Molecular　catalysts　(MC),　namely　homogeneous　catalysts,　have　demonstrated　great　promise　for　efficient　solar-to-chemical　energy　conversion　in　the　hybrid　system.　However,　the　poor　interfacial　interaction　between　MC　and　photosensitizers　(PS)　impedes　the　efficient　and　fast　interfacial　electron　transfer.　To　promote　interfacial　communication　between　PS　and　MC,　a　proof-of-concept　method　was　developed　for　the　combination　of　polymeric　carbon　nitride　(PCN)　PS　with　bipyridine　cobalt　[Co(bpy)(3)(2+)]　MC　by　covalent　bonds,　creating　molecular　junctions　to　promote　interfacial　electron　transfer　as　confirmed　by　transient　photoluminescence　lifetime　and　electrochemical　measurements.　As　a　result,　the　binary　photocatalyst　[Co(bpy)(3)(2+)/BINA(2)-CN]　showed　extensively　enhanced　photocatalytic　activity　such　as　H-2　and　CO2　reduction　in　comparison　with　the　physical　mixture　of　Co(bpy)(3)(2+)and　PCN.　This　observation　highlights　the　importance　of　construction　of　surface　molecular　junctions　between　PS　and　MC　to　accelerate　the　interfacial　charge-carrier　mobility　and,　consequently,　improve　the　photocatalytic　activity.