Exquisite　tuning　of　spatial　charge　transfer　and　separation　has　been　an　enduringly　core　issue　in　heterogeneous　photocatalysis.　Nevertheless,　precise　modulation　of　directional　charge　transfer　to　the　ideal　catalytically　active　sites　remains　challenging　owing　to　rapid　recombination　rate　of　photoinduced　charge　carriers　and　sluggish　charge　transfer　kinetics.　Herein,　bi-directional　spatially　separated　electron　and　hole　transport　channels　were　simultaneously　constructed　over　transition　metal　chalcogenides　(TMCs)-based　heterostructures　via　an　efficient　and　facile　electrostatic　self-assembly　strategy.　Tailor-made　positively　charged　non-conjugated　polymer　of　branched　polyethyleneimine　(BPEI)　and　negatively　charged　metal　nanocrystals　(NCs)　building　blocks　were　controllably　anchored　on　the　TMCs　substrate.　We　found　that　electrons　photoexcited　over　TMCs　substrate　can　migrate　spontaneously,　smoothly　and　unidirectionally　to　the　tightly　integrated　neighboring　metal　NCs,　wherein　metal　NCs　function　as　Schottky-type　electron-trapping　reservoirs　and　the　ultra-thin　intermediate　BPEI　layer　serves　as　a　directional　hole　transport　mediator,　thus　synergistically　contributing　to　the　significantly　enhanced　charge　separation　and　prolonged　charge　lifetime.　Benefiting　from　these　merits,　such　self-assembled　TMC@BPEI/metal　heterostructure　exhibits　the　markedly　enhanced　photoreduction　catalysis　toward　photocatalytic　hydrogen　generation　and　anaerobic　selective　reduction　of　nitroaromatics　to　amino　derivatives　under　visible　light　irradiation.　Our　work　would　provide　inspiring　idea　for　fine　modulation　of　charge　separation　and　transfer　toward　solar-to-chemical　energy　conversion.　(C)　2022　Elsevier　Inc.　All　rights　reserved.