Systematic Optimization of the Synthesis of Confined Carbyne.

Confined carbyne, an sp¹-hybridized linear carbon chain inside a carbon nanotube, is a novel material with remarkable properties and potential applications. Among its currently successful synthesis methods, high temperature high vacuum annealing is prevalent. Further optimization could be achieved by tuning the synthesis pathway. Here, a systematic analysis of key synthesis parameters including precursor filling, annealing step sequences, and temperature conditions during high temperature vacuum processing is performed. A novel yield determination model that overcomes previous limitations related to the irregular resonance Raman behavior of carbyne is applied to evaluate bulk yield and realized growth potential. With this refined model, it is possible to make a quantitative assessment of bulk yield optimization potential in multi-step annealing processes. These results provide crucial insights into the fundamental formation mechanisms of confined carbyne, advancing our understanding of this promising hybrid nanomaterial system. It is therefore possible to establish improved protocols for maximizing confined carbyne yields through precise control of synthesis conditions.