Weimin Liu’s research while affiliated with Northwestern Polytechnical University and other places

Superlubricity with a friction coefficient <0.01 holds great promise for reducing energy consumption and global CO2 emissions. However, current numerous innovative superlubricity techniques have persisted in specific materials, inert atmosphere or nano/micro‐scale conditions. Here, a versatile and universal superlubricity strategy is demonstrated for common engineering alloys under atmospheric environment, and emphasize an innovative superlubricity design principle through surface passivation. Such superlubricity behavior is achieved by employing electrochemical boronizing surface treatment combined with liquid polyol/water mixture lubricants, revealing significant advances in terms of wide adaptability to traditional and newly‐emerged alloy materials, high load capacity and high‐temperature resistance (≈125 °C). The atomistic simulations and experimental results demonstrate that the energy dissipation reduction and superlubricity are driven by the weak interaction between the confined lubricant molecules and ─CxHy‐terminated passivation tribofilm, which is in situ generated by the mechanochemical reaction between the boronized layer and the liquid lubricant. The role of passivation layer on driving superlubricity is further supported by the exceptionally super‐low friction coefficient (COF≈0.008) observed in octadecyltrichlorosilane (OTS) molecular layer coated surfaces. This advancement opens the door for developing industrial‐scale superlubricity techniques and has the potential to accelerate their practical applications in engineering area.

Transition metal borides as a kind of novel multifunctional superhard material remain inferior in hardness compared with traditional superhard material. To this end, this study proposes a novel approach to enhance their hardness through a synergistic hard mechanism. The large‐scale superhard WB4 bulk is synthesized by modulating the boron isomers (β‐B→T‐B phase transition) at mild temperature and press conditions using a spark plasma sintering technique. The results show that WB4‐TB bulk is composed of nanosized WB4 grains and T‐B grains with a high density of stacking faults and grain boundary distortions, which exhibits a Vickers microindentation hardness of 63.1 GPa (0.49 N load) that is a 37% enhancement over the conventional WB4 (≈46.2 GPa), surpassing all reported transition metal borides and approaching the performance of covalent superhard materials. The synergistic effects of fine grain hardening, generation of superhard T‐B phase, and grain boundary strengthening inhibit dislocation motion and crack extension. This work provides a promising paradigm for designing new materials with both superhard and functional properties.

This study introduces the formulation of an ash-sulfur-less lubricant that is designed to form an antiwear/insulating tribolayer on electrified steel surfaces. The proposed oil formulation utilizes amine salts of aliphatic phosphoric acid esters (AW-6110) in poly-α-olefin (PAO6) oil. The study aims to find a solution to address tribological issues resulting from electrification effects and the presence of sulfur in e-mobility oils. An SRV-IV tribometer evaluated the tribological performance under various conditions. Notably, the AW-6110-formulated oil (1.5-AW oil) exhibited superior performance under 9 A current, reducing the friction coefficient by 18% and the disc wear volume by 90% compared to the commercial oil used in electric vehicles. This enhancement is attributed to its exceptional ability to form a durable antiwear/insulating tribolayer.

The incorporation of multiple metal elements into a nanoparticle without phase separation holds promise for versatile applications, yet a facile synthetic strategy is lacking. Herein, a simple and facile approach is presented, i.e., gold‐autocatalyzed synthesis, in which multiple miscible or immiscible metal elements are incorporated into single‐phase nanoparticles at atmospheric pressure and temperature. This study reveals the autocatalytic reduction behavior of gold and the corresponding growth process of multi‐element alloy nanoparticles. The mechanism of autocatalytic synthetic reactions is revealed on the basis of molecular orbitals. Furthermore, quinary multi‐element nanoparticles were prepared and applied as high‐performance electrocatalysts for the hydrogen evolution reaction in alkaline electrolytes (with overpotentials of 24 and 42 mV to deliver 10 and 100 mA cm⁻², respectively) to demonstrate the application of this strategy. This strategy enables the synthesis of multi‐element materials with high tolerance of synthetic conditions for versatile applications.

The rapid and reversible adhesion between solids is of great significance, particularly in fields such as biomedicine, intelligent machines, and bioelectronic sensors. Hydrogels, as soft materials, play a vital role in reversible adhesion. To achieve a wider range of applications, it is essential to enhance the intelligence of hydrogels. However, the preparation of reversible adhesive hydrogels with remote control, reversible adhesion, rapid response, and no residue remains a challenge in the field. Herein, we developed a light-controlled reversible adhesive hydrogel by integrating temperature-controlled reversible adhesion with the photothermal response capabilities of Fe3O4. The hydrogel can adhere/desorb reversibly under temperature control and allows for remote adhesion control using infrared light. Under infrared light irradiation, surface water causes carboxylic acid groups to migrate to the surface, thereby shielding the catechol groups. This results in insufficient adhesive groups at the interface to form interactions with opposing surfaces. Without infrared light irradiation, the adhesive functional groups are exposed, allowing interaction forces to form between the surface with the adhesion groups and the opposing surfaces. This smart hydrogel holds significant potential for future applications in wound dressings, wearable devices, and soft robots.