Noble‐Metal‐Assisted Fast Interfacial Oxygen Migration with Topotactic Phase Transition in Perovskite Oxides

Abstract

Transition-metal perovskite oxides constitute a series of functional material systems for electronics, catalysis, and energy-conversion processes, in which oxygen migration and evolution play a key role. However, the stable metal-oxygen (MO) bond forms a large energy barrier inhibiting ion diffusion. Therefore, seeking efficient and facile approaches to accelerate oxygen kinetics has become a significant issue. Here, the interaction (interfacial charge transfer and cooperative bonding) between noble metal (Pt, Ag) and perovskites oxide (SrCoO 3−δ ) is employed to weaken the (MO) bond and decrease the energy barrier of oxygen migration. Noble metal layers serving as oxygen pumps can continuously extract oxygen from oxide films to the atmosphere. The temperature of the topotactic phase transition from perovskite (SrCoO 3 ) to brownmillerite (SrCoO 2.5 ) is remarkably lowered from ≈200 °C to room temperature. Furthermore, this approach can also be applied to SrFeO 3 for similar topotactic phase reduction by moderate thermal activation. The finding of this study paves a promising and general pathway to achieve fast oxygen migration in perovskite oxides, with important application prospects in low-temperature electrodes and high-activity catalysis interface.

Selective formation of propan-1-ol from propylene via a chemical looping approach

“…7), with little to none selectivity towards acetone or propan-2-ol, suggesting electrophilic behaviour and linear oxametallacycle route. The electrophilic behaviour of Au agrees with the finding 59 that noble metals…”

Compressive-Strain-Facilitated Fast Oxygen Migration with Reversible Topotactic Transformation in La0.5Sr0.5CoOx via All-Solid-State Electrolyte Gating

“…These distinctions may lead to different regulations of the Co–O bond and, thus, different diffusion barriers for O 2– ions inside and outside of the oxygen migration channel. Actually, considering the mixed covalent and ionic bonding character in the Co–O bond, , differences in lattice distortion can lead to different chemical environment such as Co 3d orbital configurations and hybridization with O 2p orbitals in Co1 and Co2 sublayers, which is directly correlated with the oxygen migration …”

“…Therefore, the observed enhancement of Co 3d band-filling and suppression of Co 3d–O 2p hybridization in compressively strained films can be ascribed to the decreased charge transfer from Co 3d to O 2p. As a result, the bond order and strength of the Co–O hybrid bond were reduced, , leading to fast oxygen migration and facile RTPT in films under compressive strain. It is worth noting that the charge transfer between Co 3d and O 2p and the Co–O hybrid bond strength are strongly correlated with the lattice distortion around Co atoms.…”

“…Consequently, numerous investigations have focused on recasting crystal structures, exploring surface chemical activity, and examining material properties by controlling O 2– -ion migration in complex oxide films − due to their promising applications in energy conversion, chemical looping, , and catalysis . Recently, researchers have revealed high O 2– -ion mobility and abundant electronic configurations in cobaltite films, ,, suggesting that these materials represent an excellent platform for ion modulation engineering. − Various methods have been applied to drive O 2– -ion migration in cobaltite films, including reductive annealing, electric field driving, , and reductive layer capping. , Multiple transformations between various crystal structures (e.g., La 2– y Sr y CoO 4 , HSrCoO 2.5 , n LCO 2.5 ), accompanied by novel properties (e.g., magnetism, electrical transport, optical transmittance), have been discovered. − However, harsh conditions (e.g., high temperature) are typically required to trigger the formation/migration of oxygen vacancies/ions and to drive the transformation in these processes, which causes significant energy and cost penalties. Recently, electric field gating via an ionic liquid (IL) has been employed to control O 2– -ion migration and induce a reversible topotactic phase transformation (RTPT) in oxides, due to the energy-saving advantages and nonvolatile nature.…”

“…18−21 Various methods have been applied to drive O 2− -ion migration in cobaltite films, including reductive annealing, 22 electric field driving, 23,24 and reductive layer capping. 25,26 Multiple transformations between various crystal structures (e.g., La 2−y Sr y CoO 4 , HSrCoO 2.5 , nLCO 2.5 ), accompanied by novel properties (e.g., magnetism, electrical transport, optical transmittance), have been discovered. 27−30 However, harsh conditions (e.g., high temperature) are typically required to trigger the formation/migration of oxygen vacancies/ions and to drive the transformation in these processes, which causes significant energy and cost penalties.…”