Synergistic　optimization　of　nitrogen　dissociation　and　hydrogen　transfer　might　be　an　efficient　strategy　to　develop　a　highly　efficient　ammonia　synthesis　catalyst.　Herein,　the　Ni-modified　molybdenum　nitride　is　used　as　the　catalyst　of　ammonia　synthesis.　The　presence　of　the　highly　dispersed　Ni　metal　results　in　enhancement　of　nitrogen　vacancy,　causing　the　acceleration　of　the　exchange　and　reaction　of　the　lattice　N　species　with　the　nitrogen　species　from　the　gaseous　phase.　In　addition,　the　presence　of　Ni　species　facilitates　the　hydrogen　transfer　and　spillover,　as　well　as　easy　hydrogen　release.　As　a　result,　the　optimized　molybdenum　nitride　catalyst　with　0.1　wt%　Ni　shows　a　2.5-times　higher　catalytic　activity　than　that　of　the　catalyst　without　Ni　species　at　400　degrees　C　owing　to　the　coupling　of　nitrogen　activation　and　hydrogen　transfer　effects.　This　general　approach　could　inspire　the　rational　design　of　other　metal　catalysts　for　ammonia　synthesis.