Hydrophobic materials that are robust to harsh environments are needed in a broad range of applications. Although durable materials such as metals and ceramics, which are generally hydrophilic, can be rendered hydrophobic by polymeric modifiers, these deteriorate in harsh environments. Here we show that a class of ceramics comprising the entire lanthanide oxide series, ranging from ceria to lutecia, is intrinsically hydrophobic. We attribute their hydrophobicity to their unique electronic structure, which inhibits hydrogen bonding with interfacial water molecules. We also show with surface-energy measurements that polar interactions are minimized at these surfaces and with Fourier transform infrared/grazing-angle attenuated total reflection that interfacial water molecules are oriented in the hydrophobic hydration structure. Moreover, we demonstrate that these ceramic materials promote dropwise condensation, repel impinging water droplets, and sustain hydrophobicity even after exposure to harsh environments. Rare-earth oxide ceramics should find widespread applicability as robust hydrophobic surfaces.

Oxides are instrumental to applications such as catalysis, sensing, and wetting, where the reactivity with water can greatly influence their functionalities. We find that the coverage of hydroxyls (*OH) measured at fixed relative humidity trends with the electron-donor (basic) character of wetted perovskite oxide surfaces. Using ambient pressure X-ray photoelectron spectroscopy, we report that the affinity toward hydroxylation, coincident with

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Scale formation is a widespread problem in industries and households—from scaling of cooking pots in ancient times to the plugging of pipelines in the modern age. Developing surfaces that have a low affinity to scale has been an area of great interest in the last decade. In this work, we demonstrate the anti‐scaling properties of textured surfaces impregnated with a lubricant. Since scale deposition can be reduced by lowering the nucleation rate, which depends on the properties of the substrate, we optimize the design of the lubricant‐impregnated surfaces (LIS) based on the surface tension of the lubricant and its spreading coefficient on the solid. Scale deposition experiments show that the nucleation rate on optimized LIS is reduced owing to their low surface energy and low density of nucleation sites. Mass gain measurements indicate that the optimized LIS perform 10 times better than uncoated smooth surfaces. This idea is extended to an engineering material like stainless steel and, along with low scale deposition, low adhesion of scale to LIS is also achieved.

These issues are especially prominent in aqueous electrolytes, as hydrogen evolution reaction readily occurs at such low potentials and water molecules act as an oxygen source for oxide film formation. [4] Remarkably, two recent works have seemingly been able to address these challenges by engineering a solid electrolyte interphase (SEI) on Al, either "in situ" by 5 m (mol kg −1 ) Al(OTF) 3 (aluminum triflate) water-in-salt electrolyte (Al-WiSE), [5] or "ex situ" by IL pretreatment. [6] These two pioneering studies have since led a surge in reports of fully reversible aqueous AMBs (AAMB). [7][8][9][10][11][12] There are however concerns regarding the validity and effectiveness of the two SEI engineering methods. First, there has not been any experimental or computational characterizations that support an SEI can form on Al from 5 m Al(OTF) 3 , especially given its low concentration compared with alkali metal WiSE. [13,14] The only reason an SEI is believed to exist is by observing a delayed onset of hydrogen evolution reaction on a glassy carbon electrode, which is not a reliable indicator given its high hydrogen evolution reaction overpotentials, particularly relative to Al. [15] On the other hand, while it is proven that IL treatment can form a residue layer on Al, its fundamental ion and electron transport properties as well as its stability in aqueous electrolytes were not investigated; hence, its ability to function as an artificial SEI, is practically unknown. To address these concerns, in this work we critically evaluated each SEI engineering method, elucidated their underlying mechanisms, and revealed whether they can allow for truly rechargeable AAMBs.