[Ca24Al28O64]4+(4e−)　electronic　compound　(C12A7:e−)　is　a　ceramic　with　extremely　low　work　function,　and　it　exhibits　outstanding　potential　in　cathode　electron　emission.　However,　the　existing　preparation　methods　for　this　material　are　cumbersome,　time-consuming,　and　have　limited　electron　density.　In　this　paper,　C12A7:e−　were　prepared　using　high-pressure　hydrothermal　reaction　and　plasma　activation　sintering.　The　free　O2−　in　the　cages　of　the　sample　achieved　accelerated　diffusion　and　transition　under　the　high　temperature,　strong　electric　field,　high-energy　pulse　current,　and　plasma　activation.　Meanwhile,　a　high　concentration　of　electrons　(2　×　1021　cm−3)　was　rapidly　injected　into　the　sample.　In　addition,　the　C12A7:e−　blocks　have　fewer　defects,　such　as　pores,　cracks,　and　impurities,　and　their　relative　density　reaches　99.6　%.　The　electron　emission　density　and　effective　work　function　of　the　C12A7:e−　are　1.49　A/cm2　and　2.25　eV,　respectively,　at　1100　°C.　This　article　provides　a　reference　for　preparing　C12A7:e−　and　their　applications　in　electronic　emission.　©　2024　Elsevier　Ltd