Enhanced AlkalineWater Electrolysis by the RationalDecoration of RuO_<i>x</i> with the In Situ-GrownCoFe Nanolayer

Rational engineering of the surfaces of heterogeneous catalysts (especially the surfaces of supported metals) can endow intriguing catalytic functionalities for electrochemical reactions. However, it often requires complicated steps, and even if it does not, breaking the trade-off between activity and stability is quite challenging. Herein, we present a strategy for reconstructing supported catalysts via in situ growth of metallic nanolayers from the perovskite oxide support. When Ru-coated LaFe_0.9Co_0.1O₃ is thermally reduced, the CoFe nanoalloy spontaneously migrates onto the Ru and greatly increases the physicochemical stability of Ru in alkaline water electrolysis. Benefiting from an 81% reduction in Ru dissolution after decoration, it operates for over 200 h without noticeable degradation. Furthermore, the underlying Ru modifies the electronic structure and surface adsorption properties of the CoFe overlayer toward reaction intermediates, synergistically catalyzing both the oxygen evolution reaction and the hydrogen evolution reaction. Specifically, the mass activity of the oxygen evolution reaction is 64.1 times greater than that of commercial RuO₂. Our work highlights a way to protect inherently unstable Ru from dissolution while allowing it to influence surface kinetics from the subsurface sites in heterogeneous catalysts.