Carbon　quantum　dot　(CQD)-decorated　CdS　nanocomposites　were　successfully　fabricated　via　the　self-assembly　of　CdS　in　the　presence　of　preformed　CQDs　and　were　found　to　be　efficient　photocatalysts　for　the　hydrogenation　of　nitrobenzene　under　visible　light.　Due　to　the　presence　of　the　frustrated　Lewis　acid-base　pairs　(FLPs)　in　their　structure,　CQDs　act　as　an　efficient　catalyst　to　promote　the　proton-coupled　hydrogenation　of　nitrobenzene　over　CQDs/CdS　nanocomposites.　Controllable　and　chemoselective　hydrogenation　of　nitrobenzene　to　produce　aniline,　azoxybenzene,　azobenzene　and　hydrazobenzene　can　be　realized　over　CQDs/CdS　via　simply　regulating　the　reaction　medium　including　the　hydrogen　source,　the　solvent　and　the　alkalinity.　This　study　provides　a　highly　efficient　and　economical　photocatalytic　system　for　the　controllable　and　chemoselective　hydrogenation　of　nitrobenzene　under　visible　light.　This　work　also　highlights　the　great　potential　of　semiconductor-based　photocatalysis　in　light-initiated　organic　syntheses.　Visible　light-initiated　chemoselective　hydrogenation　of　nitrobenzene　into　different　products　is　realized　over　CQDs/CdS　via　simply　regulating　the　reaction　medium.