Natural Sunlight-Driven Activation of Inert Aryl Halides Using Plasmonic Cu@CdS with Polysulfide Active Sites

Visible light photoredox catalysis has become a rapidly emerging area owing to its potential of using sunlight to tame previously hard-to-harness radicals for organic synthesis. At present, such a blueprint faces a significant challenge, namely how to accomplish thermodynamically demanding reactions with sunlight encompassing a wide range of low-energy photons. Here, we report a new reaction framework to overcome this bottleneck through decoupling the thermodynamic limits of photoreduction from photoexcitation. This is fulfilled based on the construction of a heterogeneous photocatalyst Cu@CdS possessing in situ-formed surficial polysulfide species (including S₃^•− and S₄²⁻), which can efficiently harvest solar energy via plasmonic absorption of Cu while manifest sufficient redox potential for activating inert aryl bromides/chlorides enacted by excited polysulfides. We demonstrate that this designed material composes a potent photoredox catalyst for efficient aryl cross-coupling, borylation, hydrogenation, as well as Birch-type dearomatization reactions, with good recyclability and stability. In particular, when exclusively using natural sunlight as an energy source, the product yield can still reach up to 90%. Our findings introduce a straightforward yet viable way to progress toward the century-long dream of leveraging natural sunlight to produce structurally complex organic molecules, just like plants on Earth.