Precise Interface Modulation Cascade Enables Unidirectional Charge Transport

Atomically Precise Metal Nanocluster-Mediated Solar Hydrogen Production

Atomically precise metal nanoclusters (NCs) stand out within metal nanomaterials due to the distinctive atomic stacking configuration, discrete energy band, quantum confinement effect, and enriched catalytic centers, positioning them as promising substitutes for conventional photosensitizers in solar energy absorption and utilization. However, the light-induced poor stability and ultrashort carrier lifetime of metal NCs as well as the difficulties in modulating charge migration collectively constrain their potential applications in photoredox catalysis. In this work, we conceptually construct the metal NC artificial photosystems by electrostatically self-assembling l-glutathione (GSH)-capped Au25(GSH)18 NCs onto transition metal chalcogenide (TMC) substrates (CdS, Zn0.5Cd0.5S, and ZnIn2S4) at ambient conditions. Benefiting from the advantageous photosensitization effect of Au25@(GSH)18 NCs, these self-assembled TMCs/Au25@(GSH)18 NC heterostructures exhibit significantly enhanced photocatalytic hydrogen production performance (λ > 420 nm). This universal photoactivity enhancement is predominantly attributed to the suitable energy level alignment between Au25@(GSH)18 NCs and TMCs, which considerably enhances the interfacial charge transfer and effectively extends the carrier lifetime. In addition, the photocatalytic mechanism is determined. This work would spark continued interest in crafting diverse atomically precise metal NC photocatalytic systems toward solar-to-hydrogen energy conversion.

Surmounting the instability of atomically precise metal nanoclusters towards boosted photoredox organic transformation

Atomically precise metal nanoclusters (NCs) have recently been recognized as an emerging sector of metal nanomaterials but suffer from light-induced poor stability, giving rise to the detrimental self-transformation into metal nanocrystals (NYs), losing the photosensitization effect and ultimately retarding their widespread applications in photoredox catalysis. Are metal NCs definitely superior to metal NYs in heterogeneous photocatalysis in terms of structural merits? To unlock this mystery, herein, we conceptually demonstrate how to rationally manipulate the instability of metal NCs to construct high-efficiency artificial photosystems and examine how the metal NYs self-transformed from metal NCs influence charge transfer in photoredox selective organic transformation. To our surprise, the results indicate that the Schottky-type electron-trapping ability of Au NYs surpasses the photosensitization effect of glutathione (GSH)-protected Au clusters [Au25(GSH)18 NCs] in mediating charge separation and enhancing photoactivities towards selective photoreduction of aromatic nitro compounds to amino derivatives and photocatalytic oxidation of aromatic alcohols to aldehydes under visible light irradiation. This work strategically provides new insights into the inherent instability of metal NCs utilized for photocatalysis and reinforces our fundamental understanding on metal NC-based artificial photosystems for solar energy conversion.