Cascade charge-transport-chain engineering in alloy nanocluster-semiconductor artificial photosystems

Atomically precise metal nanoclusters (NCs), featuring a discrete electronic structure and pronounced quantum confinement effects, are emerging as promising photosensitizers for artificial photosystems; however, their practical implementation remains fundamentally constrained by rapid charge recombination and poorly controlled charge transport. Here, we introduce a conceptual cascade charge-transport-chain engineering strategy that addresses this intrinsic bottleneck by constructing directional and continuous carrier transport pathways across NC-semiconductor interfaces. By integrating alloy NC photosensitization with atomic Ni doping of TiO₂, robust interfacial electronic coupling is established, enabling directional and accelerated extraction of photogenerated carriers. The resulting BNC/Ni-TiO₂ heterostructures exhibit markedly enhanced visible-light-driven hydrogen evolution, accompanied by effective suppression of charge recombination within alloy NCs. Combined experimental and theoretical investigations reveal that the performance enhancement originates from cascade charge-transport-chain engineering rather than simple binary synergy. This work provides a general design principle for constructing tunable charge-transport pathways with alloy NCs, advancing NC-based artificial photosystems toward solar-to-hydrogen energy conversion.