La_1−xSr_xFeO₃ perovskite electrocatalysts for asymmetric electrocarboxylation of acetophenone with CO₂

The use of La_1−xSr_xFeO₃ (x= 0, 0.1, 0.2, 0.3, 0.4 and 0.5) cathodes in asymmetric electrocarboxylation of acetophenone with CO₂ induced by chiral auxiliary Co^II-(salen) was investigated for the first time. Optically active 2-hydroxy-2-phenylpropionic acid with 94% enantiomeric excess and 68% yield were obtained. The superior asymmetric electrocarboxylation performance may derive from the Fe⁴⁺ species and the increased lattice oxygen concentration on the surface of La_0.7Sr_0.3FeO₃ (LSF-0.3) induced by Sr-doping, together with an accelerated electron transfer and an increased electrochemically active surface area. Here, perovskite oxide catalyst has an acid function, which is supplied by Fe⁴⁺ ions, can participate in the reaction by coordinating with acetophenone. Moreover, the LSF-0.3 has considerable stability and reusability. By cyclic voltammograms and contrast experiments, a mechanism was proposed for the asymmetric electrocarboxylation reaction.