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Abstract Liquid-solid contact electrification (CE) is essential to diverse applications. Exploiting its full implementation requires an in-depth understanding and fine-grained control of charge carriers (electrons and/or ions) during CE. Here, we decouple the electrons and ions during liquid-solid CE by designing binary superhydrophobic surfaces that eliminate liquid and ion residues on the surfaces and simultaneously enable us to regulate surface properties, namely work function, to control electron transfers. We find the existence of a linear relationship between the work function of superhydrophobic surfaces and the as-generated charges in liquids, implying that liquid-solid CE arises from electron transfer due to the work function difference between two contacting surfaces. We also rule out the possibility of ion transfer during CE occurring on superhydrophobic surfaces by proving the absence of ions on superhydrophobic surfaces after contact with ion-enriched acidic, alkaline, and salt liquids. Our findings stand in contrast to existing liquid-solid CE studies, and the new insights learned offer the potential to explore more applications.

Abstract As the most common but indispensable matter to humankind, water usually stays in a macroscopically electric neutral state. Due to its inherent molecular polarity, however, water can be easily electrified, which builds a connection between water and electricity. Such a coupling of water and electricity abounds deep scientific basics and technological applications. The past several decades have witnessed extensive progress in studying the mutual effects between electricity and water, but a comprehensive review of its fundamentals and applications is still largely missing. In this review, we first reassess and classify the basic electrifying methods of water according to their mechanisms, then highlight how to leverage the bond nexus of water and electricity to achieve promising technical applications. We envision that this review will inspire multidisciplinary scientific communities to think and innovate more on the research of water, electricity, and their marriage.

Abstract Programmable droplet manipulation based on external stimulation is in high demand in various modern technologies. Despite notable progress, current manipulation strategies still suffer from a common drawback such as single control means of modulating the external stimulation input, which leads to huge challenges in sophisticated and large scale‐up droplet handling. Herein, a unique pattern‐reconfiguration‐driven droplet manipulation method is developed on conductive/nonconductive pattern surfaces under charge deposition. Contactless charge deposition induces the “edge barrier” phenomenon at the boundaries of conductive/nonconductive patterns, analogous to an invisible and tunable wall guiding droplet behaviors. The edge barrier effect can be flexibly tuned by the nonconductive surface pattern. Thus, with charge deposition, surfaces are endowed with protean control functionality. The design of conductive/nonconductive patterns can effectively enable multifunction droplet manipulations, including track‐guided sliding, sorting, merging, and mixing. Moreover, dynamical pattern reconfiguration drives programmable fluidics with sophisticated and large scale‐up droplet handling capabilities in a low‐cost and simple approach.

Continuous warming climate conditions have triggered numerous extreme weather events, exerting an unprecedented impact on agricultural and food production. Based on the panel data of 3,050 small farmers engaged in maize planting from 2009 to 2018 and collected by the National Rural Fixed Observation Point in China, this study uses the Transcendental Logarithmic Production Function model to estimate the impact of temperature, precipitation, and sunshine hours on maize output. Further, considering climate condition heterogeneity, this study analyzes the development potential of five major maize production areas in China. Results show that temperature and precipitation have a positive impact on maize output and that insufficient sunshine hour is an obstacle to the growth of maize output. Five major maize production areas are affected by climate condition differently, entailing the need for tailored response measures. Additionally, land, labor, and material capital input are key factors affecting maize output. Based on conclusion, we put forward the following suggestions to promote sustainable agricultural production, including strengthening the prediction of temperature, precipitation, and sunshine hours in major maize production areas, optimizing the agricultural production layout and the planting structure based on local endowment, enhancing farmers’ adaptive behavior training toward climate change, developing irrigation and water conservation projects.

Abstract Piezoceramic films are an essential class of energy‐conversion materials that have been widely used in the electronics industry. Although current methods create a great freedom for fabricating high‐quality piezoceramic films, it requires well‐controlled synthesis conditions, including special high‐cost equipment and planar substrates particularly. The limited substrate selections hinder the applications of piezoceramic films in 3D conformal structures where most objects possess complex curvilinear surfaces. To overcome such limitations, a fast, energy‐efficient, and cost‐effective approach, named flame treated spray (FTS) coating, is developed for preparing piezoceramic films on free‐form surfaces. The flame treatment significantly enhances the hydrophilicity of a substrate, assisting in forming a uniform and continuous thin film. The followed spray coating deposits hundreds of nanometers to several micrometers thick films on 3D free‐form surfaces. Given the size controllability and arbitrary surface compatibility of the FTS method, a highly conformal piezoelectric tactile sensor array (4 × 4) is assembled on a spherical surface for mimicking robot fingers and an on‐site thin‐film sensor on the wing of an aircraft model to monitor the vibration in real‐time during flight. The FTS film deposition offers a highly promising methodology for the application of functional thin‐film from micro‐ to marcoscale devices, regardless of conformal problems.

Ice and frost buildup continuously pose significant challenges to multiple fields. As a promising de-icing/defrosting alternative, designing photothermal coatings that leverage on the abundant sunlight source on the earth to facilitate ice/frost melting has attracted tremendous attention recently. However, previous designs suffered from either localized surface heating owing to the limited thermal conductivity or unsatisfied meltwater removal rate due to strong water/substrate interaction. Herein, we developed a facile approach to fabricate surfaces that combine photothermal, heat-conducting, and superhydrophobic properties into one to achieve efficient de-icing and defrosting. Featuring copper nanowire assemblies, such surfaces were fabricated via the simple template-assisted electrodeposition method, allowing us to tune the nanowire assembly geometry by adjusting the template dimensions and electrodeposition time. The highly ordered copper nanowire assemblies facilitated efficient sunlight absorption and lateral heat spreading, resulting in a fast overall temperature rise to enable the thawing of ice and frost. Further promoted by the excellent water repellency of the surface, the thawed ice and frost could be spontaneously and promptly removed. In this way, the all-in-one design enabled highly enhanced de-icing and defrosting performance compared to other nanostructured surfaces merely with superhydrophobicity, photothermal effect, or the combination of both. In particular, the defrosting efficiency could approach ∼100%, which was the highest compared to previous studies. Overall, our approach demonstrates a promising path toward designing highly effective artificial deicing/defrosting surfaces.

Abstract Harvesting energy from water, in the form of raindrops, river, and ocean waves, is of considerable importance and has potential applications in self‐powered electronic devices and large‐scale energy needs. Recently, the droplet‐based electricity generator has shown an increase by several orders of magnitude in electrical output, overcoming the drawback of traditional droplet‐based device limited by interfacial effects. Despite this exciting result, the output performance of this novel droplet‐based electricity generator is limited by relatively low frequency of impinging droplets owing to the formation of a continuous liquid film at high impact frequency, which might hinder its practical applications. To overcome this challenge, here, we report the design of a superhydrophobic surface based droplet electricity generator, referred to as SHS‐DEG, which can timely shed water droplets from the surface without the formation of liquid film at high impact frequency, and thereby generating enhanced average electrical output. Moreover, our SHS‐DEG exhibits many distinctive advantages over conventional design including robustness, long‐term durability, and power generation stability even in harsh environments. We envision that the ability to harvest electrical energy from water droplets at high impact frequency has promising applications in various energy‐harvesting systems.