Photocatalytic dehydrogenative C(sp 3)-C(sp 3) homocoupling over an electrostatically self-assembled MoS 2/CdS heterojunction

Photocatalytic dehydrogenative homocoupling of benzyl derivatives is a green and sustainable strategy for the direct construction of C(sp³)-C(sp³) bonds. However, the efficiency of these reactions is significantly hindered by the poor surface kinetics of the hydrogen evolution reaction (HER) and severe charge recombination. Herien, we demonstrate that the electrostatic self-assembly of MoS₂ colloids on CdS nanosheets (MoS₂/CdS) can efficiently capture photogenerated electrons to drive H⁺ reduction, owing to their intrinsic excellent catalytic ability for HER and their strong electron-sink effect for charge separation. This, in turn, facilitates the migration of photogenerated holes from the bulk to the surface, enabling more holes to initiate the oxidative cleavage of C-H bonds in benzyl derivatives, such as cumene. More importantly, MoS₂ colloids, with Mo atoms sandwiched between two sulfur layers, exhibit much lower interaction with produced ·C(CH₃)₂Ph radicals compared to conventional HER cocatalysts such as noble or transition metal co-catalysts. This facilitates the departure of the ·C(CH₃)₂Ph radicals for C(sp³)-C(sp³) homocoupling reactions, thus enhancing selectivity toward bicummyl. This work presents an efficient, green and cost-effective strategy for the dehydrogenative homocoupling of benzyl derivatives to construct C(sp³)−C(sp³) bonds under mild conditions.