Dynamic Formation and Protective Role of 0D Carbon Dots During High-Temperature Catalytic Graphitization.

Phenolic resin (PR) has been extensively employed as an ablative thermal protection material in aerospace applications. While catalytic graphitization has been shown to enhance ablative resistance, the mechanism has remained unclear due to the contradiction between enhanced performance and limited graphitized domain coverage. Here, we unravel a new nanoscopic anti-ablation mechanism based on the first-time observation of residual carbon quantum dots (CQDs) in ablated Ni-doped PR, evidence of the dynamic evolution of 0D carbon dots during oxyacetylene ablation. Reactive molecular dynamics (RMDs) simulation reveals that the ultrahigh ablation temperature triggers simultaneous catalytic formation and oxidative disintegration of graphitized carbon shells around Ni particles, accompanied by dynamic generation and decomposition of graphene quantum dots (GQDs) via continuous atomic oxygen impingement. This work offers a new insight into nanoscopic thermal protection mechanisms based on the catalytic graphitization of PR and dynamic evolution of 0D carbon upon thermal ablation, which may serve as a new approach for enhancing thermal protection performance of resin-based materials.