Revealing the Correlation of OER with Magnetism: A New Descriptor of Curie/Neel Temperature for Magnetic Electrocatalysts

Abstract

Developing accurate descriptors for oxygen evolution reaction (OER) is of great significance yet challenging, which roots in and also boosts the understanding of its intrinsic mechanisms. Despite various descriptors are reported, it still has limitations in the facile prediction, given that complicated analytical techniques as well as time-consuming modeling and calculations are indispensable. In the present work, strong correlation of magnetic property with OER performance is revealed by in-depth investigations on the crystal and electronic structures. A facile descriptor of Curie/Neel temperature (T C/N ) is developed for La 2−x Sr x Co 2 O 6− perovskite oxides, based on the inference that both magnetism and OER are rooted in the electron exchange interaction. Specifically, both the T C/N and OER activity are proportional to the degree of p-d orbital hybridization, which increases with enlarged bond angle of Co─O─Co and/or increased oxidation of Co. This finding reveals that T C/N from magnetic characterizations is an effective descriptor in designing novel OER electrocatalysts, and interdisciplinary researches are advantageous for revealing the controversial mechanisms of OER process.

A universal chemical-induced tensile strain tuning strategy to boost oxygen-evolving electrocatalysis on perovskite oxides

“…For electronic structures, the properties of valence, 10 electronegativity, 11 covalency 12 and orbital information (i.e., e g occupation, 2 spin, 13 O 2p band center, 14 band gap 15 and charge-transfer energy 16 ) successfully explained the activity trends of perovskites and demonstrated the underlying correlations. Moreover, macroscopic physiochemical properties of perovskites, such as magnetism, 17 conductivity 18 and hydrophilia, 19 are also important to affect their electrochemical catalysis processes. To effectively optimize above properties, numerous perovskites were developed, including delafossite ABO 2-δ , 20 single perovskite ABO 3-δ , 2 single-layer Ruddlesden-Popper (RP) perovskite A 2 BO 4-δ , 21 double perovskite A 2 B 2 O 6-δ , 14 double-layer RP perovskite A 3 B 2 O 7δ , 22 triple perovskite A 3 B 3 O 9-δ , 23 three-layer RP perovskite A 4 B 3 O 10-δ , 24 quadruple perovskite A 4 B 4 O 12-δ , 25 5H-polytype perovskite A 5 B 5 O 14-δ 7 and hexagonal perovskite A 8 B 4 O 15-δ , 26 where A-sites are alkaline/rare-earth metal cations and B-sites are transition-metal cations.…”

Highly Oxidized Oxide Surface toward Optimum Oxygen Evolution Reaction by Termination Engineering

“…In general, a highly oxidized oxide system naturally enhances the hybridization between the metal (Co) and oxygen . It is thus interesting to see whether the specific facet configuration has also triggered oxygen state evolution that is relevant to OER activities.…”

“…In general, a highly oxidized oxide system naturally enhances the hybridization between the metal (Co) and oxygen. 39 It is thus interesting to see whether the specific facet configuration has also triggered oxygen state evolution that is relevant to OER activities. As elaborated above, O K-edge XANES signals are dominated by Co characteristics, so intrinsic oxygen state variation could be buried with no clear signature.…”

Regulation of perovskite oxides composition for the efficient electrocatalytic reactions

“…The electronic structure of the majority of perovskite catalysts is only favorable for ORR or OER. [9][10][11][12][13][14][15] Specifically, Zhou and coworkers described a series of A-site excessive perovskite oxides (La 0.8 Sr 0.2 ) 1+x MnO 3 (x = 0.05, 0.1) via the polymer-assisted chemical solution (PACS) method for both OER and ORR applications in alkaline media. [62] (La 0.8 Sr 0.2 ) 1.05 MnO 3 has showed 21% higher diffusioncontrolled ORR current density and 87% higher OER current density at 0.8 V compared to LaSrMnO 3 .…”

“…Additionally, the perovskite oxides family also includes double perovskites (A 2 B 2 O 6 ), triple perovskites (A 3 B 3 O 9 ), quadruple perovskites (A 4 B 4 O 12 ), and Ruddlesden-Popper (RP) perovskites (A n+1 B n O 3n+1 (n = 1, 2, and 3)). [4][5][6] Due to their low price, adjustable composition, ordered atomic arrangement and highly flexible electronic structure, perovskite oxides have undergone extensive research as the potential noble-metal-free electrocatalysts for metal-air batteries, [7,8] solid oxide fuel cells (SOFCs), and water splitting, including the oxygen reduction reaction (ORR), [9][10][11] the oxygen evolution reaction (OER), [12][13][14][15] and the hydrogen evolution reaction (HER). [16][17][18] However, the large particle sizes, small surface areas, and poor electrical conductivities of perovskite catalysts often result in a limited amount of catalytic activity.…”