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

To produce directly combustible hydrogen from water, highly active, acid-resistant, and economical catalysts for oxygen evolution reaction (OER) are needed. An electrocatalyst based on praseodymium ruthenate (Pr₂Ru₂O₇) is presented here that greatly outperforms RuO₂ for acid–water oxidation. Specifically, at 10 mA cm^–2, this electrocatalyst presents a low overpotential (η) of 213 mV and markedly superior stability. Moreover, Pr₂Ru₂O₇ presents a significant rise in turnover frequency (TOF) and a highly intrinsic mass activity of 1618.8 A g_Ru^–1 (η = 300 mV), exceeding the most commonly reported acid OER catalysts. Density functional theory calculations and electronic structure study demonstrate that the Ru 4d-band center related to the longer Ru–O bond with a large radius of Pr ion in this pyrochlore is lower than that in RuO₂, which would optimize the binding between the adsorbed oxygen species and catalytic metal sites and enhance the catalytic intrinsic activity.