Crystal facet engineering of perovskite cobaltite with optimized electronic regulation for water splitting

The correlation between crystal facets and electronic configurations of perovskite is closely related to the intrinsic activity for water splitting. Herein, we proposed a unique molten-salt method (MSM) to manipulate the electronic properties of LaCoO3 by fine-tuning its crystal facet and atomic doping. LaCoO3 samples with oriented (110) (LCO (110)) and (111) (LCO (111)) facets were motivated by a capping agent (Sr2+). Compared with the LCO (111) plane, the LCO (110) and Sr-doped LCO (111) (LSCO (111)) planes possessed higher O 2p positions, stronger Co 3d–O 2p covalencies, and higher Co spin states by inducing CoO6 distortion, thus leading to superior oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performances. Specifically, the overpotentials at 10 mA cm−2 were 299, 322, and 289 mV for LCO (110), LCO (111), and LSCO (111), respectively. In addition, the (110) crystal facet and Sr substitution bestowed enhanced stability on LaCoO3 due to the strengthened Co–O bonding. The present work enlightens new avenues of regulating electronic properties by crystal facet engineering and atom doping and provides a valuable reference for the electron structure-electrocatalytic activity connection for OER and HER.