu(Ⅱ)-EDTA in CEC. • CEC coupled CDI could degrade Cu(Ⅱ)-EDTA and directly capture Cu2+. • The decomplexation of Cu(Ⅱ)-EDTA in CEC was dominated by decarboxylation. [ABSTRACT FROM AUTHOR]

Contact-electro-catalysis (CEC) usually uses polymer dielectrics as its catalysts under mechanical stimulation conditions, which although has a decent catalytic dye degradation effect still warrants performance improvement. A carrier separation promotion strategy based on an internal electric field by polarization can effectively improve ferroelectric material performance in photocatalysis and piezocatalysis. Therefore, carrier separation as a necessary process of CEC also can be promoted and is largely expected to improve CEC performance theoretically. However, the carrier separation enhancement by the internal electric field strategy has not been achieved in the CEC experiment yet, because of the difficulty of building an internal electric field in an inert polymer dielectric. Herein, a polytetrafluoroethylene (PTFE) dielectric was charged through an electret process, which was believed to establish an internal electric field for CEC catalysts proved by KPFM, XPS, and triboelectric nanogenerator voltage output analysis. The fastest degradation rate of methyl orange reached over 90% at 1.5 h, while the hydroxyl free radical (•OH) yield of the PTFE electret was nearly three times that of the original PTFE. Density functional theory (DFT) calculations verified that the potential barrier of interatomic electron transfer between PTFE and H 2 O was reduced by 37% under the internal electric field. The electret strategy used herein to optimize the PTFE catalyst provides a base for the use of other general plastics in CEC and facilitates the production of easily prepared, easily recyclable, and inexpensive polymer dielectric catalysts that can promote large-scale pollutant degradation via CEC.

The treatment of organic pollutants in wastewater is becoming a great challenge for social development. Herein, a novel contact-piezoelectric bi-catalysis of a ZnO@ PVDF composite membrane was prepared by electrospinning technology. The obtained ZnO@PVDF composite membranes is superior to the pure PVDF membrane in decomposing methyl orange (MO) under ultrasonication at room temperature, which is mainly attributed to the synergy effect of the contact-electro-catalysis of dielectric PVDF, as well as the piezoelectric catalysis of tetrapodal ZnO and the β-phase of PVDF. The heterostructure of the piezoelectric-ZnO@dielectric-PVDF composite is beneficial in reducing the electron/hole pair recombination. As compared to the pure PVDF membrane, the catalytic degradation efficiency of the ZnO@PVDF composite membrane was improved by 444.23% under ultrasonication. Moreover, the reusability and stability of the composite membrane are comparable to those of the traditional powdered catalyst. This work offers a promising strategy for improving the pollutant degradation by combining contact-electro-catalysis with piezoelectric catalysis.

[Display omitted] • Applicability of contact-electro-catalysis for degradation of common antibiotics. • Novel advanced oxidation process for antibiotic removal from wastewater. • Proposed mechanism of reactive oxygen species generation revealed. • Polytetrafluoroethylene shown to be a cost-effective, stable catalytic material. • Membrane filtration allows reuse of fluoropolymer catalyst in antibiotic removal. Antibiotic contamination of water bodies is a major concern in environmental management. Despite their superior efficacy in antibiotic removal, advanced oxidation processes (AOPs) have yet to be widely adopted owing to their substantial cost associated with the large amounts of chemicals required. In this study, a novel contact-electro-catalysis (CEC) process with reusable polytetrafluoroethylene (PTFE) particles as a trigger catalyst was applied to replace traditional AOPs, and it was able to degrade three typical antibiotics (sulfamethoxazole [SMX], ciprofloxacin [CIP], and tetracycline [TET]) in the secondary effluent of a wastewater treatment plant for the first time. The PTFE particles at a concentration of 0.8 g/L were introduced into antibiotic solutions with an antibiotic concentration of 1 mg/L, and the removal rates of SMX, CIP, and TET after a 90-min operation time reached 50 %, 80 %, and 90 %, respectively. Our findings revealed that the CEC reaction generated ● OH and 1O 2 , contributing substantially to antibiotic degradation. Thus, new reactive oxygen species generation mechanisms during the CEC process were proposed. Furthermore, we fabricated polyvinylidene fluoride nanofiber membranes using electrospinning to recycle PTFE particles, where a nearly 100 % recovery rate through dead-end filtration was realized with a high water flux of 7.5 m3/(m2∙h). The results of this study provide a promising approach for antibiotic removal from wastewater. [ABSTRACT FROM AUTHOR]

Advanced oxidization processes (AOPs) offer promising solutions for addressing the fouling issues in membrane separation systems. However, the high energy requirements for electrical or light power in the AOPs can be a drawback. In this study, we present a contact-electro-catalysis (CEC)-based approach for controlling membrane fouling, which is stimulated by mild ultrasonic irradiation. During this process, electrons are transferred between a dancing polytetrafluoroethylene membrane and water or oxygen molecules, resulting in the formation of free radicals • OH and • O 2 - . These free radicals are capable of degrading or inactivating foulants, eliminating the need for additional chemical cleaners, secondary waste disposal, or external stimuli. Furthermore, the time-dependent voltage spikes/oscillations (peak, +7.8/-8.2 V) generate a nonuniform electric field that drives dielectrophoresis, effectively keeping contaminants away from the membrane surface and further enhancing the antifouling performance of the dancing membrane. Therefore, the CEC-assisted membrane separation system offers a green and effective strategy for controlling membrane fouling through mild mechanical stimulation.

Metal-organic frameworks (MOFs) have been used in triboelectric areas for either improving the outputs or expanding some novel applications. However, research on the effects of the grafted groups of MOFs molecular to triboelectricity remains scarce. Here, we modified the MIL-101(Cr) with three groups (pyridine, amino, nitro) to obtain a series of X-MOFs (X = -PY, -NH 2 , -H and -NO 2) and clarified their position in triboelectric series. The great electron-donating ability of pyridine granted PY-MOF positive tribo-polarity and effectively improved the power density by 9.6 times. Moreover, PY-MOF was proved as significant contact-electro-catalytic (CEC) material with degradation rate of 97% in 3 h via degradation of methylene blue (MB) dye in aqueous environment. This work shows that the modification of MOF molecular with functional groups can modulate the triboelectric properties of MOFs for largely improving the output performance and show great application prospects in the field of tribo-catalysis. [Display omitted] • The MIL-101(Cr) was modified with functional groups (X = -pyridine (PY), -NH 2 , -H, or -NO 2) to obtain the X-MOFs. • The position of X-MOFs in triboelectric series was clarified to be between PA and PET. • The PY-MOF with great tribo-positive effectively improved the power density by 9.6 times. • The degradation rate of methylene blue solution by PY-MOF reached 97% in 3 h. [ABSTRACT FROM AUTHOR]

Contact-electro-catalysis has been shown to be a new method for catalytic degradation of pollutants. However, the catalytic efficiency of contact-electro-catalysis (CEC) realized by ultrasonic method still has great potential for improvement. Here, we propose a wind-driven, Al@Al 2 O 3 and PTFE combined rotational mode liquid-solid triboelectric nanogenerator (TENG) contact-electro-catalytic and adsorbable device. The contact electrification of the liquid-solid interface during mechanical rotation makes the treatment efficiency of organic pollutants much higher than other advanced oxidation processes. Taking crystal violet (CV) as the target pollutant, when the linear speed of the rotator is 1.41 m s-1, the k values for low-concentration and high-concentration crystal violet are 2.24 min-1 and 0.26 min-1, respectively. This is a huge advance in the field of catalysis. In addition, the device can also monitor the treatment progress of organic pollutants in real time. [Display omitted] • A great breakthrough in the degradation efficiency (c = 10 mg L−1, k ≈ 2.24 min-1). • Al 2 O 3 is the first time to realize catalysis without light participation. • The rotating mode ensures that the whole domain is reaction domain. • Real-time monitoring of organic dyestuff degradation. [ABSTRACT FROM AUTHOR]

Contact-electro-catalysis (CEC) has been proposed as an efficient mechanism for organic pollutant degradation. However, the effects of chemical and physical properties of catalysts on the CEC efficiency have not been reported so far. Importantly, solving the secondary pollution caused by micro-nano catalysts due to the difficulty of recycling and inability to degrade is another bottleneck for achieving the commercial application of CEC. In this work, we synthesized a micro-nano catalyst with tunable chemical groups on the surface based on magnetic nanoparticles for the degradation of methyl orange (MO) via CEC. With the increase of the electronegativity of the chemical groups (R-F>R-CH 3 >R-NH 2), the degradation efficiency of MO also be improved obviously. The low surface energy of hydrophobic particles leads to the existence of a threshold (e.g., 20 mg R-F per 50 ml MO solution) for the exposed total surface area of the catalyst in aqueous solution, which is the main reason for the nonlinear increase of catalyst mass and CEC efficiency. Previously reported toxic non-degradable fluoride catalysts (e.g., FEP, PTFE) can be effectively replaced by catalysts R-CH 3. Using the R-CH 3 in CEC, the degradation efficiency of MO reaches 99% within 2 h. The micro-nano R-CH 3 catalyst can be recycled by nearly 100% through the magnetic separator, and the catalytic efficiency can reach more than 97% after ten cycles of CEC. We expect this attractive catalyst to be a promising candidate for applications in large-scale organic pollutant degradation systems although more work on system parameter optimization needs to be further addressed. [Display omitted] • Synthesized novel magnetic nano-micro catalysts for MO degradation by CEC. • Degradation efficiency of MO via CEC is still over 97% when the novel catalyst was reused by ten cycles. • Recovery of magnetic catalyst approaches 100% after CEC degradation process. [ABSTRACT FROM AUTHOR]

• Insulator polymers enable catalytic degradation of organic pollutants in sewage. • Liquid-solid contact electrification can generate reactive oxygen species. • Light plays an important role in contact electrocatalysis of polymers. • Contact electrocatalysis enables a dramatic improvement in rate constants. Under the limitation of the carrier yield and mobility of semiconductor photocatalysts and the reaction domain, it seems that the photocatalytic efficiency cannot be greatly improved. Here, an efficient contact-electro-catalysis (CEC) system based on droplet triboelectric nanogenerator (TENG) is developed. Instead of using traditional semiconductor catalysts, the electric charge transferred during the electrification process of the contact between water droplets and polytetrafluoroethylene (PTFE) is used to participate in catalysis, and the output electrical signal can also monitor the degree of catalysis. The important role of light in the circulation of this CEC system is studied and discussed for the first time. It is proved that the contact electrification at the liquid-solid interface is accompanied by the generation of a large number of strong oxidizing radicals. The efficient transport of charge carriers driven by mechanical force and the active oxygen species distributed in the whole domain greatly improve the degradation rate of dyes. The experimental data show that the degradation efficiency of crystal violet (CV) reaches 90% within 38 s, and the rate constant k is as high as 3.7 min−1. This is a breakthrough in the field of catalysis. [Display omitted] [ABSTRACT FROM AUTHOR]

Contact electrification (CE), as a well-known physical phenomenon, is widely used in energy, purifying applications. However, employing the electron-transfer in heterophase interfaces CE during mechanical stimulation to induce chemical reactions is rarely reported. Recently, the concept of contact-electro-catalysis (CEC) was proposed, which represents the reactivity of charge exchange at heterogeneous interfaces and the catalytic performance of pristine dielectric powders. In this study, we aim to investigate the optimal parameters for CEC under the ultrasonic reaction condition. We investigated the degradation of methyl orange (MO) solution by Fluorinated Ethylene Propylene (FEP) powder under different ultrasonic powers of 120 W, 240 W, 360 W, 480 W, 600 W, and different frequencies of 20 kHz, 28 kHz, 40 kHz and 89 kHz, in 240 min. The experimental results showed that the final degradation rate of MO increases with the increase of ultrasonic power. And the highest final degradation rate was obtained at the ultrasonic frequency of 40 kHz. Meanwhile, it is found that a highest reaction rate was achieved around 22 ℃ with the FEP as the catalyst in our experiment. Furthermore, we studied the effect of different dielectric particles on the organic solutions' decolorization. It is found that the CEC degradation is more prone to occur in the catalyst with strong electron-withdrawing ability (e.g. FEP vs. MO), while apparent physical adsorption occurs when the catalyst and the targeted organic ions possess opposite electric polarity (e.g. Nitrile Butadiene Rubber (NBR) vs. MO, or FEP vs. Rhodamine B (RhB)). This study helps to characterize the optimal conditions and the further understanding of CEC reactions and catalysts. [Display omitted] • Optimal ultrasonic conditions and temperatures exist for the CEC process. • CEC degradation is determined by the amount of the catalyst with strong electron-withdrawing ability in the reaction system. • The dielectric powders, as the catalysts, were compared. • Physical adsorption occurs when the polarity of the catalyst is opposite to that of the target substrate. • In some cases, physical adsorption will take the priority and inhibit CEC performance. [ABSTRACT FROM AUTHOR]