Engineering Semiconductor Quantum Dots for Selectivity Switch on High-Performance Heterogeneous Coupling Photosynthesis

Semiconductor-based photoredox catalysis brings an innovative strategy for sustainable organic transformation (e.g., C-C/C-X bond formation), via radical coupling under mild conditions. However, since semiconductors interact with photogenerated radicals unselectively, the precise control of selectivity for such organic synthesis by steering radical conversion is extremely challenging. Here, by the judicious design of a structurally well-defined and atomically dispersed cocatalyst over semiconductor quantum dots, we demonstrate the precise selectivity switch on high-performance selective heterogeneous coupling photosynthesis of a C-C bond or a C- N bond along with hydrogen production over the Ni-oxo cluster and single Pd atom-decorated CdS quantum dots crafted onto the SiO2 support. Mechanistic studies unveil that the Ph(center dot CH)NH2 and PhCH2NH2 center dot+ act as dominant radical intermediates for such divergent organic synthesis of C-C coupled vicinal diamines and C-N coupled imines, as respectively enabled by Ni-oxo clusters assisted radical-radical coupling and single Pd atom-assisted radical addition-elimination. This work overcomes the pervasive difficulties of selectivity regulation in semiconductor-based photochemical synthesis, highlighting a vista of utilizing atomically dispersed cocatalysts as active sites to maneuver unselective radical conversion by engineering quantum dots toward selective heterogeneous photosynthesis.

Automated summary

Semiconductor-based photoredox catalysis offers a sustainable and mild strategy for organic transformation, but controlling selectivity is challenging due to non-selective interactions between semiconductors and photogenerated radicals. By designing atomically dispersed cocatalysts on semiconductor quantum dots, we achieve precise selectivity in high-performance heterogeneous coupling photosynthesis. This work overcomes the difficulties of selectivity regulation in semiconductor-based photochemical synthesis, highlighting the potential of utilizing atomically dispersed cocatalysts to control unselective radical conversion for selective heterogeneous photosynthesis.