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Oxygen electrocatalytic activities in oxide perovskites are strongly dependent on their conductivity and electron configurations (eg). Herein, we show that an appropriate level of sulfur doping in oxide perovskites (such as LaCoO3, LaNiO3, and LaFeO3) can not only enhance the conductivity but also transform the spin state of Co (Ni, Fe) from low to intermediate spin and, therefore, give rise to much accelerated oxygen electrocatalytic activities. Sulfur-doped LaCoO3 (S-LCO) exhibits significantly enhanced electrocatalytic activities in both oxygen evolution reactions and oxygen reduction reactions, as confirmed by first principle calculations and experimental observation, where the potential rate-determining step is accelerated owing to the introduction of S-dopants and oxygen defects. At the optimized S-doping level, S5.84%-LCO endows a rechargeable Zn–air battery with a high power density (92 mW/cm2 at 144 mA/cm2), excellent stability of charge/recharge, and a large open-circuit voltage of 1.47 V. This study shows that the engineering of the electronic state of oxide perovskite by S-doping is an effective pathway leading to high-performing bifunctional catalysis for energy storage and conversion.
Ran et al. (Mon,) studied this question.