Mitigation of RuO₆ octahedron distortion by enhanced A-site electronegativity in pyrochlore for acidic water oxidation

Abstract

Ruthenium-based pyrochlore oxides (A2Ru2O7) have emerged recently as state-of-the-art catalysts for acidic water oxidation, however, the stability still needs to be further improved. Exploring the relationship between the A-site cation...

Highly Active Pyrochlore-Type Praseodymium Ruthenate Electrocatalyst for Efficient Acid–Water Oxidation

“…10 At 10 mA cm −2 , Ho 2 Ru 2 O 7 catalyst shows an effective OER performance with an overpotential of 280 mV. 17 Meanwhile, the pyrochlore-type Y 1.7 Sr 0.3 Ru 2 O 7 18 and Nd 2 Ru 2 O 7 19 catalysts also show similar promotions. The pyrochlore oxides have a general formula of A 2 B 2 O 7 (here, A = alkaline or rare earth element; B = Ti, Ru, Sn, or Ir).…”

“…Due to its robustness and long-term endurance, iridium (Ir) and its oxides are commonly used as commercial anode catalysts for PEM water electrolyzers. – On the other hand, as Ir is an exceptionally rare element with a greatly increased price in recent years, ruthenium (Ru) is considerably less expensive than it . Meanwhile, some Ru-based oxides have shown better performance in the OER than Ir-based catalysts. ,– The low intrinsic activity of the reported Ru-based oxides, however, significantly reduced their catalytic efficiency. Therefore, developing novel effective Ru-based catalysts with lower noble metal concentrations and better intrinsic activity is still an open issue for acid–water oxidation.…”

High entropy stabilizing lattice oxygen participation of Ru- based oxides in acidic water oxidation

“…2c and S6,† in the O 1s spectrum, the binding energies of adventitious oxygen (O adv ), oxygen vacancies (O V ), surface oxygen (O suf ) and lattice oxygen (O L ) are in descending order. 29 There is an overlap between the signal peaks of C 1s and Ru 3d (Fig. S7a†), and the valence state of Ru is further observed from the Ru 3p orbit.…”

“…The oxygen isotopes, 34 O 2 and 36 O 2 , released from the lattice oxygen-engaged OER were measured with 18 O labelled catalyst RuNiMoCrFeO x /CNT ( 34 O 2 comes from 18 O in the lattice with 16 O). 16,29,55 It is indicated that lattice oxygen is involved in the reaction and that the OER tends to proceed through the LOM. Further, in situ FTIR (Fig.…”

“…28 The second one is to modulate the electronic structure of RuO 2 by heteroatom doping, which can improve the oxygen vacancy formation energy and enhance the durability of the catalyst. 23,29,30 Third, inhibiting the lattice oxygen from participating in the reaction, thus preventing the catalyst from dissolving. 16 All the above strategies are based on the adsorbent evolution mechanism (AEM) to regulate the stability.…”