Oxygen Evolution via the Bridging Inequivalent Dual-Site Reaction: First-Principles Study of a Quadruple-Perovskite Oxide Catalyst

Abstract

Perovskite-type oxides composed of earth-abundant elements have been extensively studied as possible candidates for oxygen evolution reaction (OER) catalysts. In our recent study, quadruple perovskite oxides (e.g., Ca-Cu 3 Fe 4 O 12 and LaMn 7 O 12 ) displayed catalytic activity that was higher than that of simple perovskites (e.g., LaMnO 3 ), but the reason has not yet been unveiled. We have conducted firstprinciples calculations of the several surface energies of LaMn 7 O 12 and adsorption energies of OER intermediates on LaMn 7 O 12 using slab models to clarify the reaction mechanism. The Mn-rich surfaces, i.e., the (001) with BO 2 termination and (220) surfaces, are found to be more stable for LaMn 7 O 12 . It is found that all intermediates are preferentially adsorbed on the A′−B-bridge site on the LaMn 7 O 12 (220) surface, although only the B-top site was a stable adsorption site on the (001) surface of LaMn 7 O 12 and LaMnO 3 . The difference between theoretical overpotentials on the (220) surface of LaMn 7 O 12 and the (001) surface with BO 2 termination of LaMnO 3 is in good agreement with the experimental overpotential for OER. We propose a new design principle in which OER is enhanced via adsorption on the A′−B-bridge site consisting of two adjacent Mn sites {coordination-unsaturated pyramid [coordination number (CN) = 5] and coordination-saturated pseudosquare (CN = 4)}, where the adsorbates are strongly bound to the former and weakly bound to the latter.

Atomic Doping and Anion Reconstructed CoF2 Electrocatalyst for Oxygen Evolution Reaction

“…At present, noble metal–based materials for OER, such as ruthenium oxides, are still ranking the highest level. [ 16,17 ] Meanwhile, nonnoble metal compounds, for instance, transition metal oxides, [ 18–21 ] perovskite, [ 22,23 ] hydroxide, [ 24,25 ] nitrides, [ 26,27 ] borates, [ 28,29 ] and so on, have also captured extensive interests for preparing high‐efficient OER catalysts. Among them, the metal fluoride, mostly literature reported for supercapacitor, lithium ion battery, etc., [ 30–33 ] is rarely wielded in the field of water electrolysis, possibly due to the chemical/electrochemical instability of fluoride ions and the weak bond between the metal ions and fluoride ions.…”

Mono‐/Multinuclear Water Oxidation Catalysts

“…Song and co-workersd esigned ah eterogeneousc atalyst with dual-metal sites, consisting of single Ni and Fe atoms embedded into g-C 3 N 4 units (Scheme 17 and Figure 7). [178] They found that oxygen evolution occurredt hrough the bridg-ing-inequivalent dual-site reaction, and OER adsorbates formed as trong chemical bond to the coordination-unsaturated octahedral site and aw eak chemical bond to ac oordination-saturated tetrahedral site or asquare-planar site (Figure 8). These dual-metal-site catalysts may offer an ew route to synthesize efficient WOCs.…”

“…In addition, Ikeno and co-workers investigated the higherO ER activity of the quadruple perovskite oxide LaMn 7 O 12 than that of the simple perovskite LaMnO through DFT computations. [178] They found that oxygen evolution occurredt hrough the bridg-ing-inequivalent dual-site reaction, and OER adsorbates formed as trong chemical bond to the coordination-unsaturated octahedral site and aw eak chemical bond to ac oordination-saturated tetrahedral site or asquare-planar site (Figure 8).…”

Structure–Activity Relationship of Iron Oxides for NO Reduction in the Presence of C3H6, CO, and O2

“…For instance, the strain of MO 6 octahedra in perovskite oxides varies the splitting of e g orbitals and impacts on the strength of metal–oxygen bonds to determine the oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) activity . Also, some researchers found that distinct geometry coordination structure sites (distorted tetrahedral sites, or corner sharing of AO 4 and BO 5 sites) favorably adsorbed reaction intermediate species, which enhanced the activity of catalysts with those sites . Reports that elucidate the role of the local structure are limited to water oxidation or the ORR, the mechanisms of which have been extensively studied.…”

“…[20] Also, somer esearchersf ound that distinct geometry coordination structure sites (distorted tetrahedrals ites, or corner sharing of AO 4 and BO 5 sites) favorably adsorbed reactioni ntermediate species, whiche nhanced the activity of catalysts with those sites. [21,22] Reports that elucidate the role of the local structurea re limited to water oxidation or the ORR, the mechanisms of which have been extensively studied.…”