Efficient oxygen evolution electrocatalysis in acid by a perovskite with face-sharing IrO6 octahedral dimers

Abstract

The widespread use of proton exchange membrane water electrolysis requires the development of more efficient electrocatalysts containing reduced amounts of expensive iridium for the oxygen evolution reaction (OER). Here we present the identification of 6H-phase SrIrO3 perovskite (6H-SrIrO3) as a highly active electrocatalyst with good structural and catalytic stability for OER in acid. 6H-SrIrO3 contains 27.1 wt% less iridium than IrO2, but its iridium mass activity is about 7 times higher than IrO2, a benchmark electrocatalyst for the acidic OER. 6H-SrIrO3 is the most active catalytic material for OER among the iridium-based oxides reported recently, based on its highest iridium mass activity. Theoretical calculations indicate that the existence of face-sharing octahedral dimers is mainly responsible for the superior activity of 6H-SrIrO3 thanks to the weakened surface Ir-O binding that facilitates the potential-determining step involved in the OER (i.e., O* + H2O → HOO* + H+ + e¯).

Iridium‐Chromium Oxide Nanowires as Highly Performed OER Catalysts in Acidic Media

“…The existing strategies can be classified into three major categories: (1) the introduction of specific components to generate composites, including those containing conductive and acid‐resistant materials as supports, alloys with nonprecious metals (Ni, Co, Cu, etc. ), core‐shell structures and various mixed metal oxide composites; (2) controlling special morphologies to create and expose additional active sites, such as two‐dimensional catalysts featuring ultrathin sheets, needles, or nanowires or three‐dimensional structures featuring abundant mesopores; (3) the formation of particular structures including amorphous IrO x , SrIrO 3 perovskite, SrTi 0.67 Ir 0.33 O 3 perovskite, Y 2 Ir 2 O 7 pyrochlore and Y 2 Ru 2 O 7‐δ pyrochlore . Despite these advances, the overpotential at 10 mA cm −2 is generally ∼300 mV and the catalysts are typically stable for less than 10 h. Their catalytic activity and stability can be even worse when Ir contents are reduced.…”

Ultrafine Defective RuO2 Electrocatayst Integrated on Carbon Cloth for Robust Water Oxidation in Acidic Media

“…However, the efficiency of such device is limited by high Ohmic resistance of alkaline electrolyte and low operating pressure. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Compared with iridium oxides, ruthenium oxides possess higher OER activity and lower cost, but lower stability. Unfortunately, the widespread application of PEM electrocatalysis is restricted by the lack of efficient and durable electrocatalysts for oxygen evolution reaction (OER) in acidic media.…”

Building Electron/Proton Nanohighways for Full Utilization of Water Splitting Catalysts

“…For water electrolysis, the equilibrium potential at room temperature is 1.23 V. [ 33 ] The formation and decomposition of intermediates on the surface‐active site in Equations (S11)–(S15) results in one to tens of nanometers‐thick electrical double layer (EDL) and a typical oxidation activation overpotential of ≈0.2 V to overcome the buildup of charges. [ 34 ] Thus, the OER on the CL depends on the following: 1) the local potential should be larger than the critical potential (≈1.43 V) to overcome the barrier of the OER; 2) the proton associated with the formation of intermediates (M‐OH, M‐OOH and M‐O, M‐O 2 ) will accumulate on the catalyst surface, which lead to the proton mass gradient and increased OER overpotential, so proton must be drawn from the reaction sites easily.…”