AuPt　alloy/SnNb2O6　ultrathin　nanosheet　(AuPt/SN)　as　a　photocatalyst　is　constructed　for　selective　hydrogenation　of　p-chloronitrobenzene　(p-CNB)　under　visible　light　irradiation.　A　typical　catalyst　(Au0.5Pt0.5/SN)　exhibits　a　high　conversion　of　halonitrobenzenes　(99.8%)　and　selectivity　of　haloaniline　(99.1%).　The　results　of　in　situ　ATR-IR,　XPS　and　Raman　indicate　a　preferential　chemoselective　adsorption　of　–NO2　that　Lewis　base　sites　(Sn2+)　on　the　catalyst　could　selectively　coordinate　with　–NO2　whereas　C-Cl　bond　is　not　be　bonded,　improving　the　catalytic　selectivity.　Atom　Pt　in　alloy　is　responsible　for　the　formation　of　·H,　while　Au　inhabits　the　dissociation　of　C-Cl　via　repressing　the　generation　of　Pt-H.　The　photogenerated　electrons　can　accelerate　the　·H　formation.　·H　could　be　transferred　to　Sn2+　sites　for　the　hydrogenation　of　–NO2　by　hydrogen　spillover.　Therefore,　the　high　performance　of　the　catalyst　can　be　attributed　to　a　surface　synergetic　effect　among　Lewis　base　sites　(Sn2+),　AuPt　alloy　and　photogenerated　electrons.　©　2022　Elsevier　Ltd