Harnessing Dynamic Noncovalent Heterojunctions for Efficient Red-Light-Driven Photocatalytic Hydrogen Evolution

Abstract

Efficient hydrogen generation via photocatalysis under red or near-infrared (NIR) light remains a formidable challenge, primarily due to the limited spectral absorption of most semiconductors and rapid charge recombination. While heterojunction engineering represents a promising strategy, conventional heterostructures often suffer from rigid interfacial architectures that restrict their charge-separation capability. Here, we present an aggregation strategy for constructing a dynamic noncovalent heterojunction using Rose Bengal sodium (RBS) and Rhodamine 6G (R6G). The results confirm that the through-space conjugation between RBS and R6G extends the light absorption of the RBS/R6G system from the visible region to the red-light region, resulting in a redshift of approximately 90 nm. Concurrently, the dynamic nature of this noncovalent heterojunction effectively suppresses backward electron transfer via excited-state structural rearrangement, thereby facilitating directional charge migration, along with a reduced exciton binding energy of 13.91 meV. Consequently, the Pt/RBS-R6G-SDS system delivers high-efficiency hydrogen evolution performance under red light, achieving a quantum yield as high as 76% at 600 nm—the highest value reported to date for red/NIR-driven hydrogen production (λ ≥ 600 nm). This work proposes a design strategy based on dynamic noncovalent heterojunctions enabled by aggregation, which effectively merges broad spectral absorption with efficient charge separation, paving the way for advanced solar-to-fuel conversion.