This study investigates the growth mechanisms of graphene on copper (Cu) and nickel (Ni) substrates using carbon isotope labeling. The researchers used a carbon isotope labeling technique to elucidate the growth kinetics and demonstrate that graphene growth on Cu is primarily through surface adsorption, while on Ni it is through segregation-precipitation. The results show that surface adsorption is a self-limiting process, making it more suitable for uniform graphene film growth. The study also highlights the importance of understanding the growth mechanisms to achieve uniform and controlled graphene films, which are crucial for advanced electronic devices. The findings provide insights into the growth behavior of graphene on different metal substrates and suggest that low carbon solubility in materials like Cu offers a better path for large-area graphene growth.This study investigates the growth mechanisms of graphene on copper (Cu) and nickel (Ni) substrates using carbon isotope labeling. The researchers used a carbon isotope labeling technique to elucidate the growth kinetics and demonstrate that graphene growth on Cu is primarily through surface adsorption, while on Ni it is through segregation-precipitation. The results show that surface adsorption is a self-limiting process, making it more suitable for uniform graphene film growth. The study also highlights the importance of understanding the growth mechanisms to achieve uniform and controlled graphene films, which are crucial for advanced electronic devices. The findings provide insights into the growth behavior of graphene on different metal substrates and suggest that low carbon solubility in materials like Cu offers a better path for large-area graphene growth.