Emerging trends in metal oxide electrocatalysis: Bifunctional oxygen catalysis, synergies and new insights from in situ studies

Abstract

Metal oxide electrocatalysts with minimal or no reliance on precious metals can display outstanding activity in oxygen catalysis and thus hold promise as materials for sustainable energy storage/conversion technologies. We review recent progress in the preparation of oxides for bifunctional oxygen reduction/evolution applications (ORR/OER) and include a summary of benchmark performances achieved over the past 3 years. Parallel and complementary progress on development of activity descriptors for the OER in oxides is also covered; special attention is dedicated to synergistic effects and the importance of support choice and oxide/support interactions to maximize activity and ensure stability. Finally, exciting mechanistic insights on OER and bifunctional ORR/OER oxide catalysis gained from recent in situ and operando X-ray experiments from the recent literature are discussed.

Investigation of mixed-metal (oxy)fluorides as a new class of water oxidation electrocatalysts

“…We point the interested reader to several recent reviews and perspectives on metal-oxide OER catalysts. [12][13][14][15][16][17] The utilization of inductive effects in electrocatalysis is an effective method to modulate materials' performance. [18][19][20] Substitution with metals having different electronegativity will induce the tendency to donate or withdraw electron density.…”

Electrodeposition at Highly Negative Potentials of an Iron‐Cobalt Oxide Catalyst for Use in Electrochemical Water Splitting

“…Recently there has been a focus on developing so called bifunctional materials for overall electrochemical water splitting where the material is active for both the OER and the HER . However, it must be noted that structural changes occur during the OER and therefore the pristine as deposited material is investigated for the HER and not one which was subjected to the OER.…”

“…[57] Recently there has been a focus on developing so called bifunctional materials for overall electrochemical water splitting where the material is active for both the OER and the HER. [74][75][76][77] However, it must be noted that structural changes occur during the OER [78] and therefore the pristine as deposited material is investigated for the HER and not one which was subjected to the OER. In this context any bifunctional behaviour is related to the pristine material being active towards two reactions and not one that can be cycled between both reactions as discussed recently.…”

Photon-Induced, Timescale, and Electrode Effects Critical for the in Situ X-ray Spectroscopic Analysis of Electrocatalysts: The Water Oxidation Case

“…An X-ray absorption spectroelectrochemical cell (SEC)the device utilized for in situ studiesshould provide high quality XAS without compromising the electrochemical data. Many SECs have been designed and used for in situ experimentation, ,,,,,− although a number of designs suffer from insufficiently high signal-to-noise ratios. Spectroscopic data particularly experiences low signal-to-noise when the sample loading on the electrode is not high.…”