Delicate　modulations　of　CO2　activation　and　charge　carrier　separation/migration　are　challenging,　yet　imperative　to　augment　CO2　photoreduction　efficiency.　Herein,　by　supporting　diethylenetriamine　(DETA)-functionalized　Cd0.8Zn0.2S　nanowires　on　the　exterior　surface　of　hollow　Co9S8　polyhedrons,　hierarchical　Co9S8@Cd0.8Zn0.2S-DETA　nanocages　are　fabricated　as　an　S-scheme　photocatalyst　for　reducing　CO2　and　protons　to　produce　syngas　(CO　and　H2).　The　amine　groups　strengthen　adsorption　and　activation　of　CO2,　while　the　“nanowire-on-nanocage”　hierarchical　hollow　heterostructure　with　an　S-scheme　interface　boosts　separation　and　transfer　of　photoinduced　charges.　Employing　Co(bpy)32+　as　a　cocatalyst,　the　optimal　photocatalyst　effectively　produces　CO　and　H2　in　rates　of　70.6　and　18.6 µmol　h−1　(i.e.,　4673　and　1240 µmol　g−1　h−1),　respectively,　affording　an　apparent　quantum　efficiency　of　9.45%　at　420 nm,　which　is　the　highest　value　under　comparable　conditions.　Ultraviolet　photoelectron　spectroscopy,　Kelvin　probe,　and　electron　spin　resonance　confirm　the　S-schematic　charge-transfer　process　in　the　photocatalyst.　The　key　COOH*　species　responsible　for　CO2-to-CO　reduction　is　detected　by　in-situ　diffuse　reflectance　infrared　Fourier　transform　spectroscopy　and　endorsed　by　density　functional　theory　calculations,　and　thus　a　possible　CO2　reduction　mechanism　is　proposed.　©　2023　Wiley-VCH　GmbH.