Realizing Ultrafast Oxygen Evolution by Introducing Proton Acceptor into Perovskites

Abstract

The oxygen evolution reaction (OER) is of prime importance in multiple energy storage devices. Perovskite oxides involving lattice‐oxygen oxidation are generally regarded as highly active OER catalysts, but the deprotonation of surface‐bound intermediates limit the further activity improvement. Here, it is shown that this kinetic limitation can be removed by introducing Sr3B2O6 (SB) which activates a proton‐acceptor functionality to boost OER activity. As a proof‐of‐concept example, an experimental validation is conducted on the extraordinary OER performance of a Sr(Co0.8Fe0.2)0.7B0.3O3−δ (SCFB‐0.3) hybrid catalyst, made using Sr0.8Co0.8Fe0.2O3−δ as active component and SB as a proton acceptor. This smart hybrid exhibits an exceptionally ultrahigh OER activity with an extremely low overpotential of 340 mV in 0.1 m KOH and 240 mV in 1 m KOH required for 10 mA cm−2 which is the top‐level catalytic activity among metal oxides reported so far, while maintaining excellent durability. The correlation of pH and activity study reveals that this enhanced activity mainly originates from the improved interfacial proton transfer. Such a strategy further demonstrated to be universal, which can be applied to enhance the OER activity of other high covalent oxides with close O 2p‐band centers relative to Fermi energy.

Replacement of Ca by Ni in a Perovskite Titanate to Yield a Novel Perovskite Exsolution Architecture for Oxygen‐Evolution Reactions

“…Meanwhile, the ECSAs were significantly increased in both the Ni‐exsolved CaTiO 3 prepared by solid‐state reactions and solvothermal synthesis, but the latter (16.82 cm 2 ) was higher than the former (14.87 cm 2 ) (Figure a) (previous metal: >30 cm 2 , transition metal oxides: ≥1 cm 2 , and perovskites: ≈3 cm 2 depending on synthesis methods) . The geometric OER activities were 3.28 mA cm −2 geo , 4.80 mA cm −2 geo , and 10.88 mA cm −2 geo at 1.7 V in the mixture, solid state prepared micrometer scale Ni‐exsolved, and Ni‐exsolved CaTiO 3 sub‐micrometer spheres by solvothermal synthesis, respectively (Figure b), which is comparable to state of the art results of both base metals and perovskites (Table S3, Supporting Information) . The results clearly show that the increase in Ni utilization from the porous sub‐micrometer spheres can enhance the electrochemical activities.…”

Tuning proton-coupled electron transfer by crystal orientation for efficient water oxidization on double perovskite oxides

“…where ρ RHE is the proton reaction order 11,14,17 . When the deprotonation processes are strongly coupled with an electron transfer, its OER kinetics shows little dependence on the pH value of a solution (vs. RHE), leading to a low ρ RHE value.…”

“…In contrast, if the deprotonation process is involved in the PDS along with decoupling of the electron transfer process, the OER kinetics depends strongly on pH with a larger ρ RHE value. For instance, it was observed that various mixed ionic-electronic conductors (MIECs) (i.e., =La 0.5 Sr 0.5 CoO 3 and Pr 0.5 Ba 0.5 CoO 3 ) have lattice oxygen participation in the OER, leading to a decoupled proton-electron transfer process in OER and a strong pH dependence 15,17,38,39 .…”

Self‐Assembled Ruddlesden–Popper/Perovskite Hybrid with Lattice‐Oxygen Activation as a Superior Oxygen Evolution Electrocatalyst

“…[ 30–33 ] On the other hand, the hybrid systems can induce some synergetic effects enabling to stabilize catalytic sites, and achieve a desirable electrocatalytic stability. [ 34,35 ] Therefore, we believe that the formation of RP/perovskite hybrid may be a viable way to regulate the electronic structure and accordingly boost the electrocatalytic performance. However, such hybrid system for OER has never been explored, and a simple synthetic process for RP/perovskite hybrid is also highly needed.…”