Comparative Study of the Friction Behavior of Functionalized Graphene Oxide Additives Under Electric Stimulations

Electro-regulated friction is a widely adopted approach for reducing friction, with graphene oxide (GO) emerging as a promising lubricating additive due to its electro-responsive frictional behaviour. However, with the wide variety of functionalized GO additives available, each exhibiting distinct properties, it remains unclear which type demonstrates the most effective electro-regulated friction-reducing performance, limiting their broader industrial application. In this study, the frictional behaviour of three functionalized GO additives under electric stimulation was investigated along with an analysis of the corresponding worn surfaces. The findings reveal the role of functional groups in determining the tribological performance of functionalized GO additives and the mechanism of electric stimulation. Notably, the formation of ester groups during the friction process of GO-OH enhances the adsorption of GO additives onto steel surfaces, resulting in superior friction-reducing properties. Under lubrication with GO-OH additives, negative electric stimulation promotes the generation of ester groups and transitions the lubrication regime to mixed lubrication, thereby contributing to friction reduction. This work provides new insights into the tribological performance of functionalized GO additives and the mechanisms underlying their electro-regulated behaviours, laying a foundation for the design of GO additives with superior lubrication performance for practical engineering applications.