Defect‐Induced Atomic Arrangement in CoFe Bimetallic Heterostructures with Boosted Oxygen Evolution Activity. Issue 9 (19th December 2022)

• Record Type: Journal Article
• Authors: Zheng, Lingxia; Ye, Weiqing; Zhao, Yijian; Lv, Zhuoqing; Shi, Xiaowei; Wu, Qi; Fang, Xiaosheng; Zheng, Huajun
• Is Part Of: Small. Volume 19:Issue 9(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-12-19
• Subjects: CoFe bimetallic oxides -- defect engineering -- electronic structure modulation -- oxygen evolution reaction -- spinel oxides; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202205092
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: Three CoFe‐bimetallic oxides with different compositions (termed as CoFeOx ‐A/N/H) are prepared by thermally treating metal‐organic‐framework (MOF) precursors under different atmospheres (air, N2, and NaBH4 /N2 ), respectively. With the aid of vast oxygen vacancies (Ov ), cobalt at tetrahedral sites (Co 2+ (Th)) in spinel Co3 O4 is diffused into interstitial octahedral sites (Oh) to form rocksalt CoO and ternary oxide CoFe2 O4 has been induced to give the unique defective CoO/CoFe2 O4 heterostructure. The resultant CoFeOx ‐H exhibits superb electrocatalytic activity toward water oxidation: overpotential at 10 mA cm −2 is 192 mV, which is 122 mV smaller than that of CoFeOx ‐A. The smaller Tafel slope (42.53 mV dec −1 ) and higher turnover frequency (785.5 h −1 ) suggest fast reaction kinetics. X‐ray absorption spectroscopy, ex situ characterizations, and theoretical calculations reveal that defect engineering effectively tunes the electronic configuration to a more active state, resulting in the greatly decreased binding energy of oxo intermediates, and consequently much lower catalytic overpotential. Moreover, the construction of hetero‐interface in CoFeOx ‐H can provide rich active sites and promote efficient electron transfer. This work may shed light on a comprehensive understanding of the modulation of electron configuration of bimetallic oxides and inspire the smart design of high‐performance electrocatalysts. Abstract : Three CoFe bimetallic oxide electrocatalysts with different geometrical and electronic structures have been prepared by simply varying the annealing atmospheres. Numerous Co 2+ (t2g 6 eg 1 ) active sites and rich oxygen vacancies together with unique CoO/CoFe2 O4 hetero‐interface in CoFeOx ‐H are accounted for the splendid electrocatalytic activity and fast reaction kinetics toward water oxidation.