Photoelectron superlubricity

Abstract: Superlubricity, a state where friction between two contact surfaces is nearly zero, has a great potential to revolutionize various mechanical systems by significantly reducing energy dissipation and enhancing efficiency. It can be realized either by structural incommensurate contact between crystalline surfaces or by creating highly passive interfaces to cancel out the adhesive forces. However, fabricating and maintaining such superlubric surfaces still present challenges, often disabled by surface structural defects or susceptibility to humid atmospheres, which renders superlubricity fragile. Here, we propose a novel strategy of photoelectron superlubricity (PESL), where robust superlubricity can be achieved in humid atmospheres by in-situ laser-irradiating the contact interface of an amorphous carbon film sliding against sapphire ball. We demonstrate that PESL not only exhibits a high resistance to environmental disturbances but also features rapid response. The formation of PESL originates from the laser-irradiating induced formation of nanographene-layered interface and enrichment of photoelectrons at the interface, resulting in a repulsive electric field between the nanographene layers. The discovery of PESL opens a new avenue for achieving superlubricity, and also provides novel insights for smart friction, mechanical motion control and light manipulation.