Two orders of magnitude enhancement in oxygen evolution reactivity on amorphous Ba _0.5 Sr _0.5 Co _0.8 Fe _0.2 O _3−δ nanofilms with tunable oxidation state

Abstract

A novel strategy to tweak the oxygen evolution activity of nanofilms by exploiting the film-substrate redox interaction.

Super‐Exchange Interaction Induced Overall Optimization in Ferromagnetic Perovskite Oxides Enables Ultrafast Water Oxidation

“…For example, one pioneering study conducted by Shao‐Horn group proposed a descriptor of the e g occupancy of the first‐row transition metal ions for OER activity; one derivative of parent perovskite SrCoO 3− δ (SC), Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3− δ with an optimal e g ≈ 1.2 exhibits high intrinsic activity toward OER and outperform that of the gold‐standard IrO 2 . Besides the e g orbital occupancy of transition‐metal ions, some parameters relevant to the bulk electronic structure were also proposed to influence the OER catalytic activity, including O 2p‐band center relative to Fermi level,7a average oxidation state, d electron number, and metal–oxygen covalency . Moreover, lattice‐oxygen in some highly covalent oxides was also reported to be OER active sites by the advanced in situ isotope labeling mass spectrometry techniques, which is different from the conventional mechanism concerning surface metal sites 7b.…”

Recent Advances in Novel Nanostructuring Methods of Perovskite Electrocatalysts for Energy‐Related Applications

“…Many parameters can affect the quality of the as‐obtained thin films, including target, reactive gas atmosphere, sputtering pressure, sputtering power, sputtering time, substrate, temperature of the substrate, distance between target and substrate, and post‐treatment condition. One recent example of using RF magnetron sputtering to prepare perovskite nanostructures is reported by Chen et al, where they fabricated a series of amorphous Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3− δ (BSCF) nanofilms on a Ni foil substrate with varying thicknesses by controlling the sputtering time of a dense BSCF disk target made from a sol–gel process …”

“…In this regard, PVD has been established as a simple and versatile technique to fabricate perovskite oxide nanofilms which can have implications for both fundamental understanding and scale‐up applications toward the water splitting. Recently, Chen et al used RF magnetron sputtering deposition, one of the most common PVD processes, to synthesize amorphous BSCF nanofilms on various substrates (e.g., NF and Ni foil) . By controlling the sputtering time, they altered the thickness of the BSCF‐Ni foil heterostructures.…”

“…c) Current–voltage profiles of two‐electrode water electrolyzers using electrodes made of amorphous BSCF nanofilms on Ni foam substrates and d) time‐dependent potential response during 10 h water electrolysis at 10 mA cm −2 geo using a two‐electrode configuration of 38.7 µg cm −2 BSCF‐Ni foam anode and 38.7 µg cm −2 Pt–Ni foam cathode in 1.0 m KOH electrolyte. Reproduced with permission . Copyright 2017, American Association for the Advancement of Science.…”

Rationally Designed Hierarchically Structured Tungsten Nitride and Nitrogen‐Rich Graphene‐Like Carbon Nanocomposite as Efficient Hydrogen Evolution Electrocatalyst

“…Nowadays, electrochemical water splitting for hydrogen has received tremendous attention considering its high theoretical efficiency, easy accessibility of water, and potentially high hydrogen production rate 1, 2. Water electrolysis involves oxygen evolution reaction over the anode and hydrogen evolution reaction (HER) over the cathode.…”