Wear-Resistant Cellulose Composites: Harnessing Graphite–Graphene Synergy for Mechanical–Tribological Balance

With the increasing complexity of mechanical equipment service conditions, the conventional single-component lubricant fillers have been difficult to meet the needs of practical applications, and it is necessary to explore new solutions. To this end, in this study, cellulose-based self-lubricating films (G-GNPs/EC) synergistically reinforced with graphite and graphene were prepared by in situ exfoliation of flake graphite by cellulose. During the friction process, graphite can either act as a load-bearing subject or form a lubrication transfer film to achieve wear compensation, while graphene layers retard graphite wear, enhancing interfacial stability. The resulting material achieves a low friction coefficient of 0.104 and superior load-bearing capacity, significantly outperforming the single-lubrication system. Moreover, the “rigid–flexible” hierarchical enhancement structure formed by graphene and esterified cellulose (EC) endows the composite with exceptional mechanical properties, achieving a tensile strength of 99.84 MPa and a toughness of 10.01 MJ/m3. Notably, the waste G-GNPs/EC demonstrates excellent biosafety and environmental friendliness, effectively adsorbing heavy metal ions (Cu2+) from soil. This work provides a feasible way to realize the practical application of high-performance, environmentally friendly self-lubricating materials.