Macroscopic Polarization Enhancement Promoting Photo‐ and Piezoelectric‐Induced Charge Separation and Molecular Oxygen Activation

Efficient photo‐ and piezoelectric‐induced molecular oxygen activation are both achieved by macroscopic polarization enhancement on a noncentrosymmetric piezoelectric semiconductor BiOIO₃. The replacement of V⁵⁺ ions for I⁵⁺ in IO₃ polyhedra gives rise to strengthened macroscopic polarization of BiOIO₃, which facilitates the charge separation in the photocatalytic and piezoelectric catalytic process, and renders largely promoted photo‐ and piezoelectric induced reactive oxygen species (ROS) evolution, such as superoxide radicals (^.O₂⁻) and hydroxyl radicals (^.OH). This work advances piezoelectricity as a new route to efficient ROS generation, and also discloses macroscopic polarization engineering on improvement of multi‐responsive catalysis.     

Activation of Dioxygen at a Lewis Acidic Nickel(II) Complex: Characterization of a Metastable Organoperoxide Complex

In metal‐mediated O₂ activation, nickel(II) compounds hardly play a role, but recently it has been shown that enzymes can use nickel(II) for O₂ activation. Now a low‐coordinate Lewis acidic nickel(II) complex has been synthesized that reacts with O₂ to give a nickel(II) organoperoxide, as proposed for the enzymatic system. Its formation was studied further by UV/Vis absorption spectroscopy, leading to the observation of a short‐lived intermediate that proved to be reactive in both oxygen atom transfer and hydrogen abstraction reactions, while the peroxide efficiently transfers O atoms. Both for the enzyme and for the functional model, the key to O₂ activation is proposed to represent a concomitant electron shift from the substrate/co‐ligand.