Electrostatic dust removal using adsorbed moisture-assisted charge induction for sustainable operation of solar panels

A Soft-Soft Contact Triboelectric Nanogenerator with a Ternary Four-Phase Structure for Self-Powered High-Efficiency Dust Removal on Mars

Dust removal is essential for sustaining energy supplies in Mars exploration missions and base facilities. Existing devices typically depend on external power supplies, which may be inadequate in the harsh Martian environment. This paper proposes a novel wind-driven ternary four-phase soft-soft contact triboelectric nanogenerator (FPS-TENG) for dust removal. The device's double-stacked soft-soft contact structure outputs high-voltage electricity in four phases, generating a traveling wave electric field on the electrode surface. This field prompts dust particles to align with the wave's direction, enabling automatic dust removal without an external power supply. The FPS-TENG, as a ternary stacked soft-soft contact TENG, achieves output voltages that are 354% and 185% higher than those of conventional binary and ternary TENGs, respectively. Compared with existing dust removal devices, this device can achieve a dust removal efficiency of up to 91.8% for simulated Martian dust, even at lower voltages, without requiring the repositioning of solar panels during the cleaning process. Experimental results validate the system's operation in the Martian environment. This work provides a self-powered, high-efficiency method for dust removal that holds significant promise for promoting wider space exploration and supporting potential future Martian settlements.

Enhanced Electrostatic Dust Removal from Solar Panels Using Transparent Conductive Nano-Textured Surfaces

Dust accumulation on solar panels is a mjor operational challenge faced by the photovoltaic industry. Removing dust using water-based cleaning is expensive and unsustainable. Dust repulsion via charge induction is an efficient way to clean solar panels and recover power output without consuming any water. However, it is still challenging to remove particles of ≈30 µm and smaller because Van der Waals force of adhesion dominates electrostatic force of repulsion. Here, the study proposes nano-textured, transparent, electrically conductive glass surfaces to significantly enhance electrostatic dust removal for particles smaller than ≈30 µm. We perform atomic force microscopy pull-off force experiments and demonstrates that nano-textured surfaces reduce the force of adhesion of silica micro-particles by up to 2 orders of magnitude compared to un-textured surfaces from 460 to 8.6 nN. We show that reduced adhesion on nano-textured surfaces results in significantly better dust removal of small particles compared to non-textured or micro-textured surfaces, reducing the surface coverage from 35% to 10%. We fabricate transparent, electrically conductive, nano-textured glass that can be retrofitted on solar panel surfaces using copper nano-mask based scalable nano-fabrication technique and shows that 90% of lost power output for particles smaller than ≈10 µm can be recovered.

Enhanced dust reduction method for solar panels application

Introducing an innovative dual-layer coating technique to enhance solar panel durability against dust, this method uses a translucent aluminum zinc oxide conductive film to prevent accumulation through active dust repulsion. A secondary TiO2-infused coating, applied via a cost-effective sol-gel method, boosts anti-soiling capabilities in a passive manner. Comprehensive tests on dust accumulation, self-cleaning efficiency, mechanical robustness, UV-VIS transmission, and chemical resilience reveal promising results. These coatings improve glass clarity, reduce dust adhesion, and maintain energy production even in calm conditions. The effectiveness relies on the precise concentrations of aluminum nitrate and Titania nanoparticles, with annealing temperature affecting transmission rates. The coatings demonstrate highly desired resistance to both alkaline and acidic environments, ensuring consistent performance across various settings. This durability supports the widespread adoption of solar energy in diverse climates, advancing global sustainable energy efforts.

Navigating the Landscape of Dry Assembling Ordered Particle Structures: Can Solvents Become Obsolete?

A spur on miniaturized devices led scientists to unravel the fundamental aspects of micro- and nanoparticle assembly to engineer large structures. Primarily, attention is given to wet assembly methods, whereas assembly approaches in which solvents are avoided are scarce. The "dry assembly" strategies can overcome the intrinsic disadvantages that are associated with wet assembly, e.g., the lack of versatility and scalability. This review uniquely summarizes the recent progress made to create highly ordered particle arrays without using a wet environment. Before delving into these methods, the surface interactions (e.g., van der Waals, contact mechanics, capillary, and electrostatics) are elaborated, as a profound understanding and balancing these are a critical aspect of dry assembly. To manipulate these interactions, strategies involving different forces, e.g., mechanical-based, electrical-based, or laser-induced, sometimes in conjunction with pre-templated substrates, are employed to attain ordered colloidal structures. The utilization of the ordered structures obtained without solvents is accompanied by specific examples. Dry assembly methods can aid us in achieving more sustainable assembly processes. Overall, this Review aims to provide an easily accessible resource and inspire researchers, including novices, to broaden dry assembly horizons significantly and close the remaining knowledge gap in the physical phenomena involved in this area.

Heat-Excitation-Based Triboelectric Charge Promotion Strategy

The surface charge decay is observed at high temperatures due to thermionic emission, which, however, may not be the only mechanism contributing to the surface charge variation. Here, a triboelectric charge promotion strategy due to the heat-excitation effect of hot electrons near the fermi level is demonstrated, while the final charge is determined by the balance between thermionic emission and the heat-excitation effect. It is demonstrated that metals with lower work function exhibit a better heat excitation capability, and polymers with lower fluorine content in molecule chains further boost the charge output, where metal/Kapton pairs demonstrated a charge promotion of over 2 times at the temperature of 383 K with good durability during 90 min measurement. The heat-excitation effect and charge durability in sliding freestanding-triboelectric-layer (SFT) mode triboelectric nanogenerator (TENG) is demonstrated as well, where the energy is promoted by over 3 times and the capacitor charging speed is doubled as well, with an energy promotion from 109.34 to 373 µJ per cycle to successfully trigger a discharger. This work suggests a promising future of the heat-excitation effect as a new charge promotion strategy for TENG toward different applications in high-temperature environments.

Rapid Fabrication of Antilunar Dust Aluminum Surface by Nanosecond Laser Etching

Although a dust-repellent surface is desirable for lunar exploration missions, its fabrication process is complicated and time-consuming. Herein, we report a simple and fast method to fabricate a lunar dust-repellent surface by texturing on an Al substrate via nanosecond laser etching. The laser-induced photothermal effect can rapidly create hierarchical papillary structures on 25 × 25 mm Al substrates (within 30 s). Both atomic force microscopy (AFM) and in situ scanning electron microscopy (SEM) reveal that such structures enable a reduced contact area between the Al substrate and lunar dust and thus reduced adhesion. The reduced dust adhesion force of Al substrates facilitates improving their antidust performance. By optimizing processing parameters, the Al substrate etched with a laser scanning spacing of 80 μm exhibits a lower dust adhesion force (9.58 nN) due to the smallest contact area with dust. Accordingly, its static antilunar dust performance (dust coverage of 1.95%) is significantly improved compared to the pristine Al substrate (dust coverage of 12.98%). Besides, the accumulated dust on the laser-etched Al substrates with low surface adhesion force is easily cleaned up by flipping and gravity (the dust residual rates are less than 17%). The Al substrate with excellent antidust ability presents good potential for lunar exploration missions.

Self-Powered Autonomous Electrostatic Dust Removal for Solar Panels by an Electret Generator

Solar panels often suffer from dust accumulation, significantly reducing their output, especially in desert regions where many of the world's largest solar plants are located. Here, an autonomous dust removal system for solar panels, powered by a wind-driven rotary electret generator is proposed. The generator applies a high voltage between one solar panel's output electrode and an upper mesh electrode to generate a strong electrostatic field. It is discovered that dust particles on the insulative glass cover of the panel can be charged under the high electrical field, assisted by adsorbed water, even in low-humidity environments. The charged particles are subsequently repelled from the solar panel with the significant Coulomb force. Two panels covered with sand dust are cleaned in only 6.6 min by a 15 cm diameter rotary electret generator at 1.6 m s-1 wind speed. Experimental results manifest that the system can work effectively in a wide range of environmental conditions, and doesn't impact the panel performance for long-term operation. This autonomous system, with its high dust removal efficiency, simplicity, and low cost, holds great potential in practical applications.

Anti-fogging/dry-dust transparent superhydrophobic surfaces based on liquid-like molecule brush modified nanofiber cluster structures

Transparent protective coatings capable of preventing fog and dust accumulation have broad application prospect in photovoltaic systems, optical devices and consumer electronics. Although a number of superhydrophobic coatings have been developed for self-cleaning purpose over the past three decades, there is still a lack of surfaces that can simultaneously possess high transparency, remarkable superhydrophobicity, and excellent fog and dust resistance. In this study, we have prepared surfaces featuring sub-wavelength nanofiber cluster structures through a facile plasma etching method, and further modified the surface with liquid-like perfluoropolyether (PFPE) brushes. The prepared PFPE modified nanofibrous surface (PFPE-NS) exhibits superior optical transparency (transmittance 90.4 % ± 0.7 %) and water repellency, with a water contact angle as high as 171.0° ± 0.6° and sliding angle down to 0.5° ± 0.1° (5 µL). More importantly, benefitted from the nanofiber cluster structures and the slippery liquid-like surface chemistry, the adhesion and accumulation of fog droplets and dust particles on PFPE-NS is greatly inhibited. As a consequence, PFPE-NS can keep excellent optical clearness after 2 h fogging test and maintain an average transmittance above 87 % after 24 h dusting test. Our study provides a promising strategy through constructing liquid-like nanofibrous coating for optical protection that could be applicable in practical rainy, foggy, and dusty environments.

Spontaneous Wetting Induced by Contact-Electrification at Liquid-Solid Interface

Wettability significantly influences various surface interactions and applications at the liquid-solid interface. However, the understanding is complicated by the intricate charge exchange occurring through contact electrification (CE) during this process. The understanding of the influence of triboelectric charge on wettability remains challenging, especially due to the complexities involved in concurrently measuring contact angles and interfacial electrical signals. Here, the relationship is investigated between surface charge density and change of contact angle of dielectric films after contact with water droplets. It is observed that the charge exchange when water spared lead to a spontaneous wetting phenomenon, which is termed as the contact electrification induced wetting (CEW). Notably, these results demonstrate a linear dependence between the change of contact angle (CA) of the materials and the density of surface charge on the solid surface. Continuous CEW tests show that not only the static CA but also the dynamics of wetting are influenced by the accumulation charges at the interface. The mechanism behind CEW involves the redistribution of surface charges on a solid surface and polar water molecules within liquid. This interaction results in a decrease in interface energy, leading to a reduction in the CA. Ab initio calculations suggest that the reduction in interface energy may stem from the enhanced surface charge on the substrate, which strengthens the hydrogen bond interaction between water and the substrate. These findings have the potential to advance the understanding of CE and wetting phenomena, with applications in energy harvesting, catalysis, and droplet manipulation at liquid-solid interfaces.

Pontederia crassipes inspired bottom overflow for fast and stable drainage

Fast and stable water drainage is essential for living organisms, drainage plane construction, and protection of infrastructure from damage during rainfall. Unlike traditional anti-overflow drainage methods that rely on hydrophobic or sharped edges, this study demonstrates a bottom overflow-induced drainage model inspired by the water path employed by Pontederia crassipes leaves, leading to fast and stable drainage. A superhydrophilic bottom surface guides water to overflow and pin at the bottom of a thin sheet, resulting in dripping at a higher frequency and reduced water retention. This bottom drainage idea assists large-scale thin sheets to function as efficient and stable drainage surfaces in simulated rain environments. The flexible thin sheet can also be feasibly attached to dusty substrates to effectively remove dusty rainwater with slight dust residue. The bioinspired approach presented herein suggests a promising potential for efficient water drainage on outdoor functional photovoltaic surfaces, such as solar panels and radomes, thus ensuring effective energy conversion and stable signal transmission.

Flexible Thin Film Functionalized by Initiative Dust Removal and Anti-Fogging for Optical Device Applications

The deposition of dust and condensation of fog will block the scattering and transmission of light, thus affecting the performance of optical devices. In this work, flexible polyethylene terephthalate (PET) foil functionalized by active dust removal and anti-fogging characteristics is realized which combines electrodynamic screen (EDS) and electro-heating devices. In lieu of traditional measurement methods of dust removal efficiency, the PSNR is employed to characterize the dust removal efficiency of the film for the first time. The results show that both dust removal and anti-fogging improve the image quality, in which the dust removal increases the PSNR from 28.1 dB to 34.2 dB and the anti-fogging function realizes a film temperature rise of 16.7 ∘C in 5 min, reaching a maximum of 41.3 ∘C. According to the high sensitivity of the PSNR, we propose a fully automatic CIS film-driven algorithm, and its feasibility has been demonstrated.

Observing Real-Time Adhesion of Microparticles on Glass Surfaces

Fouling on glass surfaces reduces the solar panel efficiency and increases water consumption for cleaning. Superhydrophobic coatings on glass enable self-cleaning by allowing water droplets to carry away dirt particles. Observing the interaction between charged particles and surfaces provides insights into effective cleaning. Using a high-speed camera and a long-distance objective, we analyzed the in situ deposition of variously functionalized and charged silica dust microparticles on chemically treated glass. The ambient charges for the control, hydrophobic, and positively charged particles were approximately -0.5, -0.13, and +0.5 nC, respectively. We found that a positively charged particle of 2.3 ± 1.2 μm diameter adhered to hydroxylated glass in ∼0.054 s, compared to 0.40 and 0.45 s for quaternary ammonium- and fluorosilane-functionalized hydrophobic glass. Experiments suggest that quaternary ammonium-functionalized glass surfaces are about 77.8% more resistant to soiling than bare surfaces.

Hydrochar-nanoparticle integration for arsenic removal from wastewater: Challenges, possible solutions, and future horizon

Arsenic (As) contamination poses a significant threat to human health, ecosystems, and agriculture, with levels ranging from 12 to 75% attributed to mine waste and stream sediments. This naturally element is abundant in Earth's crust and gets released into the environment through mining and rock processing, causing ≈363 million people to depend on As-contaminated groundwater. To combat this issue, introducing a sustainable hydrochar system has achieved a remarkable removal efficiency of over 92% for arsenic through adsorption. This comprehensive review presents an overview of As contamination in the environment, with a specific focus on its impact on drinking water and wastewater. It delves into the far-reaching effects of As on human health, ecosystems, aquatic systems, and agriculture, while also exploring the effectiveness of existing As treatment systems. Additionally, the study examines the potential of hydrochar as an efficient adsorbent for As removal from water/wastewater, along with other relevant adsorbents and biomass-based preparations of hydrochar. Notably, the fusion of hydrochar with nanoparticle-centric approaches presents a highly promising and environmentally friendly solution for achieving the removal of As from wastewater, exceeding >99% efficiency. This innovative approach holds immense potential for advancing the realms of green chemistry and environmental restoration. Various challenges associated with As contamination and treatment are highlighted, and proposed solutions are discussed. The review emphasizes the urgent need to advance treatment technologies, improve monitoring methods, and enhance regulatory frameworks. Looking outlook, the article underscores the importance of fostering research efforts, raising public awareness, and fostering interdisciplinary collaboration to address this critical environmental issue. Such efforts are vital for UN Sustainable Development Goals, especially clean water and sanitation (Goal 6) and climate action (Goal 13), crucial for global sustainability.

Tribocharging of granular materials and influence on their flow

Once granular materials flow, particles charge because of the triboelectric effect. When particles touch each other, charges are exchanged during contact whether they are made of the same material or not. Surprisingly, when different sizes of particles are mixed together, large particles tend to charge positively while small particles charge negatively. If the particles are relatively small (typically smaller than a millimeter), the electrostatic interaction between the particles becomes significant and leads to aggregation or sticking on the surface of the container holding them. Studying those effects is challenging as the mechanisms that govern the triboelectric effect are not fully understood yet. We show that the patch model (or mosaic model) is suitable to reproduce numerically the flow of triboelectrically charged granular materials as the specific charging of bi-disperse granular materials can be retrieved. We investigate the influence of charging on the cohesion of granular materials and highlight the relevant parameters related to the patch model that influence cohesion. Our results shed new light on the mechanisms of the triboelectric effect as well as on how the charging of granular materials influences cohesion using numerical simulations.

Electronic thygmonasty model inMimosa pudicabiomimetic robot

Direct contact of random objects from the open environment to the panel surface of an electronic device may reduce the work efficiency and cause permanent damage. However, there is a possible way to solve this problem, notably by implementing an adaptive structure design inspired by plants. TheMimosa pudicaplant provides several interesting information on its adaptability. Various studies have been conducted on the electrical properties of its organs explaining the phytoactuator and phytosensor cells that function within it. We combined the use of sensors, actuators, and synthetic excitable tissue as the first robot model purposed to mimic the behavior of theM. pudicaplant. The Computer vision method was used to measure leaf angular movement and collected it as plant behavior data based on the mechanical stimulus experiment. The Robot structure has eight arms equipped with sensors, servo motors, and microcontrollers that are operated with two activation system models approach. The first model could imitate the stimulus process received by electronic circuits that generate action potential signals with a maximum voltage of 4.71-5.02 V and a minimum voltage of -5.33 to -3.45 V that propagated from node to node. The second model involves a trained artificial neural network model with a supervised learning pattern that provides 100% accuracy when choosing movement output based on the given combination. This robot imitates theM. pudica's intelligent sensing capabilities and its ability to change the structure shape based on the thygmonasty experiments data which could provide an overview of how plants process information and perform hazard avoidance actions efficiently. Future applications for the technology inspired by the plant's self-defense mechanisms are adaptive intelligent structures that can protect against harmful conditions, particle contamination, and adjusting panel structure to search for desired environmental parameters.

Functionality Analysis of Electric Actuators in Renewable Energy Systems—A Review

Various mechanical, hydraulic, pneumatic, electrical, and hybrid actuators can alter motion per the requirements of particular applications. However, except for electrical ones, all actuators are restricted due to their size, complex auxiliary equipment, frequent need for maintenance, and sluggish environment in renewable applications. This brief review paper highlights some unique and significant research works on applying electrical actuators to renewable applications. Four renewable energy resources, i.e., solar, wind, bio-energy, and geothermal energy, are considered to review electric actuators applicable to renewable energy systems. This review analyses the types of actuators associated with the mentioned renewable application, their functioning, their motion type, present use, advantages, disadvantages, and operational problems. The information gathered in this paper may open up new ways of optimization opportunities and control challenges in electrical actuators, thereby making more efficient systems. Furthermore, some energy-efficient and cost-effective replacements of convectional actuators with new innovative ones are suggested. This work aims to benefit scientists and new entrants working on actuators in renewable energy systems.