From a Cement Mineral Phase to an Electride: Research Progress on the Catalytic Applications of C12A7

12CaO·7Al₂O₃ (C12A7), known as mayenite, is a major phase in calcium aluminate cement and an intermediate formed during Portland cement production. In recent years, the electride derived from C12A7 has exhibited substantial potential in catalysis and related domains. This review focuses on advances in catalysis enabled by the mayenite electride (C12A7:e⁻). We first introduce the basic concept of electrides and their historical development, and elucidate the structural features of C12A7:e⁻ alongside its distinctive position in materials science. We then systematically summarize its crystal-structural characteristics and principal synthesis strategies, analyzing how different preparation routes influence the resulting material properties. Subsequently, we highlight the performance of C12A7:e⁻ across multiple catalytic reactions, including ammonia synthesis and ammonia decomposition (cracking), and delineate its advantages in enhancing catalytic activity and selectivity. Finally, we identify key challenges for practical deployment—such as chemical stability and scalable production—and offer an outlook on expanding its applications in energy and environmental catalysis through structural tuning and process optimization.