Excessive emissions of carbon dioxide (CO2) have caused the greenhouse effect and environmental crisis. Therefore, the carbon reduction and negative carbon technologies are particularly important. Among these, the negative carbon technologies that convert CO2 into carbon materials or carbon-based chemicals for reuse have attracted significant attention. However, the strong double covalent bonds make the CO2 conversion usually require harsh conditions, complex processes, and high energy consumption. Gallium-based liquid metals (LMs) are the functional materials with both metallic and liquid properties, exhibiting a unique liquid-phase structure and diverse surface characteristics. Herein, a strategy for reducing CO2  is proposed to carbon materials by utilizing the spontaneous phase transition and mechanical friction of liquid metals. The gallium (Ga) and indium (In) particles are mixed and exposed to CO2, the contact interface of metal particles spontaneously transforms into liquid metals. The system has multistage interfaces, including Ga/In, Ga/eGaIn, and In/eGaIn, capable of generating triboelectrification upon mechanical stimulation, leading to charge transfer. The high electric field generated by friction at the contact interface directly reduces CO2 to carbon materials at room temperature. The carbon materials cover the surface of eGaIn and can be directly stripped for used as fuel, or industrial applications.