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 (Pr 2 Ru 2 O 7 ) is presented here that greatly outperforms RuO 2 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, Pr 2 Ru 2 O 7 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 RuO 2, which would optimize the binding between the adsorbed oxygen species and catalytic metal sites and enhance the catalytic intrinsic activity.