晶面工程优化钴基钙钛矿电子结构及其电解水性能

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

钴基钙钛矿催化剂的晶面和电子构型与其本征电解水活性密切相关.本文中,我们提出了一种独特的熔盐方法以调控LaCoO_(3)的晶面类型和原子掺杂,进而调制其电子结构.通过引入封端剂(Sr^(2+)),我们制备了具有特定(110)晶面(LCO(110))和(111)晶面(LCO(111))的LaCoO_(3)样品.与LCO(111)相比,CoO_(6)八面体的畸变使LCO(110)和LSCO(111)具有更高的O 2p位置、更强的Co 3d–O 2p共价性以及更高的Co自旋态,从而具有更优的析氧反应(OER)和析氢反应(HER)性能.其中,LCO(110)、LCO(111)和LSCO(111)在10 mA cm^(−2)处的过电位分别为299,322和289 mV.此外,(110)晶面和Sr掺杂使Co–O键能增强,进而提升了LaCoO_(3)的稳定性.本工作通过晶面工程和原子掺杂为电子结构的调控开辟了新的途径,并为阐明OER和HER催化剂的电子结构-电催化活性关系提供了参考.

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 LaCoO_(3) by fine-tuning its crystal facet and atomic doping.LaCoO_(3) samples with oriented(110)(LCO(110))and(111)(LCO(111))facets were motivated by a capping agent(Sr^(2+)).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 CoO_(6) 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 LaCoO_(3) 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.