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Abstract Structural superlubricity (SSL) at layered material interfaces is an exciting and vibrant field of research, offering vast opportunities to achieve ultralow friction and wear with numerous potential technological applications. At increasing length‐scales, new physical and chemical energy dissipation pathways emerge that threaten to push the system out of the superlubric regime. Physical inhibitors of SSL are primarily associated with in‐plane elasticity, out‐of‐plane corrugation, moiré superlattices, grain boundaries, and lattice defects. Chemical mechanisms that may suppress superlubric behavior include interlayer bonding, wear, and external contaminants. In this article, these and other challenges are reviewed facing the scaling‐up of structural superlubricity, as reflected in recent experimental and theoretical studies. Further perspectives are offered on future directions for realizing and manipulating macroscale superlubricity, outlining technological opportunities that it entails. 

Electric vehicles (EVs) represent a new paradigm for a sustainable transportation future with the potential to offer unparalleled energy security, environmental cleanliness, and economic prosperity for all humanity. However, rapid development and adaptation of this new transportation approach depend on addressing multiple challenges, including the development of new materials and coatings that can meet the more stringent thermal, electrical, and tribological requirements of EV drivetrains. Specifically, the operating conditions of moving mechanical assemblies (i.e., bearings, gears, among others) in EVs differ radically from those found in conventional internal combustion (IC) engines—thus giving rise to notable reliability issues. In particular, as the function of bearings and gear systems shift from mostly load-carrying (in IC engines) to the torque-transferring mode in EVs, durability concerns of these assemblies due to severe deformation, wear, micro-pitting, fatigue, and scuffing may worsen—as electric motors can generate maximum torque at near zero speeds but maximum efficiency at around 90% speed (this is opposite of conventional IC engines, which generate high torques at high speeds). These conflicting requirements require a different set of lubricant-material combinations to circumvent such problems under high loads and low-speed conditions of EVs. Therefore, new materials, coatings, and lubrication strategies need to be developed and implemented for future EVs to become tribologically viable and reliable. Accordingly, EV drivetrains can potentially benefit from advanced functional coatings that have already significantly improved the functionality of moving components of IC engines. The main objective of this article is to draw attention to some of the tribological issues in EVs and how advanced functional coatings can help resolve these issues due to their unique thermal, electrical, mechanical, and tribological properties, ultimately making EVs more durable and reliable. 

Protective coatings are important for enhancing tribological behavior, preventing surface degradation, and reducing friction-induced energy losses during the operation of mechanical systems. Recently, tribocatalytically driven formation of protective carbon films at the contact interface has been demonstrated as a viable approach for repairing and extending the lifetime of protective coatings. Here, we study the effect of catalytic metals, specifically their composition and amount, on the tribocatalysis process. To achieve this, we test the tribological performance of electro-deposited amorphous CoNiP and CoCuP coatings in different hydrocarbon-rich environments. Our results indicate that the tribocatalytic repair of wear-induced damage is optimal when Ni and Cu are included in the Co-P matrix at 5 wt% Ni and 7 wt% Cu, respectively. Characterization of the wear tracks suggests that among the considered samples, the tribofilms formed on the surface of Co7CuP have the highest concentration of graphitic carbon, leading to a more significant reduction in the COF and wear rate. The carbon tribofilm formation was more pronounced in decane and synthetic oil than in ethanol, which is attributed to the difference in the length of the hydrocarbon molecules affecting viscosity and the lubricant film thickness during boundary lubrication sliding.