Al³⁺ Dopants Induced Mg²⁺ Vacancies Stabilizing Single-Atom Cu Catalyst for Efficient Free-Radical Hydrophosphinylation of Alkenes

Utilizing heterogeneous catalysts to overcome obstacles for homogeneous reactions is fascinating but very challenging owing to the difficult fabrication of such catalysts based on the character of target reactions. Herein, we report a Al³⁺ doping strategy to construct single-atom Cu on MgO nanosheets (Cu₁/MgO(Al)) for boosting the free-radical hydrophosphinylation of alkenes. Al³⁺ dopants in MgO bring about abundant Mg²⁺ vacancies for stabilizing dense independent Cu atoms (6.3 wt %), while aggregated Cu nanoparticles are formed without Al³⁺ dopants (Cu/MgO). Cu₁/MgO(Al) exhibits preeminent activity and durability in the hydrophosphinylation of various alkenes with great anti-Markovnikov selectivity (99%). The turnover frequency (TOF) value reaches up to 1272 h^-1, exceeding those of Cu/MgO by ∼6-fold and of traditional homogeneous catalysts drastically. Further experimental and theoretical studies disclose that the prominent performance of Cu₁/MgO(Al) derives from the accelerated initiating step of phosphinoyl radical triggered by individual Cu atoms.