Single-atom zinc controlled-release catalysts for efficient vulcanization of rubber
Reducing zinc oxide (ZnO) consumption in rubber vulcanization is imperative due to cost and environmental toxicity, yet lowering ZnO inevitably compromises crosslinking density and mechanical properties. This study introduces Zn single-atoms anchored on graphene oxide (Zn SAs@GO) as controlled-release catalysts for efficient natural rubber (NR) vulcanization. X-ray absorption spectroscopy (XAS) reveals a Zn–O bond length of 2.03 Å with moderate binding energy, enabling controlled release of Zn2+ ions that participate in vulcanization with enhanced activity. The homogeneous dispersion of Zn atoms ensures near-complete utilization, resulting in a 6.6% increase in crosslinking density compared to commercial ZnO while reducing Zn dosage by 82.5%. The Zn SAs@GO/NR composites exhibit faster vulcanization rates and superior mechanical and physical properties relative to ZnO nanoparticles and crystalline ZnO controls. This work demonstrates a scalable preparation of single-atom catalysts and provides a viable pathway for industrial rubber manufacturing with significantly reduced zinc content.