Enhanced oxygen evolution over dual corner-shared cobalt tetrahedra
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Chen, Yubo↗
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Chen, Yubo
Publications and source records attributed to Chen, Yubo.
Lattice site–dependent metal leaching in perovskites toward a honeycomb-like water oxidation catalyst
Metal leaching during water oxidation has been typically observed in conjunction with surface reconstruction on perovskite oxide catalysts, but the role of metal leaching at each geometric site has not been distinguished. Here, we manipulate the occurrence and process of surface reconstruction in two model ABO 3 perovskites, i.e., SrSc 0.5 Ir 0.5 O 3 and SrCo 0.5 Ir 0.5 O 3 , which allow us to evaluate the structure and activity evolution step by step. The occurrence and order of leaching of Sr (A-site) and Sc/Co (B-site) were controlled by tailoring the thermodynamic stability of B-site. Sr leaching from A-site mainly generates more electrochemical surface area for the reaction, and additional leaching of Sc/Co from B-site triggers the formation of a honeycomb-like IrO x H y phase with a notable increase in intrinsic activity. A thorough surface reconstruction with dual-site metal leaching induces an activity improvement by approximately two orders of magnitude, which makes the reconstructed SrCo 0.5 Ir 0.5 O 3 among the best for water oxidation in acid.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Active Phase on SrCo 1–x Fe x O -δ (0 ≤ x ≤ 0.5) Perovskite for Water Oxidation: Reconstructed Surface versus Remaining Bulk
Perovskite oxides based on earth-abundant transition metals have been extensively explored as promising oxygen evolution reaction (OER) catalysts in alkaline media. The (electro)chemically induced transformation of their initially crystalline surface into an amorphous state has been reported for a few highly active perovskite catalysts. However, little knowledge is available to distinguish the contribution of the amorphized surface from that of the remaining bulk toward the OER. In this work, we utilize the promoting effects of two types of Fe modification, i.e., bulk Fe dopant and Fe ions absorbed from the electrolyte, on the OER activity of SrCoO 3-δ model perovskite to identify the active phase. Transmission electron microscopy and X-ray photoelectron spectroscopy confirmed the surface amorphization of SrCoO 3-δ as well as SrCo 0.8 Fe 0.2 O 3-δ after potential cycling in Fe-free KOH solution. By further cycling in Fe-spiked electrolyte, Fe was incorporated into the amorphized surface of SrCoO 3-δ (SrCoO 3-δ + Fe 3+ ), yielding approximately sixfold increase in activity. Despite the difference in remaining perovskites, SrCoO 3-δ + Fe 3+ and SrCo 0.8 Fe 0.2 O 3-δ exhibited remarkably similar activity. These results reflect that the in situ developed surface species are directly responsible for the measured OER activity, whereas the remaining bulk phases have little impact.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗