Photochemical　N-2　fixation　offers　a　promising　route　for　the　activation　and　transformation　of　inert　nitrogen　molecules　to　generate　useful　chemicals　under　mild　conditions　by　using　solar　energy.　Plasmonic　nanostructures,　characterized　by　their　ability　to　harvest　broad　spectrum　sunlight　to　enable　energetic　hot　electron-driven　chemical　reactions,　provide　a　unique　platform　for　the　high-efficiency　utilization　of　solar　energy.　Herein,　we　report　the　realization　of　plasmon-driven　photochemical　N-2　fixation　by　semiconducting　plasmonic　MoO3-x　nanosheets.　Specifically,　the　co-existence　of　the　low　valence　state　of　Mo　with　the　oxygen　vacancy　enables　a　perfect　functional　combination　of　rich　active　sites　for　nitrogen　absorption　with　broad　spectrum　plasmon-induced　hot　electrons　within　a　single　MoO3-x　nanosheet,　which　facilitates　the　photochemical　N-2　transformation　without　any　other　co-catalyst.　Under　irradiation　with　a　broad　region　from　visible　to　NIR,　N-2　can　be　reduced　to　ammonia　in　pure　water.　The　apparent　quantum　efficiency　under　NIR　excitation　at　808　and　905　nm　reaches　0.31%　and　0.22%,　respectively,　which　are　the　highest　for　N-2　photofixation　under　NIR　excitation　ever　reported.　The　plasmon　excited　hot　electron-driven　N-2　reduction　has　been　demonstrated　to　be　responsible　for　the　photochemical　N-2　fixation.　This　work　provides　a　new　route　for　the　design　and　fabrication　of　functional　plasmonic　semiconductor　nanomaterials　towards　the　wide-band　utilization　of　solar　energy.