Synergistic Tribological Enhancement in Water‐Based Lubricants with Sodium Dodecylbenzenesulfonate‐Modified Reduced Graphene Oxide

The extent of reduction in reduced graphene oxide (RGO) significantly affects its performance as a water‐based lubricant additive. In this study, sodium dodecylbenzenesulfonate (SDBS)‐modified RGO nanofluids with controlled degrees of reduction through a simple, low‐temperature, water‐bath reduction process are synthesized. This is achieved by varying the mass ratio of L‐ascorbic acid (LAA) to graphene oxide (GO). The RGO‐SDBS(V) sample, prepared at a 5:1 LAA‐to‐GO mass ratio, demonstrates an optimized lamellar structure and colloidal stability, with no sedimentation observed over 21 days. Tribological tests using a ball‐on‐disc tribometer demonstrate that incorporating 0.1 wt% RGO‐SDBS(V) into pure water reduces the friction coefficient and wear rate by 78.8% and 88.9%, respectively. Surface analysis confirms the effective deposition of RGO‐SDBS(V) and the formation of protective Fe₂O₃/SiO₂ tribofilms. The superior lubrication performance is attributed to the synergy between the intrinsic lubricity of RGO‐SDBS(V) and friction‐induced chemical reactions, as evidenced by X‐ray photoelectron spectroscopy and Raman spectroscopy. These findings underscore the potential of SDBS‐functionalized RGO in high‐performance, water‐based lubrication systems.