Solar-accelerated chemoselective hydrogenation of 4-nitrostyrene to 4-vinylaniline with carbon dot-induced Cu over Cu3P in the absence of any sacrificial reagent

Abstract

We present an efficient method toward rational design and fabrication of multicomponent photocatalysts using carbon dots (CDs) for solar-driven chemical reactions with super selectivity and activity. CDs act not only as a reductant to enable metallic Cu formation but also as a hole trapping agent to hinder side reactions. By simple pyrolysis of the mixture of the Cu source, CDs and NaH₂PO₂, the Cu₃P–CDs–Cu nanocomposite is produced and shows a good sunlight harvesting property. Under one sun irradiation, Cu₃P–CDs–Cu can catalyze ammonia borane (AB) for selective hydrogenation of 4-nitrostyrene (4-NS) to 4-aminostyrene (4-AS) in an aqueous solvent at room temperature, achieving 100% selectivity and beyond 99% conversion rate within a few short minutes of reaction time. The superior performance of Cu₃P–CDs–Cu is attributed to the formation of the all-solid-state Z-scheme photocatalytic system, eliminating the high-energy holes—active species attacking CC groups in 4-NS—from Cu₃P. Meanwhile, metallic Cu promotes the migration and transport of excited electrons from the interior to the surface and interface, accelerating the activation of AB for selective reduction of 4-NS to 4-AS.