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.

空间电荷转移和分离的精细调整一直是非均相光催化的核心问题。然而，由于光诱导电荷载流子的快速复合率和缓慢的电荷转移动力学，精确调节向理想催化活性位点的定向电荷转移仍然具有挑战性。在此，通过有效且简便的静电自组装策略，在基于过渡金属硫属化物 (TMC) 的异质结构上同时构建了双向空间分离的电子和空穴传输通道。由支链聚乙烯亚胺 (BPEI) 和带负电的金属纳米晶体 (NCs) 构建块组成的定制的带正电非共轭聚合物可控制地锚定在 TMC 基板上。我们发现在 TMCs 衬底上光激发的电子可以自发、平滑和单向地迁移到紧密集成的相邻金属 NCs，其中金属 NCs 用作肖特基型电子俘获库，超薄中间 BPEI 层用作定向空穴传输介质，因此协同地有助于显着增强电荷分离和延长电荷寿命。得益于这些优点，这种自组装的 TMC@BPEI/金属异质结构在可见光照射下表现出显着增强的光还原催化光催化制氢和硝基芳烃厌氧选择性还原为氨基衍生物的能力。